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Geochronology and Sr–Nd–Hf isotopes of the Mesozoic granitoids from the Great Xing'an and Lesser Xing'an ranges: implications for petrogenesis and tectonic evolution in NE China
Author(s) -
Hu Xinlu,
Ding Zhenju,
Yao Shuzhen,
He Mouchun,
Shen Jun,
Zhu Bopeng,
Chen Bin
Publication year - 2014
Publication title -
geological journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.721
H-Index - 54
eISSN - 1099-1034
pISSN - 0072-1050
DOI - 10.1002/gj.2576
Subject(s) - petrogenesis , geochronology , magmatism , geology , zircon , mesozoic , geochemistry , mantle (geology) , cretaceous , tectonics , radiogenic nuclide , trace element , paleontology , structural basin
The Great Xing′an and Lesser Xing′an ranges are characterized by immense volumes of Mesozoic granitoids. In this study, we present major and trace element geochemistry, U–Pb geochronology and systematic Sr–Nd–Hf isotopes for the representative samples, in order to constrain their petrogenesis and the tectonic evolution in NE China. The granitoids generally have high SiO 2 (66.5–78.8 wt.%) and Na 2 O + K 2 O (7.0–8.9 wt.%) contents and belong to high‐K calc‐alkaline to shoshonitic series. All of them show enrichment in Rb, Th, U, Pb and light rare earth elements (LREE), and depletion in Nb, Ta, P and Ti. Zircon U–Pb dating suggests that there was continuous magmatism in both the Great Xing′an Range and the Lesser Xing′an Range during the Jurassic–Early Cretaceous interval. Seven Jurassic granitoids have ( 87 Sr/ 86 Sr) i values of 0.704351 to 0.707374, with ϵ Nd (t) values of −3.4 to 2.4 and ϵ Hf (t) values of 0.8 to 11.3, indicating that they originated from mixed sources involving depleted mantle and pre‐existing crustal components. One Early Cretaceous sample yields ( 87 Sr/ 86 Sr) i value of 0.706184, ϵ Nd (t) value of 0.6, and ϵ Hf (t) values of 7.0 to 8.2, which is in accordance with previous studies and indicates a major juvenile mantle source for the granitoids in this period. In the Jurassic, the magmatism in the Great Xing′an Range was induced by the subduction of the Mongol–Okhotsk Ocean, while the contemporaneous magmatism in the Lesser Xing′an Range was related to the subduction of the Palaeo‐Pacific Ocean. In the Early Cretaceous, extensive magmatism in NE China was probably attributed to large‐scale lithospheric delamination. Copyright © 2014 John Wiley & Sons, Ltd.