The genesis of the ores and granitic rocks at the Hongshi Au deposit in Eastern Tianshan, China: Constraints from zircon U–Pb geochronology, geochemistry and isotope systematics
The genesis of the ores and granitic rocks at the Hongshi Au deposit in Eastern Tianshan, China: Constraints from zircon U–Pb geochronology, geochemistry and isotope systematics
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DOI：
10.1016/j.oregeorev.2015.11.018
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发表时间：
2016-04
影响因子：
3.3
通讯作者：
Yin‐Hong Wang;C. Xue;Jun Gao;Fangfang Zhang;Jiajun Liu;Jianping Wang;Jichun Wang
中科院分区：
文献类型：
--
作者：
Yin‐Hong Wang;C. Xue;Jun Gao;Fangfang Zhang;Jiajun Liu;Jianping Wang;Jichun Wang
红石金存款矿床位于东天山康古尔-黄山韧性剪切带西南缘。金矿体主要产于下石炭统甘墩组火山变质沉积岩和石炭系正长花岗岩、碱长花岗岩中。正长花岗岩和碱长花岗岩的SHRIMP锆石U-Pb年龄分别为337.6 ± 4.5 Ma（2σ，MSWD = 1.3）和334.0 ± 3.7 Ma（2σ，MSWD = 1.1），表明红石金存款的形成时代小于334 Ma。花岗岩类属钾玄系列，相对富集大离子亲石元素（Rb、K、Ba、Pb），亏损高场强元素（Nb、Ta、P、Ti）。花岗岩类具有高SiO2、Al 2 O3、K2 O含量，低Na 2 O、MgO、TiO 2含量，低Nb/Ta比值和轻微的Eu正异常。正长花岗岩样品中锆石的εHf（t）值变化范围为+ 1.5 ~+ 8.8，平均值为+ 5.6;碱长花岗岩样品中锆石的εHf（t）值变化范围为+ 5.0 ~+ 10.1，平均值为+ 7.9。10个硫化物样品的δ 34 S值在-11.5 ‰ ~+4.2 ‰之间，峰值在+1 ‰ ~+4 ‰之间。上述资料表明，红石花岗岩类是早石炭世古天山洋板块向南俯冲到阿齐山-雅满苏岛弧下形成的混合地幔成分的年轻下地壳熔融产物。红石金存款是二叠纪后碰撞构造作用的产物。花岗岩类最有可能充当不透水屏障，防止含矿流体的渗漏和径流。因此，花岗岩类可能对金矿化起着重要的控制作用。
The Hongshi gold deposit is located in the southwestern margin of the Kanggur–Huangshan ductile shear zone in Eastern Tianshan, Northwest China. The gold ore bodies are predominantly hosted in the volcanogenic metasedimentary rocks of the Lower Carboniferous Gandun Formation and the Carboniferous syenogranite and alkali-feldspar granite. The syenogranite and the alkali-feldspar granite yield SHRIMP zircon U–Pb ages of 337.6 ± 4.5 Ma (2σ, MSWD = 1.3) and 334.0 ± 3.7 Ma (2σ, MSWD = 1.1), respectively, indicating that the Hongshi gold deposit is younger than 334 Ma. The granitoids belong to shoshonitic series and are relatively enriched in large ion lithophile elements (Rb, K, Ba, and Pb) and depleted in high field-strength elements (Nb, Ta, P, and Ti). Moreover, these granitoids have high SiO2, Al2O3, and K2O contents, low Na2O, MgO, and TiO2contents, low Nb/Ta ratios, and slightly positive Eu anomalies. The εHf(t) values of the zircons from a syenogranite sample vary from + 1.5 to + 8.8 with an average of + 5.6; the εHf(t) values of the zircons from an alkali-feldspar granite sample vary from + 5.0 and + 10.1 with an average of + 7.9. The δ34S values of 10 sulfide samples ranged from − 11.5‰ to + 4.2‰, with peaks in the range of + 1‰ to + 4‰. The above-mentioned data suggest that the Hongshi granitoids were derived from the melting of juvenile lower crust mixed with mantle components formed by the southward subduction of the paleo-Tianshan ocean plate beneath the Aqishan–Yamansu island arc during the Early Carboniferous. The Hongshi gold deposit was formed by post-collisional tectonism during the Permian. The granitoids most likely acted as impermeable barriers that prevented the leakage and runoff of ore-bearing fluids. Thus, the granitoids probably played an important role in controlling gold mineralization.