Evolution of the Academician Ridge Accommodation Zone in the central part of the Baikal Rift, from high-resolution reflection seismic profiling and geological field investigations |
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| Authors: | V D Mats O M Khlystov M De Batist S Ceramicola T K Lomonosova A Klimansky |
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| Institution: | (1) Limnological Institute, Siberian Branch of Russian Academy of Sciences, 664033 Irkutsk, Russia, RU;(2) Renard Centre of Marine Geology, University of Gent, Krijgslaan 281-S.8, B-9000 Gent, Belgium e-mail: marc.debatist@rug.ac.be Tel.: +32-9-2644587 Fax: +32-9-2644967, BE;(3) Institute of the Earth's Crust, Siberian Branch of Russian Academy of Sciences, 664074 Irkutsk, Russia, RU;(4) Irkutsk State Technical University, Irkutsk, Russia, RU |
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| Abstract: | New high-resolution seismic reflection data from the central part of Lake Baikal provide new insight into the structure and
stratigraphy of Academician Ridge, a large intra-rift accommodation zone separating the Central and North Baikal basins. Four
seismic packages are distinguished above the basement: a thin top-of-basement unit; seismic-stratigraphic unit X; seismic-stratigraphic
unit A; and seismic-stratigraphic unit B. Units A and B were cored on selected key locations. The four packages are correlated
with a series of deposits exposed on the nearby western shores: the Ularyar Sequence (Oligocene); the Tagay Sequence (Lower
to Middle Miocene); the Sasa Sequence (Upper Miocene to Lower Pliocene); the Kharantsy Sequence (Upper Pliocene); and the
Nyurga Sequence (Lower Pleistocene). Based on stratal relationships, sedimentary geometries, distribution patterns and principal
morphostructural elements – both onshore and offshore – we propose a new palaeogeographic evolution model for the area. In
this model progressive tectonic subsidence of the Baikal basins and successive pulses of uplift of various segments of the
rift margins lead to: (a) formation of the ridge as a structural and morphological feature separating the Central and North
Baikal basins during the Middle to Late Miocene; (b) gradual flooding of the main parts of the ridge and establishment of
a lacustrine connection between the two rift basins during the Late Miocene; and (c) total submergence of the top parts of
the crest of the ridge during the latest Pleistocene. This new model helps to better constrain numerous phases in the structural
evolution of the Baikal Rift, in which the Academician Ridge as an accommodation zone plays a crucial role.
Received: 26 November 1999 / Accepted: 12 March 2000 |
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| Keywords: | Seismic data Rift basins Sedimentation Tectonics Asia |
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