南黄海陆架区CSDP-1孔沉积物碎屑锆石U-Pb年龄物源判别

Provenance Discrimination of Detrital Zircon U-Pb Dating in the Core CSDP-1in the Continental Shelf of South Yellow Sea

南黄海作为东部陆架海的一部分,其沉积物记录了源区、气候及古环境演变等多方面的信息。本文利用激光剥蚀等离子体质谱(LA-ICPMS)的方法,对南黄海西部CSDP-1孔沉积物进行了碎屑锆石UPb年龄测定。结果表明,CSDP-1孔沉积物碎屑锆石主要表现出300～100,500～300,1 000～700,2 100～1 700和2 600～2 300Ma 5组年龄区间。由底部到顶部,钻孔沉积物中除了1 000～700和2 100～1 700Ma的锆石质量分数变化较大,其他年龄组的锆石质量分数没有明显的变化趋势;长江、黄河、废黄河和淮河作为钻孔区域可能的物质来源,其沉积物碎屑锆石U-Pb年龄分布存在显著差异,其中长江沉积物以1 000～700Ma的锆石为特征,黄河沉积物中2 100～1 700 Ma的锆石质量分数最高,废黄河与淮河沉积物中500～300Ma的锆石质量分数均比黄河和长江沉积物高。通过对CSDP-1钻孔及河流沉积物进行物源判别并结合相关性分析可认为:钻孔沉积物3.20 Ma以来存在多源物质贡献,长江源物质占优势,淮河源次之;淮河从2.16Ma开始对钻孔区域有影响;0.78Ma该区开始有黄河源的物质,且以黄河沉积物为主要物质来源;废黄河对钻孔区域几乎没有影响。

South Yellow Sea is the part of the eastern shelf sea,and its sediments record the information of the sources,the climate and the paleo-environmental evolution.The detrital zircon U-Pb dating of the Core CSDP-1in the western South Yellow Sea was determined by laser ablation inductively coupled plasma mass spectrometry(LA-ICPMS).The results show that the zircon age distribution of the Core CSDP-1sediment mainly falls into five groups:300-100,500-300,1 000-700,2 100-1 700 and 2600-2 300 Ma.From the bottom to the top,the zircon contents in the sediments do not vary greatly except in the age groups of 1 000-700 Ma and 2 100-1 700 Ma;The Yangtze River,the Yellow River,the Old Yellow River and the Huaihe River are the possible sources of the drilling area.The detrital zircon U-Pb age distribution in sediments is significantly different,among which the Yangtze River sediments are characterized by 1 000-700 Ma zircons,and the content of 2 100-1 700 Ma zircon in the Yellow River sediments is the highest.The content of 500-300 Ma zircons from the Old Yellow River and the Huaihe River sediments are higher than that in the Yellow River and the Yangtze River.Combined with the Core CSDP-1and the river sediments,it can be concluded that the core site has been contributed by multi-source materials since 3.20 Ma.The Yangtze River is the dominant source,followed by the Huaihe River.However,the Huaihe River didn’t affected the core area until 2.16 Ma.The material of the Yellow River started to be found in the drilling area at about 0.78Ma;and since then,the Yellow River has been the main material source of the core site.The Old Yellow River had almost no effect on the drilling area.