龙门山南西段飞来峰构造的基本特征

BASIC CHARACTERISTLCS OF THE KLIPPE STRUCTURE IN THE SOUTHWESTERN SECTOR OF THE LONGMEN MOUNTAINS

本文对龙门山南西段广泛分布的飞来峰——推复体构造的区域地质背景、构造地质体的组成及产状、区域应力场的特征,及其形成与演化历史等,进行了概略的描述。

The klippe structure is well developed in the southwestern sector of the Longmen Mountains.Its main part is composed of Permian-Carboniferous lime- stone.Its base is made up of Upper Triassic strata,andits root zone is located in the“Pengguan complex”.The geological conditions for the formation of the klippe structure are as follows.several SW-dire eted slips(countercoIckwise shearing)have occurred near the Maowen fault and the Jiudingshan fault along the boundary between the platform and the geosyncline,thus producing a series of major drag folds and arcuate structures convex towards the south at thir edges and meanwhile generating a SE-directed horizontal component.As a result the Paleozoic limestone was ovcrthrust in a SE direction to form a landscape of the klippe structure.The Tangbazi klippe in Pengxian County was thrust over the folded Uppor Jurassic,whih suggests that it is of Himalayan age.