GEUS Bulletin 9, Scientific results from Lopra-1, pp. 123-156

123

The regional distribution of zeolites in the basalts of the
Faroe Islands and the significance of zeolites as palaeo-
temperature indicators

Ole Jørgensen

The first maps of the regional distribution of zeolites in the Palaeogene basalt plateau of the Faroe
Islands are presented. The zeolite zones (thomsonite-chabazite, analcite, mesolite, stilbite-heulandite,
laumontite) continue below sea level and reach a depth of 2200 m in the Lopra-1/1A well. Below this
level, a high temperature zone occurs characterised by prehnite and pumpellyite. The stilbite-heulan-
dite zone is the dominant mineral zone on the northern island, Vágar, the analcite and mesolite zones
are the dominant ones on the southern islands of Sandoy and Suðuroy and the thomsonite-chabazite
zone is dominant on the two northeastern islands of Viðoy and Borðoy. It is estimated that zeolitisa-
tion of the basalts took place at temperatures between about 40°C and 230°C. Palaeogeothermal
gradients are estimated to have been 66 ± 9°C/km in the lower basalt formation of the Lopra area of
Suðuroy, the southernmost island, 63 ± 8°C/km in the middle basalt formation on the northernmost
island of Vágar and 56 ± 7°C/km in the upper basalt formation on the central island of Sandoy.

A linear extrapolation of the gradient from the Lopra area places the palaeosurface of the basalt

plateau near to the top of the lower basalt formation. On Vágar, the palaeosurface was somewhere
between 1700 m and 2020 m above the lower formation while the palaeosurface on Sandoy was
between 1550 m and 1924 m above the base of the upper formation.

The overall distribution of zeolites reflects primarily variations in the maximum depth of burial of

the basalt rather than differences in heat flow. The inferred thinning of the middle and upper basalt
formation from the central to the southern part of the Faroes is in general agreement with a northerly
source area for these basalts, centred around the rift between the Faroes and Greenland. The regional
zeolite distribution pattern is affected by local perturbations of the mineral zone boundaries that
reflect local differences in the temperature, perhaps related to the circulation of water in the under-
ground. The zonal distribution pattern suggests that these temperature anomalies are in part related
to NW-SE-trending eruption fissures or zones of weakness separating the present islands and are
subparallel to transfer zones in the Faroe-Shetland Basin. Both the regional and the local distribution
of zeolite assemblages are probably a reflection of the basic volcanic-tectonic pattern of the Faroe
Islands.

Keywords : Faroe Islands, Palaeogene basalt plateau, zeolite zone, palaeotemperature indicators

_____________________________________________________________________________________________________________________________________________________________________________________

O.J., Scandinavian Asbestos & Mineral Analysis, Kildeskovsvej 62, DK-2820 Gentofte, Denmark. E-mail: Oj@oj-sama.dk

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The zeolites of the Faroe Islands have been known for more
than 300 years (Debes 1673) although the islands remained

nearly unknown to mineralogists until the end of the eigh-
teenth century. Because of increasing interest in mineralo-

gy in the nineteenth century, the Faroe Islands were visit-
ed by many naturalists. One of these was Brewster (1825),
who proposed the name levyne for a new zeolite species
he discovered at Dalsnípa on Sandoy. The first modern
description of the distribution of Faroese minerals was
published by Currie (1905), who visited the Faroe Islands
and described the minerals at 120 localities. Five years
later a new description of the Faroese zeolites was presen-
ted by Görgey (1910). Interest in the minerals of the Faroe
Islands declined during the following 70 years until Betz
(1981) visited the islands and reviewed the classic locali-
ties. The present author started a literature study to dis-
cover, if a system of zeolite zones exists on the Faroe Is-
lands similar to that described by Walker (1960) in East
Iceland, but concluded that published descriptions were
based on minerals from the same set of localities that were
known to be rich in mineral species and where large cry-
stals could be collected. This sampling bias meant that it
was not possible to decide if zeolite zones existed on the
Faroe Islands, so in 1979 a systematic mapping of the zeo-
lites in the Faroe Islands was initiated by the present au-
thor. During the following 20 years, more than 800 local-
ities were visited and about 3000 rock samples were inves-
tigated in the field and in the laboratory. The work was
extended by studying samples from the Vestmanna-1 and
Lopra-1 boreholes drilled in 1980 and 1981, respectively
(Jørgensen 1984; Waagstein et al. 1984). In 1996, the
Lopra-1 borehole was deepened to a total of 3565 m (Lo-
pra-1/1A) and the secondary minerals in the deepened part
of the Lopra well were also described by the present au-
thor (Jørgensen 1997).

The aim of the present paper is to describe the second-

ary mineral distribution in the exposed parts of the Faroe
Islands and in the Lopra-1/1A and Vestmanna-1 wells.
The results of the mapping are used to estimate the palaeo-
geothermal gradients and the altitudes of the palaeosur-
faces at various places in the Faroes basalt succession. The
following topics will be discussed: (1) the general condi-
tions for the use of zeolites as palaeotemperature indica-
tors and the statistical distribution of zeolites in a vertical
profile, (2) the original thickness of the three basalt for-
mations and the volcanic evolution of the Faroese basalt
complex, and (3) the regional distribution of the zeolite
zones as a function of the thicknesses of the middle and
the upper basalt formations.

Outline of the geology of the Faroe
Islands

The Faroe Islands (62°N, 7°W) have a total area of 1400
km

, an average height of 300 m above sea level and form

part of the North Atlantic Brito-Arctic Cenozoic Igneous
Province that extends from the British Isles to Greenland.
The Faroe Islands consist almost exclusively of flood ba-
salts that were erupted about 59-55 Ma (Waagstein 1988;
Larsen et al. 1999).

The basalts on the exposed part of the Faroe Islands are

divided into a lower , a middle and an upper basalt forma-
tion , separated by two horizons termed A and C in Fig. 1

(see alsa Fig. 4). According to Rasmussen & Noe-Nygaard
(1969, 1970) the volcanic evolution of the Faroe Islands
may be summarised as follows: Volcanic activity started
west of the present islands with the eruption of the lower
basalt formation . With time the production rate of lava
slowed to a temporary standstill. During this quiet peri-
od, about 10 m of clay and coal bearing sediments were
deposited (the A-horizon .). Volcanic activity restarted with
an explosive phase, resulting in the deposition of coarse
volcanic ash and agglomerates. An effusive phase followed
during which the middle basalt formation was erupted from

Sandoy

Nólsoy

Skúvoy

Stóra Dímun

Lítla Dímun

Streymoy

Kallsoy

Viðoy

Fugloy

Borðoy

Svinoy

Eysturoy

62°00'N

7°00'W

20 km

Koltur

Hestur

Vágar

Mykines

Upper basalt formation
Middle basalt formation
Lower basalt formation
Irregular instrusive
bodies and sills
Coal-bearing sequence
Dykes

Suðuroy

Fig. 1. Geological map of the Faroe Islands. From Rasmussen &
Noe-Nygaard (1969).

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125

several vents and small fissures within the present group
of islands. Finally, volcanic activity moved farther east,

away from the present islands, causing the lava flows of
the upper basalt formation to transgress the middle basalt
formation from the east. The discordant surface between
the middle and upper basalt formations is named the C-
horizon . After the upper basalt formation was formed, the
basalt plateau was intruded by dykes and sills. Large sills
were intruded near the boundary between middle and
upper basalt formations in Streymoy and Eysturoy. Tec-
tonic activity continued long after the volcanism ended
until the Faroese basalt pile acquired its present gentle
easterly dip.

Methodology

Sampling and mineral identification

Renewal of a large part of the road system of the Faroes
just before initiation of the fieldwork made it possible to
collect samples in fresh road cuts and new quarries along
the roads. After most of the road sites had been examined,
the mountains were traversed and samples collected along

the old paths between the villages. In addition to the sam-
ples collected by the author, the present investigation is
based on 500 specimens of Faroese zeolites collected pri-
vately by K. Jørgensen and on the collection of Faroese zeo-

lites in the Geological Museum, Copenhagen.

The minerals were identified by their crystal morpho-

logy, optical properties, and X-Ray Diffraction (XRD) pat-
terns or by chemical analysis carried out on a scanning
electron microscope equipped with an energy dispersive
analytical system. The XRD reference patterns were taken
from Gottardi & Galli (1985).

Mapping of the mineral zones

Walker (1960, 1970) defined his zeolite zones by seven
distinctive amygdale mineral assemblages. Each zone was

Fig. 2. Mineral temperature scale. The five zeolite zones are defined by the index minerals chabasite + thomsonite, analcite, mesolite,
stilbite + heulandite and laumontite. The temperatures are shown at zone boundaries. Abbreviations used for the various minerals are
shown in Table 1.

An: analcite
Ap: apophyllite
Ca: calcite
Ce: celadonite
Ch: chabasite
Cl: chlorite
Cld: chalcedony
Ed: epidote
Ep: epistilbite
Ga: garronite
Gi: gismondine
Gy: gyrolite
Ha: harmotom
He: heulandite
La: laumontite

Table 1. Abbreviations used

for mineral names

Le: levyne
Me: mesolite: solid
Me*: mesolite: hair-like
Mo: mordenite
Na: natrolite
Ok: okemite
Op: opal
Ph: phillipsite
Pr: prehnite
Pu: pumpellyite
Qz: quartz
Sc: scolecite
Sm: smectites
St*: stellerite

Source: Kristmannsdóttir & Tómasson (1978), Kristmannsdóttir (1982) and Jakobsson & Moore (1986)

Mineral

zones

Approx.

temperatures

in °C

Ch Th* Th An Me* Ph Le Me Gy Mo St He Ep Ap La Pr Pu Ed Cl Ce Sm Qz Cld Op Ca

Zeolite free zone 40-60

High temperature zone > 300

Laumontite 190-230

Stilbite-heullandite 110-130

Mesolite 90-100

Analcite

Chabazite-thomsonite 50-70

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126

defined by the presence or dominance of certain mineral
species, termed index minerals, whose names are used to
designate the zones. In addition to the index minerals,
other minerals may be present as indicated in Fig. 2. Walk-
er's (1960) original zones are the carbonate, chabazite-
thomsonite, analcite, mesolite, laumontite, prehnite and
epidote zones. The original mesolite zone was later subdi-
vided into a mesolite and a stilbite-heulandite zone. This
extended zone definition was adopted in the present inves-

tigation (Fig. 2). The classification of the zeolite zones
was normally based on the mineral assemblages of amyg-
dales, and fracture fillings were used only in places with-
out amygdales.

Classification of the mineral assemblages from samples

from the Lopra-1/1A and Vestmanna-1 boreholes was
originally based on the abundance of the individual index
minerals expressed as the weight% of the total mass of
index minerals (Jørgensen 1984). In the present investi-
gation, which is based on about 3000 samples, quantita-

tive analysis was carried out only on two selected mineral
assemblages, one from the middle and one from the up-
per basalt formation. The assemblages from most locali-
ties consist of a large number of minerals which makes it
difficult to estimate the relative abundance of the differ-
ent minerals. Another complication was the fact that more
than one index mineral often occurred at the same local-
ity. The present investigation is therefore based on the first
formed index minerals in the amygdales, i.e. the minerals
that were deposited nearest to the host rock . Where more
than one first formed index mineral was present at a lo-
cality, the index mineral assumed to have the highest tem-
perature of formation was chosen to map the zones. The
mineral zones mapped in this way thus reflect the maxi-
mum temperature of mineralisation . This method is differ-
ent from a mapping based on abundance of the minerals,
which shows the distribution of the zeolite zones as the
result of the main mineralisation. Appendices A and B
give the observed paragenesis in the 29 sections and two

Table 2. Relative frequency (in %) of amygdales and mineralised fractures in

the exposed part of the Faroe Islands

Mineral

Zeolites:
Analcite
Chabazite
Cowlesite
Epistilbite
Garronite
Gismondine
Heulandite
Laumontite
Levyne
Mesolite
Mordenite
Natrolite
Scolecite
Stellerite
Stilbite
Phillipsite
Thomsonite

Other minerals:
Apophyllite
Calcite
Celadonite
Chlorite
CSH
Gyrolite
Smectites
Silica minerals

Visited localities

4
4

8
4
1

45
37

15
36
19

8
2

18
19

61
61

7
0
8
0

5
5

12
10

24
37
17
59

12
37
15

5
7
7

160

0
0
0

3
0
3
3
6

0
3
6
0

29
23

9
0

29
34

3
3

148

0
0
8
5

29
20

8
0
0

20
38

20
43
38
23

28
23

302

2
0
8
8

5
3

27
32
27

29
26
19

235

0
0
0
3

5
8

0
3
0
6

5
0
0

16
25

0
0
0
0

20
50

0
0
0
9

32
15

15
21

Abundant minerals in bold face , common minerals in italics and rare minerals in normal type
face. CSH is calcium silicate hydrates. Silica minerals are opal, chalcedony etc.

Average

Vágar

Suðuroy Sandoy Streymoy Eysturoy Borðoy Viðoy

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127

wells mapped. The most probable temperature range of
deposition of the zeolite zones is indicated in Fig. 2.

The rules of zone classification stated above could not

be followed strictly everywhere. In the southern part of
Suðuroy, mineralised vesicles are rare and, in this area, the
mapping had to be based mainly on mineralised fractures.
In the Lopra-1/1A borehole, the study was based on cut-
tings. They included fragments of amygdales and miner-
alised fractures, and the first formed index mineral could

be determined only when part of the host rock adhered to
the sample.

