TY - JOUR

T1 - Multistage magmatism in ophiolites and associated metavolcanites of the ulan-sar’dag mélange (East sayan, russia)

AU - Kiseleva, Olga N.

AU - Airiyants, Evgeniya V.

AU - Belyanin, Dmitriy K.

AU - Zhmodik, Sergey M.

AU - Ashchepkov, Igor V.

AU - Kovalev, Semyon A.

N1 - Funding Information: Funding: This research was funded by the Ministry of Science and Higher Education of the Russian Federation and Russian Foundation for Basic Research, grants No. 16-05-00737a, 19-05-00764a, 19-05-00788a. Work was done on state assignment to IGM SB RAS. Publisher Copyright: © 2020 by the authors. Licensee MDPI, Basel, Switzerland. Copyright: Copyright 2020 Elsevier B.V., All rights reserved.

PY - 2020/12

Y1 - 2020/12

N2 - We present new whole-rock major and trace element, mineral chemistry, and U-Pb isotope data for the Ulan-Sar’dag mélange, including different lithostratigraphic units: Ophiolitic, mafic rocks and metavolcanites. The Ulan-Sar’dag mélange comprises of a seafloor and island-arc system of remnants of the Paleo-Asian ocean. Detailed studies on the magmatic rocks led to the discovery of a rock association that possesses differing geochemical signatures within the studied area. The Ulan-Sar’dag mélange includes blocks of mantle peridotite, podiform chromitite, cumulate rocks, deep-water siliceous chert, and metavolcanic rocks of the Ilchir suite. The ophiolitic unit shows overturned pseudostratigraphy. The nappe of mantle tectonites is thrusted over the volcanicsedimentary sequence of the Ilchir suite. The metavolcanic series consist of basic, intermediate, and alkaline rocks. The mantle peridotite and cumulate rocks formed in a supra-subduction zone environment. The mafic and metavolcanic rocks belong to the following geochemical types: (1) Ensimatic island-arc boninites; (2) island-arc calc-alkaline andesitic basalts, andesites, and dacites; (3) tholeiitic basalts of mid-ocean ridges; and (4) oceanic island basalts. U–Pb dating of zircons from the trachyandesite, belonging to the second geochemical type, yielded a date of 833 ± 4 Ma which is interpreted as the crystallization age during mature island-arc and intra-arc rifting stages. The possible influence of later plume magmatic-hydrothermal activities led to the appearance of moderately alkaline igneous rocks (monzogabbro, trachybasalt, trachyandesite, subalkaline gabbro, and metasomatized peridotites) with a significant subduction geochemical fingerprint.

AB - We present new whole-rock major and trace element, mineral chemistry, and U-Pb isotope data for the Ulan-Sar’dag mélange, including different lithostratigraphic units: Ophiolitic, mafic rocks and metavolcanites. The Ulan-Sar’dag mélange comprises of a seafloor and island-arc system of remnants of the Paleo-Asian ocean. Detailed studies on the magmatic rocks led to the discovery of a rock association that possesses differing geochemical signatures within the studied area. The Ulan-Sar’dag mélange includes blocks of mantle peridotite, podiform chromitite, cumulate rocks, deep-water siliceous chert, and metavolcanic rocks of the Ilchir suite. The ophiolitic unit shows overturned pseudostratigraphy. The nappe of mantle tectonites is thrusted over the volcanicsedimentary sequence of the Ilchir suite. The metavolcanic series consist of basic, intermediate, and alkaline rocks. The mantle peridotite and cumulate rocks formed in a supra-subduction zone environment. The mafic and metavolcanic rocks belong to the following geochemical types: (1) Ensimatic island-arc boninites; (2) island-arc calc-alkaline andesitic basalts, andesites, and dacites; (3) tholeiitic basalts of mid-ocean ridges; and (4) oceanic island basalts. U–Pb dating of zircons from the trachyandesite, belonging to the second geochemical type, yielded a date of 833 ± 4 Ma which is interpreted as the crystallization age during mature island-arc and intra-arc rifting stages. The possible influence of later plume magmatic-hydrothermal activities led to the appearance of moderately alkaline igneous rocks (monzogabbro, trachybasalt, trachyandesite, subalkaline gabbro, and metasomatized peridotites) with a significant subduction geochemical fingerprint.

KW - Geochemistry

KW - Ophiolite

KW - Plume magmatic-hydrothermal activity

KW - Subduction

KW - Volcanic rocks

KW - geochemistry

KW - MANTLE PERIDOTITES

KW - volcanic rocks

KW - plume magmatic-hydrothermal activity

KW - SUBDUCTION

KW - ophiolite

KW - BREAK-UP

KW - VOLCANIC-ROCKS

KW - U-PB

KW - TRACE-ELEMENT

KW - subduction

KW - PGE MINERALIZATION

KW - EVOLUTION

KW - NORTHERN MONGOLIA

KW - SOUTHERN SIBERIA

UR - http://www.scopus.com/inward/record.url?scp=85097030587&partnerID=8YFLogxK

U2 - 10.3390/min10121077

DO - 10.3390/min10121077

M3 - Article

AN - SCOPUS:85097030587

VL - 10

SP - 1

EP - 29

JO - Minerals

JF - Minerals

SN - 2075-163X

IS - 12

M1 - 1077

ER -