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Multiple orogenic gold mineralization events in a collisional orogen: Insights from an extruded terrane along the southeastern margin of the Tibetan Plateau
Journal of Structural Geology ( IF 2.6 ) Pub Date : 2021-04-02 , DOI: 10.1016/j.jsg.2021.104333
Lin Yang , Qingfei Wang , David I. Groves , Song Lu , Huajian Li , Peng Wang , Jun Deng

The Daping and Chang'an orogenic gold deposits in the extruded Jinping terrane of the Cenozoic Ailaoshan collisional orogen, on the southeastern margin of the Tibetan Plateau, provide an opportunity to study relationships between the geodynamic evolution of a collisional orogen and orogenic gold mineralization. The Daping gold deposit comprises NW−SE-trending gold lodes hosted by ductile-brittle, dextral-reverse shear zones that developed under sub-horizontal NNE−SSW-oriented compression. In contrast, the Chang'an gold deposit comprises disseminated ores controlled by NW-trending brittle, sinistral strike-slip faults that formed under sub-horizontal NW−SE-oriented compression. Reliable Ar−Ar dating of two gold-related hydrothermal sericites at Daping constrain mineralization to ca. 46−42 Ma, whereas ca. 35 Ma gold-mineralized syenites, the inferred stress field, and published paleomagnetic evidence suggest that the Chang'an deposit formed later at ~23−21 Ma. These different mineralization ages, together with contrasting sulfur isotope compositions of gold-related sulfides at Daping and Chang'an, indicate that the Daping deposit formed in the northwestern part of the Ailaoshan orogen during crustal thickening before extrusion of the Jinping terrane, whereas the Chang'an deposit formed to the southeast at a late stage of terrane extrusion. From this rare window into a gold-mineralized Cenozoic orogen, it can be demonstrated that at least two periods of orogenic gold mineralization occurred at evolving stages of the geodynamic evolution of the collisional orogen.



中文翻译:

碰撞造山带中的多个造山带金矿化事件:从青藏高原东南缘一处挤压的地层中获得的见解

青藏高原东南缘新生代哀牢山碰撞造山带挤压的金平地层中的大坪和长安造山带金矿床,为研究碰撞造山带的地球动力学演化与造山带金矿化之间的关系提供了机会。大坪金矿床由在西北水平NNE-SSW定向压缩作用下形成的韧性-脆性,右旋-反向剪切带主宰的NW-SE趋势金矿。相比之下,长安金矿床由受西北界趋势的脆性,左向走滑断层控制的弥散型矿石,这些断裂是在近水平的西北向SE压缩作用下形成的。大坪地区两个与金有关的热液绢云母的可靠Ar-Ar年代测定将成矿作用限制在大约 46-42 Ma,而ca. 35毫金矿型正长岩,推断的应力场,以及已发表的古地磁证据表明,长安矿床形成于后来的〜23-21 Ma。这些不同的成矿年龄,以及在大坪和长安的金相关硫化物的硫同位素组成的对比,表明在金屏地层挤压前地壳增厚期间,在哀牢山造山带西北部形成了大坪矿床。在地层挤压的后期向东南方向形成了一个沉积物。从这个罕见的窗口进入金矿化的新生代造山带,可以证明,至少有两个造山带金矿化发生在碰撞造山带地球动力学演化的阶段。后来在〜23-21 Ma处形成了沉积物。这些不同的成矿年龄,以及在大坪和长安的金相关硫化物的硫同位素组成的对比,表明在金屏地层挤压前地壳增厚期间,在哀牢山造山带西北部形成了大坪矿床。在地层挤压的后期向东南方向形成了一个沉积物。从这个罕见的窗口进入金矿化的新生代造山带,可以证明,至少有两个造山带金矿化发生在碰撞造山带的地球动力学演化阶段。后来在〜23-21 Ma处形成了沉积物。这些不同的成矿年龄,以及在大坪和长安的金相关硫化物的硫同位素组成的对比,表明在金屏地层挤压前地壳增厚期间,在哀牢山造山带西北部形成了大坪矿床。在地层挤压的后期向东南方向形成了一个沉积物。从这个罕见的窗口进入金矿化的新生代造山带,可以证明,至少有两个造山带金矿化发生在碰撞造山带地球动力学演化的阶段。这表明大坪沉积在金屏地层挤压前的地壳增厚过程中在哀牢山造山带的西北部形成,而长安沉积在地壳挤压的后期形成于东南部。从这个罕见的窗口进入金矿化的新生代造山带,可以证明,至少有两个造山带金矿化发生在碰撞造山带地球动力学演化的阶段。这表明大坪沉积在金屏地层挤压前的地壳增厚过程中在哀牢山造山带的西北部形成,而长安沉积在地壳挤压的后期形成于东南部。从这个罕见的窗口进入金矿化的新生代造山带,可以证明,至少有两个造山带金矿化发生在碰撞造山带地球动力学演化的阶段。

更新日期:2021-04-11
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