In order to establish a correlation between the zeolite

zones and the temperature of formation of the minerals,
the vertical distribution of index minerals and tempera-
tures was examined in a number of boreholes in the geo-
thermal areas of Iceland (Kristmannsdóttir & Tómasson
1978; Kristmannsdóttir 1982). The result was the mine-
ral-temperature scale shown in Fig. 2. Examination showed

that the temperatures at the boundaries of individual zeo-
lite zones varied from place to place. This is probably
caused by the fact that zeolites can be formed within a
broad range of temperatures and that variations in the
chemical composition of the rock and the hydrothermal
solutions can affect the formation temperature of the zeo-
lites

(Barth-Wirsching

Höller

1989;

Breck

1974).

An-

other problem that makes it difficult to determine accu-
rately the palaeotemperatures at the zone boundaries is
the fact that zone boundaries are not well defined lines, a
problem that will be discussed below. The temperatures
at the boundaries of the zeolite zones are therefore indi-
cated in Fig. 2 at the lowest and highest temperatures that
occur at the Icelandic zone boundaries.

As mentioned above, the original classification of the

mineral assemblages of the Lopra-1/1A and Vestmanna-1
drillholes was based on the most abundant index zeolite.
It was therefore necessary to re-classify the mineral assem-
blages of the two drillholes according to the method used
in the present investigation. This had a rather small effect
on the zonation of the Lopra-1/1A drillhole. However,
the first formed minerals from the Vestmanna-1 borehole
are overgrown by abundant chabazite and thomsonite.
Neglecting these later deposits, changes the zonation from
a simple chabazite-thomsonite zone to an alternation be-
tween the mesolite and stilbite-heulandite zones.

The distribution of minerals, zones and
temperatures

Frequency of occurrence of minerals

Table 2 shows the 17 zeolites and 8 associated minerals
that were recorded in amygdales and mineralised fractures
of the basalt in the islands of Suðuroy, Sandoy, Vágar,
Streymoy, Eysturoy, Borðoy and Viðoy. In addition to the
minerals listed, prehnite, pumpellyite, native copper and
pyrite were found in the Lopra-1/1A borehole. All the
zeolites listed in Table 2 have been reported previously
from the Faroe Islands with the exception of garronite,

CH
TE
LE
PH

AP
Gy
CL
CA

ME
ST
HE
LA
AN

SU SA VA ST EY BO VI

Relativ

e fr

eque

cy as % of localities

Relativ

e fr

eque

cy as % of localities

Relativ

e fr

eque

cy as % of localities

100

Fig. 3. Variation diagrams of the relative frequency of minerals on
Suðuroy (SU), Sandoy (SA), Vágar (VÁ), Streymoy (ST), Eysturoy
(EY), Borðoy (BO) and Viðoy (VI). Contractions for zeolite names
are listed in Table 1.

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128

3500

3000

2500

2000

1500

1000

500

upper

basalt f

atio

dle

basalt f

atio

basalt f

atio

SU 1

SU 2

SU 3

SU 9

est

a
nn

a-1w

ell

ST 6W

ST 6E

SA 5

ST 10

SA 1

SA 3

EY 1

EY 2

EY 3

EY 4

EY 8

EY 10

BO 1

BO 2

BO 3

VI 1

VI 2

ST 2W

ST 2E

TH-CH zone

AN zone

ME zone

ST-HE zone

Altitude of profile

VI 3

Fig. 4. Stratigraphic location of the zeolite
zones in the 28 sections through the
exposed part of the Faroe Islands. The data
shown here are tabulated in Table 3.

which was found for the first time at several localities dur-
ing the mapping reported here.

The minerals in Table 2 were divided into three classes:

(1) very frequent minerals that occur at 60% or more of
the localities; (2) common minerals that occur at between
15% and 60% of the localities; (3) rare minerals that oc-
cur at less than 15% of the localities. The frequency of
occurrence is given as percentages of localities examined
on each island.

From the column named average in Table 2, it is seen

that chabazite, mesolite and thomsonite are the most fre-
quent secondary minerals within the exposed part of the
Faroe Islands, followed by stilbite, stellerite, heulandite,
analcite and calcite. Epistilbite and scolecite are rare min-
erals in the exposed part of the Faroe Islands, but they are
common in the Lopra-1/1A well.

Regional distribution of minerals and
zones

Fig. 3 shows how the relative frequency of a number of
index minerals and associated minerals varies from island
to island. For most of the minerals, the relative frequency
decreases from south to north and from west to east, but
for the minerals of the analcite and the chabazite-thom-
sonite zone, the relative frequency increases in the direc-
tion of Viðoy (Fig. 1). The variation in relative frequency
of minerals reflects the regional shift in the distribution
of mineral zones. The analcite and mesolite zones are the

dominant

mineral

zones

Suðuroy.

From

Sandoy

Vá-

gar, the analcite zone is gradually replaced by a stilbite-
heulandite zone that becomes widespread on Vágar. On
Streymoy and Eysturoy the stilbite-heulandite zone has a
less widespread distribution, so that the stilbite-heulan-
dite and the mesolite zones are of equal importance. The
areal extent of the mesolite and stilbite-heulandite zones
is further reduced on Borðoy and Viðoy, so the chabazite-
thomsonite zone becomes the major one on these two is-
lands.

Description of mineral assemblages and zones

Figures 5-11 show the geographic distribution of the
mineral zones on the islands Suðuroy, Sandoy, Vágar, Strey-
moy, Borðoy and Viðoy. In order to show the vertical dis-
tribution of the mineral zones, 28 local sections were con-
structed that are also shown on Figs 5-11. The sections
have been arranged such that it is possible to follow the
changes in the mineral zones both geographically and
stratigraphically (Fig. 4). The data on which the sections
are based are shown in Appendices A and B, and Table 3
gives the thickness of each zone.

In contrast to the profiles drilled by the Lopra-1/1A

and Vestmanna-1 boreholes, the profiles from the exposed
part of the Faroes have been constructed from observa-
tions along each section line, so the sections do not repre-
sent a single vertical profile through the lava pile.

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129

Suðuroy (Fig. 5)

The distribution of the secondary minerals on Suðuroy is
remarkably heterogeneous, a feature noted by Currie
(1905). To the north of section SU2 that extends across
the island from Fámjin to Holmssund, nearly all vesicles
and fractures of the basalts are mineralised, but to the
south of the section, amygdales and mineralised fractures
are rare.

The boundary (section SU2) between the two parts of

Suðuroy forms a transition zone in which the scattered
vesicles are partly mineralised by an analcite assemblage
composed of hair-like mesolite, thomsonite, analcite,
chabazite, calcite, quartz and chalcedony. This mineral
assemblage is found all along section SU2, which means
that no relationship exists between the secondary miner-
als and their stratigraphic position within the lava pile.

To the north of section SU2, the number of mineral

species and the degree of mineralisation increases gradu-

ally northwards and the area just north of Trongisvágs-
fjørður is in the mesolite zone. Despite apparent regular-
ity, the northern part of Suðuroy is a mosaic of small areas
in which the mineral assemblages vary from place to place.
The largest area of this kind occurs around the summit of
Gluggarnir (443 m). At this locality, nearly all minerals
listed in Table 2 are present.

The southern part of the island is partly devoid of zeo-

lites. The most abundant minerals are quartz, calcite and
chalcedony, while mesolite, thomsonite, chabazite, anal-
cite, heulandite and stilbite are less frequent. The mode
of mineralisation is also different on the two parts of the
island. On the northern part of Suðuroy, mineralised frac-
tures and vesicles occur in equal numbers, whereas min-
eralised fractures are more common than amygdales on
the southern part of the island, in spite of the fact that
empty vesicles occur at many localities. Because of this,
section SU1 is based mainly on mineralised fractures.

Despite the weak amount of mineralisation on south-

SU1+LO
SU2
SU5
SU9
VÁ1
VÁ4
VÁ7
ST2W
ST2E
Vestmanna-1
ST6W
ST6E
ST10
SA1
SA3
SA5
EY1
EY2
EY3
EY4
EY8
EY10
BO1
BO2
BO3
VI1
VI2
VI3

330
798
970
842

1241
1424
1461
1461

795

1799
1799
2344
2252
2545
2594
1831
1650
1745
2039
2080
2098
2084
2263
2091
2237
2140
2188

_
_
_
_

350
250
219

100
400
125

_
_

166

_
_
_
_
_
_
_
_
_
_

530

480
373
300
180
463
325
272
200
385
500
340

200
280
270
350
300
230
300
180
503
310
150
100

180
430

_
_
_
_
_

82
50

20
83

_
_

200
116

125
195
170
190
200

182
190
190
208
200

_
_
_
_
_
_
_

293
200

_
_
_
_
_

_
_
_

193
149
187

415
251
375
400

Table 3. Stratigraphic position and thickness of mineral zones (see Fig. 4)

ME zone

Thickness

in metres

CH-TH zone

Thickness

in metres

ST-HE zone

Thickness

in metres

Stratigraphic height within the exposed lava pile of the Faroe Islands.

The mesolite zone is composed of the upper 330 m of the Lopra-1 mesolite zone plus

the 200 m thick mesolite zone of section SU1.

Base level

Stratigraphic

height in m

Section

AN zone

Thickness

in metres

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131

Thomsonite-chabasite zone

Analcite zone

Mesolite-scolecite zone

Stilbite-heulandite zone

Laumontite zone

Empty vesicles

SKOPUN

SANDUR

SKÀLAVIK

HUSÀVIK

Dalsnipa

Stórafjall

Hálsur

Skarvanes

Tyrilsválur

SØLTUVIK

Sandsvatn

Pætursfjall

DALUR

SA1

SA3

SA5

1.3°

500

400

300

200

100

Metr

es abo

v
e sea le

v
el

TH-CH zone

AN zone

ME zone

ST-HE zone

Sandoy

7°00'W

62°00'N

7°00'W

20 km

SA5

SA1

SA3

5 km

ern Suðuroy, a clear zonation can nevertheless be discerned
along section SU1, where a 200 m mesolite zone is over-
lain by a 180 m analcite zone. The mesolite zone contin-
ues to a depth of 600 m below sea level in the Lopra-1/1A
borehole (Fig. 5). The most abundant minerals there are
mesolite, scolecite, stilbite, heulandite and mordenite.
Chlorite, mesolite and scolecite were deposited first. Me-
solite and scolecite are replaced by laumontite as the first
formed mineral at a depth of -626 m, indicating the top
of the stilbite-heulandite zone. At about -1200 m, epis-

tilbite replaces stilbite as the first formed mineral so that
the order of deposition becomes celadonite/chlorite-epis-
tilbite-thomsonite-laumontite or celadonite/chlorite-epis-
tilbite-laumontite-stilbite. Since an epistilbite zone has not
yet been defined elsewhere, it was decided to include the
total interval between -1200 m and -2200 m depth in
the laumontite zone. A high temperature assemblage of
laumonite, mordenite-prehnite, pumpellyite, chlorite,
calcite and quartz is found from about -2200 m to the
bottom of the Lopra-1A borehole at -3534 m.

Fig. 6. Distribution of zeolite zones on Sandoy
and on sections SA1, SA3 and SA5. The arrow
indicates the apparent dip of the zeolite zones
on section SA3.

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131

132

800

600

400

200

ME zone
ST-HE zone

Thomsonite-chabasite zone

Analcite zone

Mesolite-scolecite zone

Stilbite-heulandite zone

Laumontite zone

Empty vesicles

e
t
r
e
s

a
b
o
v
e

s
e
a

l
e
v
e
l

Eysturtindur

Akranesskarð

VESTMAN

NASUND

Hestfalsgjøgv

Oyragjøgv

VÁ4

VÁ1

VÁ7

Kvigandal

sá

eið

Malinstindur

Sandavágur

Midvágur

SØRVÁGUR

Høgafjall

SØRVÁGASFJØRDUR

Reyða-

stiggjatagi

Rógvukollur

Skjatlá

4°

Vágar

7°00'W

62°00'N

7°00'W

20 km

5 km

VÀ1 VÀ4 VÀ7

The uppermost mineral zone preserved in the SU1 sec-

tion is part of an analcite zone. In East Iceland, a chabazite-
thomsonite zone (Walker 1960) and in East Greenland a
zeolite free zone (Neuhoff et al. 1997) has been recorded
in the uppermost parts of the basalt complexes whose to-
tal thicknesses are 700 m and 1400 m, respectively. If equi-
valent zones have ever existed on the southern part of Su-
ðuroy, they must have been considerably thinner than those
on Iceland and Greenland, because the palaeosurface of
the lower basalt formation was about 300 m above the A-
horizon (see below).

Sandoy (Fig. 6)

The southern part of Sandoy is strongly mineralised while
the mineralisation in the northern part is weak. The area
north of a line from Søltuvík to Skálavík is weakly miner-
alised by quartz, calcite, chalcedony, chabazite, hair-like
mesolite, thomsonite and late formed stilbite or stellerite.
Nearly all fractures and vesicles are totally mineralised to
the south of the line. The most abundant zeolites are anal-
cite, chabazite, heulandite, mesolite, stilbite and thom-
sonite. No distinct boundary has been observed between
the northern and the southern part of the island.

Sections SA1, SA3 and SA5 (Fig. 6) show that four

Fig. 7. Distribution of zeolite zones on
Vágar and on sections VÁ1, VÁ4 and
VÁ7. The dip and strike of the zeolite
zones is indicated on the map.

GEUS Bulletin no 9 - 7 juli.pmd

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132

133

zeolite zones exist on Sandoy. In the area between Sandur
and Søltuvik, the uppermost 50 m of a stilbite-heulandite
zone are exposed. The stilbite-heulandite assemblage con-
sists of chlorite, heulandite, stilbite, mordenite and occa-
sionally of laumontite and apophyllite. The latter two
minerals occur mostly in fractures in the basalt.

However, the degree of mineralisation is low in the

stilbite-heulandite zone and, by volume, only half of the
vesicles are mineralised.

