The Middle Triassic Intermediate to Basic Rocks in the Eastern Kunlun Orogenic Belt, Northeast Tibet: Implication for the Paleo-Tethyan Ocean Closure

Large volumes of Early Mesozoic intermediate to basic igneous rocks related to the evolution of the Paleo-Tethys Ocean are exposed in the East Kunlun Orogenic Belt (EKOB). The petrography, geochemistry, and results of zircon U-Pb dating of Defusheng intermediate to basic rocks from the eastern segme...

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Bibliographic Details
Published in:Minerals (Basel) 2024-07, Vol.14 (7), p.667
Main Authors: Du, Wei, Pei, Lei, Li, Zuochen, Li, Ruibao, Chen, Youxin, Liu, Chengjun, Chen, Guochao, Pei, Xianzhi
Format: Article
Language:English
Subjects:
Ablation
Basalt
Crystallization
Dating
Earth mantle
Eastern Kunlun Orogenic Belt
Fluids
Geochemistry
Geochronometry
Geology
Igneous rocks
intermediate to basic rocks
Island arcs
Major elements
Mesozoic
Middle Triassic
Oceanic crust
Olivine
Orogeny
Paleo-Tethyan Ocean
Paleoceanography
Petrography
Petrology
Radiometric dating
Rare earth elements
Scientific imaging
Sediments
Subduction
Titanium dioxide
Trace elements
Triassic
Zircon
zircon U–Pb dating
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Summary:Large volumes of Early Mesozoic intermediate to basic igneous rocks related to the evolution of the Paleo-Tethys Ocean are exposed in the East Kunlun Orogenic Belt (EKOB). The petrography, geochemistry, and results of zircon U-Pb dating of Defusheng intermediate to basic rocks from the eastern segment of the EKOB are presented in this report. Zircon U–Pb dating of the intermediate to basic rocks yields ages of 239–245 Ma (Middle Triassic). Defusheng intermediate to basic rocks have low TiO2 contents (0.80–1.47 wt.%) and widely varying MgO (3.14–6.08 wt.%), and are enriched in large ion lithophile elements and light rare earth elements, having a geochemical composition similar to that of island arc basalts. The variation diagrams of major elements indicate that the Defusheng intermediate to basic rocks underwent fractional clinopyroxene and olivine crystallization. Depletion of the high-field-strength elements Nb, Ta, and Ti may have been caused by the mantle wedge having been infiltrated by fluids derived from the subducted slab. The Defusheng intermediate to basic rocks represent magmatic records of the Early Mesozoic oceanic crust subduction in Eastern Kunlun. This indicates that the final closure of the Paleo-Tethyan Ocean and the beginning of collisional orogeny occurred after the Middle Triassic.
ISSN:2075-163X
2075-163X
DOI:10.3390/min14070667