Geology topics

G.L. Leitchenkov

Publications and source records attributed to G.L. Leitchenkov.

4 recordsLinked to original sources

USGS2007

Cenozoic environmental changes along the East Antarctic continental margin inferred from regional seismic stratigraphy

We interpret ~40,000 km of multichannelseismic reflection lines collected by the Russian Antarctic Expedition along the East Antarctic continental margin between 32° E and 115° E, and present a revised seismic stratigraphic model for depositional paleoenvironments of the region. Variations in acoustic facies characteristics observed across major seismic horizons are correlated with paleoenvironmental changes deciphered from Antarctic drilling data and deep-sea “proxy” records. Our results, as well as otherstudies, indicate that the East Antarctic margin was glaciated at different times. Glacial ice first reached the western Wilkes Land margin in the Middle Eocene and then advanced onto most parts ofthe East Antarctic continentalshelf during the earliest Oligocene. During the Neogene, bottom currents deposited a variety of drift deposits along the margin

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USGS2007

Insight into the geology of the East Antarctic hinterland: a study of sediment inclusions from ice cores of the Lake Vostok borehole

The borehole at the southern part of subglacial Lake Vostok has been drilled into an ice layer that has been refrozen from the lake water. This ice layer contains random sediment inclusions, eight of which have been studied using state-of the-art analytical techniques. Six inclusions comprise soft aggregates consisting mainly of clay-mica minerals and micron-sized quartz grains while two others are solid clasts of fine-grained cemented rocks. The largest rock clast consists of poorly-rounded quartz and minor amounts of accessory minerals and is classified as quartzose siltstone. More than twenty grains of zircon and monazite have been identified in this siltstone and dated by SIMS SHRIMP-II. Two age clusters have been recognized for these detrital grains, in the ranges 0.8−1.2 Ga and 1.6−1.8 Ga. The compositions of the rock clasts suggest that the bedrock situated to the west of Lake Vostok is sedimentary. The age data on the detrital accessory minerals suggest that the provenance of these sedimentary rocks − the Gamburtsev Mountains and Vostok Subglacial Highlands, is mainly represented by Paleoproterozoic and MesoproterozoicNeoproterozoic crustal provinces

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USGS2007

Basement and crustal structure of the Davis Sea region (East Antarctica): implications for tectonic setting and continent to oceanic boundary definition

This study is based on about 8400 km of MCS, magnetic and gravity data as well as 20 sonobuoys collected by the Russian Antarctic Expedition during 2003 and 2004 in the Davis Sea and adjacent areas between 80°E and 102°E. Major tectonic provinces and features are identified and mapped in the study region including: 1) A marginal rift with a the extended continental crust ranging 130 to more than 200 km in width; 2) The marginal volcanic plateau of the Bruce Bank consisting of the Early Cretaceous igneous rocks; 3) The Early Cretaceous and Late Cretaceous−Paleogene oceanic basins; and 4) The Early Cretaceous igneous province of the Kerguelen Plateau. Four major horizons identified in the sedimentary cover of the Davis Sea region are attributed to main tectonic events and/or paleoenvironmental changes.

Open-File Report↗

USGS2007

Crustal structure and evolution of the Mawson Sea, western Wilkes Land margin, East Antarctica

Thisstudy is based on about 4000 km of MCS, magnetic and gravity data as well as 10 sonobuoys collected by the 2005 Russian Antarctic Expedition in the Mawson Sea and adjacent Australian-Antarctic basin between 102°E and 115°E. Major identified tectonic provinces and features of the study region include: 1) A marginal rift about 300 km wide which developed as a result of extreme crustal extension and unroofing of the upper mantle, and 2) An oceanic basin with the crust of not older than 81 Ma, which is characterized by ultraslow sea-floorspreading ratesranging from 3 to 11 mm/yr. Three major unconformities are identified in the sedimentary cover of the Mawson Sea and are interpreted to be caused by break-up between Australia and Antarctica at about 81 Ma ago (WL1), the first arrival of the ice sheet to the Mawson Sea (WL3) and continental scale glaciation at about 34 Ma ago (WL4).

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