摘要
鲁西地块上分布着一系列的北西向乃至北西西向拗陷带。从火山活动、沉积相和地质构造特征方面分析,具有明显的中、新生代裂谷性质。自北向南主要由泰安—莱芜、新泰—蒙阴和泗水—平邑裂谷组成,中间隔以新南山—孟良崮和蒙山隆起带,统称鲁西裂谷系。它是继承前晚侏罗世的古老扭性或压扭性断裂带而持续活动的。主要裂谷活动阶段有二:晚侏罗世—早白垩世的初生裂谷阶段和早第三纪的再生裂谷阶段,间夹以晚白垩世和晚第三纪—第四纪的扭性或压扭性为主的构造作用阶段。产生裂谷的力源主要是地幔上隆效应以及由太平洋板块的俯冲作用和印度板块的府冲、碰撞作用导致的区域应力场效应。
There is aseries of sag belts of NW and NWW trend in Luxi massif beside the west side of Tan u fracture zone in Shandong province. Accord- ing to analysis of the characterstics of sedimentary facies, volcanic activity and geological structure, the sag belts belong to a series of the Me-sozoic-Cenozoic complex rifts that consist of Taian-Laiwu, Xintai-Meng-yin and Sishui-Pingyi rift from north to south.The strikes in main part of them are NW 225-250°. Among them are Xinpushan-Menglianggu and Meng-shan swell belts (Fig.1).The sedimention is maily late Juarassic and early Eogene deposits that have synsedimentary tectonic feature in rift basin. Allurial deposit fan and inter mountain braided river facies developed in lower Mengyin formation of late Juarassic epoch and in upper Mengyin formation are lacustrine facies. These sedimentary facies associations are the unconpen-sated sequence, which represent a changl from early rapid tensile to late slow tensile.The Eogene deposits of Guanzuang formation apparentiy have two layered structures, the lower layer is unconpensated sequence (alluvial deposit fan-lacustrine facies) and the upper layer is ultraconpensated sequence (piedment deposit facies). The Eogene deposits are product of the reopen rifts, which had been closed in Mesozoic era. It is similar to aulacogen sedimentary.Early cretaceous Qingshan formation consists of a suit of mid-basic volcanic rocks that are mainly alkali basalt-latite association. According to analysis of a great many of petrochemical data, the tectonic setting that the volcanic rocks have been formed in double conditions is a kind of rift on the continental marign. Luxi rift system continue to active on the basis of the shear or compressive-shear fracture zone of prelate Juarassic era. In Luxi rift system, there are two main activity stages, the first rift stage is from late Juarassic to early Cretaceous epoch and the second rift stage is Eogene (Pig.10).The force source which generated rifts were mainly the effects of mantle uplift and regional stress field induced by subduction and collision of Pacific plate and Indian plate
关键词
鲁西
裂谷系
坳拉谷
地质特征
rift system, aulacogen, mantle uprift, subduction and collision
