摘要
在上扬子地台早寒武纪梅树村期,沉积了许多大型磷块岩矿床。贵州寒武系底部磷块岩发育,是我国重要含磷层位。贵州寒武系底部磷矿的研究历史比较悠久,研究方向主要还是集中于含磷物质来源以及磷块岩成因方面的研究。前者主要解决的是磷质来源与磷质赋存问题,但对于磷矿的就位问题研究较少。因此,对于磷矿控矿规律及含磷岩系沉积微相等有待深入。在总结前人研究的的基础上,对贵州织金-清镇一带寒武系底部含磷岩系进行大量的野外调查、剖面测试以及地质资料总结分析。认为清镇地区处于潮下低能泻湖环境,以条带状磷块岩和条带状磷质硅质岩为特征;织金戈仲伍一线,属于潮间-潮下高能沉积环境,沉积碎屑状磷块岩为主,局部沉积小壳生物磷块岩;织金熊家场浅滩和生物滩发育,属于潮上沉积环境。另外通过钻孔资料分析,发现织金地区寒武系底部磷块岩厚度变化很大,主要受灯影组顶部古喀斯特不整合面控制,滨岸磷质碎屑受沿岸海流的改造,搬运至古喀斯特洼地地区堆积,形成较厚度的碎屑状磷块岩。古喀斯特高地地区,受滨岸海流影响,沉积的磷块岩较薄,因此,建立织金寒武系磷块岩成矿控矿模式。该研究对贵州寒武系底部磷矿找矿预测工作有一定的理论和实际意义。
A number of large-scale phosphorite deposits were developed within the Upper Yantze Platform during Meishucun Stage of early Cambrian Period.The lower Cambrian stratum in Guizhou province,with welldeveloped phosphatic rock,is very important P-bearing sequence in China.Study of phosphatic deposits in the lower Cambrian stratum has lasted a long period with the focus on the material source and genesis of phosphorous rocks.The former issue deals with the material source and the occurrence of phosphorus,but less concern has been given on emplacement mechanism of the phosphorus.Therefore,further study should be carried out on factors controlling ore-forming,sedimentary microfacies of phosphorous-bearing strata.Combined with summarization for previous work,this study conducted field survey,geological profiles measurement and sampling for the phosphorous-bearing rock series in the Zhijin-Qingzhen area in Guizhou Province.It was found that Qingzhen area was a low-energy subtidal paleo-lagoon,deposition of which was characterized by banded phosphorites and phosphorous siliceous rocks.While the Gezhongwu in the Zhijin area was a high-energy intertidal-subtidal zone,the deposition of which is mainly fragmental phosphorites,with only partialy small-shell biological phosphorite distributing randomly.The ZhijinXiongjiachang area was a supratidal zone,where shallow shoal and biologic beach developed.Through the analysis of bore information,it can be found that phosphorite thickness occurred at the bottom of Cambrian varies greatly in the Zhijin area,which is mainly controlled by fossil karst unconformity level at the top of the Dengying Formation.The shore phosphatic fragments was transformed by coastal current,moved into the depression area of fossil karst and then accumulated,forming thicker clastic phosphorite than the highlands of fossil karst.Therefore,according to the above-mentioned information,this paper has constituted the ore-forming model of Cambrian phosphorite in the Zhijin area.This study has certain theoretical and practical significance to exploration for phosphate deposits in the lower Cambrian of Guizhou Province.
出处
《地质学报》
EI
CAS
CSCD
北大核心
2015年第12期2374-2388,共15页
Acta Geologica Sinica
基金
贵州省国土资源厅社会公益项目资助(项目编号:2012294)
关键词
贵州
下寒武统
磷矿成矿
古喀斯特面
控矿模式
Guizhou Province
Lower Cambrian
phosphorous mineralization
fossil karst unconformity
ore-controlling model
作者简介
毛铁，男，1984年生．博士研究生，从事沉积岩及沉积矿床科研工作．Email：geniusmfe@sina．com。
通讯作者：杨瑞东，男，教授，博士生导师，Email：rdyang@gzu．edu．cn。
