摘要
黔中开阳地区在震旦纪陡山沱期全球成磷事件的大背景下,发育了厚度较大的富磷矿层。通过岩石薄片观察、地层对比与划分及沉积相分析等手段,探讨黔中开阳地区震旦纪陡山沱期磷矿床沉积特征与成矿模式。结果表明:(1)开阳地区陡山沱期处于黔中古陆北缘的磷质海岸环境,磷矿层中分布最广泛、品位最高的矿石类型为砂屑磷块岩,为富磷沉积物在沉积、成岩过程中遭受多期次冲刷破碎、暴露淋滤及堆积胶结的产物。(2)开阳地区古地理环境和动荡的海水条件控制了磷矿的沉积和高品位矿石的分布,洋水、永温等地在震旦纪陡山沱期所处的海水深度适中的临滨带为成矿优势地带,而水体过浅的前滨带和过深的远滨带均不利于磷质的聚集和成矿。(3)开阳地区动态磷矿床成矿模式表明,陡山沱期海平面的频繁进退使临滨带已沉积的磷块岩遭受多期次的冲蚀、暴露、淋滤、胶结及磷质再沉积作用;通过物理分选作用和风化淋滤作用最终使磷质聚集,是研究区富磷矿形成的主要原因。
There were thick and high-grade phosphorite beds in Kaiyang area of central Guizhou Province during the global phosphogenesis events in the Sinian Doushantuo Age.This paper used thin sec-tions observation,stratigraphic comparison and subdivision and sedimentary facies analysis to study the sedimentary characteristics and mineralization model of phosphorite deposits in the Sinian Doushantuo Age in Kaiyang area,central Guizhou Province.The result showed that：（1 ） Kaiyang area was located in north margin of Central Guizhou Old Land which was a phosphorus beach during the Sinian Doushantuo Age.The high-grade phosphorite ore in Kaiyang area was mainly composed of sand clastic phosphate rocks which were formed in the process of sedimentation-diagenesis of phosphorus-rich deposits,during which they were erosion and broken,exposed and leached,accumulated and cemented repeatedly.（2） The palaeogeographic environment and unstable seawater condition controlled the deposition and enrichment of phosphorite in Kaiyang area.Shore face zone like Yangshui or Yongwen which were in a depositional condi-tion with moderately-deep seawater in the Sinian Doushantuo Age was the advantageous metallogenetic zone.Foreshore zone with too shallow seawater and offshore zone with too deep seawater were unbeneficial for phosphorus aggregation and mineralization.（3） The dynamic mineralization model of phosphorite de-posits in Kaiyang area showed that frequent transgression and regression during the Doushantuo Age made phosphate rocks which originally deposited in shore face zone experienced multi-stages erosion,exposure, leaching,cementing and redeposition.Physical winnowing action,weathering and leaching gathered phos-phorus and ultimately led to the formation of high-grade phosphorite.
出处
《古地理学报》
CAS
CSCD
北大核心
2016年第4期581-594,共14页
Journal of Palaeogeography：Chinese Edition
基金
中国地质调查局地质调查项目(编号:12120114016501)
贵州省地质矿产开发局项目(编号:黔地矿办发[2013]56号)联合资助~~
关键词
黔中
震旦纪
陡山沱期
磷矿
成矿模式
central Guizhou Province, Sinian, Doushantuo Age, phosphorite, mineralization model
作者简介
第一作者简介张亚冠，男，1990年生，中国地质大学（武汉）博士研究生，沉积地质学专业。E—mail：zyg1000800@sina．cn。
通讯作者简介杜远生，男，1958年生，中国地质大学（武汉）教授、博士生导师，主要从事沉积地质学研究。E—mail：duyuansheng126@126．com。
