Bitumens, Stains, and Oil Seepages in Greenland – a Review

Jørgen Bojesen-Koefoed

Bitumens, stains and seepages are known from most regions in Greenland that host notable volumes of sedimentary rocks as well as from a few areas where the country rock is crystalline. Even a few samples from the seabed show traces of petroleum. Some bitumens are not amenable to analysis, but most traces of petroleum can be tied to known source rocks or their origin inferred from their composition. Due to the Inland Ice the central part of Greenland is unexposed and oil traces are known only from the fairly narrow stretch of land extending around the perimeter of the island. Starting in the southwest, continuing clockwise, the occurrences can be mapped out: In southwest Greenland, where the country rock, except for the Igaliko sandstones, is crystalline, the Mesoproterozoic Illimaussaq intrusion host traces of oil as minute droplets and coatings on mineral grains. The source is unknown, but the biomarker signature suggests generation from a Late Cretaceous or younger source. The oil probably entered the intrusion prior to major Palaeogene uplift. Further north, a small inlier of Ordovician limestones is found in the basement area at the locality “Fossillik”. The limestones host droplets of liquid oil with a remarkable composition and a clear carbonate source origin. No source rock has been found, but the petroleum is regarded as intraformational. The central West Greenland sedimentary basin hosts 7+ Km of Cretaceous-Paleocene sediments, capped by up to nearly 2 Km of Palaeogene plateau basalts. Petroleum seepage and staining is widespread over an area of 7000 Km², and five different types of oil and several mixtures have been identified. Four of the oil types have known or inferred source rocks with ages ranging from the Albian to the Paleocene. The documentation of extensive oil seepage in central west Greenland has been important for the upsurge in exploration activities that has taken place in the region over recent years. The Franklinian Basin of North Greenland hosts a thick sedimentary succession of Palaeozoic age that includes several potential source rocks of both Cambrian, Ordovician and Silurian age. A number of oil-stains and bitumens are known from the region, including spectacular infillings of lumens in tabulate corals. However, high thermal maturity often precludes analysis of the oil traces and identification of their sources. Traces of petroleum are known from Northeast Greenland where a thick succession of sedimentary of Ordovician to Tertiary age. Several known potential source rock units have given rise to oil traces varying in character from solid bitumens in the vicinity of intrusions, to liquid oils bleeding form drillcores or from vugs in cemented fracture zones. In addition, the much debated “exhumed oilfields” are found here. Except for the Kangerlussuaq area, the country rocks in Southeast Greenland are crystalline, and no traces of petroleum have been reported.

AAPG Search and Discovery Article #90177©3P Arctic, Polar Petroleum Potential Conference & Exhibition, Stavanger, Norway, October 15-18, 2013