Tracing Study On Sediment Garnet Water System In Subei Basin Since Late

Study area XH2is located in Subei Basin. Subei Basin experienced the breaking and the depression. deposited thick sediments. These sediments record the provenance of Subei Basin tracer and streams adjustment information.In this paper, the choice is heavy mineral garnet electron probe provenance tracing method.By electron microprobe analysis of garnet single particle chemical composition of heavy minerals can help identify the source area and to determine the provenance of increased credibility.We select XH2(Xinghua2drilling) as the main object of study. The depth is750m,and time span is about7.75Ma, we collect10samples of XH2, and8samples of the Huaihe River and Yangtze River downstream river basin.Using Mineral garnet single electron microprobe analysis, and combining the results of previous studies have been conducted comparative analysis reveal the river adjustment and the provenance changes in the subei basin since about8MaAccording garnet electron microprobe data analysis,garnet end members of Huaihe River and Yangtze River have obvious differences. The crystal forms of garnets are mainly Almandine-Pyrope in Huaihe River Basin,and the forms are mainly Almandine-Spessartite, Almandine-Grossular in Yangtze River.It can be divided into six sections of XH2:segment Ⅰ (745.41m-630m;7.75Ma-6.55Ma). the forms of garnets are mainly alm-pyr, consistent with the forms of Huaihe River Basin. This phase is mainly affected by the Huaihe River Basin; segment Ⅱ (630m-500m,6.55Ma-5.20Ma) the forms are mainly alm-spe.alm-gro, with the Yangtze River Garnet consistent type. This phase is mainly affected by the Yangtze River;segmentⅢ(500m-410m,5.20Ma-4.25Ma) the forms are mainly alm-pyr,alm-spe, alm-gro, this phase is mainly affected by the combined effect of the Huaihe River and Yangtze River; segment Ⅳ (410m-330m,4.25Ma-3.42Ma). the forms of garnets are mainly alm-pyr, this stage is mainly affected by the Huaihe River Basin; segment Ⅴ (330m-270m,3.42Ma-2.80Ma,) the forms are mainly alm-pyr,alm-spe,alm-gro, this stage is mainly affected by the Huaihe River and Yangtze River; paragraph Ⅵ (270m-0,2.80Ma-now).the forms of garnets are mainly alm-pyr, this stage is mainly affected by the Huaihe River Basin. In addition the Yangtze river water system flowed to the sea through subei basin by not later than6Ma,and then the Yangtze downstream river diverted traffic southward, flowed through the Yangtze river delta now.