Exhumation Histories in the Barents Sea: Challenging the Post-Glacial Myth!

Paul Green and Ian Duddy
Geotrack International, Melbourne, Australia

It is well established that the Mesozoic and older sequences of the Barents Sea have been exhumed from significantly greater depths, but ideas regarding the amount of section removed and the timing of exhumation remain controversial. Estimates of the onset of exhumation vary from Quaternary to Early Cenozoic, with models relating exhumation to post-glacial rebound being favoured in the past, due to the lack of obvious mechanisms for explaining regional Cenozoic exhumation. Integration of apatite fission track analysis and vitrinite reflectance data in 26 wells across the Barents Sea defines a multi-phase exhumation history. Across most of the Southern Barents Sea, exhumation began in the Eocene, while further north a Paleocene onset is identified. Onshore data from Byornoya reveal Late Cretaceous exhumation, while a possibly correlative episode (150-70 Ma) is recognised on the Loppa High. Neogene cooling of lesser magnitude is also recognised across the entire region. Results suggest that Mesozoic-Cenozoic basal heat flows were similar to present-day values, with estimates of the thickness of section removed since the onset of exhumation varying from ~1 to ~2 km across most of the region. No significant Quaternary cooling is identified in any of the wells analysed, and despite the lack of obvious mechanisms, it is clear that exhumation began in Paleogene times or earlier across most of the Basin. Similar episodes of regional exhumation have affected many other areas. Such events, the importance of which has been seriously underestimated in the past, often exert the dominant influence on hydrocarbon prospectivity.

AAPG Search and Discovery Article #90072 © 2007 AAPG and AAPG European Region Conference, Athens, Greece