Abstract
A series of early Carboniferous volcanic rocks, i.e., basalt, andesite, and dacite, occur in the West Junggar. Zircon U-Pb isotopic data indicate that these rocks coevally erupted at 331-344Ma. These volcanic rocks have comparable trace element patterns, characterized by the enrichment of large ion lithophile elements (LILE) and the depletion of high field strength elements (HFSE). Isotopically, they display consistently depleted Sr-Nd isotopic compositions (initial 87Sr/86Sr ratios=0.7034-0.7054, εNd(t)=4.2-7.7). These rocks are interpreted to be derived from a slightly metasomatized depleted mantle in a normal subduction environment. In the context of a previously proposed ridge subduction model, this study constrains that ridge subduction, if it indeed occurred, commenced between 331 and 310Ma in the central West Junggar.
| Original language | English |
|---|---|
| Pages (from-to) | 854-866 |
| Number of pages | 13 |
| Journal | Journal of Asian Earth Sciences |
| Volume | 42 |
| Issue number | 5 |
| Early online date | 8 Feb 2011 |
| DOIs | |
| Publication status | Published - 10 Oct 2011 |
| Externally published | Yes |
Bibliographical note
We thank Ying Liu, Chaofeng Li, and Xiaoping Xia for laboratory assistance. Xiaoping Long, Keda Cai, Kenny Wong, Yingde Jiang and Jiyuan Yin are thanked for their kindly help during the field work as well as for many helpful discussions. An earlier version of this paper was greatly improved by in-depth reviews by Paul T. Robinson and an anonymous reviewer. An HKU postgraduate studentship to Hongyan GENG is gratefully acknowledged.Funding
This study was supported by research grants from National Basic Research Program of China (2007CB411308), Hong Kong Research Grants Council (HKU7043/07P), Hong Kong–Germany Research Scheme and a CRCG Grant from the University of Hong Kong.
Keywords
- Central Asian Orogenic Belt
- Geochemistry
- Subduction
- Volcanic
- West Junggar