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Geological map of Greenland 1 : 2 500 000

Geological Survey of Denmark and Greenland (GEUS)
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Description


Introduction

The geological development of Greenland spans a period of 4 Ga, from the earliest Archaean to the Quaternary. Greenland is the largest island in the world with a total area of 2 166 000 km, but only c. 410 000 km are exposed bedrock, the remaining part being covered by an inland ice cap reaching over 3 km in thickness. The adjacent offshore shelf areas underlain by continental crust have an area of c. 825 000 km.
Greenland is dominated by crystalline rocks of the Precambrian shield, formed during a succession of Archaean and early Proterozoic orogenic events which stabilised as a part of the Laurentian shield about 1600 Ma ago. The shield area can be divided into three distinct basement provinces: (1) Archaean rocks (3100–2600 Ma old, with local older units), almost unaffected by Proterozoic or later orogenic activity; (2) Archaean terranes reworked during the early Proterozoic around 1850 Ma ago; and (3) terranes mainly composed of juvenile early Proterozoic rocks (2000–1750 Ma old).

Subsequent geological developments mainly took place along the margins of the shield. During the later Proterozoic and throughout the Phanerozoic major sedimentary basins formed, notably in North and North-East Greenland, and in places accumulated sedimentary successions which reached 10–15 km in thickness. Palaeozoic orogenic belts, the Ellesmerian fold belt of North Greenland, and the East Greenland Caledonides, affected parts of these successions; the latter also incorporates reworked Precambrian crystalline basement complexes.
Upper Palaeozoic and Mesozoic sedimentary basins developed along the continent–ocean margins in North, East and West Greenland and are now preserved both onshore and offshore. Their development was closely related to continental break-up with formation of rift basins. Initial rifting in East Greenland in latest Devonian to earliest Carboniferous time and succeeding phases culminated with the opening of the North Atlantic in the late Paleocene. Sea-floor spreading was accompanied by extrusion of Tertiary plateau basalts in both central West and central East Greenland.
During the Quaternary Greenland was almost completely covered by ice sheets, and the present Inland Ice is a relic of the Pleistocene ice ages. Vast amounts of glacially eroded detritus were deposited on the coastal shelves offshore Greenland.
Mineral exploitation in Greenland has so far mainly been limited to one cryolite mine, two lead-zinc deposits and one coal deposit. Current prospecting activities in Greenland are concentrated on the gold, diamond and lead-zinc potential. The hydrocarbon potential is confined to the major Phanerozoic sedimentary basins, notably the large basins offshore East and West Greenland. While proven reserves of oil or gas have yet to be found (as of 1998), geophysical data combined with extrapolations from onshore studies have revealed a considerable potential for offshore oil and gas.

Geological Map of Greenland in scale 1:2.5 million reduced to c. 10%.
For more details go to index map


This has been prepared with the needs of the professional geologist in mind as a key to the most relevant information sources.


Two different legend concepts have been used – one for the onshore ice-free areas and one for the offshore regions.
In the legend for the ice-free land areas a distinction has been made between rocks older and younger than 1600 Ma. In the older group, which mainly comprises crystalline rocks of the stable Precambrian Greenland shield, the rock units are distinguished according to their lithology and age; the extent of regional tectono-metamorphic provinces is also depicted. Developments younger than 1600 Ma are shown in relation to the formation of sedimentary basins and orogenic belts along the margins of the stable shield. The principal subdivision depicted on the map illustrates the general depositional environment, age and extent of the main sedimentary and volcanic basins and, in the Franklinian Basin in North Greenland, the overall depositional setting. Younger crystalline gneisses and plutonic rocks are distinguished by lithology, and age of orogenic formation and emplacement. A schematic chronological representation of the geological units shown on the map is included in the map legend.
The legend concept for the offshore areas is based on geological interpretation of the available geophysical data. Distinction is made between areas underlain by continental crust and areas underlain by oceanic crust; a transition zone is also recognised. Areas with oceanic crust are further subdivided into time slices of 15 Ma based on magnetic anomaly patterns. Magnetic anomaly lines with chron-numbers are shown, together with spreading axes and transform faults. Major sedimentary basins are indicated by isopachs showing the sediment thickness superimposed on a representation of crustal type. Volcanic rocks exposed on the seabed (mostly Tertiary in age) are also shown. Geological units indicated by key numbers in bracnets ( ) in the following text refer to numbers in the map legend.


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