西南石油大学学报(自然科学版)

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A Research on Characteristics of Dolostones in Akeshake
Formation,Lower Carboniferous,Ili Basin

Qu Jianhua1*, Yu Chaofeng2, Li Xiao1, Ding Jing1, Tang Yong1   

  1. 1. Research Institute of Exploration and Development,Xinjiang Oilfield Company,PetroChina,Karamay,Xinjiang 834000,China
    2. Hangzhou Institute of Petroleum Geology,PetroChina,Hangzhou,Zhejiang 310023,China
  • Online:2015-02-01 Published:2015-02-01

Abstract:

Ili Basin is an area where the carbonate is best developed in north Xinjiang,both the distribution range and the
depth being large. By observing outcrops,we found that dolostones was widely distributed in ILi Basin,with 2nd of Akeshake
upper-subunit developed lengthways,and distributed in(but not all)platform edge shallow facies. There developed dolostones
in south of basin,with bigger thickness,scale and expansion range than northern part,which is closely related to fracture or
later intrusions. Lamella observation indicates that dolostones are mainly in powder-fine grain texture,the majority of which
is finegrain,with block structure,and carbonate with larger type of rocks are fine grain dolostones according to size fraction.
Through contrasting the rare earth element distribution pattern of the dolomite,gray matter dolomite and limestone,we found
the three rock curve shapes are very similar,which make clear that there is close inner link between dolomite and limestone.
According to the δCe we conjecture the limestone is formed from the deoxidation environment and the dolomite is formed from
the oxidation environment. In conclusion,the genetic type of the dolomite in the research area is hydrothermal dolomite.

Key words: ILi Basin, Akeshake Formation, characteristic of dolostones, genetic type