Cenozoic Seismic-Stratigraphy, Depositional Systems and Fluid-Flow Features in NE Baffin Bay, West Greenland
Paul Knutz, Ulrik Gregersen, and John R. Hopper
Geophysics, Geological Survey of Denmark and Greenland, Copenhagen, Denmark.
The Cenozoic architecture in the NE Baffin Bay has been analysed using newly acquired seismic reflection data. The main scope is to identify depositional systems and fluid-flow features as part of the ongoing assessment of hydrocarbon prospectivity in the region. The Cenozoic strata is divided into 5 mega-units by mapping regional unconformities with age estimates based on correlation to wells further south and onshore geological evidence in Greenland and Canada.
Units A and B construct a 1500-2500 m thick package of glacigenic clinoform units that has shaped the present West Greenland margin into its present topography, notably by development of trough-mouth fans at the termination of Pleistocene icestreams and a thick basin succession interpreted as stacked mass-transport deposits. Unit C (~MidMiocene - Pliocene) appear as a condensed, truncated package over the mid-shelf region with seismic facies implying a contourite depositional regime. In the southern Melville Bay Graben (MBG) Unit C show a depocentre that is truncated at sub-seabed position and presently form the flank of a glacial trough. Unit D (~MidEocene - MidMiocene) is mainly interpreted as a mudstone package, intensely faulted by syn-depositional fluid escape. In the MBG it attains thicknesses of up to 2500 m with strata truncated at subsea-level toward the main boundary fault. Unit D thins along the shelf margin, partly due to erosion and mass-mobilisation, while thickening >1000 m into the conformable succession of the central basin. Unit E (~post-basalt Paleogene) is characterised by wedge geometries building westward into the MBG and Kivioq Basin. This pattern generate large thickness variations with >2000 m deposited in the grabens and thinning/onlap along structural highs. Over the basin area Unit E is more uniform, showing lenticular and hummocky strata filling in the basement topography.
A combination of fluid-flow/DHI and depositional systems with sand-potential are seen on several sections of the seismic grid, notably within Unit D. In the MBG mounded features, 10-20 km wide and 3-400 ms thick, may possibly represent differential compaction of a major sand fairway along the graben axis. In the NW basin region the presence of gull-wing reflectors below a broad aggradational bulge, covering an area of at least 1600 km2, is interpreted as channel-levee components of a deep-sea fan system.
AAPG Search and Discover Article #90096©2009 AAPG 3-P Arctic Conference and Exhibition, Moscow, Russia