Geochemical and Sr-Nd-Os Isotopic Characteristics of Middle Silurian Volcanic Rocks in Northwest of the Xiemisitai Mountains, West Junggar and Its Tectonic Implications

Jia-fu CHEN; Xu MA; Chao LI; Wen-jun QU; Hou-yuan DU; Ran ZHAO; Bao-fu HAN

doi:10.15898/j.cnki.11-2131/td.201704060051

2017 Vol. 36, No. 3

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Article navigation > Rock and Mineral Analysis > 2017 > 36(3): 318-325

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Jia-fu CHEN, Xu MA, Chao LI, Wen-jun QU, Hou-yuan DU, Ran ZHAO, Bao-fu HAN. Geochemical and Sr-Nd-Os Isotopic Characteristics of Middle Silurian Volcanic Rocks in Northwest of the Xiemisitai Mountains, West Junggar and Its Tectonic Implications[J]. Rock and Mineral Analysis, 2017, 36(3): 318-325. doi: 10.15898/j.cnki.11-2131/td.201704060051

Citation:

Jia-fu CHEN, Xu MA, Chao LI, Wen-jun QU, Hou-yuan DU, Ran ZHAO, Bao-fu HAN. Geochemical and Sr-Nd-Os Isotopic Characteristics of Middle Silurian Volcanic Rocks in Northwest of the Xiemisitai Mountains, West Junggar and Its Tectonic Implications[J]. Rock and Mineral Analysis, 2017, 36(3): 318-325. doi: 10.15898/j.cnki.11-2131/td.201704060051

Geochemical and Sr-Nd-Os Isotopic Characteristics of Middle Silurian Volcanic Rocks in Northwest of the Xiemisitai Mountains, West Junggar and Its Tectonic Implications

1.
College of Resources and Civil Engineering, Northeastern University, Shenyang 110819, China
2.
School of Earth and Space Sciences, Peking University, Beijing 100871, China
3.
Key Laboratory of Re-Os Isotope Geochemistry, Chinese Academy of Geological Sciences, Beijing 100037, China

Received Date: 06 April 2017

Revised Date: 20 May 2017

Accepted Date: 01 June 2017

Abstract

Abstract

Volcanic rocks in the Xiemisitai Mountains, in Northwest Junggar were recently considered to form in the Silurian rather than the Devonian period. However, the characteristic and tectonic setting of Middle Silurian volcanic rocks in this area are poorly constrained. In this study, major and trace elements and Sr-Nd-Os isotopic composition analyses were synthetically conducted on the Middle Silurian basalt and basaltic andesite in northwest of the Xiemisitai Mountains, West Junggar. These volcanic samples are characterized by high MgO (5.15%-7.81%) with Mg of 56.0-60.7, low CaO (4.56%-5.09%) and FeO_T/MgO (1.15-1.40), similar to those of high-Mg volcanic rocks. Basalts have εNd(t) of 2.65, (⁸⁷Sr/⁸⁶Sr)_i of 0.70439, and (¹⁸⁷Os/¹⁸⁸Os)_i of 0.4901. The slightly enriched isotopic signatures, high Th/Yb (2.2-2.7) and low Ba/La (17.4-33.4) indicate that they originated from depleted mantle metasomatized by melts from subducted sediments and suffered from crustal contamination. The volcanic rocks are calc-alkaline and exhibit arc-like geochemistry with the enrichment of light REE and large ion lithophile elements. It is suggested that these rocks were probably formed in a back-arc setting due to northward subduction of the Junggar Oceanic slab.
- Middle Silurian /
- volcanic rocks /
- Sr-Nd-Os isotopes /
- back-arc /
- West Junggar

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References

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