(1. 中南大学 地球科学与信息物理学院，有色金属成矿预测与地质环境监测教育部重点实验室，长沙 410083；
2. 湖南省煤炭地质勘查院，长沙 410019)
摘 要: 广西平果铝矿集区是我国重要的铝土矿产地，有岩溶堆积型和原生沉积型两种铝土矿类型。前人主要专注于堆积型铝土矿的成因研究，而对于原生矿的沉积相、古地貌、沉积环境及其对铝土矿矿层的控制作用尚未开展具体分析。本文对矿区多种原生矿石开展了精细的矿物学及地球化学研究，结果表明：平果原生铝土矿总体富集Zr、Ga、Th、U、V，亏损Sr、Ba；87Sr/86Sr值普遍较高，大多为0.7080~0.7085；原生矿中的鲕粒能谱扫描电镜及电子探针分析显示，不同样品具有差异较大的O、Al、Si、Fe、K、Ti以及Ga元素含量。结合矿体野外产状及空间分布特征，本文提出平果矿集区古地貌特征为东部、北部地势较高，南部、西部地势逐渐变低，从太平矿区到那豆矿区再到新安矿区，沉积环境呈现出近陆到远陆、水浅到水深的沉积环境变化，总体表现为海陆交汇沉积环境格局。原生铝土矿成矿物质依次被搬运至太平矿区、那豆矿区和新安矿区沉积成矿，总体沉积环境为三角洲相；矿区三角洲沉积环境可进一步分为分支河流相、沼泽相、沙坝相等沉积微相，其中，沙坝微相最有利于原生矿富集，因此平果矿集区的那荣地区和塘琴地区最有利于原生矿的形成。
关键字: 原生铝土矿；沉积鲕粒；沉积相；成矿环境；广西平果
（1. Key Laboratory of Metallogenic Prediction of Nonferrous Metals and Geological Environment Monitoring of Ministry of Education, School of Geosciences and Info？Physics, Central South University, Changsha 410083, China;
2. The Coal Geological Exploration Institute of Hunan Province, Changsha 410083, China）
Abstract:The Pingguo bauxite mining area in Guangxi is an important bauxite producing area in China. There are two types of bauxite ores: Karst accumulation type and primary sedimentation type. Previous researches mainly focused on the genesis of accumulative bauxite, but no specific analysis has been carried out on the sedimentary facies, paleogeomorphology, sedimentary environment and its control on the formation of primary sedimentation type ore. In this paper, detailed mineralogical and geochemical studies have been carried out on a variety of primary ores in the Pingguo area. The results show that the primary bauxite ore is generally enriched in Zr, Ga, Th, U and V but depleted in Sr and Ba. The 87Sr/86Sr values are generally high, mostly between 0.7080 and 0.7085. Energy spectrum scanning electron microscope and electron probe microanalysis of oolites in primary ore show that different samples have variable contents of O, Al, Si, Fe, K, Ti and Ga. Combined with the field occurrences and spatial location of the ore bodies, this study puts forward that the paleogeomorphic characteristics of the Pingguo mining area are that the terrain in the east and north is higher, whereas the terrain in the south and west is lower. The sedimentary environment from the Taiping area to Nadou area and then to Xin''''an area in Pingguo changed from near-land to far-land, and from shallow-water to deep-water, presenting the pattern of sea-land intersection sedimentary environment. The primary bauxite ore-forming materials were transported and deposited from Taiping to Nadou and then to Xin''''an. On the whole, it was a delta sedimentary environment which can be divided into more detailed sedimentary microfacies such as branch fluvial facies, swamp facies and sandbank facies. It is pointed out that sandbank microfacies were most conducive to the enrichment of primary ore. Therefore, the Narong and Tangqin areas in Pingguo were most conducive to the deposition of primary ore.
Key words: primary bauxite ore; sedimentary oolitic; sedimentary facies; metallogenic environment; Pingguo-Guangxi
