Early Mesozoic intracontinental orogeny and stress transmission in South China: evidence from Triassic peraluminous granites
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2017
Authors
Song, M.
Shu, L.
Santosh, M.
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Journal of the Geological Society, 2017; 174(3):591-607
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Meijia Song, Liangshu Shu and M. Santosh
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Abstract
The Early Mesozoic tectonic and magmatic events in South China are considered to represent intracontinental
orogeny, although the mechanism and geodynamic setting remain debated. Here we report zircon U–Pb geochronology, Hf
isotopes and whole-rock geochemistry from four granitic plutons in the Nanling and Yunkai domains. The zircon data define
seven groups of weighted mean ²⁰⁶Pb/²³⁸U ages as 218 ± 2, 222 ± 4, 225 ± 3, 227 ± 3, 221 ± 2, 224 ± 3 and 231 ± 3 Ma,
representing the magmatic crystallization ages. These intrusions are characterized by a peraluminous nature, with high A/CNK
values (>1.1), negative Eu, Ba, Sr, Nb and Ti anomalies, and enrichment in LREE, Rb, Th, U and Pb. Zircon grains from all the
samples show variably negative εHf(t) values (−3.8 to −18.6) with two-stage Hf model ages clustered in the range 1.4–2.5 Ga.
Our data indicate that the Early Mesozoic granitic magmas were generated by the partial melting of crustal rocks with
insignificant input of mantle materials. In conjunction with other geological evidence, we suggest that Triassic intracontinental
deformation was triggered by far-field stress propagation from the plate boundary of South China.
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© 2017 The Author(s). Published by The Geological Society of London. All rights reserved. For permissions: http://www.geolsoc.org.uk/permissions. Publishing disclaimer: www.geolsoc.org.uk/pub_ethics