A Unifying Tectonic Model for Early Mesozoic Development of the South Kara and Russian Barents Basins
Michael A. Sullivan1, Nial W. McAllister2, George M. Thomas2, Robert J. Ferderer1, and Steve Creaney1
1ExxonMobil Exploration Co., Houston, TX.
2ExxonMobil International Limited, Leatherhead, United Kingdom.
Although several tectonic scenarios exist for creation and fill of the South Kara and Russian Barents basins, no satisfactory model addresses the nature, timing and role played by the intervening Novaya Zemlya Fold Belt. We present a single solution that establishes a genetic framework for basin development across the region. Our approach focuses on the final closure of the northernmost Uralian Ocean.
South Kara basin represents a northern continuation of the larger West Siberia basin. Both are viewed as Permo-Triassic post-collisional successor basins founded on Altaid accretionary basement. Separating South Kara and Russian Barents basins are tectonic fold belts of Novaya Zemlya and Pay Khoy. Contractional deformation in both is Late Triassic in age, and as such is largely contemporaneous with extension and basin formation in the South Kara. Moreover, no significant folding is recorded in the South Kara until weak Tertiary far-field contraction.
In contrast, the Russia Barents is founded on Precambrian accretionary crust. Basin history is complex, with at least 2 phases of extension identified. The first occurred during Ordovician opening of the Uralian Ocean. Extension returned in mid-Devonian, but this time the cause is enigmatic and may be related to a combination of post-Caledonian plate reorganizations and hot-spot magmatism. Today the deepest part of the basin comprises thickness approaching 14-16 km and the majority of the fill is Permo-Triassic foreland material derived from the Urals Orogenic Belt to the south. Surprisingly little was provided by the Novaya Zemlya collision zone.
To accommodate largely contemporaneous mid-late Triassic basin formation and contractional deformation around South Kara basin margins, we invoke roll-back of the last remnants of southward subducting Uralian oceanic crust under northernmost West Siberia. As arc and fore-regions collided into the re-entrant formed by the Pay Khoy, Novaya Zemlya and N. Kara margins, complexly orientated depo-centers opened in the South Kara Sea, and into these were shed sediments derived from the Altaids. At the same time, the Russia Barents was receiving ongoing Uralian lateral fore-land fill.
Several key challenges remain regarding adoption of this tectonic model. No arc is identified along the NW Siberia margin, although it may lie in the basement of the South Kara basin.
AAPG Search and Discover Article #90096©2009 AAPG 3-P Arctic Conference and Exhibition, Moscow, Russia