Gravity anomaly and crustal density structure in Jilantai rift zone and its adjacent region

详细信息    查看全文

• 作者：Guiju Wu ; Chongyang Shen ; Hongbo Tan ; Guangliang Yang
• 关键词：Yinchuan ; Helanshan uplift ; Jilantai rift zone ; Gravity profile ; Bouguer gravity anomaly ; Crustal density structure ; Normalized full gravity gradient ; Seismogenesis
• 刊名：Earthquake Science
• 出版年：2016
• 出版时间：August 2016
• 年：2016
• 卷：29
• 期：4
• 页码：235-242
• 全文大小：2,945 KB
• 刊物主题：Geophysics/Geodesy;
• 出版者：Springer Berlin Heidelberg
• ISSN：1867-8777
• 卷排序：29

文摘

This paper deals with the interpretation of Bouguer gravity anomalies measured along a 250 km long Suhaitu-Etuokeqi gravity profile located at the transitional zone of the Alxa and Ordos blocks where geophysical characteristics are very complex. The analysis is carried out in terms of the ratio of elevation and Bouguer gravity anomaly, the normalized full gradient of a section of the Bouguer gravity anomaly (Gh) and the crustal density structure reveal that (1) the ratio of highs and lows of elevation and Bouguer gravity anomaly is large between Zhengyiguan fault (F4) and Helandonglu fault (F6), which can be explained due to crustal inhomogeneities related to the uplift of the Qinghai-Tibet block in the northeast; (2) the main active faults correspond to the Gh contour strip or cut the local region, and generally show strong deformation characteristics, for example the Bayanwulashan mountain front fault (F1) or the southeast boundary of Alxa block is in accord with the western change belt of Gh, a belt about 10 km wide that extends to about 30 km; (3) Yinchuan-Pingluo fault (F8) is the seismogenic structure of the Pingluo M earthquake, and its focal depth is about 15 km; (4) the Moho depth trend and Bouguer gravity anomaly variation indicates that the regional gravity field is strongly correlated with the Moho discontinuity.