塔里木盆地玉北地区奥陶系层序界面识别及特征

Recognition and the Character of Sequence Boundary of Ordovician in Yubeiarea of Tarim Basin

以层序地层学理论为指导,结合奥陶系沉积地质背景,在研究层序界面标志基础上,对玉北地区奥陶系层序界面的识别及特征进行研究。层序界面识别标志主要有暴露标志、岩性岩相组合、测井及地震等,其中表生暴露较普遍,可见渗流粘土、渗流粉砂、褐铁矿化(染)、淡水方解石充填溶蚀缝洞及示底构造等典型标志。共识别出3个二级层序界面(SSB1、SSB2、SSB3)和4个三级层序界面(SB2、SB3、SB5、SB6)。

By means of sequence stratigraphy theory, combined with the Ordovician sedimentary geological background, based on a detailed study of the sequence boundary signs, we study on the recognition and the character of sequence boundary of Ordovician in Yubei area.The main identification sign of sequence boundary are supergene exposure character, combination of lithology and facies, log and seismic character and so on. Supergene exposure is common among them, it consist of vadose clay, vadose silt, ferritization, emposieu filled with freshwater calcite, geopetal structure, etc. On this basis, three supersequence boundaries（SSB1, SSB2, SSB3） and four sequence boundaries（SB2, SB3,SB5, SB6） of Ordovician are identified in the study area. In the meantime we analyse the character of sequence boundary, the conclusion can provide basis for division of sequence stratigraphy of Ordovician in Yubei area.