DISSCUSSION ON THE PROBLEMS OF BAUXITE DEPOSITS AND THEIR LATERITIC RESIDUUM AS MECHANISM FOR THE MINEROGENETE OF BAUXITE IN CHINA

The bauxite deposits in China can be divided into palaeoresidiuum bauxite deposits type (type Ⅰ) and laterite deposits type (type Ⅱ ) . The former can be diviede into six subtypes: I_a, alumina silicates rock palaeoresidiuum autochthonous residure bauxite deposit subtype; I _b, carbonates rock palaeoresidiuum autochthonous accumulated bauxite deposit subtype; I _c, the one of carbonate rock palacordsidiuum allogenically accumulate; I _d, the one of carbonate rock palaeoresidiuum allogcnically sedimentary (lacustrine; I _e, the one of palaeoresidiuum allogenically sedimentary (marine); I _e, the one ofcarbonatcs rock palaeoresidiuum autochthonous accumulate (or sedimented) -the one or modern karst accumulate. 2. The minerals association of palaeoresidiuum bauxite deposit and laterite bauxite deposit of China are all the same, they are: alumina mincral+clay mincral+iron mineral+a small quantity titanic mineral and heavy mineral. The alumina mineral in type II is gibbsite, and in type I is diaspore, because the type I was prod-ucted in paloeozoic. and was dehydrated easy. The texture and structure of bauxite ores in type I . and type II such as clastic, pisolitic, oolitie, nodules (concretions) are the very same, therefore the type I and type n are all the product of latcritization in the palaeoresidiuum. According to the oxygen and hydrogen isotope constitute of the mineral composition in type I and type II and the mineral composition in the textures such as clastic, oolitic, pisolitic of the type I and type II, the δ¹⁸O‰ (SMOW) range from +5 to +20, δD‰ from -50 to -100.The data indicate that the clastic, oolitic, pisolitic bauxite ores are the product of weathering as well. 3. The laterite bauxite deposit (type II) and 60% of palaeoresidiuum bauxite deposit such as subtype I _a, I _b. I _c are the lateritization weathering alumina material autochthonous residue. accumulated or allogencally accumulated occured under the atmosphere condition. 40% of palaeoresidiuum bauxite deposit such as subtype I _d. I_c is the aluminal materials allogenically sedimented in lacustrine or marine which are the product of lateritization. Subtype I _e is the karst accumulated under modern atmosphere condition which is from the subtype I _bor I _d.