Petrogenesis of magmatism in the Yandong region of Eastern Tianshan, Xinjiang: geochemical, geochronological, and Hf isotope constraints

The petrogenesis and geodynamic setting of magmatic rocks in Eastern Tianshan, Xinjiang, are attracting increasing attention. This study explores these issues by providing SHRIMP zircon U-Pb dating, and element geochemical and Hf isotope data of magmatic rocks exposed in the Yandong region of Easter...

Full description

Saved in:
Bibliographic Details
Published in:International geology review 2015-07, Vol.57 (9-10), p.1130-1151
Main Authors: Wang, Yinhong, Xue, Chunji, Wang, Jianping, Peng, Runmin, Yang, Juntao, Zhang, Fangfang, Zhao, Zenan, Zhao, Yunjiang
Format: Article
Language:English
Subjects:
Eastern Tianshan
Hf isotope
Isotopes
Lava
Magma
Petrogenesis
SHRIMP zircon U-Pb dating
subduction
tonalite
Yandong
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:The petrogenesis and geodynamic setting of magmatic rocks in Eastern Tianshan, Xinjiang, are attracting increasing attention. This study explores these issues by providing SHRIMP zircon U-Pb dating, and element geochemical and Hf isotope data of magmatic rocks exposed in the Yandong region of Eastern Tianshan, Xinjiang. SHRIMP zircon U-Pb dating data indicate that the magmatic activities occurred around 335 Ma, and that mineralization of the Yandong porphyry Cu deposit occurred during the same period as that of the rock formation in the region or slightly later. All the magmatic rocks in Yandong are sub-alkaline or high-K, calc-alkaline with A/CNK values ranging from 0.91 to 2.70, enriched in K, Rb, and Ba and clearly depleted in Nb, Ta, P, Ti, and Th, and have geochemical characteristics typical of adakites (i.e, high Al 2 O 3 , high La/Yb ratios and Sr contents, low Y and HREE contents, and positive Eu anomalies). In situ Hf isotopic analyses of zircons that had previously been dated by SHRIMP yielded positive initial ε Hf (t) values ranging from +9.4 to +15.8. We suggest that the Palaeo-Tianshan oceanic crust subducted northward beneath the Dananhu-Tousuquan arc belt during the early Carboniferous, and the Yandong magmatic rocks were induced by partial melting of the subducted Palaeo-Tianshan oceanic slab, subsequently having been hybridized by peridotite in the mantle wedge. The slab melts play a crucial role particularly in the relatively closed magma system responsible for generating the Yandong porphyry Cu deposit.
ISSN:0020-6814
1938-2839
DOI:10.1080/00206814.2014.900653