The southern and the eastern parts of Sandoy are domi-

nated by a mesolite zone. The most abundant minerals
are chabazite, heulandite, mesolite (solid or hair-like), stel-
lerite, thomsonite and calcite together with minor gyro-
lite, gismondine and levyne. Heulandite and mesolite are
the first deposited minerals. Dalsnípa at the south-east
coast of Sandoy is the type locality of levyne (Brewster
1825). A detailed quantitative analysis of the mineral as-
semblage and the zeolite zones in section SA3 is given
below.

Vágar (Fig. 7)

In contrast to Suðuroy and Sandoy, Vágar is totally mine-
ralised and the island may be divided into two areas. North-
east of a line from Sørvágur to Sandavágur, a stilbite-heu-
landite assemblage occurs at 40% of the localities that has
not been observed farther south. South-east of the boun-
dary line, the localities are dominated by a mesolite and
analcite assemblage. Around Miðvágur hair-like mesolite
with up to 100 mm long crystal needles can be found in
larger fractures and cavities in the basalt.

The distribution pattern of the mineral assemblages on

Vágar is controlled by the rise of the stilbite-heulandite
zone towards the north-east. A calculation shows that the
stilbite-heulandite zone dips from between 1-3°SSW to
0.6°ESE, while the basalt flows dip 3-4°ESE, i.e. the mine-
ral zones are discordant to the lava stratification.

A quantitative analysis of the mineral assemblage and

the zeolite zones on section VÁ1 is given below.

Streymoy (Fig. 8)

Streymoy can be divided into a northern, a central and a
southern area. A stilbite-heulandite assemblage occurs
along the coast from Tjørnuvík to Langasandur in the
north. The observed minerals are stilbite, heulandite,
thomsonite, compact mesolite, laumontite, gyrolite, oken-
ite, tobermorite, apophyllite, celadonite and smectite. The
mineral assemblage in the amygdales changes gradually

towards the west. The hydrated calcium silicates, stilbite
and laumontite, disappear from the amygdales although
they still occur in fractures in the basalt. At Saksun near
the north-west coast, the stilbite-heulandite assemblage is
replaced by a mesolite assemblage, characterised by solid
mesolite, thomsonite, heulandite, chabazite, calcite and
montmorillionite. Gyrolite and stilbite are present, but
only in fractures. The distribution pattern is reversed in
the central part of Streymoy (between Langasandur, Vest-
manna, Dalsnipa and Kollafjørður). There the stilbite-
heulandite assemblage occurs along the west coast from
Vestmanna to Dalsnipa, while a mesolite assemblage is
found along the east coast between Langasandur and Kol-
lafjørður.

Only the mesolite assemblage is found in the southern

part of Streymoy. Because of the differences in mineral
distribution, sections ST2 and ST6 have been divided in-
to two columns, showing the eastern and the western parts
of the sections, respectively (Fig. 8). The dip of the zeolite
zones in the northern part of Streymoy is 2°SW and
2°NNE the central area.

The distribution of secondary minerals is rather com-

plex at many localities in northern and central Streymoy
and shows repetitive zoning , i.e. a regular repetition of two
mineral zones. For example, on the path from Saksun to
the summit of Borgin (643 m), a mesolite zone is first
encountered, then a stilbite-heulandite zone, then, near
the summit, a second mesolite zone. Repetitive zoning
has also been observed at Loysingafjall (638 m), where
the mesolite zone is overlain by a stilbite-heulandite zone,
and along the main road between the villages of Vestman-
na and Kvívík. Between Vestmanna and Kvívík, zones oc-
cur within which the vesicles and fractures of the basalt
flows are mineralised, either by heulandite, stilbite, mor-
denite plus minor laumontite, or by compact mesolite,
heulandite, stilbite, thomsonite and chabazite. The widths
of the zones are from a few hundred metres to about 1 km.

Repetitive zoning also exists in the Vestmanna-1 bore-

hole. The first classification of the Vestmanna-1 mineral
assemblages was based on the mass concentration of ma-
jor index minerals. Since chabazite and thomsonite are
the most abundant minerals, the entire mineral assem-
blage was classified as a thomsonite-chabazite assemblage.
During the reclassification based on the first formed min-
erals for the present work, it became apparent that the
drilled lava succession contains a repetitive zoning of me-
solite and stilbite-heulandite assemblages (Fig. 8).
It is unlikely that repetitive zoning is caused by vertical
fluctuations of the geothermal gradient within such rela-
tively short distances, but the repetitive zoning may re-
flect flows of water of different temperature that changed

GEUS Bulletin no 9 - 7 juli.pmd

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133

134

Streymoy

7°00'W

62°00'N

7°00'W

20 km

Thomsonite-chabasite zone

Analcite zone

Mesolite-scolecite zone

Stilbite-heulandite zone

Laumontite zone

Empty vesicles

TJØRNUVIK

HALDARSVIK

SUN

DINI

SAKSUN

HVALVIK

HÓSVIK

KOLLAFJØRDUR

KALDBAKSFJØRDUR

ST2E

ST2W

Langasandur

Tórshavn

KVIVIK

Givrufelli

Langafjall

Borgin

Saksun

ardalur

Loysingfjall

Vestmanna-1

ST6W

Bøllufjall

Hundsarabotnur

Sund

Hvitanes

Sundshalsur

Dalsnipa

Øksnagjogv

Kirkjubøur

ST10

2°3.4°

TH-CH zone
AN zone
ME zone
ST-HE zone

700

600

500

400

300

200

100

e
t
r
e
s

a
b
o
v
e

s
e
a

l
e
v
e
l

ST-HE zone 2
ME zone 2
ST-HE zone 1
ME zone 1

-100

-200

-300

-400

-500

-600

e
t
r
e
s

a
b
o
v
e

s
e
a

l
e
v
e
l

Vestmanna-1

ST 2W

ST 2E ST 6W ST 6E ST 10

4°

3.4°

ST 2E

ST 6W

ST 6E

ST 10

ST 2W

Saksuna

rdalur

Loysingfjall

Bøllufjall

Hundsarabolnur

Sundshálsur

Hvitanes

Øksnaglógv

Kirkjubøur

Vestmanna-1

VESTMAN

NASUND

Sund

1.5°

2°

5 km

Givrufelli

Langafjall

Borgin

2°

Fig. 8. Distribution of zeolite zones on Streymoy and on sections ST2E, ST2W, ST6E, ST6W, ST10 and in the Vestmanna-1 borehole.
The dip and strike of the zeolite zones is indicated on the map. The arrows indicate the calculated strike of the zeolite zones between the
sections.

GEUS Bulletin no 9 - 7 juli.pmd

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134

135

GØTUVIK

LAMBAVIK

SUNDINI

Selatrað

Breiða

Morskarnes

Raktangi

Nes

Æðuvik

Rituvik

Runavik

Lambareiði

Stórafjall

Syðrugøta

Ritufjall

Heltnará

Sandfelli

Urðará

Glyvur

Inran

Svinár

Nordskáli

Litlafelli

Skerðingur

Elduvik

Funningur

Slættaratindur

Eiði

Gjógv

EY10

EY4

EY8

EY3

EY2

EY1

SKÁ

LAF

JØR

TH-CH zone
AN zone
ME zone
ST-HE zone

700

600

500

400

300

200

100

e
t
r
e
s

a
b
o
v
e

s
e
a

l
e
v
e
l

OYNDARFJØRDUR

FUGLAFLØRDUR

FUNNINGSFJØRDUR

Oyri

Kolbanargjógv

Kambur

5 km

0.8°

Thomsonite-chabasite zone

Analcite zone

Mesolite-scolecite zone

Stilbite-heulandite zone

Laumontite zone

Empty vesicles

Eysturoy

7°00'W

62°00'N

7°00'W

20 km

EY1

EY2

EY3

EY4

EY10

EY8

1.7°

2°

0.4°

0.8°

2.8°

1.1°

2°

4 °

4°

Fig. 9. Distribution of zeolite zones on
Eysturoy and on sections EY1, EY2, EY3,
EY8 and EY10. The dip and strike of the
zeolite zones is indicated on the map. The
arrows indicate the calculated dip of the
zeolite zones between the sections.

locally the vertical distribution of temperature. Alterna-
tive explanations for repetitive zoning are: (1) local varia-
tions in the chemical composition of the basalt, or: (2)
mineralisation in an open and closed system, caused by
variations in the percolation speed of the geothermal wa-
ter (Barth-Wirsching & Höller 1989; Gottardi 1989).

Eysturoy (Fig. 9)

Eysturoy may be divided into two for descriptive purpos-
es. North of a line from Norðskáli to Fuglafjørður, the
stilbite-heulandite assemblage occurs at 64% of localities.
South of that line mineral assemblage occurs at only 12%
of the localities (Fig. 9). The actual strike and dip of the

GEUS Bulletin no 9 - 7 juli.pmd

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135

136

zeolite zones can be determined by combining the dip of
the zeolite zones along the sections with the dips between
them. On Fig. 9 it can be seen that the strikes and dips
change to follow the changes in mineralogy. North of a
line from Svinár/Norðskáli to Fuglafjørður, the zeolite
zones dip about 2° towards the east. To the south of the
line, the dips of the zones shift gradually from 4° to the
SW to 2° to the S. This means that the mineral zones are
discordant to the lava bedding on the northern part of
Eysturoy, but nearly concordant to it on the southern part
of the island.

Borðoy (Fig. 10)

The mesolite, analcite and chabazite-thomsonite zones are
the only ones exposed on Borðoy. At Klakkur (section
BO1) the vesicles and fractures in the basalt are mineral-
ised by heulandite, stilbite, mesolite (massive and hair-
like), thomsonite (massive and hair-like), chabazite, levyne,
phillipsite, montmorillionite and celadonite, but no clear
relationship exists between the distribution of mineral and
height in the lava pile. Since analcite and mesolite are the
first deposited minerals in most vesicles, the mineral as-
semblage of section BO1 was classified as a mesolite zone
assemblage. The poor zoning west of Borðoyavik suggests

800

600

400

200

TH-CH zone
AN zone
ME zone

Met

r
es ab

o
v
e sea l

e
v
el

VAN

ASU

HARALDSSUND

BORD

AVIK

Høgahadd

Hálgafelli

Klakkur

Ánir

Strond

Húsadalur

Norðtoftir

Depil

Bor

ðo

y +

ðo

2°

1.1°

NAFJORDUR

BO3

BO2

BO1

Thomsonite-chabasite zone

Analcite zone

Mesolite-scolecite zone

Stilbite-heulandite zone

Laumontite zone

Empty vesicles

Borðoy

7°00'W

62°00'N

7°00'W

20 km

BO 3

BO 1

BO 2

5 km

Fig. 10. Distribution of zeolite zones on
Borðoy and on sections BO1, BO2 and
BO3. The arrow shows the strike of the
zeolite zones between BO2 and BO3. The
common dip and strike of the zeolite zones
on Borðoy and Viðoy is shown in the
upper right corner.

GEUS Bulletin no 9 - 7 juli.pmd

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136

137

Altitude

metres

Table 4. Quantitative analysis of section SA3, Sandoy. The table shows the number of observed

and calculated amygdales containing the index mineral per 25 amygdales

25
50
75

100
120
150
180
200
210
220
243
270
320
340
360
375
380
400
420
446

18
18
10
16

0
4
6
2
0
2

1
0
1
1
1
0

0
0
0
0
0

cal

obs

0
0
0
0
0
0
2
3
7

14
15
22
22
10

5
0
1
1
0
0
0

0.0
0.0
0.02
0.1
0.3
0.8
1.4
5.9

5.6
2.0
0.7
0.5
0.1
0.0
0.0

cal

obs

Me*

14
12

8
5
4
3
3
1
1
0
0
0
0
0
0
0
0
0
0
0
0

9.2
7.2
5.5
4.3
2.8
1.7
1.1
0.9
0.7
0.5
0.2
0.1
0.0
0.0
0.0
0.0
0.0
0.0
0.0

0.875

cal

obs

0
0
0
0
0
0
0
2
3
2
0
3
5
9

14
14
23
23
23

0.1
0.1
0.1
0.2
0.3
0.5
0.7
1.0
1.5
1.8
2.2
2.8
4.4
8.5

11.2
14.0
16.3
17.1
20.1
22.8
24.6

cal

obs

Th*

8
0
8
5
5
4
5
0
3
3
2
1
0
0
0
1
0
0

12.8
11.5
10.2

9.2
8.2
7.4
6.3
5.2
4.5
4.2
3.8
3.3
2.5
1.5
1.1
0.9
0.7
0.7
0.4
0.3
0.3

cal

obs

0
0
1
1
0
2
3
0
0
0
6
6
6
8

0
0
0

1.1
1.3
1.5
1.8
2.1
2.4
2.7
3.6
4.2
4.4
4.8
5.4
6.7
9.3

11.3
12.0
13.2
13.8
15.4
17.2
19.1

cal

obs

N,U

: Correlation coefficient of the regression line InH versus U(N

obs

). See equation (2).

: Standard deviation on Hcal. in m. See equation (3).

