摘要
近年来,鄂西走马地区发现了“大塘坡式”锰矿(化),但该区锰矿(化)的成矿物质来源、成矿机制以及氧化还原环境的C-O同位素地球化学示踪研究较少。对鄂西走马地区的锰矿开展详细的野外地质调查与钻孔新鲜岩芯样品的C、O同位素研究。结果表明含锰矿物主要为菱锰矿,部分为含锰方解石,呈纹层状、透镜状、条带状、团块状、鲕状及结核状;δ^(13)_C(V-PDB)值为-6.98‰~-2.75‰,δ^(18)O_(V-PDB)值为-17.29‰~-9.12‰,均为负值。结合前人研究成果,认为走马地区大塘坡组锰矿(化)的锰质来源主要受到陆源物质和海底热水的双重作用影响,大塘坡间冰期锰质沉积时古海水温度较高,洋底热流上涌将Sturtian冰期水体内富集的Mn^(2+)与陆源输入的Mn^(2+)在氧化性水体中形成了锰的氧化物,随后沉降在氧化—还原环境界面之下,在成岩过程中和有机物质互相作用,氧化物被还原释放出的Mn2+和有机碳被氧化释放出的CO_(3)^(2-)结合形成菱锰矿。
Dangtangpo type manganese deposit was found in Zouma area,Western Hubei Province in recent years.However,the C-O isotope geochemical tracing of source for ore-forming materials,ore-forming mechanism and redox environment in this area have not been reported.In this paper,the authors present detailed field geological survey and carbon and oxygen isotope data of manganese from the Zouma manganese deposit in Western Hubei Province.It shows that main manganese bearing minerals are rhodochrosites,the minor are manganese bearing calcite,they are laminar,lenticular,banded,massive,oolitic and tuberculous.Both δ^(13)C_(V-PDB) and δ^(18)O_(V-PDB) show negative values respectively,from-6.98‰to-2.75‰and from-17.29‰to-9.12‰.In combination with previous published data,the manganese is mainly affected by terrigenous materials and submarine hot water,the paleoseawater temperature was higher during the interglacial period in Datangpo,manganese oxides were formed in the oxidized water by the upwelling Mn^(2+) form the oceanic hydrothermal solution and the inputting Mn^(2+) from the terrestrial source.Subsidence was buried under the redox interface,during the process of diagenesis,manganese oxides were reduced to release Mn2+and organic matter.Carbon dioxide is oxidized to form manganese carbonate.
作者
赵军
吉雪峰
陈林
曹文胜
冉中夏
Zhao Jun;Ji Xuefeng;Chen Lin;Cao Wensheng;Ran Zhongxia(Second Geological Brigade of Hubei Geological Bureau,Enshi,Hubei 445000)
出处
《资源环境与工程》
2021年第3期291-296,共6页
Resources Environment & Engineering
基金
湖北省地质局科技项目——恩施走马地区南华系大塘坡式锰矿物质来源及成矿模式研究(KJ2020-6)
湖北省地质勘查基金项目——湖北省鹤峰县走马地区铅锌多金属矿调查评价(〔2019〕6号)。
关键词
大塘坡式锰矿
C-O同位素
走马地区
鄂西
Datangpo type manganese deposit
carbon and oxygen isotope
Zouma Area
western Hubei Province
