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胶东三山岛金矿床构造-热历史:^(40)Ar/^(39)Ar和裂变径迹年代学制约

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岩石学报 2016年第8期32卷 2465-2476页

作者：张良李广伟郑小礼安平陈兵宇中国地质大学地质过程与矿产资源国家重点实验室北京100083 蒙纳什大学地球科学大气与环境学院墨尔本大学地球科学学院山东黄金矿业股份有限公司莱州261400 山东黄金矿业股份有限公司三山岛金矿莱州261442

胶东金成矿省目前已探明黄金资源储量超过4000t,是世界上最大的花岗岩容矿的单金成矿省之一。三山岛金矿床位于该金成矿省西北部,是产于早白垩世郭家岭型花岗中的世界级金矿床。锆石U-Pb数据表明该矿床内赋矿围岩郭家岭花岗岩侵位于~128... 详细信息

胶东金成矿省目前已探明黄金资源储量超过4000t,是世界上最大的花岗岩容矿的单金成矿省之一。三山岛金矿床位于该金成矿省西北部,是产于早白垩世郭家岭型花岗中的世界级金矿床。锆石U-Pb数据表明该矿床内赋矿围岩郭家岭花岗岩侵位于~128Ma,其后郭家岭花岗岩快速冷却并普遍经历了亚固态韧性变形。已有绢云母Rb-Sr数据表明,该矿床大规模金成矿作用和脆性变形发生于约117Ma。本次获取的1件~99Ma白云母^(40)Ar/^(39)Ar年龄揭示了主期成矿后一期微弱的构造-流体活动。4件锆石裂变径迹年龄中相对较老的单颗粒锆石年龄组分90±10Ma说明,该矿床大致于该时间段冷却至锆石裂变径迹封闭温度240±50℃。13件磷灰石裂变径迹年龄分布于69.8±7.2Ma^46.1±4.8Ma之间;8件磷灰石裂变径迹长度集中于13.1±0.2~12.3±0.2μm,并且呈单峰型略带负偏态的分布,说明该矿床大致于70~50Ma单调缓慢冷却通过磷灰石裂变径迹部分退火带125~60℃。最终,该矿床缓慢冷却剥露至现今近地表温度。相对缓慢的成矿后冷却和剥蚀以及新近深部钻探成果说明,三山岛及其周缘金矿床主断裂下盘脆性变形和热液蚀变作用叠加部位成矿潜力巨大,为有利的找矿靶区。

关键词：氩-氩定年裂变径迹构造-热历史三山岛金矿床胶东

柴北缘榴辉岩的峰期和退变质年龄:来自U-Pb及Ar-Ar同位素测定的证据

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地球化学 2000年第3期29卷 217-222页

作者：张建新杨经绥许志琴张泽明陈文李海兵中国地质科学院地质研究所北京100037

柴北缘大柴旦榴辉岩呈透镜状产于以角闪岩相变质条件为特征的片麻岩中。选择新鲜的保存较好的榴辉岩分别进行Ｕ－Ｐｈ和Ａｒ－Ａｒ同位素年代学测定，含石榴子石的白云母片麻岩（此榴辉岩的围岩）被选用于白云母的Ａｒ－Ａｒ测定。榴辉... 详细信息

柴北缘大柴旦榴辉岩呈透镜状产于以角闪岩相变质条件为特征的片麻岩中。选择新鲜的保存较好的榴辉岩分别进行Ｕ－Ｐｈ和Ａｒ－Ａｒ同位素年代学测定，含石榴子石的白云母片麻岩（此榴辉岩的围岩）被选用于白云母的Ａｒ－Ａｒ测定。榴辉岩的Ｕ－Ｐｈ测定显示^（２０６）Ｐｂ／^（２３８）Ｕ表面年龄统计权重平均值为（４９４．６±６．５）Ｍａ，代表榴辉岩的峰期变质作用年龄。同样榴辉岩样品的多硅白云母被分选出用于^（３９）Ａｒ－^（４０）Ａｒ年代学测定。测定结果获得的坪年龄为（４６６．７±１．２）Ｍａ，等时线年龄为（４６５．９±５．４）Ｍａ，代表榴辉岩在退变过程中的冷却年龄；围岩中白云母的^（３９）Ａｒ－^（４０）Ａｒ年代学测定，获得等时线年龄为（４７７．６７±１７．７２）Ｍａ。相似的Ａｒ－Ａｒ年龄值表明，榴辉岩和围岩在抬升过程中经历了一致的冷却及退变质历史。

关键词：榴辉岩柴达木盆地铀-铅定年氩-氩定年

Whole-rock Ar-Ar dating for low-grade metavolcanics within the Dabie orogen and its geological significance

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Chinese Science Bulletin 2006年第12期51卷 1494-1500页

作者： GAO Tianshan TANG Jiafu SANG Haiqing HU Shiling QIAN Cunchao CAS Key Laboratory of Crust-Mantle Materials and Environments School of Earth and Space Sciences University of Science and Technology of China Hefei 230026 China Anhui Survey of Regional Geology Hefei 230001 China Institute of Geology and Geophysics Chinese Academy of Sciences Beijing 100029 China Anhui Institute of Geological Survey Hefei 230001 China

The genetic relationship between low- grade and ultrahigh-pressure (UHP) metamorphic units in the interior of the Dabie orogen has been controversial with respect to preservation of volcanic texture during continental subduction to mantle depths. In order to resolve this issue, whole-rock Ar-Ar dating was carried out for greenschist-facies metatuff that is in contact with UHP eclogite in Yuexi County, Anhui Province. One sample gave a plateau age of 784.4±2.0 Ma and an isochron age of 785.0± 4.7 Ma, and the other sample a plateau age of 770.9± 2.0 Ma and an isochron age of 769.5±3.1 Ma. It ap- pears that the Ar isotopic system was not disturbed since the volcanic eruption at the middle Neopro- terozoic. Because of the low closure temperature of Ar diffusion in volcanic rocks, retention of the Neo- proterozoic ages indicates that the low-grade metavolcanics did not experience high-grade meta- morphism up to eclogite-facies conditions during the Triassic subduction of continental crust. Furthermore, the Neoproterozoic Ar-Ar ages are also in agreement with protolith ages of UHP metaigneous rocks in the Dabie orogen. Therefore, the metatuff is interpreted as a tectonic relict that was scraped off during the Triassic subduction and thus was not subducted to mantle depths like the adjacent eclogite. This lends support to the model for crustal detachment between cover and basement during continental collision. A tectonic mélange model is proposed to explain theoccurrence of contrasting grades of metamorphic rock within the UHP metamorphic zone.

关键词：凝灰岩大陆俯冲氩-氩定年造山带超高压变形