9.1
6.6
4.1
2.4
1.3
1.1
0.6
0.4
0.1
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0

N,U

_
_

0.988

_
_

0.996

_
_

0.991

_
_

0.982

_
_

0.952

10.3
13.0
15.9
21.4
24.9
11.9

21.3
18.6
15.5
12.2

13.4
11.3

cal

obs

cal

Table 5. Quantiative analysis of section VÁ1, Vágar. The table shows the number of observed

and calculated amygdales containing the index mineral per 25 amygdales

metres

Altitude

0
0
0
0
0
0
2
2
3
3
6
3
5
6

_
_

0.2
0.3
0.6
0.7
1.2
1.2
1.4
1.7
2.2
2.4
2.7
3.5
4.8
5.3

0
0
0
3

19
18
19
21

_
_

0.8
1.7
3.9
3.9

10.1
10.7
12.6
14.8
18.4
19.4
21.1
23.8
25.0
24.8

0
0
0
0
0
1
3
6
7
9

_
_

0.0
0.1
0.3
0.4
1.9
2.2
3.1
4.5
7.6
8.8

11.0
16.1
22.0
23.5

4
9

24
23
15
18
10

7
3
2
1
0
0
0

_
_

3.7

11.3
22.7
24.8
17.7
16.3
11.9

7.9
3.1
2.2
1.2
0.2
0.0
0.0

15
21

0
7
5
0
0
0
0
0
0
0
0

_
_

3.7

14.3
25.0
23.2

6.7
5.4
2.6
1.1
0.2
0.1
0.0
0.0
0.0
0.0

Correlation coefficient of the regression line InH versus U(N

obs

). See equation (2).

: Standard deviation on Hcal. in m. See equation (3).

100
200
235
340
350
380
410
460
475
500
550
610
630

N,U

0.987

0.972

0.851

0.837

0.871

GEUS Bulletin no 9 - 7 juli.pmd

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137

138

that the area has been affected by several generations of
mineralisation.

The zoning becomes distinct farther eastwards on sec-

tions BO2 and BO3. The exposed part of the mesolite
zone is 500 m on BO1, but 300 m on BO2 and 150 m on
BO3 (Fig.10). The analcite and thomsonite-chabazite
zones also appear at higher levels on sections BO2 and
BO3. The mineral zones have apparent dips of about 1º
towards the north and east. The analcite zone is about the
same thickness on both BO2 and BO3, which suggests
that the vertical displacement of the two zones reflects
differences in altitude of the palaeosurface of the basalt
plateau. The lava flows of Borðoy dip 1.6º to the SE, which
means that the zeolite zones are discordant to the lava
bedding.

Viðoy (Fig.11)

The distribution pattern of the secondary minerals on
Viðoy is a continuation of that on Borðoy. The mineral
zones are displaced downwards compared to those of
Borðoy with the result that only between 100 m and 200
m of the mesolite zone is exposed on sections VI1 and
VI2. On section VI3 a lower analcite zone about 200 m
thick is exposed, which is separated from the thomsonite-
chabazite zone by about 130 m of repetitive zoning. The
chabazite-thomsonite zone is about 430 m thick, which
is the maximum thickness recorded for that zone within
the basalts exposed on the Faroe Islands.

Quantitative analysis of mineral
distributions

Once the position and temperatures are known of the
boundaries of the zeolite zones, the geothermal gradient

ANN

ASUND

TH-CH zone 3

AN zone 3

TH-CH zone 2

AN zone 2

TH-CH zone 1

AN zone 1

ME zone

Metr

es abo

v
e sea le

v
el

800

600

400

200

Malinsfjall

Tunnafjall

Enni

Vl1

Vl2

Vl3

2.1°

2°

oy + Bor

Thomsonite-chabasite zone

Analcite zone

Mesolite-scolecite zone

Stilbite-heulandite zone

Laumontite zone

Empty vesicles

2°

VI3

VI2

VI1

VID

VIK

7°00'W

62°00'N

7°00'W

20 km

5 km

Viðoy

Fig. 11. Distribution of zeolite zones on
Viðoy and on sections VI1, VI2 and VI3.
The dip and strike of the zeolite zones is
indicated on the map. The arrows indicate
the strike of the zeolite zones in the
profiles. The common dip and strike of
the zeolite zones on Borðoy and Viðoy is
shown in the upper left corner.

GEUS Bulletin no 9 - 7 juli.pmd

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139

and the altitude of the palaeosurface of the basalt plateau
can be estimated using least squares regression, assuming
a linear palaeotemperature gradient. However, in order to
make a reliable estimate, the regression must be based on
three or more zone boundaries. This requirement is ful-
filled only where the Lopra-1/1A and SU1 sections can be
combined. Elsewhere, the number of exposed zone bound-
aries is too small to calculate a geothermal gradient. In
order to overcome this limitation, an attempt has been
made to estimate the position of unexposed mineral
boundaries from a detailed analysis of the distribution of
the exposed mineral zones.

Quantitative analyses carried out on the mineral as-

semblages of the Lopra-1/1A and Vestmanna-1 boreholes
showed that the relative vertical frequency of the minerals
followed a skewed distribution with one or more maxima
(Jørgensen 1984). This observation has been used to extra-
polate non exposed zone boundaries on section VÁ1 on
Vágar and SA3 on Sandoy. The two sections were chosen
because they are through the middle and the upper basalt
formations respectively, the distribution of minerals in
them is simple and nearly all rocks sampled contain a large
number of well developed amygdales. In order to exam-
ine the relationship between the thickness of the zeolite
zones and the distribution of index minerals, the number
of amygdales containing a particular index mineral was
recorded for 25 amygdales (see below). To ensure that the
amygdales were selected randomly, all amygdales in the
samples from each locality were numbered and the 25
amygdales for examination were selected by using a com-
puterised random number generator. After the amygdales
had been chosen, the first formed index mineral was deter-
mined and the total number of amygdales containing the
same index mineral was recorded. These results are pre-
sented as columns N_obs in Tables 4 and 5.

Trials were carried out using different exponential dis-

tribution functions to find the best correlation between
altitude and number of amygdales containing the same
index minerals. The experiments showed that the best fit
between the observed distribution and the calculated dis-
tribution was obtained by the log normal distribution
function:

N_i,cal = N₀ exp(-½[(lnH - lnH₀) / a]²

)

(1)

where:

N_i,cal is the calculated number of amygdales containing

index mineral i.

N₀ is the total number of amygdales investigated; in

this case N₀ = 25.

H is the altitude of the sample above sea level.

H₀ is the altitude where the distribution function at-

tains its maximum value.

a is a constant.

By transforming equation (1) to a linear form and replac-
ing N_i,cal by N_i,obs, we obtain:

lnH = aU + lnH₀, where U = ± [2 (lnN₀ - lnN_i,obs)]^½

(2)

The constants a and H₀ can be determined by linear re-

gression on U and lnH. The calculated number of amy-
gdales (N_i,cal) containing index mineral i is shown in Ta-

bles 4 and 5. A t-test shows that U

and lnH fit a straight

line at the 1% confidence level.

The distribution curves in Figs 12 and 13 give only a

best estimate for the height above sea level of the zone
boundaries. To assess the degree of uncertainty of these
estimates (see below) we calculate the standard deviation
of the altitude (H) defined as:

S_H = [1/(n - 2) S (H - H_c)²]^½

(3)

where:

n is number of pairs (H, N_i) along the distribution

curve.

H is the altitude of the sample above sea level.
H_c is the calculated altitude of a point on the distribu-

tion curves corresponding to N_i amygdales that contain

index mineral i.

In equation (3), n is reduced by 2 because of the loss of

two degrees of freedom by the least squares estimation of
a and H₀ in equation (1) (Miller & Freund 1977).

When N_i, H₀ and a are known, H_c can be calculated

from equation (1). S_H for the distribution curves is shown

in Tables 4 and 5 and a graphic representation of the cal-
culated distributions of chabazite, thomsonite, mesolite,
analcite, heulandite and stilbite on sections SA3 and VÁ1
is shown in Figs 12 and 13. The shape of the curves sug-
gests that a temperature range existed around the altitude
H₀ in which conditions were favourable for the formation

of a particular zeolite. Where H < H₀, palaeotemperatures

decreased away from H>₀ to where they became too low

for the zeolite to form. Where H > H₀, palaeotempera-

tures increased away from H₀. The zeolite that was most

stable at H₀

would have been formed in some interval

below H₀ but, at higher temperatures, formation of the

first zeolite would gradually be inhibited and another one
would have become stable. So a zeolite will most likely be
found between the maximum slopes of its distribution
curve versus height, which corresponds to a palaeotem-
perature interval.

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140

LA zone

ST-HE zone

ME zone

TH-CH zone Zeolite free

zone

AN zo

LA zone

ST-HE zone

ME zone

TH-C H zone Zeolite free

zone

AN zo

LA zone

ST-HE zone

ME zone

TH-CH zone Zeolite free

zone

AN zo

Analcite-chabazite

1000

800

600

400

200

-20 0

-400

-600

-800

-1000

-1200

Solid mesolite-hair-like mesolite

Solid thomsonite-hair-like thomsonite

Ch (obs)
Ch (cal)
An (obs)
An (cal)

ber of a

y
g
dales co

tai

i
ng

/Ch per 25 a

y
g
dales

Altitude (m above sea level)

1000

800

600

400

200

-200

-400

-600

-800

-1000

-1200

Altitude (m above sea level)

ber of a

y
g
dales co

tai

i
ng

Me/Me per 25 a

y
g
dales

1000

800

600

400

200

-200

-400

-600

-800

-1000

-1200

Altitude (m above sea level)

ber of a

y
g
dales co

tai

i
ng

/Ch per 25 a

y
g
dales

Me (obs)
Me (cal)
Me*(obs)
Me*(cal)

Th (obs)
Th (cal)
Th*(obs)
Th*(cal)

LA zone

ST-HE zone

ME zone

CH zone

Zeolite free

zone

LA zone

ST-HE zone

ME zone

CH zone

Zeolite free

zone

Chabasite-mesolite

Thomsonite-stilbite-heulandite

1600

1200

1400

1000

600

400

200

-200

-400

800

Altitude (m above sea level)

ber of a

y
g
dales co

tai

i
ng

Ch/Me per 25 a

y
g
dales

1000

800

600

400

200

-200

-400

-600

-800

-1000

-1200

Altitude (m above sea level)

ber of a

y
g
dales co

tai

i
ng

/Ch per 25 a

y
g
dales

Ch (obs)
Ch (cal)
Me (obs)
Me (cal)

Th (obs)
Th (cal)
He (obs)
He (cal)
St (obs)
St (cal)

numbers are small. A zone boundary is defined for map-
ping purposes to be reproducible with a probability of
95%. The probability (P) of discovering N_i,obs objects

(amygdales containing the new zeolite i) among N₀ ob-

jects (amygdales) can be calculated by means of the bino-
mial distribution function (see e.g. Kreyszig 1975 or Miller
& Freund 1977). It can be shown that when N

= 25 and

P = 95%, then N_i,obs = 3. Fig. 12 shows that this reasoning

can be applied to define the upper boundaries of the thom-
sonite-chabazite, analcite and mesolite zones at the heights
where the upper end of the appropriate distribution curve
intersects the line N

= 3. However, this method cannot

be used on the upper boundaries of the stilbite-heulan-
dite and laumontite zones, because stilbite, heulandite and
laumontite do not exist as first formed index minerals in
section SA3. Fig. 12 shows that solid mesolite occurs most
commonly in the mesolite zone and thomsonite occurs
most commonly in the stilbite-heulandite plus the meso-
lite zone. If we assume that 95% of the two index miner-
als occurs within the zones in question, we can define the

Fig. 12. The calculated distribution of chabazite, analcite, thom-
sonite (compact and hair-like) and mesolite (compact and hair-
like) on section SA3, Sandoy.

Fig. 13. The calculated distribution of chabazite, mesolite, thom-
sonite, stilbite and heulandite on section VÁ1, Váger.

The calculated distribution curves shown in Figs 12

and 13 show that the number of amygdales containing a
particular zeolite decreases rapidly as |H - H₀| increases.

This has the practical consequence that it becomes harder
to define a zone boundary by field mapping when sample

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140

141

heights of the lower boundaries of the mesolite and the
stilbite-heulandite zones where the lower end of the dis-
tribution curves interest the line N

= 3. That 95% of an

index mineral occurs within the interval in question can
be verified by plotting the accumulated distribution of
the index mineral in a probability diagram.

Analcite occurs only sporadically below 340 m on sec-

tion VÁ1 (Fig. 13), so the analcite zone cannot be defined
on this profile. The other zone boundaries were calculat-
ed as described above.

Estimation of palaeothermal gradients
and altitudes of palaeosurfaces

If we assume that the palaeothermal gradient was con-
stant with depth, it may be estimated by linear regression
on the data from the combined Lopra-1/1A plus SU1 sec-
tions, the mineral zone boundaries obtained by calcula-
tion and shown in Figs 12 and 13 and the temperatures
shown in Fig. 2. The resulting estimates are shown in Ta-
ble 6. The new estimate from southern Suðuroy is consid-

ered more accurate than that in Jørgensen (1984), which
was based on the mineral distribution in the Lopra-1 bore-
hole only. From these palaeogeothermal gradients and as-
suming a surface temperature of 7°C, the altitudes of the
palaeosurface of the basalts has been estimated (Table 6).

The altitude differences between the estimated palaeo-

surface and stratigraphic marker horizons A and C is dif-
ferent at the three localities (Table 7). On southern Su-
ðuroy, the palaeosurface was about 0.7 km (± 0.3 km)
above present day sea level, i.e. close to the extrapolated
top of the lower basalt formation. On Vágar, the palaeo-
surface was 1.9 ± 0.2 km above the extrapolated top of
the lower basalt formation (or 0.5 ± 0.2 km above the top
of the middle formation), while on Sandoy, the palaeo-
surface was 1.7 ± 0.2 km above the top of the middle
basalt formation. This suggests that the focus of volcan-
ism shifted laterally with time as will be discussed below.

