Petrogenesis and tectonic settings of the Late Carboniferous Jiamantieliek and Baogutu ore-bearing porphyry intrusions in the southern West Junggar, NW China

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• 作者：Ping Shen ; Wenjiao Xiao ; Hongdi Pan ; Lianhui Dong ; Chaofeng Li
• 关键词：Zircon U&ndash ; Pb age ; Sr&ndash ; Nd&ndash ; Pb isotope ; Jiamantieliek ; Baogutu ; West Junggar ; Xinjiang
• 刊名：Journal of Asian Earth Sciences
• 出版年：2013
• 出版时间：5 October, 2013
• 年：2013
• 卷：75
• 期：Complete
• 页码：158-173
• 全文大小：5606 K

文摘

Porphyry Cu deposits occurred in the southern West Junggar of Xinjiang, NW China and are represented by the Baogutu and newly-discovered Jiamantieliek porphyry Cu deposits. Petrographical and geochemical studies show that both Jiamantieliek and Baogutu ore-bearing intrusions comprise main-stage diorite stock and minor late-stage diorite porphyry dikes and are the calc-alkaline intermediate intrusions. Based on U-Pb zircon SHRIMP analyses, the Jiamantieliek intrusion formed in 313 ¡À 4 Ma and 310 ¡À 5 Ma, while, based on U-Pb zircon SIMS analyses, the Baogutu intrusion formed in 313 ¡À 2 Ma and 312 ¡À 2 Ma. Rocks in the Jiamantieliek intrusion are enriched in light rare earth elements (LREE) and large ion lithophile elements (LILE) with negative Nb anomaly. Their isotopic compositions (¦Å_Nd(t) = +1.6 to +3.4, (⁸⁷Sr/⁸⁶Sr)_i = 0.70369-0.70401, (²⁰⁷Pb/²⁰⁴Pb)_i = 15.31-5.41) suggest a mixing origin from depleted to enriched mantle sources. In the Baogutu intrusion, the rocks are similar to those of the Jiamantieliek intrusion. Their Sr-Nd-Pb isotopic composition (¦Å_Nd(t) = +4.4 to +6.0, (⁸⁷Sr/⁸⁶Sr)_i = 0.70368-0.70385, (²⁰⁷Pb/²⁰⁴Pb)_i = 15.34-5.42) shows a more depleted mantle source. These features suggest generation in an island arc. The Jiamantieliek and Baogutu intrusions have similar characteristics, indicating that a relatively uniform and integrated source region has existed in the southern West Junggar since the Palaeozoic. A larger contribution of calc-alkaline magma would be required to generate the Jiamantieliek intrusion, which may reflect the development of magma arc maturation towards the western section of the southern West Junggar.