http://www.sciencedirect.com/science/article/pii/S1674987111000594 |
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| Authors: | Victor D Mats Tatiana I Perepelova |
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| Institution: | 1. 13/10 Shaar Hagay Str., Carmiel 20101, Israel;Limnological Institute, Siberian Branch of the RAS, 3 ul. Ulan-Batorskaya, Irkutsk 664033, Russia
2. Sobolev Institute of Geology and Mineralogy, Siberian Branch of the Russian Academy of Sciences,3 Koptyug ave, Novosibirsk 630090, Russia |
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| Abstract: | A new model is suggested for the history of the Baikal Rift, in deviation from the classic twostage
evolution scenario, based on a synthesis of the available data from the Baikal Basin and revised correlation
between tectonicelithologicalestratigraphic complexes (TLSC) in sedimentary sections around Lake
Baikal and seismic stratigraphic sequences (SSS) in the lake sediments. Unlike the previous models, the
revised model places the onset of rifting during Late Cretaceous and comprises three major stages which
are subdivided into several substages. The stages and the substages are separated by events of tectonic activity
and stress reversal when additional compression produced folds and shear structures. The events thatmark the
stage boundaries show up as gaps, unconformities, and deformation features in the deposition patterns.
The earliest Late CretaceouseOligocene stage began long before the IndiaeEurasia collision in a setting of
diffuse extension that acted over a large territory of Asia. The NWeSE far-field pure extension produced an
NE-striking half-graben oriented along an old zone of weakness at the edge of the Siberian craton. That was
already the onset of rift evolution recorded in weathered lacustrine deposits on the Baikal shore and in
a wedge-shaped acoustically transparent seismic unit in the lake sediments. The second stage spanning Late
OligoceneeEarly Pliocene time began with a stress change when the effect from the Eocene IndiaeEurasia
collision had reached the region and became a major control of its geodynamics. The EWand NE transpression
and shear from the collisional front transformed the Late Cretaceous half-graben into a U-shaped one
which accumulated a deformed layered sequence of sediments. Rifting at the latest stage was driven by extension from a local source associated with hot mantle material rising to the base of the rifted crust. The
asthenospheric upwarp first induced the growth of theBaikal dome and the related change fromfiner to coarser
molasse deposition. With time, the upwarp became a more powerful stress source than the collision, and the
stress vector returned to the previous NWeSE extension that changed the rift geometry back to a half-graben.
The layered Late PlioceneeQuaternary subaerial tectonicelithologicalestratigraphic and the Quaternary
submarine seismic stratigraphic units filling the latest half-graben remained almost undeformed. The rifting
mechanisms were thus passive during two earlier stages and active during the third stage.
The three-stage model of the rift history does not rule out the previous division into two major stages but
rather extends its limits back into time as far as the Maastrichtian. Our model is consistent with geological,
stratigraphic, structural, and geophysical data and provides further insights into the understanding of rifting
in the Baikal region in particular and continental rifting in general. |
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| Keywords: | Sedimentary unit Tectonic phase Stress reversal Rifting mechanism Three-stage rift history Baikal Rift |
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