鞍本地区大孤山条带状铁建造含铁矿物和相分带特征及形成环境分析   总被引：1，自引：1，他引：0  

佟小雪  张连昌  王长乐  彭自栋  南景博 《岩石学报》2018,34(4):1119-1138

鞍山-本溪条带状铁建造(Banded Iron Formation,简称BIF)位于华北克拉通东北缘,是世界上典型BIF之一,也是我国最重要的铁矿资源基地。大孤山位于鞍山地区南部矿带,为新太古代典型的Algoma型BIF,与华北克拉通其它大多数BIF相比,具有较低变质程度(绿片岩相-低角闪岩相)和较完整的沉积相分布特征。因此,通过大孤山BIF的研究有利于追踪Algoma型BIF的原生矿物组成及其后期成岩-变质过程,进而通过分析原生矿物形成的物理化学条件探讨古海洋环境。依据原生矿物共生组合及产出特征,可将大孤山BIF沉积相划分为氧化物相(30%)、硅酸盐相(50%)和碳酸盐相(20%)。氧化物相主要分布于主矿体南部,主要矿物组成为磁铁矿和石英;硅酸盐相分布于主矿体中部,主要矿物组成除了石英和磁铁矿之外,还有黑硬绿泥石、绿泥石、镁铁闪石等;碳酸盐相分布于矿体北部,主要矿物组成为菱铁矿、磁铁矿和石英等。本文通过大孤山BIF岩相学观察和含铁矿物化学成分研究,推测原生沉积物的组成为无定形硅胶、三价铁氢氧化物和富铝粘土碎屑,在经历了成岩和低级变质作用后转变为具不同相带的条带状铁建造。通过分析磁铁矿、菱铁矿和黑硬绿泥石等矿物在不同P_(O_2)-P_(CO_2)和pH-Eh条件下的共生相图可知,这些矿物均是在较低氧逸度、中到弱碱性环境下形成。综合考虑矿物成分、共生组合及受变质作用较弱等信息,本文推测制约原生矿物形成的控制因素主要是古海水氧化还原状态、酸碱度、CO_2含量和硫逸度。  相似文献   

Review on Lithospheric Diamonds and Their Mineral Inclusions     

Zhao Xin  Shi Guanghai  Zhang Ji 《地球科学进展》2015,30(3):310-322

Diamonds and their mineral inclusions are valuable for studying the genesis of diamonds, the characteristics and processes of ancient lithospheric mantle and deeper mantle. This has been paid lots of attentions by geologists both at home and abroad. Most diamonds come from lithospheric mantle. According to their formation preceded, accompanied or followed crystallization of their host diamonds, mineral inclusions in diamonds are divided into three groups: protogenetic, syngenetic and epigenetic. To determine which group the mineral inclusions belong to is very important because it is vital for understanding the data’s meaning. According to the type of mantle source rocks, mineral inclusions in diamonds are usually divided into peridotitic (or ultramafic) suite and eclogitic suite. The mineral species of each suite are described and mineralogical characteristics of most common inclusions in diamonds, such as olivine, clinopyroxene, orthopyroxene, garnet, chromite and sulfide are reviewed in detail. In this paper, the main research fields and findings of diamonds and their inclusions were described: ①getting knowledge of mineralogical and petrologic characteristics of diamond source areas, characteristics of mantle fluids and mantle dynamics processes by studying the major element and trace element compositions of mineral inclusions; ②discussing deep carbon cycle by studying carbon isotopic composition of diamonds; ③determining forming temperature and pressure of diamonds by using appropriate assemblages of mineral inclusions or single mineral inclusion as geothermobarometry, by using the abundance and aggregation of nitrogen impurities in diamonds and by measuring the residual stress that an inclusion remains under within a diamond ; ④estimating the crystallization ages of diamonds by using the aggregation of nitrogen impurities in diamonds and by determine the radiometric ages of syngenetic mineral inclusions in diamonds. Genetic model of craton lithospheric diamonds and their mineral inclusion were also introduced. In the end, the research progress on diamonds and their inclusions in China and the gap between domestic and international research are discussed.  相似文献   

