桂西南地区下三叠统含锰岩系沉积特征研究

发布时间：2018-03-21 14:54

本文选题：含锰岩系　切入点：沉积特征　出处：《成都理工大学》2015年硕士论文　论文类型：学位论文

【摘要】：广西锰矿层位多,类型杂,分布广,储量居全国之首。桂西南是其中一个重要的找矿远景区,本区锰矿床主要分布于天等县、德保县和靖西县等地。桂西南地区锰矿虽具有空间分布不均衡的特点,但其含锰层位却表现出了一定的分布规律,如上泥盆统特定的含锰层位为五指山组和榴江组,下三叠统含锰矿层位为北泗组。本文依据对桂西南一带的扶晚地区下三叠统含锰岩系野外考察和实测剖面资料的室内详细研究,结合前人的资料,通过沉积相分析、古地理格局分析以及控矿因素与沉积相关系分析等手段,对本区含锰岩系的沉积特征进行研究。主要工作、认识和成果概括如下:1.选取扶晚锰矿区的四口钻井岩芯进行了现场岩芯磁化率测量试验,实测磁化率值5504个,其中锰矿297个,围岩5207个。分析结果表明,含锰岩系中矿层磁化率较围岩磁化率存在明显异常,通常碳酸锰矿磁化率值比围岩要高出1-2个数量级,而围岩中硅质岩和泥质岩的磁化率无明显差异。磁化率可作为野外快速判别含锰岩系的代用指标。2.收集区域地质资料,结合野外实测地层剖面以及室内镜下薄片鉴定资料,根据岩石类型及岩石组合、沉积构造、古生物门类等特征,进行了沉积相分析。查明研究区含锰岩系主要存在四种沉积环境,包括局限台地、开阔台地、台地边缘斜坡和深水台盆。岩性上局限台地以白云质灰岩或灰质白云岩沉积为主,开阔台地以泥质灰岩沉积为主,台地斜坡以角砾状灰岩出现为标志,深水台盆主要为硅质岩和泥岩的沉积。3.编制了研究区早三叠世古地理图,认为下三叠统地层主要沉积于台地相和台盆相中,次为台地边缘相沉积。东西部碳酸盐岩台地通过相对狭窄的台地边缘逐渐过渡到深水台盆。4.根据编制的锰矿床分布图与岩相古地理图,发现桂西南地区的大型、中型和小型锰矿床主要分布于台盆相区,仅少数小型锰矿床位于台地相区和台地边缘相区。为了进一步研究岩相、地层厚度、成矿要素与锰矿床成因的关系,以德保县扶晚锰矿床为研究对象,进行控矿因素与沉积相关系的分析。发现锰矿分布与北东向沉降中心、断裂构造、火山岩分布走向一致,认为锰质的来源及定位与海底热液喷流可能有一定的关系。
[Abstract]:There are many layers of manganese ore in Guangxi, which are of various types and are widely distributed, and the reserves are the first in the whole country. Southwest Guangxi is one of the most important mineral prospecting areas, and the manganese deposit in this area is mainly distributed in Tianding County. Although manganese deposits in southwestern Guangxi have the characteristics of uneven spatial distribution, the manganese bearing horizon of Debao County and Jingxi County shows a certain distribution law, such as the Wuzhishan formation and the Ewejiang formation in the upper Devonian. The lower Triassic manganese bearing strata are Beisi formation. Based on the laboratory detailed study on the field investigation and the measured profile data of the Lower Triassic manganese bearing rock series in the Fupian area of southwest Guangxi, combined with the previous data, the sedimentary facies are analyzed. Based on the analysis of paleogeographic pattern and the relationship between ore-controlling factors and sedimentary facies, the sedimentary characteristics of manganese bearing rock series in this area are studied. The results are summarized as follows: 1. Four drilling cores in Fuwangmanganite area are selected to measure the magnetic susceptibility of core in situ. The measured magnetic susceptibility is 5504, of which 297 are manganese ores and 5207 are surrounding rocks. The results show that the magnetic susceptibility of the core is 5504, among which 297 are manganese ores and 5207 are surrounding rocks. The magnetic susceptibility of ore bed in manganese bearing rock series is obviously abnormal than that of surrounding rock. Generally, the magnetic susceptibility of manganese carbonate ore is 1-2 orders of magnitude higher than that of surrounding rock. However, there is no obvious difference in magnetic susceptibility between siliceous rock and argillaceous rock in surrounding rock. Magnetic susceptibility can be used as a substitute index for quick identification of manganese-bearing rock series in the field. 2. Regional geological data are collected, combined with field measured stratigraphic profile and sheet identification data under indoor microscope. According to the characteristics of rock types and rock assemblages, sedimentary structures and paleontological families, the sedimentary facies are analyzed. It is found that there are four kinds of sedimentary environments in manganese bearing rock series in the study area, including limited platform, open platform, etc. Platform margin slope and deep water platform basin. The lithologic limitation platform is dominated by dolomite or lime-dolomite deposition, the open platform is dominated by argillaceous limestone, and the platform slope is marked by breccia limestone. Deepwater platform basin is mainly composed of siliceous and mudstone deposits .3.The early Triassic paleogeographic map of the study area is compiled. It is considered that the Lower Triassic strata are mainly deposited in platform facies and platform basin facies. The carbonate platform in the eastern and western parts of China gradually transitioned from the relatively narrow platform margin to the deep-water platform basin .4.According to the compiled manganese deposit distribution map and the lithofacies paleogeography map, the large-scale carbonate platform in southwest Guangxi was found. Medium and small manganese ore deposits are mainly distributed in platform basin facies area, only a few small manganese ore deposits are located in platform facies area and platform marginal facies area. In order to further study the relationship between lithofacies, formation thickness, metallogenic elements and genesis of manganese ore deposit, a few small manganese ore deposits are located in platform facies area and platform margin facies area. The relation between ore controlling factors and sedimentary facies is analyzed with the Fuwangmanganite deposit in Debao County. It is found that the distribution of manganese ore is consistent with that of NNE subsidence center, fault structure and volcanic rock distribution. It is considered that the source and location of manganese may be related to the submarine hydrothermal jet.
【学位授予单位】：成都理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P618.32

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