Cooperative program helps decipher tectonics of northeastern Russia

Abstract. A total of 11 700 km of multichannel seismic reflection data were acquired during recent reconnaissance surveys of the wide, shallow shelves of the Laptev and western East Siberian Seas around the New Siberian Islands. To the north of the Laptev Sea, the Gakkel Ridge, an active mid-ocean ridge which separates the North American and Eurasian Plates, meets abruptly the steep slope of the continental shelf. Extension has affected the Laptev Shelf since at least the Early Tertiary and has resulted in the formation of three major, generally north-south trending rift basins: the Ust' Lena Rift, the Anisin Basin, and the New Siberian Basin. Our data indicate that the rift basins on the Laptev Shelf are not continuous with those on the East Siberian Shelf. The latter shelf can best be described as an epicontinental platform which has undergone continuous subsidence since the Late Cretaceous. The greatest subsidence occurred in the NE, manifested by a major depocentre filled with inferred (?)Late Cretaceous to Tertiary sediments up to 5 s (twt) thick. On the basis of deep reflection data we revise and adjust Mesozoic domain boundaries around the New Siberian Islands.

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“…Fujita and Newberry, 1982;Zonenshain et al, 1990;Parfenov, 1991;Fujita et al, 1997;Khain, 1994;Drachev et al, 1998;Fig. 1).…”

Section: Geological Settingmentioning

confidence: 99%

Geology of the Shelves surrounding the New Siberian Islands, Russian Arctic

Franke

Hinz

2009

Stephan Mueller Spec. Publ. Ser.

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“…From the Laptev Sea, some workers (e.g., Chapman and Solomon, 1976;DeMets, 1992;Steblov et al, 2003) favor extending the North America-Eurasia boundary south across northeast Russia to join with the seismicity of Sakhalin Island, then on to northern Japan, attaching the Okhotsk region to the North American plate. Others (e.g., Zonenshayn et al, 1978;Savostin and Karasik, 1981;Cook et al, 1986;Parfenov et al, 1988;Fujita et al, 1990aFujita et al, , 1997Riegel et al, 1993;Seno et al, 1996) prefer to have the North America boundary follow the band of earthquakes along the Chersky Range to northern Kamchatka and suggest that the Sea of Okhotsk, Kamchatka, northern Japan, eastern Sakhalin, and the area around Magadan comprise a separate Okhotsk microplate or block. The present-day geodynamics of northeast Asia is controlled by the interactions of the Eurasian, North American, and Pacific plates (Fig.…”

Section: Introductionmentioning

confidence: 99%

“…The present-day geodynamics of northeast Asia is controlled by the interactions of the Eurasian, North American, and Pacific plates (Fig. 1 inset; Cook et al, 1986;Parfenov et al, 1988;Fujita et al, 1990aFujita et al, , 1997, and possibly the presumed far-field effects of the Indian plate (e.g., Peltzer and Tapponnier, 1988;Worrall et al, 1996). The movement of these giant plates with respect to each other has resulted in the development of diffuse seismic zones between them and the apparent formation of at least three independent blocks or microplates (Fig.…”

Section: Introductionmentioning

confidence: 99%

Seismotectonics of the Chersky Seismic Belt, eastern Sakha Republic (Yakutia) and Magadan District, Russia

Fujita

Козьмин

Mackey

et al. 2009

Stephan Mueller Spec. Publ. Ser.

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Abstract. The Chersky seismic belt represents a zone of deformation between the North American and Eurasian plates in northeast Russia. The belt extends from the Laptev Sea into the Chersky Range where it splits into two branches. One branch extends to Kamchatka and the Aleutian-Kurile Junction, while the other branch extends south towards Sakhalin Island. Focal mechanisms indicate a change from extension to transpression in the northern Verkhoyansk Range and generally left-lateral transpression in the Chersky Range extending to northern Kamchatka. The few focal mechanisms on the second branch suggest rightlateral transpression. A large number of faults, sub-parallel to the seismicity and presumed to be strike-slip, are visible in satellite imagery and topographic maps and are also associated with seismically generated landslides.These data support a model in which the Sea of Okhotsk forms the core of a separate Okhotsk microplate surrounded by diffuse boundaries on the north and west. Microseismicity in continental northeast Russia is most heavily concentrated within and between the fault systems along the northern boundary of the proposed Okhotsk plate and indicates a high level of deformation. The sense of slip on the faults (both from focal mechanisms and geology) are also generally consistent with the extrusion of the Okhotsk plate to the southeast as it is compressed between its larger neighbors. The northernmost part of the Okhotsk plate may be decoupled to some degree from the more stable central Sea of Okhotsk.

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“…The onshore structures were adopted from the geological map (Nalivkin, 1983). on the North by the Arctic Ocean Basin and are surrounded by Phanerozoic fold belts: the Chukchi fold belt, which includes the mainland, Wrangel Island, and associated Chukchi Sea shelf, the New Siberian fold belt, which includes the New Siberian Islands and surrounding Laptev Sea-East Siberian Sea continental shelves, and the Taimyr, Verkhoyansk and Cherski fold belts (e.g., Drachev et al, 1998;Fujita and Newberry, 1982;Fujita et al, 1997;Khain, 1994;Parfenov, 1991;Zonenshain et al, 1990;Fig. 12.1).…”

Section: Tectonic Setting and Structure Of The Shelvesmentioning

confidence: 99%