Zeolite zone

Temperatures at
the zone boundaries

Zeolite

free

40-

60°C

St-He

110-

130°C

Palaeothermal

gradient

°C/km

Altitude of

palaeosurface

m above sea

level

Correlation

coefficient

Altitude of zone boundaries
(m above sea level):

Lopra-1/1A + SU1
VÁ1
SA3

0.9547
0.9181
0.8689

Table 6. Estimated palaeothermal gradients and the altitude of the palaeosurfaces at Lopra-1/1A and

sections SU1, VÁ1 and SA3

Ch-Th

50-

70°C

90-

100°C

190-

220°C

-590

380

425

-1200

825

-2200

-
-

443-983

1760-2080
1150-1524

1325

653

900
150

66 ± 9
63 ± 8
56 ± 7

- -

Table 7. Estimated thicknesses of the basalt formations along various sections across the Faroe Islands

Altitude of

palaeo surface

in m above sea

level (Table 6)

Present

stratigraphic

thickness in m

Local altitude

(m) of

A- and C-horizons

Altitude of

palaeosurface

in m above

A- or C-horizon

443-983

1760-2080
1150-1525

> 3100

1410

700-900

1,3

A-horizon:
A-horizon:
C-horizon: 1550-1924

Sources:

Larsen et al. 1999,

Waagstein & Hald 1984,

Waagstein 1988.

S. Suðuroy
W. Vágar
E. Sandoy

Area

Section

Formation

Lopra-1/1A + SU1

VÁ1

SA3

L. Formation
M. Formation
U. Formation

A-horizon: 700
A-horizon:
C-horizon: -400

-257-283

1700-2020

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142

Discussion

Palaeothermometry and zone boundaries

The use of zeolites as palaeotemperature indicators is based
on the assumptions: (1) that the zeolite zones reflect uni-
variant equilibrium with a high coefficient dP/dT of the
Clausius-Clapeyron equation and: (2) that the formation
temperature of the minerals is independent of the chemi-
cal composition of the hydrothermal solution.

Assumption (1) is fulfilled because the properties of

condensed systems are nearly independent of pressure, if
the pressure is not extremely high and the temperature is
below the supercritical temperature (374ºC) of water. We
can also estimate the error of the temperature determina-
tion when we ignore the external pressure of the system.
The coefficient dP/dT is known only for a small number
of systems that involve zeolites, but experimental studies
of the systems stilbite-laumontite-H₂O and laumontite-

wairakite-H₂O show that dP/dT is of the order of 25-33

bars/degree in the range P_fluid = 0-2000 bars (Liou 1971;

Jové & Hacker 1997). Consequently, if the external pres-
sure is equal to the fluid pressure and the original thick-
ness of the lava pile is 2 km, the likely maximum error of
the temperature determination is 8°C, disregarding the
depth between the boundary of the zeolite zone and the
unknown altitude of the palaeosurface.

In contrast to the effect of pressure, the chemical com-

position of the rock and the hydrothermal fluids has a
much larger effect on the formation temperature of the
minerals. Barth-Wirsching & Höller (1989) studied the
formation of zeolites in glasses of different chemical com-
positions. They found that replacing rhyolitic glass by
basaltic glass caused the formation temperature of differ-
ent zeolites to increase by between 50°C and 100°C. This
demonstrates the importance of choosing a reference area
for the thermometry that consists of rocks with a chemi-
cal composition similar to that of the rocks in the area
studied.

Other factors may also affect the formation of zeolites

such as the texture of the rock, the content of glass and
the porosity of the rock (Gottardi 1989).

The geothermal areas on Iceland were used as a refer-

ence for the thermometry in the present study. The ba-
salts from the Faroe Islands are all tholeiites, but show
large compositional variations that range from picritic to
ferrobasaltic (Waagstein 1988). Most of the Icelandic ba-
salts are also tholeiites, but minor amounts of acid rocks
(rhyolites, andesites, granophyres, acid tuff ) are found,
mainly associated with volcanic centres (Sigurdsson 1967).
This compositional variation of the Icelandic rocks may

partly explain the large variation in temperature at the
boundaries of the zeolite zones mentioned above (Fig. 2).

From the description of the sections shown in Figs 12

and 13 (and listed in Appendix A), it can be seen that the
distribution of index minerals varies gradually between
successive zeolite zones. An index mineral that defines a
zone may thus overlap the boundaries of neighbouring
zones which makes it difficult to define the exact bound-
aries between mineral zones. The problem was solved by
statistical analysis on sections SA3 and VÁ1 from which
the boundaries of the zeolite zones could be defined as the
locations where 3 out of 25 amygdales contain the appro-
priate index mineral.

The overlap problem occurs in all the sections described

in Appendix A and, because of the lack of quantitative
mineral data, the distributions in SA3 and VÁ1 were the
only ones that could be described by a simple distribution
model. On all other sections, the zone division was based
on a crude estimate of the abundance of the index miner-
als around the zone boundaries. Figs 12 and 13 show that
the overlap between the zeolite zones varies from 100 m
to 300 m. which means that, in the worst case, the zone
boundaries could be determined with an accuracy of only
± 150 m when the zone boundary localities are based on a
subjective estimate of the abundance of index minerals.

Volcanic and tectonic evolution

The average of the three calculated palaeogeothermal gra-
dients is about 60°C/km and there may be a small de-
crease in the gradient from the lower to the upper basalt
formation. If real, this decrease could reflect either a re-
duction in heat flow with time or a variation in heat flow
with locality.

Rasmussen & Noe-Nygaard's (1969, 1970) summary

of the volcanic evolution of the Faroe Islands that volcan-
ic activity started in the west and moved eastwards with
the times, must be modified, because evidence from the
Lopra-1 drillhole indicates that the lavas of the lower for-
mation were erupted from local centres (Waagstein 1988)
and not from centres situated west of the present islands.
This change might explain the change in the palaeogeo-
thermal gradients shown in Table 6. The eruption centres
of the lower and middle formations were located in the
Faroe Islands and the geothermal gradient was high. Move-
ment away to the east during eruption of the upper for-
mation led to a decrease in the gradient.

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143

Regional distribution of the zeolite zones

At the time when the Faroe lava pile was first mineralised,
the thermal gradient seems to have been fairly constant,
at least regionally and for some time. This is suggested by
the rough equality of the calculated palaeogeothermal
gradients from the southern, western and central part of
the Faroes that represent different stratigraphic levels (Ta-
ble 6). The overall regional distribution of zeolites is thus
considered to reflect primarily variations in the maximum
depth of burial of the basalt rather than differences in
heat flow. The inferred palaeosurface on southern Suðuroy
is close to the extrapolated top of the lower formation
(Table 7), indicating that the total thickness of middle
and upper formation lavas must have been small in this
area. In contrast, in eastern Sandoy about 50 km farther
north where the exposed thickness of the upper forma-
tion is of the order of 1 km, the estimated palaeosurface is
>1.5 km above the base of the upper formation or strati-
graphically approximately 3 km above the lower-middle
formation boundary. If we use the palaeogeothermal gra-
dient calculated on Sandoy, then the palaeosurface of the
upper formation on Viðoy may have been at about 1.3
km ± 0.2 km above sea level. These results suggest that
the upper formation had a similar or only slightly smaller
thickness in the north-eastern part of the Faroes compared
with the central part of the islands. On the other hand,
the upper formation seems to have been much thinner or
non existent in both the western and southern parts of
the Faroes (Table 7) and the middle formation must also
have been thin in the south.

The inferred thinning of the middle and upper forma-

tions from the central to southern part of the Faroes is
consistent with a northerly source area for these basalts,
centred on the rift between the Faroes and Greenland
(Waagstein 1988; Hald & Waagstein 1991; Larsen et al.
1999). The thinning of the upper formation towards the
west is consistent with Rasmussen & Noe-Nygaard's (1969,
1970) interpretation of an easterly source for this part of
lava pile and may suggest a shift in the focus of volca-
nism.

The first order regional zeolite distribution pattern is

affected by local perturbations of the mineral zone bound-
aries (Fig. 4). These perturbations show up as shifts in the
dip of the zone boundaries within and between neigh-
bouring islands as well as shifts in the degree of minerali-
sation. The latter effect is clearly seen towards the south.
Southern Sandoy and northern Suðuroy are heavily min-
eralised, although at different temperatures, whereas the
vesicles of the basalt in the adjoining areas of northern
Sandoy and southern Suðuroy usually contain no zeolites.

On the northern and western islands, the zone distribu-
tion shows a tendency to symmetry around the narrow
NW-SE-trending sounds that separate the islands (Figs
7-9). The distributions on the neighbouring north-east-
ern islands of Borðoy and Viðoy similarly seem to be mir-
ror imaged, a distribution difficult to explain by varia-
tions in depth of burial. It is more likely that the distribu-
tions reflect local differences in palaeotemperature, per-
haps related to the circulation of water underground with
high temperatures in areas of up welling and low tempera-

tures in areas of down welling. The symmetry of the zonal
distribution patterns suggests that these temperature anom-

alies are in part related to NW-SE-trending eruption fis-
sures or zones of weakness separating the present islands
(Noe-Nygaard 1968; Rasmussen & Noe-Nygaard 1969,
1970). They are subparallel to the transfer zones in the
Faroe-Shetland Basin described by Rumph et al. (1993)
and later authors, and may indicate the presence of simi-
lar deep seated features. Both the regional and the local
distribution of zeolite assemblages probably reflect the
basic volcanic-tectonic systems that led to the develop-
ment of the Faroe Islands.

Acknowledgements

I want to express my gratitude to the late Arne Noe-Ny-
gaard and Jóannes Rasmussen for discussions and support
during the first phase of this project. I also want to ex-
press my thanks to the Geological Survey of Denmark
and Greenland for financial support to the present project,
to curator Ole V. Petersen, Geological Museum, Copen-
hagen for permission to study the collection of zeolites
from the Faroes and to Mrs. Kitty Jørgensen, Næstved,
who kindly made her collection of zeolites from the Faroes
available for my study. Finally, I want to thank Regin
Waagstein, James Chalmers and Kjeld Alstrup for discus-
sions and constructive criticism of the various versions of
the manuscript. The comments of two anonymous review-
ers are likewise greatly acknowledged.

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Appendix A: Locations of sites along the sections discussed in the paper and minerals found in vesicles and fractures at
each locality. The mineral zones are defi ned in Fig. 2

Profi le

Locality

Altitude

(m)

Vesicles

Fractures

Zone

SU1

Road exposure 0.5 km nor

No vesicles.

He-Me. He-St-Ch.
An-Ch. Ca. Qz.

2-3

SU1

The northern entrance of the Sumba tunnel

He-Me. He-Ch.
Me-An. Ca. Ch-An.

2-3

SU1

Road exposure at the W slope of Siglidalur

200

Ch-An. Ca.

1-3

SU1

Road exposure at small stream on the W
slope of Spinarnir

380

Ch-Th*. Op. Qz.

1-2

SU1

288

Ch-An. Op. Qz. Ca.

1-2

SU1

Road exposure at Stórá, 1km SE of Spinarnir

340

Th*-An. Op. Qz. Ca.

1-2

SU1

Lambaklettur

235

As above.

1-2

SU2

Road exposure 3 km E of Øravík

100

Empty vesicles.

Ca. Qz.

1-2

SU2

Road exposure 2.5 km E of Øravík

Ce-An. Ch-Me*-Th*.

An. Ca. St.

1-2

SU2

Exposure in Dalsá, 1.5 km W of Øravík

100

An, Me*. Ch. Ca. Cld.

Cld. Qz.

1-2

SU2

Road exposure just north of Høgiklovningur,
2.5 km S of Øravík

250

Ca-An. Ph-Th*.

Cld. Me*.

1-2

SU2

278

Empty vesicles.

Ca.

1-2

SU2

NW slope of Nónfjall

360

Th*-An-Ch.

Th-Th*-An-Ch.

1-2

SU2

The summit of Nónfjall

427

An-Me* Ca. Qz.

An.

1-2

SU2

Road exposure 0.8 km S of the church in
Fámjin

Ac. Ch.

Ch. An. Qz.

1-2

SU2

Road exposure 0.5 km S of the church in
Fámjin

An-Th. Th*-Ch.

An. St. Me*.

1-2

SU5

Høvdatangi, Fr

0-25

Empty vesicles.

Empty fractures.

SU5

Skarvatangi

Na-(Th, An). Me-Th. Ch.

Me-Me*. Me-St.
Me-An. St-Ch. St*-St.

2-3

SU5

Exposure at the road Fr

An-St. Me-St. Th-St. Th-Me.

Me*-Ch.

2-3

SU5

- do -

130

Na. Ch. Me-Sc. Me-Ch. Th-Ga-Ch.

Na-St*-St. An-Th.
St-Ch.

2-3

SU5

- do -

140

An-Th*-Ch.

An-Me. St-Me-St.
Me-La, Ch.

2-3

SU5

- do -

250

Me-Me*. Th-Me.

An. He-St. Op, Cld, Ca.

2-3

SU5

Summit of Kambur

483

Ce-He. Me in large acicular crystals like
scolecite.

Ce-Me*, Ce-An. He.

2-3

SU9

Hamranes and the southern entrance of the
tunnel Hvalba-Sandvík

0-100

He-St. He-Me-Ch. An-Me. Me-Me*-
Gy. Me-Gy+Ap.

He-St-Ap. Me*-La.
Th-Ch; He-(St, La).
He-Ap. He-La. La-Ca.
La-Gy.

2-3

SU9

The southern slope of Skálafjall

An-He. Me-Th. Cld.

As in the vesicles.

2-3

SU9

- do -

120

As above.

2-3

SU9

- do -

160

Scolecite-like Me. An-He. Me-He.

He-Me-Me*. Ca.

2-3

SU9

- do -

200

As above.

2-3

SU9

- do -

240

Me-St. He-St. He-Ch.

Ca-(Ch, Le).

2-3

SU9

- do -

260

Me-Me*-Ch. Th-Ch.

2-3

GEUS Bulletin no 9 - 7 juli.pmd

07-07-2006, 14:19

145

146

Profi le

Locality

Altitude

(m)

Vesicles

Fractures

Zone

SU9

The southern slope of Skálafjall

290

Th*-Ch. Me-Me*-Ch. Ca.

