【摘要】 本文以洛坝矿床的硅岩为例,对以沉积岩为主岩的沉积-喷气矿床的一种重要容矿岩石——硅岩,从其产状形态,物质成份等方面,进行了岩石学、矿物学、化学组成、微量元素及同位素研究,提出了同生热液沉积-准同生交代成因的论点,并论证了新发现的多孔状硅岩是蒸气爆裂成因的可能性。更多还原

【Abstract】 The Luoba lead-zinc ore deposit occurs in eastern Xicheng metallo-genetic province and is believed to be the silicarock-type lead-zinc-copper ore of hydrother-mal-sedimentary ( sedimentary-exhalative ) origin.The silicarock formation is thought to be pertinent to penecontemporaneous hydrothermal replacement and deposition according to occurence, morphology, chemical composition, mineralogy, isotopes, structure and texture of the rocks.In detail, our conclusion is drawn from the following facts: 1, lenticular ore body; 2, occurrence near F1 which is assumed to be a hydrothermal passageway; 3, residual biobodies and stylolite structure; 4, prism-grain texture; 5, anomalous contents of elements F, B and As; 6, the REE distribution similar to the pellite from the same area; 7, σ18O value is between average value of abysmal chert and magmatic hydrothermal quartz veins; 8, mixing-genetic 87Sr/86Sr rates; 9, obvious composition variation of the liquid inclusions.The silicarock is a kind of the vesicular silicified rock and is presumably formed during hydrothermal boiling periods.It is also characterized by existence of fluorite and tourmaline, richness in F and B, breccioid structure and occurrence at definite levels. Obviously, the silicarock formed by means of vapour cryptoexplosion.更多还原