Age and origin of the South Caspian Basin |
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Authors: | V G Kaz’min E V Verzhbitskii |
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Institution: | 1.Shirshov Institute of Oceanology,Russian Academy of Sciences,Moscow,Russia |
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Abstract: | The South Caspian Basin (SCB) is a relic of the back-arc basin in the margin of the Tethys paleoocean. The SCB has an oceanic-type
crust and is filled with a thick (15–28 km) sedimentary series. In the modern structure, it is a part of the South Caspian
microplate, which also comprises the Lower Kura and West Turkmenian depressions, parts of the Kopet Dagh and Alborz ranges.
The geological and seismological data evidence an underthrust (or, probably, subduction) of the South Caspian Basin’s lithosphere
beneath the Apsheron threshold and the simultaneous westward displacement of the South Caspian Microplate (SCM). Different
authors refer the South Caspian Basin’s formation to the Early Mesozoic, Late Jurassic, and Paleocene. In this paper, on the
basis of geologic information, a two-phase model of the South Caspian Basin’s opening is considered. The first phase is referred
to the Late Triassic-Early Jurassic, when the sinking of the Kopet Dagh Basin and the opening of the Great Caucasus rift began
as well. Jointly, these three structures formed a prolonged basin related to the development of the Early Mesozoic subduction
zone. The age of the oceanic crust in the central part of the South Caspian Basin calculated by the thermal flux is 200 Ma.
The second phase of the South Caspian Basin opening referred to the Eocene is related to the extension in the back-arc part
of the Elbrus volcanic arc. The formation of the oceanic crust in the southwestern part of the South Caspian Basin and in
the Lower-Kura depression is associated with this phase, which is proved by the high values of the thermal flux. |
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