Q value structure of geoscience transect from Korla to Jimsar and its geodynamic implication  

作　　者：赵俊猛 樊吉昌 李植纯 

机构地区：[1]Institute of Geology, China Seismological Bureau [2]Center for Geophysical Exploration, China Seismological Bureau [3]Institute of Occupational Disease Protection for Laboring Hygiene of Hunan Province

出　　处：《Science China Earth Sciences》2003年第8期779-788,共10页中国科学（地球科学英文版）

基　　金：the National 973 Research Project(Grant No.G1999043301).

摘　　要：In this paper, the methods for Q value inversion in 2-D lateral inhomogeneous medium have been introduced. The 2-D Q value inversion has been conducted using seismic wide-angle reflection/refraction data of the profile from Korla to Jimsar. The result shows that the 2-D Q value structure of the transect from Korla to Jimsar is characterized by vertical stratifying and lateral zoning. Vertically, the crust can be divided into upper crust, middle crust and lower crust with the Q value increasing downwards. Horizontally, the total transect can be classified as three regions— the northern margin of the Tarim Basin, the Tianshan orogenic belt (TOB) and the southern margin of the Junggar Basin. At the northern margin of the Tarim Basin the Q value increases northwards, indicating a northward subduction of the Tarim Basin into the The Q value within the TOB jumps near Kumux, making a stage-like difference in Q value. The Q value distribution at the southern margin of the JB suggests a southward subduction of the Junggar Basin (JB) into theThe double subduction pattern of the and JB into the TOB revealed by the transect from Korla to Jimsar has a big difference from the model “lithospheric subduction with intrusion of the layers into the crust” developed according to the results of the geoscience transect from Xayar to Burjing. The differences between the two provide some dynamic evidence at lithospheric scale for the segmentation of theIn this paper, the methods for Q value inversion in 2-D lateral inhomogeneous medium have been introduced. The 2-D Q value inversion has been conducted using seismic wide-angle reflection/refraction data of the profile from Korla to Jimsar. The result shows that the 2-D Q value structure of the transect from Korla to Jimsar is characterized by vertical stratifying and lateral zoning. Vertically, the crust can be divided into upper crust, middle crust and lower crust with the Q value increasing downwards. Horizontally, the total transect can be classified as three regions——the northern margin of the Tarim Basin, the Tianshan orogenic belt (TOB) and the southern margin of the Junggar Basin. At the northern margin of the Tarim Basin the Q value increases northwards, indicating a northward subduction of the Tarim Basin (TB) into the TOB. The Q value within the TOB jumps near Kumux, making a stage-like difference in Q value. The Q value distribution at the southern margin of the JB suggests a southward subduction of the Junggar Basin (JB) into the TOB. The double subduction pattern of the TB and JB into the TOB revealed by the transect from Korla to Jimsar has a big difference from the model ?lithospheric subduction with intrusion of the layers into the crust?developed according to the results of the geoscience transect from Xayar to Burjing. The differences between the two provide some dynamic evidence at lithospheric scale for the segmentation of the TOB.

关 键 词：Q value structure  Tarim Basin  Tianshan orogenic belt  JUNGGAR Basin  subduction  geodynamics. 

分 类 号：P631.42[天文地球—地质矿产勘探]