TY - JOUR

T1 - Orogenic Volcanism in Eastern Kazakhstan: Composition, Age, and Geodynamic Position

AU - Khromykh, S. V.

AU - Semenova, D. V.

AU - Kotler, P. D.

AU - Gurova, A. V.

AU - Mikheev, E. I.

AU - Perfilova, A. A.

N1 - Funding Information: The study was carried out according to the state task of IGM SB RAS (Novosibirsk, Russia), with the support of the Russian Foundation for Basic Research (project nos. 17-05-00825, 20-05-00346, 20-35-70 076). Publisher Copyright: © 2020, Pleiades Publishing, Inc. Copyright: Copyright 2020 Elsevier B.V., All rights reserved.

PY - 2020/7/1

Y1 - 2020/7/1

N2 - Studies of volcanic rocks in orogenic troughs of Eastern Kazakhstan were carried out. The troughs were formed at late-orogenic stages of evolution of Hercynian Altai collision system. Volcanic rocks are represented by basalts, andesites, dacites and rhyolites. Based on geochemical and isotopic data, the basalts and andesites derived from mafic magmas that formed as a result of partial melting of garnet peridotites in the upper mantle under the orogen. U–Pb zircon data prove two volcanic stages: more-scaled Middle Carboniferous (~311 Ma) and less-scaled Early Permian (297–290 Ma). Basalts and andesites in lower parts of the orogenic troughs and independent dacite-rhyolite structures were formed at the Middle Carboniferous stage. Parental mafic magmas were formed as a result of partial melting of mantle substrates in local transtensional zones along large shear faults. The formation of dacites and rhyolites could have been caused by partial melting of crustal substrates under effect of mafic magmas. Transtensional movements in the lithosphere of orogenic belts may indicate the beginning of collapse of orogens. A smaller volume of basalts and andesites formed at the Early Permian stage. Geochemical data prove the independent episode of partial melting in upper mantle. Synchronous basalts and andesites also appeared at wide territory in Tian Shan, Central Kazakhstan, and Central and Southern Mongolia. Early Permian volcanism indicates general extension of the lithosphere at the postorogenic stages. Large-scaled Early Permian mafic and granitoid magmatism in Central Asia has been interpreted in recent years as the Tarim Large Igneous Province caused by Tarim mantle plume activity. Thus, the extension of the lithosphere and associated volcanism in the Early Permian can be an indicator of the onset of the plume–lithosphere interaction process.

AB - Studies of volcanic rocks in orogenic troughs of Eastern Kazakhstan were carried out. The troughs were formed at late-orogenic stages of evolution of Hercynian Altai collision system. Volcanic rocks are represented by basalts, andesites, dacites and rhyolites. Based on geochemical and isotopic data, the basalts and andesites derived from mafic magmas that formed as a result of partial melting of garnet peridotites in the upper mantle under the orogen. U–Pb zircon data prove two volcanic stages: more-scaled Middle Carboniferous (~311 Ma) and less-scaled Early Permian (297–290 Ma). Basalts and andesites in lower parts of the orogenic troughs and independent dacite-rhyolite structures were formed at the Middle Carboniferous stage. Parental mafic magmas were formed as a result of partial melting of mantle substrates in local transtensional zones along large shear faults. The formation of dacites and rhyolites could have been caused by partial melting of crustal substrates under effect of mafic magmas. Transtensional movements in the lithosphere of orogenic belts may indicate the beginning of collapse of orogens. A smaller volume of basalts and andesites formed at the Early Permian stage. Geochemical data prove the independent episode of partial melting in upper mantle. Synchronous basalts and andesites also appeared at wide territory in Tian Shan, Central Kazakhstan, and Central and Southern Mongolia. Early Permian volcanism indicates general extension of the lithosphere at the postorogenic stages. Large-scaled Early Permian mafic and granitoid magmatism in Central Asia has been interpreted in recent years as the Tarim Large Igneous Province caused by Tarim mantle plume activity. Thus, the extension of the lithosphere and associated volcanism in the Early Permian can be an indicator of the onset of the plume–lithosphere interaction process.

KW - basalts and andesites

KW - Central Asia

KW - Eastern Kazakhstan

KW - fold belts

KW - orogeny

KW - partial melting in the mantle

KW - Tarim Large Igneous Province

KW - U–Pb age

KW - volcanism

KW - ZIRCON

KW - INTRUSIONS

KW - TECTONICS

KW - XINJIANG

KW - MAGMATISM

KW - U-PB

KW - GEOCHRONOLOGY

KW - WEST JUNGGAR

KW - ALTAI COLLISIONAL SYSTEM

KW - U-Pb age

KW - GEOCHEMISTRY

UR - http://www.scopus.com/inward/record.url?scp=85091283490&partnerID=8YFLogxK

U2 - 10.1134/S0016852120040044

DO - 10.1134/S0016852120040044

M3 - Article

AN - SCOPUS:85091283490

VL - 54

SP - 510

EP - 528

JO - Geotectonics

JF - Geotectonics

SN - 0016-8521

IS - 4

ER -