1-3

SU9

The summit of Skálafjall

374

As above.

1-3

SA1

Exposure at the cost line and at road
cuttings in Søltuvík

0-50

Many empty vesicles. He. St. La. Ca.

La-St-Ca. Mo-He-St.
Ca.

2-4

SA1

Road exposure at the road Sandur-Søltuvík,
1.5 km west of Sandur

He-St. He+Me-St. Th-St.

He+Me-St. Ca.

2-4

SA1

Large quarry at lake Sandvatn, 1 km north
of Sandur

No vesicles.

St-La-Ca. He. St.

2-4

SA1

Sprutthol, Sandsvágur Bay

He-Me. Ch. Ca.

St. Ca.

2-4

SA3

Húsavíklið N of Húsavík

0-75

He-Me. Ce-Me. Th-Me.

St.

2-3

SA3

Road exposure 2 km W of Skálavík

Me-Ch. Gi. Cld.

He-St-Ca.

2-3

SA3

Road exposure at Hálsur, 3 km W of Skálavík

119

Me-Th. Me-Me*. He-Th.

St-St*. Ap.

2-3

SA3

Urðarklettar NW of Húsavík

120

Me-Th-Ch. An-Me-Th.

2-3

SA3

Húsavíklið N of Húsavík

150

Me-Th-Me. An. He. Ca.

2-3

SA3

Exposure at Gravaráin

140

Me-Th. He-St. He-Ch. An.

St. La.

2-3

SA3

Urðatklettar, NW of Húsavík

150

Ce-Me-Th-Me*, Me-Me*-Gy.

Me*.

2-3

SA3

- do -

180

Ca-Me-Me*. An-Me.

2-3

SA3

Húsavíklið, N of Húsavík

180-200

Me-Th*. An-Th-Me*.

2-3

SA3

Exposure at Gravaráin

210-220

Me-Ca-.Me*. An-Me*. An-Th*.

Ca-He-St. Ca-Ap.

1-2

SA3

Exposure at Stórá

243

Me-Me*. Me-Th*-Ca. Gi.

Ca-St.

1-2

SA3

Summit of Heiðafjall

266

He-Me*. An-Me*-An. Th*.

1-2

SA3

Exposure at Stórá

320-340

Me-An-Me*. Ch. Th*.

1-2

SA3

Skriðubakki

360-380

Th*-Ch. Me*-Ch.

Me*.

1-2

SA3

- do -

400-420

Ch-Th*. Th*-Ch. An. Many empty
vesicles.

0-1

SA3

The summit of Pætursfjæll

447

Ch-Th*. Many empty vesicles.

0-1

SA5

Dalsnípa

150

Me-An. Me-Ap-St. Th-Ap. Ch-Ap.
Th-Ch. An-Ch.

Le. He-St-Ap. Cld.

2-3

SA5

The S slope of Skúvoyafjall, 0.6 km NW of
Dalsnipa

280

Me-St, Me-An, He.

2-3

SA5

The summit of Skúvoyafjall

354

Ce-Ch. Ce-Th-Th*.

St.

1-3

SA5

Road exposure at the end of the road
Dalur-Skuvoyafjall

308

He-Me. Th-Me*. Ch-Th*.

1-3

SA5

Road exposure 2 km SW of Dalur

260

Th-Ap. St-Me-Le. Th-Le.

He-Me-La.

2-3

SA5

Dalur harbour

0-30

Ch. Ch-Le. An-Th-Th*. He-Me-St.

Ch. Le. Me-Ap-St.
Me-Me*.

2-3

SA5

Road exposure at Kinnartangi

100

Ch. Ch-Th-Ch. St-Me-Gy. Gy-Me.

2-3

SA5

The SE slope of Stórafjall

160

Ch. An-Me-Me*. St-Th.

Ch. St. He. Gy.

2-3

SA5

- do -

220

Me-Me*-Ch. Th-Me.

2-3

SA5

- do -

260

As above.

2-3

SA5

- do -

300

Ph. Gi-Me*. Th*-Le. Me-Me*.

1-2

SA5

- do -

340

As above.

Ch-Le. He-Me-St-Ap.

1-2

SA5

- do -

360

As above.

He-Le.

1-2

GEUS Bulletin no 9 - 7 juli.pmd

07-07-2006, 14:19

146

147

Profi le

Locality

Altitude

(m)

Vesicles

Fractures

Zone

SA5

The summit of Stórafjall

396

Ch+Ph. Gi-Me*. Me*-Ch. Th-Ch.

1-2

SA5

The NE slope of Stórafjall

310

Ch. Me*-Ch. He.

1-2

SA5

Trigonometric station on the NE slope of
Stórafjall

217

Ch. An. Me-Ch. He-St. He-Me-Gy.

2-3

SA5

Road exposure at Tjarnaheyggjur

As above.

Me-Ca.

2-3

VÁ1

Reyðastiggajatangi

0-10

He-St, An.

Cl-St-Ca-La.

3-4

VÁ1

Gásadalur, exposure along the path
Gásadalur-Rógvukollur

100

He-St, St-La.

Cl-St-La.

3-4

VÁ1

- do -

200

He, St.

Me, La, An.

3-4

VÁ1

Gásadalur, exposure at the path Gásadalur-
Rógvukollur

235

He-Th.

La, Ca.

3-4

VÁ1

Gásadalur. The pass between Knúkarnir-
Neytaskarð

340

He, St, Th, An, Cl.

3-4

VÁ1

Grunnadalur, exposure at the branching of
small streams

380

Cl-He-Th, Cl-He-St, Cl-St-Me.

St-La-St.

3-4

VÁ1

Rógvukollur , exposure at the W slope

380

He-Me, Me-Ch, Th-Ch-Th, Mo-He,
Mo-Ch ± Cld.

Me, Ca.

2-3

VÁ1

Neytaskarð, exposure at the SE slope

400-420

As above.

2-3

VÁ1

The summit of Rógvukollur

464

He-Me, Me-He-Me, Th-Me, Th-Ch,
Me-Ch.

2-3

VÁ1

Djúpidalur (the NW slope of Eysturtindur),
exposure at stream

470-480

He-Me, He-Ch, Me-Ch, Th-Ch.

2-3

VÁ1

500

He, Me, Th, Ch.

2-3

VÁ1

Grunnadalur, exposure at the end of small
streams

550

Th-Me*-Ch.

La, Ca.

2-3

VÁ1

Djúpidalur (the NW slope of Eysturtindur)

600-610

Ce-Th-Th, Ce-Ch.

St-Me-La, Ca.

2-3

VÁ1

The plateau between Eysturtindur and
Akranesskarð

620-640

An, Th, Me, Sm.

2-3

VÁ4

Oyrargjógv ferry harbour and the path to
Sørvágur

0-136

St-St*. Ep-St. La. Th. Ch.

St. La.

3-4

VÁ4

Large quarry 1 km W of Sørvágur

Cl-St-St*. St-La. Mo-He. Mo-Gy.
An-Gy. Me-Me*-Ch. Me-Ap±Sm.

He-St-St*. Ep. La, Me.

3-4

VÁ4

Sjatlá, 1.5 km N of Sørvágsvatn

45-60

Cl-He-St. St-La. Ap.

2-4

VÁ4

Exposure at N end of small road from
Sørvágur, just W of Sjatlá

114

Cl-St-Me. Cl-An. Cl-Ch±Sm.

St-La. Ap.

2-4

VÁ4

- do -, exposure at small tributary of Skjatlá

150

Cl-He-St. St-Ap. Cl-Me-Th. Cl-Me-
Ch. Me-Ap. Me-Ch.

Me-Ap. An-Ap. He-Ch.

3-4

VÁ4

- do -

190

As above.

3-4

VÁ4

- do -

220

Cl-St-St*. Cl-He ± La. Th.

Mo-St.

3-4

VÁ4

End of Breiðá (Oyrargjógv)

250

Ce-Me. He-Me.

3-4

VÁ4

- do -

304

Ce-Me-Th. Ce-Th-Ch.

Gy-Me.

2-3

VÁ4

Kvígandalur, exposure at the SE tributary of
Kvígandalsá

250

An. He-Le. Me-Le. An-Th-Ch.

2-3

VÁ4

Husadalur, exposure at the W? tributary of
Kirjuá

275

An. Me. He.

Me-An.

2-3

GEUS Bulletin no 9 - 7 juli.pmd

07-07-2006, 14:19

147

148

Profi le

Locality

Altitude

(m)

Vesicles

Fractures

Zone

VÁ4

Kvígandalur, exposure at the SE tributary of
Kvígandalsá

300-365

An. He. Le. Ch.

2-3

VÁ4

The cross between the path Oyrargjógv-
Sørvágur and Sandavágur-Slættanes

436

Me. Th. St. Ch.

2-3

VÁ7

Road exposure 3 km north of Sandavágur

100-120

Ce-He-St. Ce-St-Me. Ce-He-Th.
Ce-Mo-St. Ce-Me-St.

Ce-Mo-He. Ce-He-St.
Ce-Me*-Ch. Ce-Ap.

2-4

VÁ7

The western slope of Malinstindur

219

As above.

2-4

VÁ7

- do -

235

Ce-He-Me. Ce-Me-Gy.

St-Ca.

2-3

VÁ7

- do -

280

Ce-Me-Ch.±Ca. ±Sm.

2-3

VÁ7

- do -

345

As above.

2-3

VÁ7

- do -

386

Empty vesicles.

VÁ7

- do -

410

Ce-He-Me. Th-Me. Th-An.

St. Ch.

2-3

VÁ7

- do -

500

As above.

2-3

VÁ7

- do -

538

He. An. Me. Th. Th*. Cld. Ca.

He-Me. Me*. Cld.

1-2

VÁ7

- do -

563

Me-Me*. Th*-Ph. Th*-Ch+Le.

1-2

VÁ7

The summit of Malinstindur

580

Ce-Me*.

1-2

VÁ7

- do -

620

He. Me. Ph. Ch. Th.

Ca. Cld.

1-2

VÁ7

- do -

683

Me-He. Me*-Ch. Ph-Ch.

1-2

VÁ7

- do -

690

He. Ch. Le. Th. Cld.

1-2

ST2W The path Saksun-Haldarsvík: Kvíggjarhamar,

Saksun

0-100

He. St. Th. Me. Ch.

St-Ca-St. Gy. Tb. Ok.

2-3

ST2W The slope of the mountain between Skipá

and Gellingará

150

He-Ch-Th. Me-St.

2-3

ST2W - do -

200

Me. Ca.

2-3

ST2W - do -

250

Th-Me. He-Me. Me-Ch.

St. La.

2-3

ST2W - do -

310

As above.

2-3

ST2W - do -

325

Me. Me*. Th*-Ch. He-Me.

Ok. Gy. Ca.

2-3

ST2W - do -

355

Me-Me*. Th-Me*. Th*-Ch.

2-3

ST2W - do -

360

Ce-Th*. He-Me*-Sm.

1-2

ST2W - do -

380

An-Th*. Th*-Le.

Me*-Ca.

1-2

ST2W - do -

407

Ce-Ph-Ch. Ce-Th*-Ch.

1-2

ST2W - do -

430

Th*-Ch.

1-2

ST2W - do -

460

Empty vesicles.

0-1

ST2W - do -

555

Le-Ch. Th-Th*.

0-1

ST2W Víkarskarð

600

Ce. Th. Ch. Cld.

0-1

ST2W The NE slope of Gívrufelli

650

As above.

0-1

ST2W The summit of Gívrufelli

701

As above.

0-1

ST2E

Víkarnes N of Haldarsvík

0-30

He-St. Ca.

Ca-La.

3-4

ST2E

The SE slope of Fjallið

100

As above + Th. Gy. Ok.

To-Gy. La.

3-4

ST2E

- do -

150

He. Me. Th.

To-St. Th-Gy-Ap.

2-3

ST2E

The summit of Fjallið

180

He-Me. He-Th*. Ca.

2-3

GEUS Bulletin no 9 - 7 juli.pmd

07-07-2006, 14:19

148

149

Profi le

Locality

Altitude

(m)

Vesicles

Fractures

Zone

ST2E

The path Haldarsvík-Saksun: exposure 0.5
km SW of Haldarsvík

148

He-St. Me.

Me-Th-Ch. Me-An.
Ph-Le-Ch.

2-3

ST2E

- do -, exposure 1 km SW of Haldarsvík

200

He-St. He-Me.

2-3

ST2E

- do -, exposure at the Svínstiáir tributaries
of Kluftá, 1 km SW of Haldarsvík

230

Me. Th. He.

St. Ca.

2-3

ST2E

- do -, exposure 1.2 km SW of Haldarsvík

250

He. Me. Mo.

He. St. Ap. Ca.

2-3

ST2E

- do -, exposure 1.5 km SW of Haldarsvík

280

Me-Th-Me-Gy-Sm.

2-3

ST2E

- do -, exposure 1.8 km SW of Haldarsvík

350

Me-Th.

2-3

ST2E

- do -, exposure 2 km SW of Haldarsvík

360

Me-Th. Me-Ph-Ch.

2-3

ST2E

- do -, exposure 2.3 km SW of Haldarsvík

370

Me-Th. An-Me-Me*.

2-3

ST2E

- do -, exposure 2.5 km SW of Haldarsvík

400

Th*-Ch. Me-Th*.

Ph-Ch. Ch + Le.

1-2

ST2E

- do -

410

Me-Me*. Ch-Le-Ch.

1-2

ST2E

The SE slope of Víkartindur

420

Me-Me*-Le. Ch-Ph-Sm.

1-2

ST2E

- do -

440

.Me*. Th-Th*-Ch.

1-2

ST2E

- do -

500

Th*. Ch.Cld.

0-1

ST2E

- do -

540

As above.

0-1

ST2E

- do -

620

As above.

