中国主要镍矿类型及其与古板块构造的关系

新中国成立后,开展了大规模持续的地质找矿工作,发现了一系列镍矿床。这些矿床的探明,充分证实我国是一个镍矿资源十分丰富的国家。本文在归纳划分了镍矿类型之后,试图对在古板块构造作用下镍矿区域成矿问题作些探讨。主要依据现代海洋资料建立起来的板块构造学说,生动而又精辟地阐述了晚近地质时期某些地质构造规律和成矿作用。但是,对于古板块构造作用和受古板块制约的古成矿作用来

A discussion on the main types of Nickel deposits in China with an approach to their relations with the paleoplate tectonics

So far three main genetic types of nickel deposits have been recognized in China: magmatic copper-nickel sulfide deposits, nickel deposits in crust of weathering, and sedimentary nickel deposits. On the basis of geotectonic locations of intrusive bodies, genetic types of these bodies and the way sulfides concentrated, the copper-nickel sulfide deposits fall into two large groups: deposits that intruded along the edge of the paleolandmass and those which found their way into its active outer zone. They can be subdivided into five minor groups and then a variety of types. The magmatic copper-nickel sulfide deposits constitute the main genetic type in China. Among them the single ferruginous ultrabasic body (lherzolite) that intruded along the edge of the paleolandmass has the best mineralization. The ultrabasic body, steep in dip, is about several kilometers in length and 200-300 meters in width. Present in this ultrabasic body are hundreds of upper segregation ore bodies, stratoid ore bodies on bottom, injection ore bodies and contact-metasomatic ore bodies, making up a deposit with mineralization at every stage and a variety of its own peculiarities, According to an analysis of the paleostructure the author has drawn the inference that there existed three possibilities to form nickel-containing ultrabasic bodies: (1) The unsteadiness of the basement of the paleolandmass during the early stage of its formation caused tensile clastation and expansion of rift valleys and then the intrusion from the mantle of the ultrabasic magma rich in sulficles along huge fracture zones, forming ultrabasic bodies such as Jinchuan deposit. (2) After the gradual solidification of the paleolandmass there intruded the nickel-bearing ultrabasic magma along the active continental edge. The nickel-bearing ultrabasic bodies along the northern border of the Sino-Korean paleoiandmass can be referred to as examples. They were mostly formed during the Variscian orogeny, so it is imaginable that the Tianshan-Xingan oceanic crust got refused when its descending movement beneath Sino-Korean paleolandmass reached the mantle, thus resulting in the intrusion of the basic-ultrabasic magma containing copper-nickel sulfides and the formation of the corresponding deposits. (3) Owing to the moving forward, folding and uniting with the paleolandmass on the part of the oceanic crust, intense compression and deep faulting took place along the edge of the subduction zone outside the paleolandmass, followed as a consequence by the tectonic emplacement of the ophiolite suite. If this happened under the tropical or subtropical wet climate the top layer of the magnesian ultrabasic body in ophiolite suite might have been altered into nickel deposit of the crust of weathering type. ln addition to this, deep fault might have caused the refusion and invasion of the mantle substances, forming basic-ultrabasic bodies rich in copper-nickel sulfides. Deposits in Ailaoshan fold system are association of these two types.