--> Abstract: New Insight into the Ammassalik Basin, Southeast Greenland, by Will Bradbury; #90177 (2013)

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New Insight into the Ammassalik Basin, Southeast Greenland

Will Bradbury

This contribution presents the results of the first of TGS’ interpretations from newly available long offset modern 2D seismic data acquired in southeast Greenland in conjunction with seafloor samples acquired during the ABS 2012 cruise. The previously available short offset data in the area was not designed to image deeper sedimentary packages and define basin geometries (DLC transects were intended to sample the continental–oceanic transition of the seaward-dipping reflectors). The new survey location and parameters builds on many years of combined gravity and magnetic interpretations conducted in association with VBPR. These interpretations have indicated the presence of a basin to the south of Ammassalik. Coupling new seismic and seafloor samples with existing gravity and magnetic data allows a high level assessment of the overall structural and stratigraphic framework of this basin and represents the first steps towards understanding prospectivity in the area. The southeast Greenland margin is a rifted margin with a narrow (50km) wide platform in the south and several hundred kilometers in the north. The margin was formed by continental breakup between Greenland and Europe about 56 Ma ago. The Ammassalik shelf has a width of approximately 200km and a length of 240km between 63 and 65 deg north. The free-air gravity anomaly map is characterized by broad NE-E trending anomalies correlating with the main morphological features. The 400km high-pass filtered Bouguer anomaly map in conjunction with the 200km Bouguer anomaly map reveals intermediate to deep crustal density changes or Moho relief. The resulting gravity field delineates structural highs and gravity lows corresponding to deep basin(s). Magnetic facies maps created using the 200km high pass filtered magnetic and Bouguer anomaly maps are used for delineating areas with major differences in crustal configuration and physical properties. Newly acquired in 2011 TGS’ airborne gravity and magnetic data indicated the presence of a relatively large basin in the area. Good correlations are seen between the gravity and magnetic anomalies over the Ammassalik Basin. The combined gravity and magnetic analyses allows delineation of the general extent and geometry of the basin. Potential prospectivity is partly supported by evidence from the scientific drilling in the area (Ocean Drilling Project); previous seafloor sampling recovering Late Cretaceous or Paleocene aged sediments with high porosities (30%) and new data from the ABS12 cruise recovering gravity cores. Preliminary geochemical analyses on good to very good seep samples indicate live oil from deeper source rocks in what is interpreted as a pre-breakup basin. The interpretation based on newly acquired seismic data in the area greatly enhances our knowledge of the overall basin geometry coupled with the structural and stratigraphic framework tied into the seafloor sampling and shallow borehole data.

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