豫西偃师-龙门地区铝土矿三水铝石的赋存特征及成因分析

Occurrence characteristics and genesis of the gibbsite in bauxite in Yanshi-Longmen area,western Henan province

在豫西偃师-龙门地区本溪组地表露头新发现三水铝石,这一发现不仅可以为岩溶堆积型铝土矿的存在提供直接证据,而且其赋存特征和成因分析也具有重要的理论意义。新发现的三水铝石主要赋存在马家沟组灰岩和本溪组铝土质泥岩接触处的白色与红色沉积物条带中,以及本溪组杂色铝土质泥岩中,对上述沉积物条带和铝土质泥岩分别采集样品并进行X衍射、差热和SEM-EDS分析。结果表明,新发现的三水铝石具有典型的三水铝石的X衍射特征峰和差热吸收峰,宏观上主要呈条带状和团块状,微观上为致密状集合体。在此基础上,根据土壤地球化学基本原理,认为这些三水铝石是本溪组铝土矿抬升地表后再次富铁铝化作用的结果。

Gibbsite is newly discovered in the surface outcrop of the Benxi Formation in YanlonHenan province. The discovery provides direct evidence for the existence of karst accumulated has significance theoretical values for analyzing its characteristics and genesis. The newly discovered gibbsitemainly occurred in the white and red sedimentary bands that is convergence zone of Majiagou Formation lime-stone , Benxi Formation and variegated bauxitic mudstone of Benxi Formation. X-Ray difraction analysis, dif-ferential thermal analysis and SEM-EDS analysis were conducted to those above-mentioned sedimentary bandsand bauxitic mudstone. The results showthat the gibbsite has typical X-Ray diffraction characteristic peaks and differential thermal absorption peaks of gibbsite,which appers banded structure at macro level and compact aggregates at microscopic level. Based on the principles of soil geochemistry,we conclude that the gibbsite is the mineral of the ferrallitization after Benxi Formation bauxite was uplifted to the surface.