LA-ICP-MS U-Pb Age of Zircons from Haopinggou Biotite Granite Porphyry in Xiong'er Mountain,Western Henan Province,and Its Geologic Implications
LA-ICP-MS U-Pb Age of Zircons from Haopinggou Biotite Granite Porphyry in Xiong'er Mountain,Western Henan Province,and Its Geologic Implications
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发表时间：
2015
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通讯作者：
Liang Ta
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作者：
Liang Ta
好坪沟黑云母花岗斑岩位于熊耳山西沙沟—龙门店银多金属矿区。确定其年龄对于讨论岩石成因、地球动力学和估算成矿潜力具有重要意义。采用LA-ICP-MS锆石U-Pb定年方法对郝坪沟黑云花岗斑岩进行了年龄确定。 HPG304测年样品为黑云母花岗斑岩。分析了33个锆石点，其中18个结果与n(207Pb)/n(235U)—n(206Pb)/n(238U)协和体相邻，其U-Pb年龄集中在2435±9Ma、2310±13Ma～2340±10Ma、1784±10Ma和129± 1Ma～131±1Ma。 129±1Ma~131±1Ma内8个锆石斑点的加权平均n(206Pb)/n(238U)年龄为129. 9±0. 6Ma(MSWD = 0. 69)。已发表的5份锆石U-Pb同位素结果中的13颗锆石的加权平均n(206Pb)/n(238U)年龄为130. 5 ± 1. 1Ma(MSWD = 3. 5),可作为郝坪沟黑云花岗斑岩的形成年龄。利用SHRIMP和LA-ICP-MS方法对好坪沟黑云花岗斑岩共34个U-Pb锆石斑点进行了年龄分析，形成了元古代至早白垩世的锆石年龄谱，记录了相应的区域岩浆事件。郝坪沟黑云花岗斑岩是早白垩世岩石圈拆沉的产物，其引发的岩浆（流体）混合形成了锆石U-Pb年龄谱。好坪沟黑云花岗斑岩的形成时代接近小秦岭—小山—熊耳山地区中生代广泛强烈的成矿成岩时代，岩石圈拆沉过程中深部流体迅速排出。在好坪沟黑云花岗斑岩周围发现了良好的地球物理和地球化学异常。值得作为沙沟—龙门店银多金属矿区找矿目标之一。
Haopinggou biotite granite porphyry is located at Shagou—Longmendian silver polymetallic ore district in the west of Xiong 'er Mountain. It is important to accheive its age for discussing petrogenesis,geodynamic and esitmating mineralization potential. The zircon U-Pb dating method of LA-ICP-MS was used to confirm the age of Haopinggou biotite granite porphyry. The sample of HPG304 used to be dated is biotite granitic porphyry. There are 33 zircon spots were analysed,and 18 results of them are adjacent to n(207Pb) / n(235U) —n(206Pb) / n(238U) concordia,whose U-Pb ages are clustered in 2435 ± 9Ma,2310 ± 13 Ma ~ 2340 ± 10 Ma,1784 ±10Ma and 129 ± 1Ma ~ 131 ± 1Ma. The weighted average n(206Pb) / n(238U) age of 8 zircon spots among 129 ±1Ma ~ 131 ± 1Ma is 129. 9 ± 0. 6Ma( MSWD = 0. 69). The weighted average n(206Pb) / n(238U) age of total 13 zircons include 5 published zircon U-Pb isotopic results is 130. 5 ± 1. 1Ma( MSWD = 3. 5),which is regarded as the formation age of Haopinggou biotite granite porphyry. The ages of total 34 U-Pb zircon spots by SHRIMP and LA-ICP-MS methods from Haopinggou biotite granite porphyry have formed a zircon age spectrum from Proterozoic to early Cretaceous,which recorded the corresponding regional magmatic events. Haopinggou biotite granite porphyry is the product of lithosphere delamination in the early Cretaceous,and magma( fluid) mixing triggered by it forms the zircon U-Pb age spectrum. The formation time of Haopinggou biotite granite porphyry is close to the Mesozoic extensive and intense mineralization and diagenesis epoch in Xiaoqinling Mountain—Xiaoshan Mountain—Xiong'er Mountain area,and deep fluids was rapidly discharged in the process of lithosphere delamination.Excellent geophysical and geochemical anomalies around Haopinggou biotite granite porphyry have found. It should be considered as one of prospecting targets in Shagou—Longmendian silver polymetallic ore district.