崆岭地区中元古代地层多种碎屑副矿物研究及其对扬子板块早期演化的制约

近年来，对扬子板块古老基底岩石的持续报道和研究表明其经历了多期次的构造热事件和复杂的地壳演化过程，但关于扬子板块太古宙至古元古代的地壳生长和再造的历史，以及古元古代造山过程还存在较大争议。对古老地层中具有不同地质成因和矿物学特性的多种碎屑副矿物进行年代学和同位素分析，是解决以上科学问题的重要途径。本项目拟对扬子板块崆岭地区出露的中元古代地层进行详细的碎屑锆石、独居石和金红石的微量元素、U/Th-Pb年代学和Lu-Hf/Sm-Nd同位素测定，确定不同碎屑副矿物分别记录的岩浆和变质事件的时代和性质，结合前人对基底岩石的研究结果，厘定扬子板块早期重要构造热事件的准确时代和地质意义。联合碎屑锆石Hf和独居石Nd同位素组成，限定扬子板块早期基底的主要地壳生长和再造历史。通过对比不同成因的副矿物年代学记录，为解析扬子板块古元古代造山事件的性质、扬子陆核的增生和演化过程提供关键性证据。

Much progresses have been made in recent years in exploring the ancient basement of the Yangtze Block, which indicate multiple tectothermal events and complicated crustal evolutionary processes. However, there are controversies on the crustal growth and reworking history in Archean and Paleoproterozoic, as well as the orogenic process of the Paleoproterozoic orogen in the Yangtze Block. Integrating the geochronology and isotope analyses of multiple detrital minerals of different geological origins and mineralogical properties from old sedimentary rocks provides a crucial approach to address these issues. In this project, detrital zircon, monazite and rutile from Mesoproterozoic strata in the Kongling area will be studied, for their trace elements, U/Th-Pb geochronology and Lu-Hf/Sm-Nd isotope compositions. Combined with previous studies on basement rocks, these results will reveal the timings and nature of the major magmatic and metamorphic events in northern Yangtze Block. A more comprehensive crustal growth and reworking history can be also gained by an integration of zircon-Hf and monazite-Nd isotope data. Comparative syntheses of both igneous and metamorphic U-bearing minerals will help to address the nature of Paleoproterozoic orogen and lateral growth and evolution of the continental nucleus in northern Yangtze Block.