Continued geophysical and petroleum geological activities in West Greenland in 1995 and the start of onshore exploration

The 1995 summer season saw continued petroleum activities in West Greenland, both onshore and offshore. The activities took place both as major geological and geophysical projects led by the Geological Survey of Denmark and Greenland (GEUS)

A preliminary seismic interpretation of an area with extensive Tertiary basalts offshore central West Greenland

A seismic and geological interpretation of the area between latitudes 67°30'N and 73°N offshore West Greenland, was completed in 1995 and has been published as an Open File Series report (Whittaker, 1995). The area is characterised by extensive Early Tertiary basalts which are the seaward extension of the plateau basalts exposed in the Disko - Nuussuaq - Svartenhuk Halvø area onshore (Clarke & Pedersen, 1976). These basalts present special problems in the processing and interpretation of seismic data. The interpretation incorporates all the seismic data acquired prior to the 1995 field season, inc1uding those lines acquired during the first phase of exploration in the 1970s. Ties to two of the exploration wells drilled offshore southem West Greenland have led to a greater understanding of the timing and kinematics of teetonie events during the Tertiary period; such events are not recorded in the onshore area. The area is considered to have significant exploration potential and warrants additional studies to determine the thickness of the basalt formation in the area.

The Danish Lithosphere Centre in 1995

The Danish Lithosphere Centre (DLC) is funded by the Danish National Research Foundation and was established in 1994 (Larsen, 1995). In 1995 DLC undertook major field geological investigations in both West and East Greenland, and within the Ocean Drilling Program (ODP) drilling on the continental shelf offshore East Greenland. More than 50 national and international researchers were involved in DLC field geological programmes, and 25 researchers from ODP member countries took part in the offshore drilling operations. The general aims and scope of these activities as well as the continued development of the Centre are summarised below. Preliminary results of the 1995 work programmes are given by van Gool et al., Larsen et al. and Brooks et al. (all this report).

Cretaceous – Tertiary pre-drift sediments of the Kangerlussuaq area, southern East Greenland

The main objects of the present study were to supplement the volcanic rifted margin investigations carried out by the Danish Lithosphere Centre and to provide an insight into the basin development during Cretaceous to earliest Tertiary rifting.

Upper Cretaceous dinoflagellate cyst stratigraphy, onshore West Greenland

This study is part of the Geological Survey of Greenland (GGU) project 'Sequence stratigraphic analysis of the Cretaceous sediments in West Greenland', and aims to establish a palynostratigraphy for the Disko-Nuussuaq- Svartenhuk Halvø area in West Greenland.

Filling and plugging of a marine basin by volcanic rocks: the Tunoqqu Member of the Lower Tertiary Vaigat Formation on Nuussuaq, central West Greenland

The volcanic Tunoqqu Member formed at the end of the second of three volcanic cycles in the Paleocene Vaigat Formation. The Tunoqqu Member consists of brown aphyric and feldspar-phyric basalts and forms a marker horizon within the grey picritic rocks of the Vaigat Formation. Most of the basalts are siliceous and were produced by contamination with crustal rocks of magmas ranging in composition from picrite to evolved basalt. Some of the basalts were erupted from local volcanic centres of which four have been identified, whereas other basalts form more regional flows. The four identified eruption centres are located along fault lines and zones of uplift and subsidence, indicating tectonic control. Tectonic control is also inferred to be important in terminating the volcanic cycle and causing the development of high-level magma chambers where the magmas stagnated, fractionated, and became contaminated. The basalts of the Tunoqqu Member form subaerial lava flows in western Nuussuaq. Central Nuussuaq constituted a marine embayment in which the volcanics were deposited as eastward prograding foreset-bedded hyaloclastite breccia fans which indicate water depths of up to 160 m. Eastern Nuussuaq was a gneiss highland with a more than 700 m high NW-SE-elongated gneiss promontory stretching into the sea. During Tunoqqu Member time the volcanic rocks reached the gneiss promontory and blocked the outlet from the south to the sea in the north. This resulted in increased water levels in the enclosed embayment and transformation of the outlet into a torrential river. This river eroded the concomitantly forming Tunoqqu Member volcanics and the gneiss promontory and deposited the material in up to more than 250 m thick foreset-bedded boulder conglomerates in the sea where the north coast of Nuussuaq is now situated.

ODP Leg 163, South-East Greenland volcanic rifted margin

The South-East Greenland margin is a type example of a volcanic rifted margin. The margin is characterised by a broad seaward-dipping reflector sequence (SDRS) composed of basalt that onlaps continental (mainly Precambrian) crust to the west and terminates eastward in oceanic crust of early Tertiary age (Figs 1, 2).

Inglefield Land 1995: geological and economic reconnaissance in North-West Greenland

The state wanted to monitor the exploration developments in Inglefield Land, and consequently, the Government of Greenland, Minerals Office agreed to fund a 4 million kr. follow-up project. This project, carried out by the Geological Survey of Denmark and Greenland, had the main objectives of explaining the geophysical anomalies and circular structures in the area. Apart from the study of the latter, the field work comprised locating selected anomalies by GPS navigation and relating the sites to the regional geology, as well as ore geological studies and geochemical mapping.

Conclusion of the 1:500 000 field mapping in eastern North Greenland

The third and last field season of the mapping project in eastern North Greenland (1993-95) was completed with full accomplishment of all geoscientific goals. The programme included producing a general overview of the onshore geology of the region between Jøkelbugten and Kronprins Christian Land (78°-81°N) aiming at production of a 1:500 000 geological map sheet.

The drilling of stratigraphic borehole Umiivik-1, Svartenhuk Halvø, West Greenland

Svartenhuk Halvø is one of the few areas onshore West Greenland where Upper Cretaceous and Lower Tertiary marine sediments are exposed (Fig. 1). Geological studies in the area have been made intermittently since the late 1930s but have intensified since 1990 as part of the Survey's overall effort to assess the petroleum potential of the Disko - Nuussuaq - Svartenhuk Halvø area and adjacent offshore basins.