The Material Source Tracing Study Of The Stream Sediments In The Middle-Lower Yangtze River Ore Concertration Area

At present,the source analysis of stream sediments is more and more common.Although there are many methods for indicating the material source,it is still the most reliable tracer of detrital zircon source.In this paper,with these methods,the major trace elements analysis,detrital zircon dating?TJL1-2,CMS01,JGS09,MT05,TC05and TC06?and zircon trace elements,carried out on 46 samples of stream sediments from 4 typical ore deposits in the Middle-Lower Yangtze River.Through the comprehensive analysis and discussion of the source of stream sediment samples,achieve the main understanding:?1?From the point of view of the major elements of stream sediments,there is generally no difference between the deposits and the stream sediments.Using the CIA and CIW index,it can be seen that the MT series samples may have a low index due to the presence of potassium feldspar in the rock mass of the Matou copper-molybdenum deposits.On the trace elements,it can be concluded from the enrichment factor and the element correlation chart that the ore-forming elements mainly ways of migrate is in the form of Fe-Mn?hydrogen?oxides,and a small amount through the combination of clay minerals and organic matter.?2?It can be inferred from the discriminant diagrams of TiO₂-Ni,Al₂O₃-TiO₂,La/Yb-?REE and La/Th-Hf of trace elements that the sediment source may come from the upper crust felsic rocks.?3?Compared with the samples near the deposits,the stream sediments has a higher HREE,while the LREE performance is not obvious,but the REE composition does not reflect the source of the ore metal element.?4?Most of the detrital zircons in the stream sediment samples are mainly magmatic genesis;zircon particles which are opposite to each era appear on the histogram of age frequency distribution,indicating that in addition to the ore-forming substances in the sediments,There are also the contribution of the surrounding rock of the deposit area and the ancient crystalline basement,which reflects the complex characteristics of the sediments of the stream system.The age peak corresponding to the age of ore-forming diagenesis appears in the detrital zircon,indicating that the ore-forming material will enter the stream sediments after the later weathering and dispersion,resulting in the enrichment of ore-forming elements and influenced by different factors.?5?In the single lithology mining area,when the clastic zircon is highly consistent with the age information of the ore-forming diagenesis,it can be basically discriminated that the stream sediments mainly comes from the contribution of the mining area.?6?The more rivers meet,the more obvious the cover of the sedimentary age information,so that the zircon particles that meet the age of ore-forming diagenesis in the mining area become less and less disappeared.This phenomenon is also reflected in the element enrichment factor.And may be mixed with ancient base materials,and there is no reasonable limit to whether there is a positive connection between the sediment source and the deposit.