Provenance Analysis Of The Permian Sedimentary Sandstones In Keshiketeng Of Inner Mongolia

The thesis takes west of northeast China as its study area which including Keshiketeng,Linxi,Dongwu Banner,Horqin's Ring Wing Front Banner and Solon area. The geographical position for the north part of north latitude 42°,east part of east longitude 110°30′. Its geotectonic position lies in the intersection part of Siberia Plate,North China Plate and Pacific Plate,which suffered from interaction time after time. When Pre-mesozoic the area was influenced by the Paleo-Asian ocean tectonic domain,and went through a evolution history of subduction of Paleo-Asian ocean,the accretion between two Plates margines,at last matching each other. Since Mesozoic Era,it experienced a strong reform and superposed acrrection from Pacific Plate. So it become a hot area in geological studies. Simulately,there still have many arguments in tectonic evolution of this area.Aiming at these problems,this article make a source analysis on Permian sedimentary rock from Eastern Inner Mongolia. As a important method of sedimentary basin analysis,Source analysis is widely applied in deducting different sedimentary basins evolution.Through systematic sampling and statistical data,the paper considers that Permian sedimentary rock samples(Linxi Formation,Yujiabeigou Formation,Gegen'aobao Formation,Zhesi Formation) in the study area are feldspathic lithic sandstone,this show that the transportation distance of sediments is very short. And a great deal of immature crustal components provided provenance to Permian sedimentary rocks. Futhermore,most of Permian sedimentary rock samples fall in the recycled Orogen Provenances in the QtFL and QmFLt triangular diagram delinested by Dickinson(1979). But in the QpLvLs triangular diagram we can see samples of south part which include Keshiketeng and Linxi fall in mixed Orogen Provenances,and samples of north part which include Dongwu Banner and Solon fall in island arc Orogen Provenances. Studys from microscopy observation,rare earth and trace element geochemical analysis show that the major source area was tectonic background of continental island arc and active continental margin. The provenance of south part are Xar Moron River Matching Belt and island arc orogenic belt in the North.And the source area of north part is island arc orogenic belt. Moreover,Permian sedimentary rock in study part is characterized by relatively enriched light rare earths,obvious fractionation of REE and a negative Eu anomaly. This has similar distribution of basic trend with PAAS and NASC,so it shows that its original substance mainly come from felsic rock of upper crust. To contrast with upwards geochemical analysis and distribution , lithologic fearures and geochemical analysis of the Late Palaeozoic volcanics in research area,it was clear that the provenance probably be the volcanic rocks in Late Devonian to Early Carboniferous and Late Carboniferous to Early Permian. In addition,by the contrast this study and geochemical analysis of old basements from surrounding area,they have certain similarity and affinity. So the provenance also contains these old basements——Xinghuadukou Group and epimetamorphic rock series in Zhalantun area.