桂东鹰扬关地区1∶5万区域地质矿产调查成果与主要进展

桂东鹰扬关地区位于钦杭结合带西南段,通过开展该区1∶5万区域地质调查,以国际地层表(2015)为指南,对调查区地层进行了多重地层划分与对比研究。从岩石学、构造学、地球化学角度,对鹰扬关岩群进行了详细研究,明确了其为一套构造混杂岩,通过获得的变质火山碎屑岩锆石LA-ICP-MS U-Pb年龄,认为其主要形成于新元古代。根据岩性特征、野外接触关系及同位素年龄等将区内岩浆岩划分为8个岩体,16个填图单位,获得了各岩体的高精度测年数据,确定了岩浆岩年龄格架;研究了其岩石成因,探讨了岩浆源区以及形成的大地构造背景。建立了调查区构造格架,阐明了构造形成演化历史,划分了构造变形阶段,通过构造解析,于鹰扬关构造混杂岩中识别出5期构造变形,结合区域构造演化确定了相对时序。通过1∶5万水系沉积物测量,查明了1∶5万太保圩幅水系沉积物地球化学特征,编制了元素地球化学图等系列图件。

New Progress in 1:50000 Regional Geological and Mineral Survey in Yingyangguan Area,Eastern Guangxi

Yingyangguan area in Eastern Guangxi is located in the southwest section of Qinhang Junction Zone. Four regional geological and mineral surveys have been completed in Fuchuan County, Guangxi, at a scale of 1:50 000. Guided by the International Stratigraphic Table(2015), the stratigraphic division and correlation of the survey area have been studied. From petrology, tectonics and geochemistry, the Yingyangguan Group is studied in detail, which is a set of tectonic mélanges. According to the zircon LA-ICP-MS U-Pb dating of metamorphic volcaniclastic rocks, it is believed that it was mainly formed in Neoproterozoic. According to lithological characteristics, field contact relationship and isotopic age, the magmatic rocks in this area are divided into 8 rock masses and 16 mapping units. High-precision dating data of each rock mass are obtained, age framework of magmatic rocks is determined, rock genesis is studied, magmatic source area and tectonic setting are discussed. The tectonic framework of the investigation area was established, the history of tectonic formation and evolution was clarified, and the stage of tectonic deformation was divided. Five tectonic deformation stages were identified in Yingyangguan tectonic mélange by structural analysis, and the relative time series was determined by regional tectonic evolution. The geochemical characteristics of the stream sediments in the Taibaoxu area were identified by the 1:50 000 stream sediment survey, and a series of maps such as elemental geochemical anomaly maps were compiled.