中文摘要:次生岩溶坠积再生铝土矿属铝土矿床的新类型。首先发现于广西平果，矿床属后期风化壳、次生岩溶、硫化物风化复合成因，以硬水铝石铝土矿层为主要来源。其中三水铝石含量为10一25％，直至50％，A12O3>40％，A／S>2.6。后又在太平矿区的背斜轴部发现该类型铝土矿，而且属于大型矿床，A／S平均36.95。在颗粒小于1nm的过去认为“无用的泥巴”中找到较多的三水铝石及石英(游离SiO2在拜尔法中不溶)等，扩大了储量、提高了经济效益。
Abstract:The secondary karst colluvial palingenic type bauxite deposits seem to be a new type of accumulated bauxite deposits. Formed as a result of secondary karst weathering and colluviation of primary karst bauxite deposits(diasporite type), these deposits occur on the older plain of limestone karst and are usually distributed in the axis of anticline. Among them, No. 121 orebody of Taiping mine is a large-sized deposit with average gibbsite(whole sample)21.52％, A/S ratio 3.84 or 6.45 and reduced free SiO2(quartz). If the so-called “mudores” with grain size smaller than 1 mm are included, the amount of resources will be doubled. The author believes that these deposits are a new type of bauxite deposits and their main metallogenic conditions are as follows: (1)Protore beds(secondary bauxite located on the bottom of Permain Heshan Formation, belonging to karst type); (2)Effects of moisture and hot climate; (3)Geological setting: ore bodies are formed along anticline(axis of anticline being a favorable position for weathering and leaching)and at the superimposition of neo tectonic movement causing upwarping of crust and drawdown of groundwater table); (4)Apparent difference in resistance to weathering between protore and wall rocks; (5)Planar weathering control; (6)Weak or moderate mixing process; (7)Inheritance and continuity of structure, texture and composition of ores; (8)The strict control of Quaternary landform and geomorphic features over the orebodies; (9)Quite a large amount of pyrite contained in protore beds, the thorough weathering of hanging wall and footwall rocks leading to the formationof sulfuric solution and the generation of certain amounts of gibbsite and free SiO2(quartz); (10)High topography-favorable to ore-formation; low topography, on the other hand, to the forming of halloysite and clay. After dressing and washing, the average A/S ratio of ores with grain size smaller than 1 mm from No.121 orebody of Taiping mine reaches 36.96, showing that this deposit is the highest-grade large-sized bauxite deposit in China. The secondary karst colluvial palingenic type bauxite deposits are most likely to be found along anticlinal axes containing secondary karst detrital bauxite in southwestern Guangxi, southeastern Yunnan and some other area, which are well worth noticing. The A/S ratios of ores with grain size 1一0.005 mm in the bauxite deposits and those in original deposits are respectively 3.75 and 4.77, which coincide with the definition of bauxite deposits. The mineral composition of ores with average size<1 mm is gibbsite 32.44％, diasporite 10.22％, kaolinite 13.76％, chlorite 11.36％, and gibbsite in gothite 2.13％, together with small amounts of gothite, hematite, illite-chlorite mixed-layer clay minerals, quartz, pyrophyllite, hydromica, boehmite and zircon.
文章编号：
中图分类号：
文献标志码：
引用文本：
刘长龄.1988.次生岩溶坠积再生铝土矿床新类型的物质成分与成因[J].矿床地质,7(2):83~91.1988.Material composition and genesis of secondary karst colluvial palingenic type Bauxite deposits[J].Mineral Deposits7(2):83~91
图/表
