Breakup of Eastern Gondwana as inferred from the Lower Cretaceous Charong Dolerites in the central Tethyan Himalaya, southern Tibet

The separation of the Indian Plate from the Australia Antarctic Plate and its accretion to the Eurasian Plate is the key to understanding the evolutionary history and paleogeographic reconstruction of Eastern Gondwana in the Jurassic Cretaceous. In this paper, zircon U-Pb dating indicates that the C...

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Bibliographic Details
Published in:Palaeogeography, Palaeoclimatology, Palaeoecology
Main Authors: Zeng, Yun-Chuan, Xu, Ji-Feng, Chen, Jian-Lin, Wang, Bao-Di, Huang, Feng, Yu, Hong-Xia, Chen, Xue-Feng, Zhao, Pei-Pei
Format: Report
Language:English
Published: ELSEVIER SCIENCE BV 2019
Subjects:
Physical Geography
Geology
Paleontology
Neotethyan Ocean
Crustal recycling
Geochemistry
Continental basalt
Zircon
Geography
Physical
Geosciences
Multidisciplinary
ZIRCON U-PB
CONTINENTAL FLOOD BASALTS
LARGE IGNEOUS PROVINCE
ZANGBO SUTURE ZONE
FOLD-THRUST BELT
GEOCHEMICAL EVIDENCE
MAFIC MAGMATISM
TRACE-ELEMENT
TECTONIC IMPLICATIONS
ISOTOPIC CONSTRAINTS
Antarctic
Indian
Antarc*
Online Access:http://ir.gig.ac.cn/handle/344008/53028
https://doi.org/10.1016/j.palaeo.2017.10.010
Description
Summary:The separation of the Indian Plate from the Australia Antarctic Plate and its accretion to the Eurasian Plate is the key to understanding the evolutionary history and paleogeographic reconstruction of Eastern Gondwana in the Jurassic Cretaceous. In this paper, zircon U-Pb dating indicates that the Charong Dolerites (similar to 142 Ma) are newly recognized Lower Cretaceous magmatic rocks in the central Tethyan Himalaya in southern Tibet. These dolerites are characterized by moderate contents of SiO2 (49.9-56.9 wt%), high contents of MgO (4.66-9.69 wt %) and TiO2 (2.20-2.81 wt%), high Zr/Y ratios (7.5-13.1), enrichments in Rb and Th, moderately negative Nb-Ta anomalies, and no Zr-Hf anomalies. Taking into account the narrow range of whole-rock initial Sr-87/Sr-88 ratios (0.7068 to 0.7086), the negative values of epsilon(Nd)(t) (-2.4 to -4.1), and the geochemical makeup of the zircons, the Charong Dolerites are akin to continental basalts, indicating that the central Tethyan Himalayan area was in an extensional setting during the Early Cretaceous. Although the Charong Dolerites indicate a relatively high mantle-melting temperature (similar to 1469 +/- 44 degrees C), this is still lower than the temperature required for a mantle plume origin. In combination with the Lower Cretaceous mafic rocks in the eastern Himalaya and the coeval volcaniclastic sediments, we suggest that the Charong Dolerites were partial melts of a rising asthenospheric mantle, this process having been triggered by rifting between the Indian Plate and the Australia Antarctic Plate. This episode of continental lithospheric extension may have led to the opening of a post-Neotethyan oceanic basin that extended between the Indian Craton and the Tethyan Himalaya during the late Early Cretaceous, a feature that is highly significant in paleogeographic reconstructions of Eastern Gondwana.

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