大巴山弧形构造的成因——来自数值模拟的证据

大巴山弧形构造带位于秦岭南缘，以其醒目的几何形态而获得广泛的关注。对于大巴山弧形构造的成因向来是研究的热点。本文运用数值模拟的方法对大巴山弧形构造的成因进行了探讨。模拟结果表明，大巴山地区印支-燕山主造山期的最大水平主应力轨迹受城口-房县弧形断裂和前缘两侧隆起所控制。大巴山弧形构造是在早期伸展背景下形成的城口-房县弧形断裂、前缘两侧隆起的砥柱作用、滑脱作用为主要控制因素而形成的。

Origin of the Dabashan Salient: Evidence from Numerical Modelling

Dabashan structural belt, located in the southern margin of the Qinling orogenic belt, has attracted much attention by its remarkable geometric shape of salient. The mechanics of the salient has long been discussed. Using the numerical modelling method, the formation mechanism of the Dabashan salient is studied in the article. Modelling results show that the pre-existing salient-shaped boundary originated in extensional setting and a pair of indenters in the front control the trajectory of the maximum horizontal principal stress during intra-continental orogeny. Considering the background and the former work done by the author, décollement is also considered to be a key role in the process. It is proposed that Dabashan salient resulted mainly from pre-existing salient-shaped boundary formed in extensional setting, a pair of indenters in the front and décollement.