鲁西幔枝构造及其控矿特征

内容摘要: 从区域地层(岩体)中老外新分布，环状、放射状断裂的展布，轴部缓倾拆离滑脱构造的发育，幔源岩浆活动以及区域岩石学、岩石化学、同位素地质学等方面，探讨了鲁西幔枝构造特征。研究认为鲁西地区北西向陡倾韧性剪切带切割了深部华北地幔亚热柱向外拆离的地幔岩，导致其减压释荷形成深熔岩浆，强烈而完整的岩浆演化序列表现出岩浆基性程度由高变低、侵入深度由深变浅、围岩蚀变由强变弱的总体演化趋势。幔枝构造演化对内生成矿作用具有明显的控制作用，并带动围岩一起隆升，形成了典型的鲁西幔枝构造。其顶部发育的拆离掀斜断块，使部分内生矿产被抬升到浅部。

Mantle branch structure in western Shandong and its Characteristics of ore-controlling*

AbstractThis work discusses the characteristics of mantle branch structure in western Shandong Province, China,with respect to the distribution characteristics and ages of the regional strata, the development of ring-like and radial faults, the development of gently inclined detachment-slip structures in the axial part, mantle-source magmaticactivities, regional petrology, petrochemistry and isotope geology. The study indicated that the N-W sharply plunged ductile shear zone in the region of western Shandong cuts through the mantle rocks detached from the deep-seated North China mantle sub-plume, hence leading to unloading in response to depressurization and thereafter the formation of anatexis magma. The intense and complete magmatic evolution series not only manifests a variation trend of alkalinity of magma from high to low and its intrusive depth from deep to shallow, but also reflects that the wall-rock alteration shows a general evolution trend from strong to weak. The evolution of mantle structure played an important role in controlling endo-mineralogenesis, accompanied with the rise of the country rocks. As a result, typical mantle branch structures were formed as observed in western Shandong. At the top of the mantle branch structure was developed an obvious detachment-tilt fault block, and some endogenic ores, at the same time, were uplifted onto the shallow levels.