Speaker
Dr
Andrey Korzhenkov
(Schmidt Institute of Physics of the Earth RAS)
Description
The Issyk-Kul intermountain depression has a border with the Terskey Ala-Too Range in the south. Formation of these structures of the Tien Shan goes in conditions of the continental compression caused by a collision of Eurasian and India lithosphere plates. In the south a contact of the depression and mountains goes along Pre-Terskey Border Fault.
Structure of this fault is a complicated system consists of main plane and second-order faults responsible for foothills formation. It is known that mountain ranges thrust onto adjoining depressions and their faults are tilted under the ranges. In the south of the Issyk-Kul Depression the faults behave differently: their planes tilted northwards forming reverse faults or underthrusts. Last decade there is proposed an idea that Terskey Ala-Too Range is so called "flower structure". From "flower stem" in a depth the second-order faults are splayed upwards. The last faults form foothills. For the southern part of the Issyk-Kul Lake region Reed Burgette [2008] has elaborated a model of the fault tilted southward and becoming more gentle northward.
Pre-Terskey Border Fault goes along a contact zone of Cenozoic deposits of the Issyk-Kul Depression with Paleozoic rocks of the Terskey Range. The Dzhety-Oguz horst-anticline (located southern) is torn from the south by a young fault of reverse or underthrust's type. The fault torn its steep and short southern limb. At the same time in northern - long and gentle limb of the Dzhety-Oguz anticline one can observe firstly the conform overlapping of the pre-orogenic peneplain by Jurassic deposits, then secondly (moving northward) the conformable overlapping of Jurassic by deposits of Paleogene, Neogene and Quaternary periods. The age of Cenozoic deposits becoming younger northward, an angle of their tilt is becoming more gentle.
To the south from the Dzhety-Oguz foothill fault which is tilted northward there is the plane of Pre-Terskey border fault tilted southward. Between these faults there is a small intramontane depression filled by Quaternary deposits. The only one significant fault is located north of Dzhety-Oguz fault, it is a fault limited from the north the Orgochor intradepression uplift. To the last one as well as to Birbash, Sukhoy Khrebet, Tepke, Tosma and other intradepression uplifts there is located the fault tilted southward and becoming more gentle northward. All these structures have clear northern asymmetry: their northern limbs are short and steep, torn by the fault. Sothern limbs - long, they gently subside under extensive alluvial plane of south-eastern Issyk-Kul Lake region. These fault-generated anticline uplifts substitute each other in echelon-like manner eastward and are morphological manifestation of most northern appearance of Pre-Terskey fault zone, which we called Southern Issyk-Kul Fault. Thus besides vertical component formed mentioned intradepression uplifts there is also horizontal sinistral component of recent strike-slip fault's tectonic movements.
Our study was conducted at financial support of the International Science and Technology Center (grant No. G-2153) and State Program of Scientific Research of Schmidt Institute of Physics of the Earth RAS.
Primary author
Dr
Andrey Korzhenkov
(Schmidt Institute of Physics of the Earth RAS)
Co-authors
A.A. Sorokin
(Schmidt Institute of Physics of the Earth, RAS, Moscow, Russia)
A.B. Fortuna
(Eltsyn Kyrgyz-Russian Slavic University, Bishkek, Kyrgyzstan)
E.A. Rogozhin
(Schmidt Institute of Physics of the Earth, RAS, Moscow, Russia)
J.V. Mazeika
(State Research Institute "Center of Natural Research", Vilnius, Lithuania)
S.V. Abdieva
(Eltsyn Kyrgyz-Russian Slavic University, Bishkek, Kyrgyzstan)
