华北石炭——二叠纪煤系粘土岩夹矸中铝的氢氧化物矿物研究

华北石炭——二叠纪煤系太原组和山西组不同煤层粘土岩夹矸中,广泛含有一水软铝石、一水硬铝石和三水铝石。大多数一水铝石矿物呈薄纹层状、似层状及层状聚集于富岩质及富有有机质粘土岩夹矸条带中,有的呈细脉状沿炭质条带及粘土岩夹矸层理的节理裂隙分布,并与玉髓、方解石、高岭石或迪开石和铵云母细脉共生。铝的氢氧化物矿物可以作为成岩古温度和成岩阶段划分的标志矿物。最后还讨论了该矿物的成因。

STUDY OF ALUMINUM HYDROXIDE MINERALS IN TONSTEINSFROM CARBONIFEROUS-PERMIAN COAL-BEARINGSERIES IN NORTHERN CHINA

The regional geological surveys and detection analyses show that the kaolinite, tobelite-bearing kaolinite and tobelite tonsteins in the seams with different caolficafion degrees widely contain boehmite, diaspore and gibbsite in the Taiyuan. and Shanxi Formations of the Carboniferous-Permian coal-bearing series in the northem China. The gibbsite and boehmite are microcrystal granular aggregates, but the diaspore in the tabular crystals wilh irregular to regular shapes and the interlocldng crystals are common. Most of the boehimte and diaspore. rich in the carbonaceous and organic-rich bandings of the tonsteins at thin laminations, sublayers and layers, or as fine veins, are distributed along the caobonaceous fragment bandings and joint fissures of parallel, diagonal, vertical to the beddings of tonsteins, and associated with the fine veins of authgenic chalcedony, calcite, kaolinite or dickite, and tobelite. There are a few spherical particles of boehmite and diaspore aggregates dispened in the tonsteins. The reladons between the kinds, assemblages, features and evolutions of the aluminum hydroxide minerals and the coafication degrees of host coal seams, as indicated the table, can be regarded as the indexmdneral used to detenmine the diagenetic temperatures and stages. The kaolinite, especially grain kaolinite is commonly replaced by boelmnite or diaspore, suggesting that the aluminum hydroxide minerals were mainly formed by the disilication of kaolinites and have gone throught the diagenetic transformation. The gel-like spherical particles of the boehmite and (or) diaspore aggregat are the proof that they were formed by the coacervation and diagenetic transformation of the sedimentary AlOOH+n H₂O gels. The parageneses of the gibbsite and boehmite, boehmite anddiaspore, and the remains of boehmite within the diaspore furnish full evidence for the transform series from gibbsite into boehmite, and fromboehmite into diaspore with enhancement of the diagenesis.