--> ABSTRACT: Heat-Flow Prediction from Gravity Inversion Mapping of Crustal Thickness and Lithosphere Thinning: Application to Arctic Rifted Continental Margins, by Kusznir, Nick J.; Alvey, Andy; #90135 (2011)

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Heat-Flow Prediction from Gravity Inversion Mapping of Crustal Thickness and Lithosphere Thinning: Application to Arctic Rifted Continental Margins

Kusznir, Nick J.1; Alvey, Andy 2
(1)Earth and Ocean Sciences, University of Liverpool, Liverpool, United Kingdom. (2) Badley Geoscience, Hundleby, Spilsby, United Kingdom.

The prediction of heat flow at the ocean-continent transition of rifted continental margins presents a substantial scientific and technical challenge in frontier deep-water hydrocarbon exploration. We determine top basement heat-flow for the Amerasia and Eurasia Basins of the Arctic using gravity inversion mapping of crustal thickness and continental lithosphere thinning. Using gravity anomaly inversion, we have produced the first comprehensive regional maps of Moho depth, crustal thickness, continental lithosphere thinning and oceanic lithosphere distribution for the Arctic. Continental lithosphere thinning and post-breakup residual thicknesses of continental crust determined from gravity inversion have been used to predict the preservation of continental crustal radiogenic heat productivity and the transient lithosphere heat-flow contribution within thermally equilibrating rifted continental margin and oceanic lithosphere. The resulting crustal radiogenic productivity and lithosphere transient heat flow components, together with base lithosphere background heat-flow, are used to produce regional maps of present-day Arctic top-basement heat-flow. We determine crustal thickness, continental lithosphere thinning factors and ocean-continent transition location using a new gravity inversion method which incorporates a lithosphere thermal gravity anomaly correction (Greenhalgh & Kusznir, 2007; Chappell & Kusznir, 2008). NGA (U) Arctic Gravity Project and IBCAO bathymetry data are used in the gravity inversion. The ocean basins of the Arctic formed during the Late Jurassic, Cretaceous and Tertiary as a series of small distinct ocean basins leading to a complex distribution of oceanic crust, rifted continental margins, micro-continents and ridges. Our gravity inversion predicts thin crust and high continental lithosphere thinning factors in the Makarov, Podvodnikov, Nautilus and Canada Basins consistent with these basins being oceanic or highly thinned continental crust. Larger crustal thicknesses, in the range 20 - 30 km, are predicted for the Lomonosov, Alpha and Mendeleev Ridges. Locally thinner crust is also predicted in the Laptev Sea, North Chuchki and East Siberian Sea Basins. The sensitivity of present-day Arctic top basement heat-flow to initial continental radiogenic heat productivity, continental breakup age and oceanic lithosphere age has been examined. The techniques described above are applicable globally to all rifted continental margins.

 

AAPG Search and Discovery Article #90135©2011 AAPG International Conference and Exhibition, Milan, Italy, 23-26 October 2011.