四川地区海泡石粘土矿的地质特征及分布规律

Geological Features and the Distribution of Sepiolite Deposits in Sichuan Province

摘要:

海泡石(sepiolite)是很有发展前途的一门新兴矿种,是当今世界上用途很广的非金属矿物原料之一。在石油、油脂、酿造、轻工、化工、医药、国防、农牧业、环保、橡胶、涂料以及深井钻探泥浆等方面都有应用,就目前所知,其用途广达130余种,随着科学技术的发展,其用途还将不断地扩大。由于海泡石具有特殊的晶体结构、较好的纤维性质、较高的负电动电位、低的比磁化率,以及一定的耐酸碱腐蚀性、过滤性、阳离子交换性及吸附性等,因而世界上许多国家已越来越重视该矿物的找矿、开发和应用。我国在海泡石的找矿方面已有较大的进展,已找到海泡石矿床(点)五十余处,其中大型矿床六个,分布在江西、湖南、陕西等省。

Abstract:

The sepilite deposits in South China commonly occur at the top of the Lower Permian Qixia Formation or at the bottom of the Maokou Formation. The sedimentary environments of the deposits are characterized by shallower sea water of the Yangzi Sea, the semi-closed conditions, enough silicon and magnesian supply, weak hydrodynamic conditions, slightly higher salinity of sea water, alkalic pH values and abundant bioligic fossils. It is suggested that the deposits occur in lagoons and tidal zones or on the platforms near seas. On the basis of the early Maokouian palaeogeographic maps, however, they are mostly confined to the area from below the storm wave base of the Yangzi Sea to the upper shelf side on the upper-lower continental shelf boundary, i. e., the area from Ningqiang, Shanxi Province to Shimen, Hunan Provinve. The presence of the element Sr in the area might have resulted in the formation of "chrysanthemum-stone" composed of celestite from the ore-bearing strata or the strata above or below them. The siliceous and calcareous concretions and nodules have also been recognized in the ore beds as lumps and eyeballs. Sepiolite clay occurs right in the claystone which are referred to as the "eyelid" around these concretions, nodules and eyeballs. Besides,sepiolite is usually preserved in the geological environments with low temperatures and pressures. The well-known sepiolite deposits abroad tend to be confined chiefly to the Mesozoic and Cenozoic strata, whereas those in South China to the Lower Permian strata. Therefore, it is necessary to find sepiolite deposits in the areas of the above-mentioned strata where geological structures are simple, volcanic activity is rare or absent, crustal movement is less strong and the strata slope gently.