The Formation of the Deepwater Basin in the Eastern Central Arctic by Rapid Subsidence of Continental Crust

Eugene V. Artyushkov¹ and V. A. Poselov^2
1Institute of Physics of the Earth, Moscow, Russia.
²VNII Oceangeologia, St. Petersburg, Russia.

The area in question 1.200.000 km² in size and 1 to 4 km deep comprises the Lomonosov Ridge, Mendeleev Rise and Makarov Basin. The crust nature of the area is debatable so far. Over most of the area, the crust is 15-30 km thick and includes the granitic layer which is typical of the attenuated continental crust. Similar structure is observed, however, in the oceanic crust on the past and present hot spots, e.g., in Iceland and the Ontong Java Plateau. Hence the nature of the crust in the Eastern Central Arctic cannot be reliably inferred from its structure. We suggest a different approach to the problem. After ceasing of activity of mantle plumes, the extinct hot spots on the oceanic crust subside in the same way as the oceanic crust formed in the spreading ridges. At the initial stage, the water depth increases rapidly as a square root of time. In ~ 80 Ma, its final depth of 2000-3000 m is reached on the crust, 20-30 km thick. According to the deep-sea drilling data, no volcanism occurred on the Lomonosov Ridge in the Late Cretaceous and Cenozoic. This means that the hot spot, if existed in this region earlier, had become already extinct. During ~ 70 Ma in the Late Cretaceous and Paleocene, subsidence was insignificant, and the ridge remained near to sea level. At the end of the Early Miocene, rapid subsidence began, and in ~ 16 Ma the water depth reached 1.5-2 km. Such an evolution of the crustal movements cannot be explained by cooling of the oceanic lithosphere. It could occur only in the continental crust. In the absence of significant stretching in the Neogene, the rapid formation of the deep-water basin can be explained by the gabbro to eclogite transformation in the lower continental crust which was catalyzed by infiltration of active fluid from the mantle. In the Makarov Basin and the Mendeleev Rise, the subsidence evolved in a similar way which indicates the occurrence of continental crust in the region. Rapid crustal subsidence is a typical feature of large hydrocarbon basins, e.g., of the West Siberian and North Caspian basins. Hence the Eastern Central Arctic is expected to have a very large reserve.

AAPG Search and Discover Article #90096©2009 AAPG 3-P Arctic Conference and Exhibition, Moscow, Russia