粤东盆地早侏罗世金鸡组物源分析及其对华南构造背景的约束

华南早中生代构造背景一直存在争议。粤东盆地位于华南东南缘，记录了华南早中生代构造背景的地质信息。文章 以粤东盆地早侏罗世金鸡组碎屑沉积岩为研究对象，采用锆石U-Pb定年方法，结合岩相学、地球化学和古水流数据，探讨 盆地物源及构造背景。测年结果显示早侏罗世金鸡组样品存在八个峰值：196 Ma、247 Ma、320 Ma、432 Ma、770 Ma、 1060 Ma、1820 Ma和2430 Ma。物源分析表明粤东盆地金鸡组物源主要来自盆地的东北侧和北侧两个方向。粤东盆地碎屑 锆石与位于盆地东北侧的永安盆地和北侧的东坑盆地的物源特征相似，反映出早侏罗世中国东南部盆地尽管还是以稳定的 克拉通边缘盆地为特征，但古太平洋板块向华南板块更东侧的俯冲已经开始为中国东南缘盆地提供物源。

Detrital Provenance of the Lower Jurassic Jinji Formation and Its Constrains to the Early Jurassic Geodynamic Background of South China

Early Mesozoic geodynamic background of the South China Block (SCB) is still controversial. The Late Triassic-Early Jurassic Eastern Guangdong basin locates at southeastern margin of the SCB and contains key records of its geodynamic background. Detrital zircon LA-ICP-MS dating was carried on the Lower Jurassic Jinji Formation in the basin in this study. The results display eight age peaks, i.e. ca. 196 Ma, 247 Ma, 320 Ma, 432 Ma, 770 Ma, 1060 Ma, 1820 Ma, and 2430 Ma. Provenance analysis suggests that the sources of the Lower Jurassic Jinji Formation were mainly derived from the northeast and north directions. Correlation of the detrital zircon age spectra reflects that the studied basin resembles the Yongan basin to the northeast and Dongkeng basin to the north. Integrated analysis of the sediment provenance, petrology and geochemistry of the Jinji Formation reveals that the Early Jurassic basins in southeastern China, even though bear characteristics of passive continental margin, already received sediment supply from the uplifts in more eastern region resulted from the northwestern subduction of the paleo-Pacific plate toward the SCB.