Provenance, depositional setting, and crustal evolution of the Cathaysia Block, South China: Insights from detrital zircon U-Pb geochronology and geochemistry of clastic rocks

We report the results of a combined study of detrital zircon U-Pb geochronology and bulk-rock elemental geochemistry on late Neoproterozoic to Cambrian clastic sedimentary rocks from South Jiangxi within Cathaysia. These clastic rocks are characterized by moderate chemical index of alteration (CIA)...

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Bibliographic Details
Published in:Geological Journal
Main Authors: Xiong, Chen, Chen, Hongde, Niu, Yaoling, Chen, Anqing, Zhang, Chenggong, Li, Feng, Xu, Shenglin, Yang, Shuai
Format: Report
Language:English
Published: WILEY 2019
Subjects:
Cathaysia Block
crustal evolution
geochemistry
provenance
South China
tectonic
zircon U-Pb geochronology
Geology
Geosciences
Multidisciplinary
EARLY PALEOZOIC TECTONISM
LU-HF ISOTOPES
EAST ANTARCTICA
OROGENIC BELT
YANGTZE BLOCK
METASEDIMENTARY ROCKS
CAMBRIAN SANDSTONES
CONTINENTAL-CRUST
SEDIMENTARY-ROCKS
PLATE-TECTONICS
East Antarctica
Antarc*
Antarctica
Online Access:http://ir.qdio.ac.cn/handle/337002/161139
https://doi.org/10.1002/gj.3253
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Summary:We report the results of a combined study of detrital zircon U-Pb geochronology and bulk-rock elemental geochemistry on late Neoproterozoic to Cambrian clastic sedimentary rocks from South Jiangxi within Cathaysia. These clastic rocks are characterized by moderate chemical index of alteration (CIA) values of 73 and high Th/U ratios (>3.8), indicating moderate weathering of the source area. The relatively high index of compositional variability (ICV=0.62-1.30) values indicates a source compositionally dominated by immature material that lacks alumina-rich minerals. Bulk-rock major and trace element systematics on discrimination diagrams are consistent with the source provenance being felsic-intermediate igneous rocks of ancient continental crust origin. The geochemistry is also consistent with the clastic sedimentary rocks being deposited in a setting at or in the vicinity of passive continental margins. Detrital zircon U-Pb ages of the clastic rocks record five major age populations: 2,614-2,376Ma (peak at ca. 2,482Ma), 1,953-1,353Ma, 1,000-900Ma (peak at ca. 958Ma), 850-730Ma (peaks at ca. 845 and 763Ma), and 685-571Ma (peak at ca. 635Ma). The age data provide a record of igneous activity in the source provenance: the 2,482Ma peak is consistent with the global Neoarchean continental crust growth; the 1,953-1,353Ma population correlates with the period of assembly and breakup of the Columbia supercontinent; the prominent peak at ca. 958Ma corresponds to a common thermal-tectonic event associated with the assembly of Rodinia, and the 850-730Ma population is consistent with the breakup of the Rodinia supercontinent. The ca. 850Ma age is indicative of initial stage of Rodinia breakup in South China. Our data also reveal a 670-530Ma population that correlates well with the Pan-African event associated with the formation of the Gondwana supercontinent, although no direct geological evidence for this event has been found within the SCB. Moreover, complex zircon morphology and comparisons of detrital zircon U-Pb age ...

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