河南省渑池铝土矿田地质特征及成矿规律

Geological characteristics and metallogenic regularity of bauxite in Mianchi,Henan Province

渑池铝土矿田是豫西地区重要的铝土矿聚集区,已发现大型铝土矿床10余处,但综合研究程度低、成矿规律认识不清晰,未开展深部成矿预测。文章对渑池铝土矿田的地质背景、矿体、矿石矿物和地球化学特征等进行了详细地研究,重点介绍了侯岭铝土矿和礼庄寨铝土矿的矿体特征、矿物组成、结构构造和主要化学成分,分析了含铝岩系化学组分的变化规律、物源风化强度、风化沉积环境、成矿物质来源和成矿作用规律等,结合岩相古地理及构造演化等研究成果,认为渑池铝土矿是长期风化残余堆积的产物,成矿物质具有多源性,经历了多期次、周期性的沉积成矿,淋滤作用使铝土矿品位大幅提高。渑池铝土矿具有受古岩溶地貌控制的多沉积中心成矿特征,铝土矿形成时,渑池地区呈缓倾的准平原喀斯特地貌,铝土矿大面积富集成矿,经成岩后的多期构造改造,形成了以向斜为主的构造格局,使向斜核部和南翼的含矿地层深埋,预测向斜的中深部仍赋存大规模的优质铝土矿。

The Mianchi bauxite field is an important bauxite accumulation area in western Henan,where more than 10 large bauxite deposits have been discovered.However,the low degree of comprehensive research on bauxite deposits has resulted in unclear metallogenic regularity and no deep metallogenic prediction has been car-ried out.This paper introduced geological background,orebody,ore minerals and geochemical characteristics of Mianchi bauxite field in detail,focusing on the orebody characteristics,mineral composition,ore structure and main chemical composition of Houling and Lizhuangzhai bauxite deposits.Based on the analysis of the chemical composition changing rule,the weathering intensity of provenance,the weathering depositional environment,the metallogenic materials and the metallogenic regularities in aluminum-bearing rock series,combined with the re-search results of lithofacies paleogeography and tectonic evolution of aluminum-bearing rock series,it is proved that Mianchi bauxite has experienced multi-stage and periodic deposition and is the product of long-term weather-ing residual accumulation.The ore-forming materials of bauxite in Mianchi is multi-source.Leaching during bauxite formation results in significant improvement in ore grade.The bauxite deposit has the characteristics of multi-sedimentary center mineralization controlled by paleo-karst terrain.During the forming of bauxite,the Mi-anchi area was a gently inclined peneplain karst terrain,and bauxite extensively enriched in this area.After multi-stage structural transformation after diagenesis,a tectonic pattern dominated by syncline was formed in Mianchi,which deeply buried the ore-bearing strata in the core and south wing of the syncline,and it is predicted that large-scale high-quality bauxite still exists in the middle and deep parts of the syncline.