Occurrence And Origin Analysis Of Analcimein Pingdiquan Formation,Huoshaoshan Area,Easternjungar Basin,Xinjiang,China

Huoshaoshan located in the eastern part of the Junggar Basin,The regional tectonic background of it is intracontinental downfault-rift setting from Late Carbonatiferous to Early-Middle Permian.The Pingdiquan Formationin Permian has a good prospect of exploration,our study group found that the reservoir rocks are made of a lot of tuff except the normal clastic rock,and see aegirine,aegirine-augite,fresnoite and other alkaline rock minerals.Analcime is widely distributed in the core samples,and its occurrence and content are rich.In this paper,we will discuss the different types of anacimes through the mineralogy,petrology and geochemistry and other comprehensive research.After systematic observation and identification with the microscope,we find that occurrence of most analcimes scatter into lamellar,massive,vein,pellet,oolitic,clot.A few analcimes can be seen like light abnormalities and bio-shell filling.Lots of analcimes occur as idiomorphic granular to hypidiomorphic granular crystals,which own clean crystal surface and little contact with outside fine-grained sediments.Paragenetic minerals are calcite,dolomite,alkaline feldspar,quartz,bastnasite etc.Analcime is mainly present in tuff,dolomite,limestone and analcime rocks?analcime content>25%?.The average contents of Na₂O,Al2O3 and SiO₂ of analcimes are 11.22%,50.21%and 57.22%,which is close to the ideal analcime with characteristics of low Si and high Na.Analcimes and paragenetic carbonates are relatively rich in Sr,Mn.The Xsi and Si/Al ratio calculated from chemical components of analcime according to the different analcime show that analcimes in this area are characterized by magmatic-hydrothermal and volcanic sedimentary transformation.The geochemical analysis consist of the ratio of SiO₂/Al2O3,SiO₂/?K2O+Na₂O?,SiO₂/MgO,trace elements and their identification diagram,abundance of LREE and ?REE and negative Eu and positive Ce anomaly,show that sediments with analcimes originate from pyroblast characterized by hydrothermal water,and form in oxygen reduction environment.In this paper,it is believed that there are three kinds of genesis in hydrothermal deposition,magmatism-hydrothermalism and diagenetic sedimentation that forming analcimes,and the most analcimes are formed in exhalative hydrothermal deposit,which consist of magmatism-hydrothermalism and hydrothermal synthesis.