Isostatic Anomaly and Vertical Tectonic Stress Analysis by Gravity Observations in Qinling Area
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摘要: 确定秦岭地区准确的均衡异常与垂向构造应力对认识该地区深部构造特征、动力学机制等具有重要意义。目前，高精度重力数据是获取均衡异常与垂向构造应力的重要手段之一。采用高精度重力/GPS联测数据，得到秦岭地区的自由空气重力异常与布格重力异常，反演均衡异常与垂向构造应力。研究结果表明，均衡面深度在40~49 km之间，莫霍面深度范围为39~48 km，垂向构造应力大小在-28~24 MPa之间。秦岭北侧的渭河盆地处于不均衡状态；四川盆地北部的均衡异常与垂向构造应力几乎为零，地壳处于均衡状态；在秦岭出现局部的负均衡异常，表明存在一定的地壳运动。Abstract:Objectives It is important to determine the isostasy anomaly and the vertical tectonic stress for understanding the deep tectonic features and dynamics in Qinling area. At present, high-precision observation gravity data is one of the important means to obtain the isostasy anomaly and the vertical tectonic stress.Methods The free-air gravity anomaly and the Bouguer gravity anomaly are computed by using gravity and GPS data, and the isostasy anomaly and the vertical tectonic stress are further inferred.Results The results show that the isostasy depth is 40-49 km, the Moho depth is 39-48 km and the vertical tectonic stress carried by the crust is -28-24 MPa.Conclusions The Weihe Basin on the northern of Qinling area is in a non-isostatic state. The isostasy anomaly and the vertical tectonic stress are approximately zero in the Northern Sichuan Basin, which indicates the basin is in an isostatic state. The local negative isostasy anomaly in Qinling indicates that there is existence crustal movement.
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Keywords:
- the Moho depth /
- the isostatic depth /
- vertical tectonic stress /
- Qinling area /
- isostatic anomaly
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表 1 莫霍面深度统计结果/km
Table 1 Statistics of Moho Depths /km
类型 最大值 最小值 平均值 标准差 所有测点 47.448 39.774 41.862 1.373 P1剖面 47.448 41.408 43.529 1.656 P2剖面 43.064 40.611 41.725 0.592 P3剖面 42.254 39.838 40.798 0.581 P4剖面 44.176 39.774 41.517 1.069 P5剖面 41.857 40.789 41.250 0.263 
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