川西北飞来峰成因探讨

Discussion of klippe genesis in Northwest Sichuan

川西北飞来峰广泛分布,关于飞来峰的成因说法有多种不同的观点,近来周自隆等提出的巨型冰川漂砾成因受到重视。为验证此观点的准确性,在岷江断裂带附近进行野外考察,分析飞来峰的地层及其与构造运动的关系。结果表明:研究区飞来峰的分布位置与断裂有较好的匹配关系,其形成时期与断裂活动期具有很好的一致性,表明飞来峰主要受构造运动的控制,通过断裂的逆冲推覆将岩体从远处带到现今的位置,是构造运动的产物,且以大规模的推覆作用为主,并伴随有重力滑覆,在它们的共同作用下,形成了现在的飞来峰,而并非冰川活动所致。

The klippen wildly distribute in Northwest Sichuan, and there are different ideas for the klippe genesis. The idea proposed by ZHOU Zilong is that the klippe glided on the giant glacier and the ice water as the lube and power. In order to verify the idea＇s accuracy, field observation near the Minjiang fracture was done, and the stratum and its relationship with tectonic movement of klippe were analyzed. The results show that the klippen distribution and the fracture reveal good matc- hing relationship and the klippen forming period agrees well with the fracture action period. The kilppen were controlled by tectonic movement and the rock was brought to the contemporary situation by the fracture overthrusting. The klippen were the product of tectonic movement, and the large scale overtbrust accompanied by gravity gliding and capping rather than the glac- ier action was the main dynamics.