泰山周围下古生界与泰山群不整合面上滑动构造的发现

DISCOVERY OF SLIDING STRUCTURES ON THE PLANE OF UNCONFORMITY BETWEEN THE LOWER PALAEOZOIC AND THE TAISHAN GROUP IN THE VICINITY OF TAISHAN MOUNTAINS

近年来,笔者在泰山周围下古生界沉积盖层与太古宙结晶基底的角度不整合面上发现许多滑动构造现象,特征十分明显,属于一种不整合面上重力滑动构造类型。这一发现对我们今后在鲁西开展滑动构造研究,进一步认识鲁西总体构造具有重要意义。本文着重论述了它们的特征,并对其成因作了初步探讨。

In recent years, the authors have discovered a lot of sliding structures on the plane of unconformity between the Lower Palaeozoic and the Archean Taishan Group in the vicinity of Taishan Mountains. The plane of unconformity is a slide surface a ong which there are a lot of slide breccia and elastic dikes and on which there are a lot of striations and polished surfaces. The hanging wall of the Palaeozoic is a sliding system with complicated structures. Moderately thick dolomitic limestone bearing chert bands and thin bedded dolomitic marl at the base of the Cambrian Mantou Formation were folded and some of them disappeared due to sliding. The foot-wall is an autochthonous system having simple structures. There is only some cataclasite in it. After analysing the features of sliding structures, the authors think that they are gravitation sliding structures caused by tilting of fault blocks, and the hanging side moved to the north after the Yanshanian movement. This discovery explains from a tectonic view of point why some beds at the bottom of the standard section of the Cambrian at Zhangxia, Changqing, are absent, which is of major significance for carrying out the study of sliding structures in western Shanddong and gaining a further knowledge of the tectonics therein.