岩浆硫化物矿床勘查研究的趋势与小岩体成矿系统

摘要

通过2009年西安Ni-Cu(Pt)岩浆矿床国际学术研讨会和近10年来的勘查研究现状.可以看出岩浆硫化物矿床勘查领域的发展趋势为:与大型层状岩体有关的铂族矿床仍然受到关注;Sudbury矿床的特殊性和不可参照性取得了共识;小岩体矿床是勘查研究的主流;通道成矿作用受到重视.以大型层状岩体Bushveld为例,介绍了其中的Merensky矿层、UG-2矿层和北翼接触带的Platreef矿床.由于中国没有发现这种大型层状岩体,因此应当重视那些中小型层状岩体中可能赋存的铂族矿床.迄今为止,除了Sudbury矿床这个特殊的实例之外,国内外所有具有经济意义的Ni-Cu矿床都寄生于小岩体中并自成一个成矿系统.这个小岩体成矿系统包含成矿背景、邻近深大断裂、原始岩浆、先导性岩浆成岩作用、继发性岩浆成矿作用以及深部熔离-分期贯入-终端岩浆房聚集成矿等.近10年的勘查实践进一步说明,这类小岩体矿床仍是中国今后的主要勘查研究方向.最后,介绍了Noril'sk-Talnakh 和Voisey's Bay矿床的深部熔离一通道成矿机制,这种机制增添了小岩体成矿作用的多样性;但是,其现存空间是开放性岩浆通道还是封闭性终端岩浆房,还有待更多的研究和实践.%The trends of research in exploration of magmatic sulfide deposits can be seen from the Xi'an International Ni-Cu(PGE) Deposit Symposium 2009 and the achievements of exploration research over the past decade as following: the PGE deposits related to the large-layered intrusions still receive much attention; it is agreed that the Sudbury deposit is unique and worthy of little reference; small intrusion metallogenic system becomes the main stream of the research; the theory of magma plumbing mineralization receives much attention. Bushveld, which is a large-layered intrusion, is taken as an example with brief introduction for the Merensky ore bed, UG-2 ore bed and Platreef ore deposit in the north wing of the contact zone. As there is no large rock mass discovered in China, the exploration of potential PGE deposits hosted in small- and medium-scale layered rock mass should be paid much attention. Except the particular instance of Sudbury deposit, most of the Ni-Cu deposits with economic values discovered all over the world were hosted in the small intrusions as individual metallogenitic system. The system includes metallogenic background, adjacent to deep fault, primary magma, and the digenesis of pilot magma, the mineralization of secondary magma and the segregation in deep-stage chamber, the pulsing penetrationmineralization in terminal magma chamber, etc. The exploration result over the past decade suggests that the type of small intrusion deposit is still the main target of research and exploration in China in the future. The metallogenic mechanism of deep liquation and conduit system of Noril'sk-Talnakh and Voisey's Bay deposits is introduced, and adds the diversity of small intrusions mineralization. However, it is to be answered by the future research and practice whether the ore-host space is an open conduit system or an closed terminal magma chamber.