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Mesozoic-Tertiary deposits

 
Carboniferous-Tertiary deposits of the Wandel Sea Basin,Late Palaeozoic and Mesozoic rift basins

Carboniferous–Tertiary deposits of the Wandel Sea Basin, central and eastern North Greenland
The Wandel Sea Basin deposits were laid down along the northern and north-eastern margin of the Greenland shield. Three main phases of basin formation are recognised, commencing with a widespread Carboniferous to Triassic event of block faulting and regional subsidence. Later, during the Late Jurassic and Cretaceous, more localised basin formation took place during two separate events in a strike-slip zone formed at the plate boundary between Greenland and Svalbard.

Distribution of the Walndel Sea Basin sequences in central and eastern North Greenland

Lup Composite section of the Wandel Sea Basin successions in eastern North Greenland.
Late Palaeozoic and Mesozoic rift basins in East Greenland
A series of Carboniferous–Mesozoic sedimentary basins formed in East Greeland following initial post-Caledonian Devonian deposition. The basins formed as N–S trending coast-parallel depocentres which reflect prolonged subsidence. Important phases of block faulting and rifting took place during the Early and Late Carboniferous, Late Permian, Late Jurassic and Cretaceous, presaging the opening of the North Atlantic in the Late Paleocene. There is a marked difference in post-Carboniferous structural style and depositional history between the basins south and north of Kong Oscar Fjord (c. 720N). The Jameson Land Basin to the south developed as a Late Permian – Mesozoic sag basin, while the region to the north was characterised by continued block faulting and rifting.
The Jameson Land Basin contains a stratigraphically complete succession of Upper Permian to earliest Cretaceous sediments. Sediment infill was derived from both the east and west during most of the basin history.
Upper Palaeozoic - Mesozoic basin in East Greenland. Southern development at Jameson Land (c. 71°N). Colours approximately as used on the map.

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Schematic section of the southern (Jameson Land) developments in the Late Permian and Mesozoic rift margin basins of East Greenland.

Cretaceous–Tertiary sediments
In central West Greenland Cretaceous–Tertiary sediments [8] outcrop in the Disko–Svartenhuk Halvø region (69–72oN) of West Greenland, where they are overlain by Lower Tertiary basalts. The sediments were laid down in the Nuussuaq Basin. Although now bounded to the east by an extensional fault system, the sediments may originally have extended both east and south of their present area of outcrop. Recently acquired seismic data indicate that the maximum thickness of sediments in the basin exceeds 8 km, but the age and character of the deepest sediments are not known.

Tertiary volcanics, intrusions and post-basaltic sediments
The early Tertiary lava regions of both West and East Greenland represent major eruption sites at the edges of the continent, from which lavas spilled over Mesozoic sedimentary basins and lapped onto the Precambrian basement of the continental interior. The volcanic products were formed during the initial phase of continental break-up and initiation of sea-floor spreading in the early Tertiary.

Tertiary basalts, central West Greenland
In central West Greenland Tertiary volcanics crop out between latitudes c. 69o and 73oN. They are noted for the presence of native iron-bearing basalts and the large volumes of high-temperature picrites and olivine basalts. The composite thickness of the sequence varies between 4 and 10 km, with the smallest thickness on Disko and a maximum on Ubekendt Ejland/Illorsuit (71oN).
Eruption of the basalts began in a submarine environment, and the earliest basalts, which occur to the west, consist of hyaloclastite breccias. When the growing volcanic pile became emergent, thin subaerial pahoehoe lava flows started to form. They flowed eastwards into a deep marine embayment where they became transformed into hyaloclastite breccias which prograded eastwards in large-scale Gilbert-type deltas with foresets up to 700 m high.

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Lithostratigraphic sections in the Nuussuaq Basin, Disko-Nuussuaq region, central West Greenland.
Tertiary basalts, East Greenland
In East Greenland early Tertiary volcanic rocks crop out in East Greenland between latitudes 68o and c. 75oN. South of Scoresby Sund/Kangertittivaq (c. 70oN) plateau basalts cover an extensive region of c. 65 000 km2, resting on Mesozoic–Tertiary sediments in the east and south, and on Caledonian and Precambrian gneisses in the west. North of Scoresby Sund lower Tertiary basic sills and dykes are widespread in the Mesozoic sediments, and a further sequence of plateau basalts is found between latitudes 73o and 75oN.
The earliest Tertiary volcanics are a c. 1.8–2.5 km thick succession of tholeiitic basalts with subordinate picrite [49], which occurs in the southernmost part of the volcanic province between 68o and 68o 30'N. The basalts are aphyric or olivine-pyroxene-phyric, and the succession consists of intercalated subaerial flows, hyaloclastites, tuffs and sediments.
The main part of the region 68o–70oN is made up of a thick succession of tholeiitic plateau basalts which form 5–50 m thick subaerial flows of plagioclase-phyric to aphyric basalt. The succession is at least 5.5 km thick in the central Blosseville Kyst area and thins inland and to the north to 2–3 km.
Major Tertiary intrusive centres in East Grennland (c. 66°30' - 74°N)

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A succession of c. 1100–1200 m of plateau basalts [32] occurs in the Hold with Hope to Shannon region (73°–75°N) in a block-faulted area. The succession is divided into a lower part of uniform tholeiitic lavas and an upper part with variable tholeiitic and alkali basaltic lavas.
Numerous Tertiary intrusions are exposed along about 1000 km of the coastal region of East Greenland between latitudes 66o30' and 74oN, in addition to the many dykes and sills; approximately 20 of these intrusions are shown on the map, separated into felsic [53] and intermediate and mafic [57] types. They reflect episodes of alkaline magmatism linked to the continental break up of the North Atlantic, and range in age from Late Paleocene to Oligocene. The oldest intrusions occur in the south, and have ages between 57 and 47 Ma, whereas the more northerly intrusions (72o–74oN) are all younger, with ages in the range 48–28 Ma.

Lup


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Mesozoic-Tertiary depositis