海南岛与扬子板块亲缘关系：海南昌江地区中-新元古代变沉积岩约束

海南岛位于华南大陆最南端，其与扬子、华夏板块在元古宙时期亲缘关系的厘定是正确认识华南板块元古宙构造属性进而进行华南板块古位置重建的关键。岛内发育有中-新元古代变沉积岩，碎屑锆石年龄谱系初步显示出海南岛与扬子而非华夏板块的亲缘性。然而这些碎屑岩的沉积时代尚未得到精确限定，其物质来源及沉积构造背景长期存疑，限制了海南岛与扬子板块亲缘关系的进一步认识。基于此，本项目拟对海南岛昌江地区石碌群及石灰顶组开展碎屑独居石、碎屑锆石及自生独居石U-Pb定年，精确约束这些变沉积岩的沉积时代，并以此为基础，综合野外地质，岩石(相)学，矿物学，碎屑独居石、碎屑锆石年龄谱系及锆石原位Hf、O同位素组成等特征，建立海南岛、扬子板块等时构造-地层格架，系统对比石碌群、石灰顶组与扬子板块内同时期沉积序列的异同，揭示海南岛与扬子板块的亲缘关系，为构建华南前寒武纪构造格架提供新的证据。

Hainan Island lies at the southern tip of the South China mainland. Unraveling the relationship between Hainan Island and the Yangtze as well as the Cathaysia Block is the key to correctly understand its Proterozoic tectonic attribution and then establish the paleographic location of the South China Block. Meso-Neoproterozoic metasedimentary rocks are outcropped on the island, and their detrital zircon age spectrum indicate linkage between Hainan and the Yangtze Block, rather than the Cathaysia Block in Proterozoic. However, the affinities between Hainan and the Yangtze Block need to be further validated because the loosely constrained depositional age and the doubtful provenance and tectonic setting for these metasedimentary sequences in Hainan Island. In this project, detrital monazite and zircon and authigenic monazite U-Pb dating will be carried out, in order to constrain depositional ages for the Shilu Group and Shihuiding Formation. Based on this, the isochronous tectono-stratigraphic framework will be established and then an integrated comparison including petrologic, mineralogical, as well as Hf and O isotopic compositions will be conducted to their coeval sequences in Hainan Island and the Yangtze Block, to reveal the relationship between them. This study will provide new constraints on the Precambrian tectonic framework of the South China Block.