GEUS Geology of Greenland

GEUS Geology of Greenland (ONEGEOLOGY)

Part of the digital version of Geological map of Greenland 1 : 2 500 000 (Escher, J.C. and Pulvertaft, T.C.R. 1995). Available in this OGC WMS service for personal, non-commercial use only and being served as a contribution to the OneGeology initiative(www.onegeology.org). Separate layers for unit polygons, contacts, and linearments are available in this service. The layer titles are geology, contacts and lines respectively. 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. 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. In the legend 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.

GRL GEUS 1:2.5M Contacts (GRL_GEUS_2500k_CON)

GRL GEUS 1:2.5M Contacts