投稿时间：2016-11-01
修订日期：2018-02-05
网络发布日期：2018-07-12
中文摘要:文章对东天山玉海铜钼矿区含矿岩体石英闪长（玢）岩及围岩二长花岗岩的成岩年龄进行研究。LA-MC-ICP-MS锆石U-Pb定年结果显示石英闪长（玢）岩形成于（427.80±0.98）Ma，即中志留世；二长花岗岩形成于（318.40±0.66）Ma，即晚石炭世。石英闪长（玢）岩w（SiO2）为58.30%~64.28%，w（Al2O3）为15.24%~17.36%，w（MgO）为1.73%~4.80%，w（Y）为10.20×10-6~17.40×10-6，w（Yb）为1.33×10-6~1.98×10-6，石英闪长（玢）岩Sr/Y比值为41.58~79.22，（La/Yb）N为4.19~10.04，为类埃达克岩（adakite-like）。石英闪长（玢）岩具轻稀土元素富集、重稀土元素亏损的配分型式，Eu无异常或正异常，富集大离子亲石元素，亏损高场强元素，具有典型岛弧岩浆岩的特征。Sr-Nd同位素（εNd（t）=+5.4~+7.1，（87Sr/86Sr）i=0.703 59~0.703 83）表明其源区是亏损地幔。通过与土屋-延东斑岩矿床含矿岩体的对比研究，认为玉海石英闪长（玢）岩也形成于岛弧环境，但源区可能是俯冲流体改造过的地幔楔。综合区域早古生代岩浆岩的资料，认为大南湖-头苏泉岛弧带早古生代为不成熟弧环境，与准噶尔洋向南俯冲有关。
Abstract:This study focused on ore-forming ages of the ore-bearing quartz diorite (porphyrite) and its country rock monzonitic granite from the Yuhai copper-molybdenum deposit in Eastern Tianshan Mountains. LA-MC-ICP-MS zircon U-Pb dating yielded crystallization ages of (427.8±0.98) Ma for quartz diorite (porphyrite) and (318.4±0.66) Ma for monzonitic granite, respectively. The Yuhai quartz diorite (porphyrite) has the data of 58.30%~64.28% SiO2, 15.24%~17.36% Al2O3, 1.73%~4.80% MgO, 10.20×10-6~17.40×10-6 Y, 1.33×10-6~1.98×10-6 Yb, 41.58~79.22 Sr/Y, and 4.19~10.04 (La/Yb)N, indicating that the Yuhai quartz diorite (porphyrite) has adakite-like affinity. The REE patterns of quartz diorite (porphyrite) exhibit moderate fractionation, with light rare earth element enrichment and heavy rare earth element depletion, and positive or no Eu anomalies. The quartz diorite (porphyrite) is enriched with large-ion lithophile elements, but depleted in high field strength elements, which is similar to the typical island arc igneous rocks. High εNd(t) values of +5.4~+7.1 and low (87Sr/86Sr)i values of 0.703 59~0.703 83 suggest that quartz diorite (porphyrite) originated from a depleted mantle source. A comparison with the ore-bearing rocks in the Tuwu-Yandong porphyry copper deposits shows that the Yuhai quartz diorite (porphyrite) was also formed in Dananhu-Tousuquan island arc, and probably originated from a mantle wedge metasomatized by slab fluids. Combined with other Early Paleozoic igneous rocks data in this area, the authors infer that the Dananhu-Tousuquan immature island arc was formed by the southward subduction of the Junggar Ocean during the early Paleozoic.
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基金项目:本文得到中国地质调查局地质调查项目（编号：12120115055601、DD20160007）资助
引用文本：
刘帅杰,余金杰,王铁柱,陆邦成.2018.新疆东天山玉海铜钼矿区志留纪侵入体岩石成因及构造意义[J].矿床地质,37(3):535~555LIU ShuaiJie,YU JinJie,WANG TieZhu,LU BangCheng.2018.Petrogenesis of Silurian intrusions in Yuhai Cu-Mo deposit in eastern Tianshan Mountains, Xinjiang, and its tectonic implications[J].Mineral Deposits37(3):535~555
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