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New Insights on the Deeper Crustal Structure of the Western Greenland Margin and Implication for Hydrocarbon Prospectivity

Abstract

This study investigates the crustal structure of the Western Greenland margin by integrating gravity and magnetic modelling with seismic reflection data interpretation. We use this definition of crustal structure to consider heat flow variations associated with lithospheric stretching and consider its implications on the hydrocarbon prospectivity of the margin. Seismic interpretation of representative 2D reflection profiles along the entire West Greenland Margin from Labrador Sea, Davis Strait and Baffin Bay were undertaken to identify sedimentary and structural component of the margin. Having established the tectonic framework we calculate crustal thinning factors on depth-converted seismic profiles with the objective of understanding the driving mechanism for rifting on the margin. Based on our analyses we find that the stretching factor ß from the upper crust faulting (typically ∼1.1 to 1.4) is less than the stretching factor ß from the whole lithosphere (from ∼1.5 to >10). Furthermore, we then compare the results of gravity and magnetic modelling with observed data to better constrain interpretation of oceanic and continental crust. There is a good correlation between modelled gravity anomaly and observed anomaly in areas of oceanic crust. In these areas we use the vertical derivative of the magnetic data to better define oceanic lineaments; in particular we can define the now extinct spreading axis between Canada and Greenland. This interpretation is consistent with seismic interpretation. In areas of continental crust higher variability in the correlation exists reflecting greater uncertainty in the structure of the continental lithosphere. Through integrating our lithospheric understanding from gravity and magnetic modelling with reflection interpretation we derive a well constrained model of the margin geometry along its length. In particular the variation in degrees of crustal stretching provided hint on the nature of the transition between ocean-continent along western Greenland. By applying integrating this variation in heat flow to the basin architecture we consider the implications for hydrocarbon prospectivity of the margin. Potential source rocks are mid cretaceous strata deposited in rift-depressions and are characterised by maxima on the heat flow gradient.