摘要： 息烽磷矿是贵州地区震旦纪陡山沱期磷矿的重要组成部分,以矿层厚、品位高、断裂构造发育、叠层石丰富而独具特色。通过对矿床地质特征及矿床地球化学特征综合研究认为,从陡山沱组底到顶气候经历温湿—干热—湿热变化,海平面对应经历了海进—海退—海进,其内的磷块岩和磷质岩是在热水沉积作用、生物作用和正常海水沉积作用等共同作用下形成于前滨—临滨环境。综合以上,反演息烽陡山沱期成矿过程,发现矿床经历了“海进—海退—海进”三阶段成矿,在陡山沱早期海进阶段形成下矿层,随后的海退阶段和海进阶段形成上矿层。空间上,2矿层之间夹白云岩,且交于靠黔中古陆一侧,当第2次海进越过第1次海进的前滨—临滨位置后,只形成上矿层,是开阳、息烽磷矿床1层矿体形成的对应部位。瓮福磷矿床有2层矿体,对应处于经历了“三阶段成矿”的前滨—临滨部位,且瓮福磷矿成矿时的位置高程明显低于息烽磷矿、息烽磷矿略低于开阳磷矿,通过岩性特征对比,与实际基本吻合。因此,在对陡山沱期的磷矿进行成矿预测和找矿勘查中,与息烽磷矿床相似的黔中及附近区域的动态前滨—临滨环境,均为磷矿床的找矿靶区,利用“三阶段成矿”形成相交的2矿层特点,可高效对已知矿床、矿化点和前滨—临滨带周围进行成矿预测。

关键词: 成矿环境, 成矿作用, 成矿模式, 磷矿, 黔中

Abstract: The Xifeng phosphate deposit is an important component of the Ediacaran Doushantuo phosphate deposits in Guizhou Province,Southwest China,which is characterized by a thick ore layer,a high quality,a developed fault system,and rich and unique stromatolites. We reveal that the Xifeng phosphorite rocks were formed in the foreshore and shoreface environments under the combined conditions of hot water,biological and normal seawater sedimentation. The Doushantuo Formation underwent a palaeoclimate shift from a warm and humid climate to a dry and hot climate,and to a hot and humid climate,related to transgression,regression,and transgression,respectively. Therefore,the metallogenic process of the Xifeng phosphate deposits also underwent three stages of mineralization related to the transgression,regression and transgression again. The lower ore layer formed during the early transgression stage of the Doushantuo Period,whereas the upper ore layer formed in the subsequent regression and transgression stages. The two ore layers are separated by dolomite on the margin of the palaeo-continent of central Guizhou. When the second transgression crossed the foreshore position of the first transgression,only the upper ore layer formed,namely the Kaiyang and Xifeng phosphorus deposits. The Wengfu phosphate deposit has two layers of ore bodies,corresponding to the foreshore and shoreface zone that experienced three stages of mineralization. The location elevation of Wengfu phosphate deposit during mineralization is significantly lower than the Xifeng phosphate deposit,and the Xifeng phosphate deposit was slightly lower than the Kaiyang phosphate deposit. During mineralization prediction and prospecting exploration of the phosphate deposits in the Doushantuo Period,the dynamic foreshore and shoreface environment in central Guizhou and its vicinity,similar to the Xifeng phosphorus deposit,is the prospecting target area. Meanwhile,using the characteristics of two intersecting ore layers formed by “three-stage mineralization”,mineralization prediction surrounding the known deposits,mineralized points and foreshore and shoreface zones can be efficiently performed.

Key words: mineralization, metallogenic environment, metallogenic model, phosphate ore, central Guizhou

中图分类号: 

• P601.2