| 南海北部古近纪沉积物碎屑锆石U-Pb年龄及物源演化 |
| |
| 引用本文： | 崔宇驰,曹立成,乔培军,陈淑慧,庞雄,邵磊.南海北部古近纪沉积物碎屑锆石U-Pb年龄及物源演化[J].地球科学,2018,43(11):4169-4179. |
| |
| 作者姓名： | 崔宇驰 曹立成 乔培军 陈淑慧 庞雄 邵磊 |
| |
| 作者单位： | 1.同济大学海洋地质国家重点实验室, 上海 200092 |
| |
| 基金项目： | 国家自然科学基金项目91128207国家自然科学基金项目41576059国家科技重大专项项目2011ZX05025-006-02 |
| |
| 摘 要： | 长期以来，由于地质资料的限制，有关南海早期裂陷过程中的沉积演化问题一直缺乏相对深入的认识与了解.采用碎屑锆石U-Pb定年方法，对南海北部古近纪沉积物进行"源-汇"对比分析.结果表明，该时期南海北部不仅接受来自北部河流搬运的陆源碎屑物质，同时还受到盆地内部局部隆升区物源的影响.其中，始新世沉积物以下白垩统物源为主，至早渐新世，琼东南盆地接受了来自海南岛及西沙隆起带的沉积物，珠江口盆地珠一坳陷同时期的锆石磨圆度较高，年龄谱系同华南沿海地区一致，说明很可能接受了来自华南沿海地区的陆源物质；而处于盆地南侧的白云凹陷同时期存在自形程度极高的锆石，反映其物源极可能为盆地内近源的局部隆起区.到晚渐新世荔湾凹陷沉积物中开始出现较多元古代锆石，与其北部同时期沉积物明显不同，琼东南盆地N6井也开始出现较多元古代锆石，其物源可能与南海西侧隆起有关.资料显示，在古近纪，现代意义上的珠江并未形成，其在早渐新世仅影响到珠一坳陷，到晚渐新世影响到珠二坳陷北侧.因此，珠江在古近纪具有从小到大逐步演化的特点.
|
| 关 键 词： | 沉积物 锆石U-Pb定年 白云凹陷 琼东南盆地 古近纪 南海 |
| 收稿时间： | 2017-12-11 |
Provenance Evolution of Paleogene Sequence (Northern South China Sea) Based on Detrital Zircon U-Pb Dating Analysis |
| |
| Abstract: | The early rift provenance evolution of the South China Sea (SCS) remains unsystematically explored due to limitations of borehole coverage and shortages of reliable dating results. In this study, detrital zircon U-Pb dating methodology was used to investigate the "source to sink" patterns of Paleogene syn-rift sequences in the northern SCS. In addition to the terrigenous supply transported from the north, it is found that intrabasinal provenances are also of great significance. The Eocene samples are dominated by Early Cretaceous zircon. The Early Oligocene sediments of Qiongdongnan basin indicate a source from Hainan Island and Xisha uplift while contemporary sediments of Zhu-1 depression in northern Pearl River Mouth basin were supplied by southeastern South China with highly-grained zircons sharing similar U-Pb age characteristics. Nevertheless, based on the existence of euhedral zircon shapes, Baiyun sag in southern Pearl River Mouth basin was most likely dominated by intrabasinal sources. The late Oligocene sequence of Liwan sag and Qiongdongnan basin could have been supplied by western uplift of the SCS with the increasing abundance of Proterozoic zircon ages. It has been revealed that the Pearl River could only have contributed to the infill of Zhu-1 depression during Early Oligocene before evolving into the terrigeous source for northern Zhu-2 depression in Late Oligocene. Conclusively, the Paleogene provenance development of the northern SCS is remarkably featured as episodic and diachronic Pearl River evolution processes. |
| |
| Keywords: | |
|
| 点击此处可从《地球科学》浏览原始摘要信息 |
| 点击此处可从《地球科学》下载免费的PDF全文 |
