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Source Facies Prediction in the Mesozoic and Cenozoic Circum-Arctic

Previous HitPaulNext Hit Markwick1, Lawrence Gill1, and Previous HitPaulTop Valdes2
1GETECH Group plc, Leeds, United Kingdom
2Department of Geographical Sciences, University of Bristol, Bristol, United Kingdom

The Circum-Arctic is one of the last potentially large frontier exploration targets, but is data poor in many areas. Consequently, predictive lithofacies models are an important tool for reducing risk. We have used process-based models, which combine detailed palaeogeography with the results of palaeo-ocean-atmosphere model experiments, to predict lithofacies in the Arctic during the Mesozoic and Cenozoic. Here we concentrate on source facies, comparing predictions with our growing database of lithological and geochemical information.

The Circum-Arctic provides an intriguing palaeoenvironmental puzzle, as Early Cretaceous collisions in the Russian Far East and Alaska led to the closure of all deep water connections to the main ocean system, although shallow seaway connections occurred intermittently through the Cretaceous and Palaeogene (sill depths <100m). This would have affected the structure and chemistry of the palaeo-Arctic ocean basin, and made the ocean extremely sensitive to nutrient and freshwater flux changes from the adjacent hinterland. Our model results support this. Primary productivity does not appear to have been a limiting factor in the palaeo-Arctic with persistent ocean upwelling around the margins, modified locally and regionally by nutrient fluxes from surrounding rivers. Transport of organic matter would have been dominated by ocean and gravity currents, with minimal tidal influence due to the high latitude; we predict that high freshwater fluxes during specific intervals would have increased the importance of hypopycnal transport of fine material.

Our research suggests that prospectivity in the Arctic is not limited by source facies, but that the character and distribution of these is dictated by both oceanographic processes (stratification and upwelling) and also nutrient and freshwater flux changes from the hinterland.

 

AAPG Search and Discover Article #90078©2008 AAPG Annual Convention, San Antonio, Texas