Greenland from Archaean to Quaternary. Descriptive text to the Geological map of Greenland, 1:2 500 000

Abstract

NOTE: This monograph was published in a former series of GEUS Bulletin. Please use the original series name when citing this monograph, for example:
 Henriksen, N., Higgins, A., Kalsbeek, F., & Pulvertaft, T. C. R. (2000). Greenland from Archaean to Quaternary. Descriptive text to the Geological map of Greenland, 1:2 500 000. Geology of Greenland Survey Bulletin, 185, 2-93. https://doi.org/10.34194/ggub.v185.5197
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 The geological development of Greenland spans a period of nearly 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 km2, but only c. 410 000 km2 are exposed bedrock, the remaining part being covered by an inland ice cap reaching over 3 km in thickness. The adjacent offshore areas underlain by continental crust have an area of c. 825 000 km2. Greenland is dominated by crystalline rocks of the Precambrian shield, which formed during a succession of Archaean and early Proterozoic orogenic events and which stabilised as a part of the Laurentian shield about 1600 Ma ago. The shield area can be divided into three distinct types of basement provinces: (1) Archaean rocks (3100-2600 Ma old, with local older units) almost unaffected by Proterozoic or later orogenic activity; (2) Archaean terraines reworked during the early Proterozoic around 1850 Ma ago; and (3) terraines 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 activity affected parts of these successions in the Ellesmerian fold belt of North Greenland and the East Greenland Caledonides; the latter also incorporates reworked Precambrian crystalline basement complexes. Late 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 and southern 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 continental 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, geophysical data combined with extrapolations from onshore studies have revealed a considerable potential for offshore oil and gas. The description of the map has been prepared with the needs of the professional geologist in mind; it requires a knowledge of geological principles but not previous knowledge of Greenland geology. Throughout the text reference is made to the key numbers in the map legend indicated in square brackets [ ] representing geological units (see Legend explanation, p. 79), while a Place names register (p. 83) and an Index (p. 87) include place names, geological topics, stratigraphic terms and units found in the legend. The extensive reference list is intended as a key to the most relevant information sources.

High export of dissolved silica from the Greenland Ice Sheet

“…Given the GrIS area of 1.710.000 km 2 , this translates into a DSi yield of 7–17 mmol Si m −2 yr −1 , which is similar to yields from the Siberian Arctic [ Dürr et al , ]. Note that these are conservative estimates as the GrIS drains large areas with basaltic rock formations that are likely associated with higher DSi concentrations [ Yde et al , ; Henriksen et al , ]. Our export estimate of 22 Gmol Si yr −1 represents around 7% of riverine DSi flux to the Arctic [ Holmes et al , ] and corresponds to 0.3% of the global DSi input to the ocean [ Tréguer and De La Rocha , ].…”

Glacial landscape evolution in the Uummannaq region, West Greenland

“…; Henriksen et al . ). These softer lithologies are more susceptible to both basal and lateral erosion than Archean basement rocks and Tertiary basalt and we propose that the decrease in the number of fjords into a single broad trough is geologically controlled.…”

“…; Henriksen et al . ). The Uummannaq region is dissected by an east–west trending fjord system, which routes outlet glaciers towards the sea where they converge to form the onset zone of the Uummannaq Ice Stream (UIS; Ó Cofaigh et al .…”

“…; Henriksen et al . ); and Tertiary basalts, which form Ubekendt Ejland, Svartenhuk, the western half of Nuussuaq, and extend offshore (Area 3 in Fig. ; Henriksen et al .…”

A 10Be chronology of early Holocene local glacier moraines in central West Greenland

“…The Nákâgajoq mountain region is dominated by Archean gneiss that experienced granulite facies metamorphism during the Proterozoic (Henriksen et al . ). Much of the bedrock in the uplands of our study area has undergone extensive frost shattering and there is evidence of solifluction along the lower slopes of the Nákâgajoq mountain massif.…”