TY - JOUR

T1 - The age and petrologic and geochemical conditions of formation of the Kogtakh gabbro-monzonite complex in the Kuznetsk Alatau

AU - Vrublevskii, V. V.

AU - Kotel'nikov, A. D.

AU - Izokh, A. E.

PY - 2018/7/1

Y1 - 2018/7/1

N2 - We present new data on the U-Pb age of zircons, geochemistry of trace elements, and isotope (Nd, Sr, O) composition of rocks of the Kogtakh gabbro-monzonite complex on the eastern slope of the Kuznetsk Alatau Ridge. The established age of zircon in the rocks of the main intrusive phases (500-480 Ma) is taken as the time of formation of the Kogtakh complex in the Late Cambrian-Early Ordovician, during the accretion-collision stage of evolution of the Central Asian Orogenic Belt. The distribution and ratios of LILE and HFSE in the rocks suggest that the intrusions proceeded under interaction of the PREMA + EM/OIB mantle plume and the suprasubductional lithospheric IAB mantle. The mantle-crust interaction led to the heterogeneous isotopic composition of neodymium in the magma source (ɛNd(T) ~ 3.5-5.4). The mixing of different mantle and continental-crust materials resulted in an increase in isotope parameters: (87Sr/86Sr)T ~ 0.7039-0.7052, ɛSr(T) ~ 0-19, and δ18O ~ 6.5-8.8‰ (SMOW). The REE ratio in the least differentiated gabbroids indicates different depths of probable magma chambers and the formation of their primary (Tb/YbPM > 1.8) mafic melts at different degrees of melting of the model garnet peridotite.

AB - We present new data on the U-Pb age of zircons, geochemistry of trace elements, and isotope (Nd, Sr, O) composition of rocks of the Kogtakh gabbro-monzonite complex on the eastern slope of the Kuznetsk Alatau Ridge. The established age of zircon in the rocks of the main intrusive phases (500-480 Ma) is taken as the time of formation of the Kogtakh complex in the Late Cambrian-Early Ordovician, during the accretion-collision stage of evolution of the Central Asian Orogenic Belt. The distribution and ratios of LILE and HFSE in the rocks suggest that the intrusions proceeded under interaction of the PREMA + EM/OIB mantle plume and the suprasubductional lithospheric IAB mantle. The mantle-crust interaction led to the heterogeneous isotopic composition of neodymium in the magma source (ɛNd(T) ~ 3.5-5.4). The mixing of different mantle and continental-crust materials resulted in an increase in isotope parameters: (87Sr/86Sr)T ~ 0.7039-0.7052, ɛSr(T) ~ 0-19, and δ18O ~ 6.5-8.8‰ (SMOW). The REE ratio in the least differentiated gabbroids indicates different depths of probable magma chambers and the formation of their primary (Tb/YbPM > 1.8) mafic melts at different degrees of melting of the model garnet peridotite.

KW - Central Asian Orogenic Belt

KW - crustal contamination

KW - garnet peridotite

KW - geochemistry

KW - geochronology

KW - geodynamic setting

KW - Kuznetsk Alatau

KW - magma genesis

KW - mantle plume

KW - petrogenesis

KW - subalkalic magmatism

KW - ALKALINE

KW - U-PB

KW - MANTLE

KW - PB SHRIMP-II

KW - TRACE-ELEMENT

KW - MAFIC MAGMATISM

KW - CENTRAL-ASIA

KW - CHEMICAL-COMPOSITION

KW - PALEOZOIC GRANITOID BATHOLITHS

KW - SM-ND

UR - http://www.scopus.com/inward/record.url?scp=85049968099&partnerID=8YFLogxK

U2 - 10.1016/j.rgg.2018.07.002

DO - 10.1016/j.rgg.2018.07.002

M3 - Article

AN - SCOPUS:85049968099

VL - 59

SP - 718

EP - 744

JO - Russian Geology and Geophysics

JF - Russian Geology and Geophysics

SN - 1068-7971

IS - 7

ER -