由层序地层学角度分析大塘坡式锰矿沉积过程——以湘西北民乐锰矿为例  

The Analysis of the Sedimentary Process for Datangpo-type Manganese Ores from the Point of Sequence Stratigraphy:A case of the Minle manganese deposits in northwestern Hunan

作　　者：曹默雷 陈建平[1,2] CAO MoLei;CHEN JianPing(School of Earth Sciences and Resources,China University of Geosciences(Beijing),Beijing 100083,China;Beijing Key Laboratory of Land and Resources Information Research and Development,Beijing 100083,China)

机构地区：[1]中国地质大学(北京)地球科学与资源学院,北京100083 [2]北京市国土资源信息研究开发重点实验室,北京100083

出　　处：《沉积学报》2022年第4期1083-1094,共12页Acta Sedimentologica Sinica

基　　金：国家重点研发计划(2017YFC0601502)。

摘　　要：以湘西北民乐锰矿为例,基于矿区内钻孔信息对成矿期(大塘坡组下段)进行地层对比,由新分层信息及厚度变化分析沉积特征并建立三级、四级层序格架,由三级、四级层序尺度的古地貌变化分析成矿期沉积演变特征。主要认识有:1)民乐锰矿含矿层(大塘坡组下段)可根据岩性细分为下亚段1段(致密块状、密集条带状矿体夹黑色炭质页岩)、下亚段2段(黑色页岩夹薄层锰矿条带)、上亚段(黑色炭质页岩夹黄铁矿)。2)民乐锰矿的三级层序凝缩层体系域可划分为四个四级层序,其中第二、三层序菱锰矿发育较厚,形态以块状和密集条带状为主;第一、四层序菱锰矿发育薄,形态多为条带状。3)民乐锰矿沉积过程可以通过三级层序和四级层序两个研究尺度共同解释,三级层序尺度解释锰矿沉积过程,而四级层序尺度则揭示了多期不同形态、厚度锰矿的沉积过程。The Datangpo-type manganese ores have developed widely in the adjacent area of Hunan,Guizhou,and Chongqing provinces.This kind of manganese ore develops in the lower section of the Datangpo Formation,forming ore bodies with different grades and thicknesses in multi-periods.Current mineralization regularities are not suitable for analyzing the sedimentary process of each period.The mineralization process is controlled by ancient faults,paleo⁃geography,paleoclimate,and variations of sea levels;all these factors are important bases in the study of the se⁃quence stratigraphy.Applying sequence stratigraphic theories to explain the sedimentary process in each mineralizing period is feasible and can also provide help with perfecting metallogenic regularities and new thoughts with explora⁃tion and prediction.Previous studies of the Datangpo-type manganese deposit stratigraphic sequences are not accurate and seldom utilized in the analysis of mineralization regularities.Taking the Minle manganese deposit,the largescaled manganese carbonate deposit in northwestern Hunan province,as an example,we make stratigraphic correla⁃tions based on lithological description of wells and measured profiles to build a new stratigraphic classification for the lower section of the Datangpo Formation(the mineralization period)for the Minle manganese deposits.We next ana⁃lyze the sedimentary characteristics of each period according to changes in the lithology and thickness of the new stra⁃ta.Then,using sedimentary features to build the third order and fourth order sequence framework,we summarize fea⁃tures of the sedimentary evolution based on the ancient terrain changes in third order and fourth order sequence scales.Finally,we combine all of these achievements with marine carbonated manganese forming mechanisms and geological background to investigate mineralizing laws,modes,and sedimentary processes based on sequence strati⁃graphic theories and the sequence stratigraphic application in mineralizing exploration and prediction

关 键 词：民乐锰矿 三级层序 四级层序 沉积环境 沉积过程 

分 类 号：P536[天文地球—古生物学与地层学]