0-1

ST6W Road exposure at the main road Kvívík-

Stykkið, 1.5 km E of Kvívík

He. St. La. Me. Th. Ap.

He. St. Ap. Me*. Th. Ch.
An.

2-4

ST6W Tunnel workplace at the village of Leynar

Me. St. La.

2-4

ST6W Exposure at Leynarvatn along the old road

Tórshavn-Vestmanna

60-125

He. St. Wa. La. Ce. Cld.

St. Ca. He. St. St*. La.
Me*, Th, Le.

2-4

ST6W The path Leynarvatn-Hósvík, exposure 0.3

km NE of Leynarvatn

150-190

Ce-He-St. Ce-Me-Gy. Cld.

Ph, Gy, Ap.

2-3

ST6W - do -, 0.4 km NE of Leynarvatn

210

Ce-He-St. Ce-Me-Th. Ce-St-La.

2-3

ST6W - do -, 0.5 km NE of Leynarvatn

260

Ce-Me-Th. Ce-He-Me. Ce-He-Th.

Me-Ca.

2-3

ST6W The path Leynarvatn-Hósvík, exposure

0.5 km NE of Leynarvatn

300

As above.

2-3

ST6W - do -, 0.6 km NE of Leynarvatn

340

As above.

2-3

ST6W á Halsi, 1 km NE of Leynarvatn

380

As above.

2-3

ST6W - do -, 1.5 km NE of Leynarvatn

463

Ce-He-Me-Me*. Ce-Th-Ch.

2-3

ST6W - do -, 1.9 km NE of Leynarvatn

500

As above.

2-3

ST6W - do -, 2 km NE of Leynarvatn

510

Me-He-Me*. Me-Me*. Th*-Ch.

He-Me.

2-3

ST6W Hósvíksskarð

520-530

Th. Th*. Ph. Ch. Le. + Ce.

2-3

ST6W The SW slope of Bøllufjall

550

As above.

1-2

ST6W The summit of Bøllufjall

584

As above.

1-2

ST6W The SW slope of Gívrufjall

530

As above.

1-2

ST6E

Road exps. between við Áir and Hosvík

He-St*. He-St-Ap. He-St-Ch. He-
Th-Ch. Th-St. Th-Ch. Ga-Th. An-Ch.
An-Ap. An-Th. An-Th-Ch±Ce.

He-Ch-St. Th-Gy+Ap.

Ch-Th*-Ap.

2-3

ST6E

The path Hosvík-Leynar: Smørdalsá

160-203

He-Me. He-Ch-Th, Me-Gy. He-An-Th.

2-3

GEUS Bulletin no 9 - 7 juli.pmd

07-07-2006, 14:19

149

150

Profi le

Locality

Altitude

(m)

Vesicles

Fractures

Zone

ST6E

The path Hosvík-Leynar: Smørdalsá

240-260

Ce-Me-He. Ce-Th-Me. Cld.

Me-Th-Ap-Gy.

2-3

ST6E

- do -

360

As above.

Ca-La. Cld.

2-3

ST6E

The NE slope between Bøllufjall and
Gívrufjall

436

Me-Th. He-Me-Ca. He-Th.

2-3

ST6E

- do -

480

He-Me-Me*. Th-Ch. Th-Th*.

2-3

ST6E

- do -

500

Th-Th*-Gy. Me*-Gy.

2-3

ST6E

The NE slope of Bøllufjall

530

Th-Th*. Th-Ph, Th*-Ch.

1-2

ST6E

The summit of Bøllufjall

584

As above.

1-2

ST10

Large quarry 0.5-1 km NW of Sund,
Kalsbaksfjørður

Me. Me*. Th. An. Ph. Gi. Ap.

2-3

ST10

Exposure at Sundá, 1.2 km S of Sund

227

He. Me. Ca.

2-3

ST10

- do -, 1.6 km SW of Sund

265

Me. Th.

St-He.

2-3

ST10

Quarry 0.5 km SW of Lambafelli at the high
road Tórshavn-Kollafjørður

340

Ce-He. Ce-Ch-Le. Ce-An. Ce-Ch.

Ce-He-Sm, Ce-He-Ch.
Ce-He-Th-Ch.

2-3

ST10

Road exps. 1 km W of Sundshálsur along the
high road Tórshavn-Kollafjørður

310

Ce-He-Me. Ce-Me-Ch. Ce-Th-Me.

2-3

ST10

Small quarry at end of road to the water
reservoir of Havnardalur

170

He. Me. Th. Ch.

2-3

ST10

Road exposure at the road Tórshavn-
Velbastaður, 0.5 km N of Velbastaður

160

Ce-Me. Ce-Th-Ch.

2-3

ST10

Exposure at the road Tórshavn-Velbastaður,
just N of Velbasta ur

123

Me-Me*. Me-Ch. Me.Th-Ch. Th-Me-
Me*.

Cld, Ca.

2-3

EY1

Road exposure at the road Eiði-Norðskáli,
0.4-0.5 km SE of Eiði

60-100

Ap-Gy-Me. Me-Ph. He-Gy-Me. He-
Me-Ch. St-Aå-Sm. Th-Ap. Th-St-Ap.
Th-Ch-Sm.

St-La-St*-Ca. He-St-

Ch-Sm.

3-4

EY1

Localities on the road Eiði-Funningur:
Quarry in Djúpidalur, 2 km east of Eiði

150

St-Gy. St-Th-Gy. Th-Ga-Th. Me-Th.
Me-Ch.

St-La.

3-4

EY1

50 m long road cutting on W slope of
Slættaratindur, 3.5 km east of Eiði

200-230

Me-Th*-Gy. Me-Th*-Ch. Me-He-Me.
He-Me.

St-St*. La-Me*-Sm.
He-Ap. St. Cld. Qz.

2-3

EY1

Road exposure 0.4-0.5 km E of Eiðisskarð
just at the N slope of Vaðhorn

336-346

Ce-Me-Th*. Ce-Me-Ch.

2-3

EY1

The N slope of Vaðhorn

410

As above.

He-St-St*. Mo-St.

2-3

EY1

- do -

435

As above.

2-3

EY1

Small quarry at the road fork Eiði, Funningur,
Gjógv, 1 km west of Funningur (165)

165

He. St. Me. Me*. Ch.

2-4

EY1

Exposure at the coast line at Funningur

5-10

Mo. He. St. Me. +Ce.

St. An. Me. Cld.

3-4

EY2

Exposure at the coast between Stórá and
Marká

0-20

Mo. He. St.

St. Qz. Cld. Ca.

3-4

EY2

The path Svínár-Funningur

30-40

He-Me. He-St-Gy. He-Me-Gy.

3-4

EY2

- do -

100

Me-Th-Ch. Th-Gi. Th-Me*. An-Ch.
An-Th-Ch.

Th-Gy-Ap. Me-Ap-St.

2-3

EY2

- do -

212

As above.

2-3

EY2

- do -

280

Me. Th. An. Ch.

An-Th*-Gy.

2-3

EY2

- do -

346

An. Me. Me*. Th. Th*. Th-Ch-Sm.

2-3

EY2

- do -

400

Ce-Th-Th*-Ch. Ce-Ch.

Th-Th*-Ch.

1-2

EY2

- do -

420

Ch-An. Ch.Gi-Th*. An-Ph-Ch.

1-2

GEUS Bulletin no 9 - 7 juli.pmd

07-07-2006, 14:19

150

151

Profi le

Locality

Altitude

(m)

Vesicles

Fractures

Zone

EY2

Kvígandalsskarð

460

Me*. Th*. Ch. Gy. Sm.

1-2

EY2

- do -

480

As above.

1-2

EY2

The E slope of Skerðingur

500

As above.

1-2

EY2

- do -

525

As above.

1-2

EY2

- do -

450

Ce-Th*. Ce-Me-Me*-Ch.

1-2

EY2

- do -

430

As above.

2-3

EY2

- do -

415

Ce-An. Ce-Qz. Cld.

2-3

EY2

- do -

380

Me.

2-3

EY2

Kvígandalur

363

He-Me. He-Th.

EY2

Skipagjógv

180

Me-Th-Th*. Ch-Gi-Th.

An-Th-Ap-Gy-Sm.
Cl. Ca.

2-3

EY2

- do -

He. Me. Th.

Ca.

2-3

EY2

- do -

Gy-He. Gy-Th-Me.

3-4

EY2

Skipagjósoyran

0-10

He. St. Th. La. Gy.

He. Me-La-St.

3-4

EY3

Large quarry 1 km S of Oyri

20-30

Me-Th-Sm. Me-Th-Ch-Sm. Me-Gy-
Me*.

Cl-He-Th-Ap.

2-3

EY3

Oyrargjógv

100

Me-Th, Me-Gy.

2-3

EY3

- do -

210

No vesicles.

He. St. Me. Th. Gy.

2-3

EY3

The path Oyri-Skálafjørður

251

Me. Th. Ch.

2-3

EY3

- do -

300

He-Me. Th-Me. Th-Ch.

2-3

EY3

- do -

340

An. Me*-Ch.

1-2

EY3

- do -

350

Me*-Ch. Th-Th*.

1-2

EY3

- do -

400

Th-St-Gy. Ch. St.

1-2

EY3

- do -

426

An-Th*. An-Th*-Ca. Ch.

1-2

EY3

- do -

495

Th*-Ch+Le.

1-2

EY3

The SW slope of Sandfelli

527

Ce-Th*-Ch. Ce-Cld.

He. Me. Ca. Cld.

0-1

EY3

- do -

545

As above.

0-1

EY3

The summit of Sandfelli

572

As above.

0-1

EY3

The path on the S slope of Skálafjall

440

Me-Th. He-Me.

2-3

EY3

- do -

405

As above.

2-3

EY3

- do -, just at Öksnagjógv

200

As above.

2-3

EY4

Small quarry just N of Morskarnes, about
1 km N of Nesá

He-Th-Ch. Me-Th.

He-St. He-Ap. Ca.

2-3

EY4

The W slope of Neshagi, just E of the locality
above

140

Cl-Me-Th. He-Th.

2-3

EY4

Exposure at Skotá

194

As above.

2-3

EY4

- do -

230

Me-Me*. Ch.

1-2

EY4

- do -

320

Th*. Me-Me*. Ch.

He-Me. He-St.

1-2

EY4

The SE slope of Kambur: exposure between
the source of Skotá and Urðará

380

Me*. Ch, Le +Ce.

1-2

GEUS Bulletin no 9 - 7 juli.pmd

07-07-2006, 14:19

151

152

Profi le

Locality

Altitude

(m)

Vesicles

Fractures

Zone

EY4

The SE slope of Kambur: exposure between
the source of Skotá and Urðará

400

As above.

1-2

EY4

- do -

430

Th*. Ch. Le. Ce.

0-1

EY4

- do -

462

Ch. Many empty vesicles.

0-1

EY4

The path Steffanstangi-Kambur

480

As above.

0-1

EY4

- do -

500

Th-Ch-Th*. Cld. Ca.

0-1

EY4

- do -

540

As above.

0-1

EY4

The summit of Kambur (trigonometric
station)

593

As above.

0-1

EY4

The E slope of Heygshagi

440

Me*-Ch. Th*-Ch.

1-2

EY4

- do -

400

As above.

1-2

EY4

- do -

250

As above.

1-2

EY4

Markrá

250

Me-Me*. He-Th. He-Me*.

2-3

EY4

- do -

160

As above.

2-3

EY8

Road exposure at the old road Lervík-
Fuglafjørður/Norðragøta, about 2 km NW
of Lervík

Ce-Mo-He-Me. Ce-Ch.

He-Me-St.

2-3

EY8

Localities along Kálvadalsá in Kálvadalur

200

Mo-He-Me-Me*. An-Th-Ch.
Le-Ch-Le.

He-Me-St-St*. An-Th.

2-3

EY8

- do -

270

As above.

2-3

EY8

- do -

300

He-Me*-Ch. An-Th*-Ch.

2-3

EY8

Mannsgjógv

400

An-Ph-Ch. An-Th-Ch, Me*-An.

1-2

EY8

The NE slope of Navirnar

300

He-Me-St*. He-Ch, He-Le. An-He.

He-St. He-Me.

2-3

EY8

The E slope of Ritafjall

440

He-Me*-Ch. An-Th*-Ch.

1-2

EY8

- do -

490

He-Th-Ch. Me*-St*.

1-2

EY8

- do -

520

Th-Ch. Me*-Ch.

He. St. Ca.

0-1

EY8

The summit of Ritafjall

560

Th.Ch. Le.

0-1

EY8

- do -

641

Th*. Nearly all vesicles are empty.

0-1

EY10

Large quarry just N of the road fork
Skálafjørður-Runavík-Lambi

60-80

Me-St*. Th-St*. Th-Me-An. Th-Ch-St*.
Co-Th. Ha.

He-St*. He-Th-Ca.
Ph-Ch-Ph. Ha-Ca.

2-3

EY10

The SW slope of Ritafelli, NE of the locality
above

180

No vesicles.

He-Me-Ch-Sm.
Me*-Le-Ch-Sm.
An-Me*-Sm.

2-3

EY10

- do -

200

Me-Me*. Ch. Th*. Ph.

An-Me*-Sm. Me*-Ph-
Le. Ap-Sm.

1-2

EY10

- do -

230-240

As above.

1-2

EY10

- do -

270

He-Th-Ch. Th*-Ph. An-Th*, Ch-St.
An-St. Ap-Th-Ph. Ca.

St-La. Me-Ap.

1-2

EY10

The edge of Ritafelli

350

St, Me*. Th*. Ph. Ch. Ce.

1-2

EY10

The SW slope of Stórafjall

380

Th*. Ch. Ph.

1-2

EY10

The W edge of Stórafjall

440

Th. Ph. Ch. An. Ce.

