物探成果在探讨青海鄂拉山活动断裂带控热控震的分段差异性中的应用

The application of geophysical exploration results to the investigation of segmented differences of the role of the Ngola Mountain active faulted zone in Qinghai Province in the control of geothermal and seismic activities

通过对鄂拉山断裂带上不同地段的两次地热物探勘查成果差异的对比,在区域重力场和地质构造分析的基础上,从研究现代构造应力场和构造变形入手,探讨了鄂拉山右行走滑活动断裂带控热、控震的分段差异性。在断裂南段呈NNW向,与青藏高原NE向应力呈锐角相交,剪切分力作用下以走滑为主,断裂带中不连续右行走滑羽列的右阶拉张区控制着温泉群呈串珠状分布,而无中强震发生。在断裂北段走向转为NW向,与应力方向趋近正交,在挤压应力作用下逆冲断裂易形成发震构造,却无温泉分布和地热形成条件,探讨其形成机制,着重论述温泉镇温泉具备良好地热地质条件,同时,也阐明了乌兰地段不具地热形成的地质背景。

Through a comparison of the differences between the results obtained by two times of geothermal geophysical exploration conducted in different segments of the Ngola Mountain active faulted zone and on the basis of an analysis of regional gravity field and geological structure,the authors,starting with the study of modern tectonic stress field and tectonic deformation,investigated the segmented differences of the role of the Ngola Mountain active faulted zone in Qinghai Province in the control of geothermal and seismic activities. The southern segment of the faulted zone strikes in NNW direction and intersects the NE-trending stress of the Tibetan Plateau at an acute angle and mainly assumes strike- slip nature under the stress component force; the right-lateral pull-apart area controls the cluster distribution of the warm spring groups and has no intermediate and strong seismic activities. In the northern segment of the faulted zone,The strike turns in NW direction and is nearly perpendicular to the diection of the stress; under the action of compressive stress,the thrust fault is likely to become causative fault,but possesses no conditions for the formation of warm springs and geothermal fields. This paper investigates the formation mechanism of the warm springs and geothermal fields,emphatically describes the good geothermal and geological conditions of the warm springs in Wenquan Town,and also points out that there exists no geological setting for the formation of geothermal fields in the Wulan segment.