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Laptev Sea: A Natural Laboratory fo Studying Breakup of Continents

Author(s): Sergei Drachev ExxonMobil International Ltd., ExxonMobil House, MP44, Ermyn Way, Leatherhead, Surrey, KT22 8UX, United Kingdom

Laptev Sea continental margin in the Siberian Arctic is one of a few places worldwide where a spreading ridge (the Gakkel Ridge) abuts upon a continental margin shaping its structural style, which is unusual for a typical continental passive margin. This mega-structural T-junction has been evolving since at least Late Cretaceous resulting in a continental lithosphere breakup along a Timanian edge of Baltica in Barents-Kara region, and in fmmation of a wide continental rift zone within Laptev Sea underlain by a younger crust dominated by Mesozoic fold belts. The present day divergent plate tectonic boundary between NA and EUR plates crosses the Laptev Sea, and associated extension represents a most recent attempt of breaking up the Eurasia continent- a reminder of the Pangaea Supercontinent. Two earlier successful attempts were realized in the Newfoundland-Iberia and LabradorBritish Isles segments of the North Atlantic in Jurassic and Cretaceous times. All three cases are characterized by:

(i) Similar T-like conjugation of a spreading ridge with a large transcurrent fault (fracture zone) shaping a continent-ocean transition: the Azores-Gibraltar, Charlie Gibbs, and Khatanga-Lomonosov faults; (ii) Development of wide continental rift zones on an apparent projection of oceanic spreading axis; (iii) Broad strain partitioning from low-magnitude half-grabens to hyperextended rift basins underlain by exhumed mantle; lo the Laptev Sea, the first failed attempt of a spreading axis breakthrough has probably taken place in Late Cretaceous to Early Eocene in its westem patt. And resulted in forrnation of a hyperextended Ust' Lena Rift. Its failure has probably been caused by a pre-existing Khatanga-Lomonosov Fracture Zone, which started to defer extension strain eastward soon after the breakup event in the Eurasia Basin at c. 56 Ma. The Laptev Sea rifting has probably ceased between c. 56 and 33 Ma during the main spreading phase along the Gakkel Ridge, and resumed around Mid Miocene. The recent extension is focused in the eastem Laptev Shelf along another zone of weakness in the basement - offshore extent of the Early Cretaceous South Anyui Suture.

Laptev Sea: A Natural Laboratory for Studying Breakup of Continents
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ExxonMobil International Ltd., ExxonMobil House, MP44, Ermyn Way, Leatherhead, Surrey, KT22 8UX
United Kingdom
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