An. St. Ch. Ph. Sm.

0-1

EY10

- do -

490

Empty vesicles.

St, Th*. Ch. Ca. Cld. Sm.

0-1

GEUS Bulletin no 9 - 7 juli.pmd

07-07-2006, 14:19

152

153

Profi le

Locality

Altitude

(m)

Vesicles

Fractures

Zone

EY10

The W edge of Stórafjall

520

Th. Many empty vesicles.

0-1

EY10

The summit of Stórafjall

567

As above.

0-1

BO1

Large quarries at Klakkur

Me-Ch. He-Me. Cld.

Mo-St-La. Ca-St.

2-3

BO1

The NE slope of Klakkur

100

Mo-An. Mo-He. Me-Ch. Ca.

2-3

BO1

- do -

140

Me-Th*. Ga-Me. Ch-Gi-Th.

As in the vesicles.

2-3

BO1

The NE slope of Klakkur

160

Th-Me*-Ph. Ph-Ch.

He-St. Ca-St.

1-2

BO1

- do -

210

Mo-He-Ch. Ch-Th. Th-Ph. Le-Ch.

Ca-St.

1-2

BO1

- do -

260

Me-Th-La. An-St-La. An-Th-Ch.

2-3

BO1

The summit of Klakkur

414

Ch-Th. Th-Ph.

2-3

BO1

The S slope of Klakkur

380

As above.

2-3

BO1

- do -

300

Me-Th. Th*-Ch. Th-Ph-Ch.

He-St-La.

2-3

BO1

- do -

260

He-Me-Th. He-Th.

2-3

BO1

The NE slope of Hálgafelli

280

Ce-He-Me-St. Ce-Me-An.

2-3

BO1

- do -

300

As above.

2-3

BO1

- do -

360

As above.

2-3

BO1

- do -

380

Ce-Mo-He-Th. Ce-He-Me.

2-3

BO1

- do -

400

Ce-St-Ch.

He-Th-Me-St.

2-3

BO1

- do -

450

As above.

2-3

BO1

- do -

480

An-Me-Me*. Th-Ch.

2-3

BO1

The summit of Hálgafelli

503

Ce-He-Me.

St-La.

2-3

BO2

Exposure at stream 0.6 km SW of Norðoyri

20-80

He. Me. Ch. An. Ap.

St. Cld. Ca.

2-3

BO2

The W slope of Høgahædd

140

An. Me. Ch. Many empty vesicles.

As above.

1-3

BO2

- do -

220

He-St. He-Ch-St. Th-Ph.

St. Ca.

2-4

BO2

- do -

270

Empty vesicles.

BO2

- do -

310

He-Me-Me*. Me-An. Me-Ch.

2-3

BO2

- do -

320

Ch-Th*-Ch. He-Ch.Th*. An.

1-2

BO2

- do -

330

Me*. Th'. Ch. Ca.

1-2

BO2

- do -

360

As above.

Ch. Th*. Ca.

1-2

BO2

- do -

440

Th*. Ca. Op.

Cld.

1-2

BO2

- do -

474

Me. Me*. Th*. Ch.

1-2

BO2

- do -

510

Th-Th*. Ca. Cld. Many empty vesicles.

0-1

BO2

- do -

550

As above.

0-1

BO2

The summit of Høgahædd

563

As above.

0-1

BO3

Large quarry between Norðdepil and Depil

40-50

Ce-He-Th. Ce-He-Na-Th. Ce-Th-Ch. Cl-He-St-Ap. Cl-Th-

Ap. Cl-Ph.

2-4

BO3

Depilsá

150

Me-Me*-Ch-Le. Me-Me*-Ch. He-Me.

2-3

BO3

- do -

200

Me*-Ch, An-Ch.

1-2

BO3

- do -

300

He-Me*-Ch. He-Th*-Ch. An-Ph-Ch.
+Ce.

He-St. He-Th-Ca.

1-2

GEUS Bulletin no 9 - 7 juli.pmd

07-07-2006, 14:19

153

154

Profi le

Locality

Altitude

(m)

Vesicles

Fractures

Zone

BO3

Depilsá

340

As above.

1-2

BO3

E slope of Lokki

375

Ch-Gi-Th'. Ch-An.

0-1

BO3

- do -

400

Ch-Th*-Ch. Ch-Le.

0-1

BO3

- do -

450

As above.

0-1

BO3

- do -

470

Th. Ch. Ca.

He-St-Th-Ca.

0-1

BO3

E slope of Lokkanøv

460

Ce-An-Ch. Ce-Th-Ch-Th*. Many
empty vesicles.

0-1

BO3

- do -

580

As above.

0-1

BO3

- do -

700

As above.

0-1

BO3

The summit of Lokki (trigonometric station)

754

As above.

0-1

VI1

The starting point of the profi le is the
largest stream 0.5 km SE of Hvannasund

Ce-Me-St. Ce-An-Th-Me. Ce-Me-Ch.
Ce-He-St-Me.

Ce-Cl-St. Ce-Cl-Me-
Ca.

2-3

VI1

SW slope of Enni

120-132

Empty vesicles.

VI1

SW slope of Enni

180

Mo-An.

2-3

VI1

- do -

210

An. Ph-Ch. An-Th. Me-Me*. He-Me-
Ch.

He-Me*-Ch. He-Ph-
Ch. He-Th-Me.

2-3

VI1

- do -

225

As above.

1-2

VI1

- do -

240

Me*. Th*. An.

1-2

VI1

- do -

270

Ce-Th-Th*-Ch. Ce-Ch-Le. Ce-An-
Ch. Ce-Ch-St. Ce-He. Ce-He-Cld.

He-St. Cld.

1-2

VI1

- do -

310

Ch-Gi-Th*. St-Ch. Ph-Ch. Th-Th*.

1-2

VI1

- do -

360

Ce-Ch. Ce-Ph-Ch. Ce-Th*. Ch.

1-2

VI1

- do -

380

Ch. Th. Le. Sm.

Cld.

1-2

VI1

- do -

420

Th*-Le-Ch-Sm.

Op. Sm.

0-1

VI1

- do -

550

As above. Many empty vesicles.

0-1

VI1

- do -

600

Ca and Siderite.

0-1

VI1

The summit of Enni

651

As above.

0-1

VI2

Small quarry at the road Hvannasund-
Viðareiði, 2.6 km N of Hvannasund

40-80

Ce-He-Me. Ce-He-Th. Ce-He-
Ch-Sm. Ce-Ch-Sm. Ce-Ph-Me*.
Ce-Me-Me*.

He-Me-St.

2-3

VI2

W slope of Tunnafjall

80-100

He-Me-Me*. An-Th-Me. An-Th-Ch.
An-Ph-Ch.

He-St. St-Me.

2-3

VI2

- do -

150

As above.

1-2

VI2

- do -

200

As above.

1-2

VI2

- do -

225

Me*. Th*. Ch. Ph. An.

He. St. Ca.

1-2

VI2

- do -

250

Me*. Th*. Ch.

1-2

VI2

- do -

300

Th*. Ch.

1-2

VI2

- do -

315

As above.

0-1

VI2

- do -

390

An. Th'. Ch. Ph.

Me*. Ph. St.

0-1

VI2

- do -

460

Th*. Ch. Le. Sm.

St. Sm.

0-1

VI2

- do -

520-550

Empty vesicles.

Qz. Cld. Ca.

0-1

GEUS Bulletin no 9 - 7 juli.pmd

07-07-2006, 14:19

154

155

Profi le

Locality

Altitude

(m)

Vesicles

Fractures

Zone

VI2

The summit of Tunnafjall

593

Th. Th*. Ch.

0-1

VI2

The S Slope of Myrnafjall

620

No vesicles.

Th. Th*.

0-1

VI2

The summit of Myrnafjall (trigonometric
station)

688

Th. Th*. Only 20% of the vesicles are
mineralised.

0-1

VI3

Small quarry at the road Viðareiði-
Hvannasund, 2.5 km south of Viðareiði

He-Th*. Me-Me*-Ch-Se.

As in the vesicles.

1-2

VI3

The W and the SW slope of Malinsfjall

150

He-Th*. Me-Me*-Ch. An-Me*-Ph.

1-2

VI3

- do -

200-220

Th*. Ch. Le.

Me. Me*. Th. Th*. An. St.

0-1

VI3

- do -

255

Th*. Ph. An.

He-St.

1-2

VI3

The W and the SW slope of Malinsfjall

310

Th*-Ch.

0-1

VI3

- do -

300-330

Me-Th*. Gi-Ch.

0-2

VI3

- do -

440

Th*. Ch. About 50% of the vesicles are
empty.

An-St.

0-1

VI3

- do -

540

As above.

0-1

VI3

- do -

605

Ch-Th-Le. Ca.

Ca-Th-Ca.

0-1

VI3

- do -

660

All vesicles are empty.

0-1

VI3

- do -

680

As above

0-1

VI3

- do -

710

Scattered mineralisations of Th and Ch.

0-1

VI3

The summit of Malinsfjall

750

As above.

0-1

GEUS Bulletin no 9 - 7 juli.pmd

07-07-2006, 14:19

155

156

Max depth

Min depth

Vesicles

Zone

Lopra-1/1A

-3543 -3400

La , Pr, Ca, Cl.

-3400 -3200

La, Mo , Pr, Cl.

-3200 -3000

La, Mo , Pr, Sm, Qz.

-3000 -2800

La , Pu, Qz, Cl.

-2800 -2600

(no data)

-2600 -2400

La , Ca, Pr ,Cl.

-2400 -2200

La , Pr, Pu.

-2200 -2000

Th,

Ep,

He,

La , Pr, Wa, Mo, Ca, Ce,

Sm, Cl, Si.

5-6

-2000

-1800

Sc, Th, Ep, He, La, An, Ca, Ce, Cl,

Si.

3-5

-1800 -1600

Sc,

Th,

St , Ep, La , An, Ca, Ce, Sm,

Cl,

Si.

3-5

-1600 -1400

Sc,

Th,

St , Ep, He, La , An, Ca, Ce,

Sm, Si.

4-5

-1400 -1200

Me,

Th,

St, Ep, He , La, Ce, Sm, Cl,

Si.

4-5

-1200 -1000

Me, Sc, Th, E p, He, La.

3-4

-1000 -800

Me, Sc, Th, St, Ep , He, La, An, Ca,

Cl,

Si.

3-4

-800 -600

Th,

St,

Ep, He , La, An, Cl.

3-4

-600 -400

Me,

Sc , Th, Ep, He. An. Ca.

2-3

-400 -200

Me, Sc , Th, Ep , He, An, Ca, Cl, Si.

2-3

-200 0

Me, Sc, Th, St, He , An, Mo, Ca, Cl, Si.

2-3

Vestmanna-1

-600 -575

He.

He-Ch.

3-4

-575 -550

He.

An. St-St*. Ch-Sm. 3-4

-550

-525

He-Ch. Ap. Th-Ap. Ch-Sm. 3-4

-525

-500

He. He-Ac. Th-Ch. St-Ch.

-500 -475

An-Th-Mt. Th-Sm. 3-4

-475 -450

An-Th-Sm. Th-Sm. 3-4

-450 -425

Gy-Th-Sm. An. An-Th-Sm. Th. Sm. 3-4

-425 -400

An. He-La-Ch. Me-Ch. Th-Sm.

Ch-Sm. 3-4

-400 -375

He-La-Ch.

Me-Ap-Ch.

Me-Ch+Le-Sm. Ch-Sm. 3-4

-375 -350

Me.

Gy-Th-Sm. Th-Sm. Th*-Ch.

Ch+Le.

2-4

-350

-325

Ap. Th-Ap. Gy-La. Gy-Th-St. Ph.

Th*-Sm. Th*-Ch.

1-4

-325

-300

He. He-Me. He-La-Ch. Mo-He-Ch,

Th*-Sm. Th*-Ch, Ch-Sm. 2-4

-300

-275

He. He-Ch. Me-He-St. Th-Ga-Ch.

Th*-Ph-Ch. Th*-Ch. Ch-Sm. 2-4

-275

-250

Me. Me-Th-Ch. Me-Th-Ph-Ch..

La-Me. Ap. Th-Ch-Sm. Ch-Sm. 2-4

-250 -225

Th-Gy-Sm. Th-Th*-Ch. He-Th-Ap.

Le-Sm. 2-4

-225 -200

-200 -175

He.

He-Ch-Ap-Sm. Me-Ch, Th-Th*-

Ch. Th-Gy-Mt. Th-Ap. An. Ap. Le-Sm. 2-3

-175

-150

Me-He-Me*. Me-He-Ap. Me-Ap. Me-

He-Th-Le.

Me-Th-Ph-Ch.

Th*-Ch

-Le. Na-Ch. Ch-Sm. 2-3

-150

-125

Me. Me-Th-Ph-Ch. Ph-Sm. Me*-Ch

An-Sm. 2-3

-125 -100

-100 -75

Me.

Me-Th-Ch-Sm. Me+Na-Ap-Sm.

Me*-Ch.

An-Ep-Ch. Mo-Ch. Th-Ch.

2-3

-75

-50

He. He-Th. Mo-He. Me-Th. Na-Ch.

Th-Ch. Me*-Ch. Ch-Sm. 3-4

-50 -25

Ch-Sm. Ep-Ch.

3-4

-25

Me. Me*. Me-Ap. Me-Th. Me*-Ch.

Mo-Ch.

2-3

Appendix B. Minerals found in vesicles within different depth intervals in

the Lopra-1/1A and Vestmanna-1 boreholes

GEUS Bulletin no 9 - 7 juli.pmd

07-07-2006, 14:19

156

Geological Survey of Denmark and Greenland Bulletin

Nr. 9, Scientific results from the deepened Lopra-1-, Faroe Islands, pp. 123-156

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