鄂尔多斯盆地马家滩油田延长组油气成藏规律研究   总被引：1，自引：1，他引：0       下载免费PDF全文

马国良 《沉积与特提斯地质》2015,(2):35-44

本文以油气成藏的基本理论为指导,以测井、录井、分析测试等资料为依据,结合前人的研究成果,对鄂尔多斯盆地马家滩油田延长组的油气来源、储集条件、盖层条件、油气运移、圈闭形成与分布等油气成藏的基本条件进行分析研究。研究表明,长7油层组为马家滩油田最主要油气来源,长10油层组为其主要储集层,长10油层组顶部泥岩为主要盖层。马家滩油田断层发育,断层圈闭为主要圈闭类型,断层油气藏为该地区主要油气藏类型。有机质生烃作用作为油气运移的主要动力来源,断层为油气主要垂向运移通道。马家滩油田具有3大有利勘探区块,即马家滩、古峰庄、马儿庄-于家梁勘探区块,可作为未来的勘探方向。  相似文献   

坡折带对陆相湖盆辫状三角洲层序和沉积的控制——以准噶尔盆地东缘三工河组为例          下载免费PDF全文

万力  于兴河  李胜利  李文  王建忠  单新 《沉积与特提斯地质》2015,35(3):11-18

通过对钻探、地震及露头资料的研究,将准噶尔盆地东缘三工河组划分为两个三级层序。在地震和测井剖面上识别出挠曲坡折带和断裂坡折带两种构造坡折带。坡折带对于研究区层序和沉积的控制作用主要表现为:对于层序,"径向沟梁辐射,纬向阶梯分布"的坡折带体系使得本区三工河底部低水位体系域发育,坡折带加强河道侧向迁移,削弱河道下蚀,增加准层序数量,坡折带高部位低水位体系域会侵蚀下覆地层;对于沉积,在精细开发区的三工河组识别出6种沉积微相组合,顺物源连井剖面上自下而上识别出3个沉积微相组合序列,陡坡区发育富河口坝三角洲前缘,缓坡区发育富河道三角洲前缘。  相似文献   

潜江凹陷潜江组深层卤水矿产特征与资源评价     

黄华  张士万  张连元 《盐湖研究》2015,(2):34-43

利用潜江凹陷大量井筒及试水资料,研究古盐湖深层卤水赋存方式及成矿规律,开展卤水资源评价,为深层卤水开发利用提供建议。研究表明潜江凹陷潜江组卤水赋存于砂岩孔隙中,纵向上划分为5个卤水组,平面上受砂岩物源影响由北向南矿体厚度逐渐变薄直至尖灭;卤水总矿化度垂向分带平面分异明显,垂向上随着深度增加而增加,平面上凹陷中心矿化度高,向四周逐渐降低;卤水中的钾、锂、硼、溴、碘、铷、铯等元素含量与总矿化度呈正比,平面上与总矿化度规律一致,均呈环带状分布。通过对该区资源量进行测算和评价,得出潜江凹陷潜江组砂岩卤水为中孔、中渗、中产能、中深层、氯化钠型,含锂、溴、硼、钾大型工业卤水矿床;由此提出利用油田钻井和油田伴生卤水采卤并进行综合利用,提取食盐、碘、溴、氨水、氯化钾、硼砂、碳酸锂、氯化铷、氯化铯等产品,具有良好的开发前景。  相似文献   

Sediment–water interaction, acidity and other water quality parameters in a subtropical setting, Pimpama River, southeast Queensland     

M. Preda  M. E. Cox 《Environmental Geology》2000,39(3-4):319-329

 The geological setting and landuse activities of the Pimpama River catchment are typical for many drainage systems in southeast Queensland. The river originates in coastal ranges of Late Paleozoic age, crosses a floodplain developed during the Late Pleistocene-Holocene sea-level fluctuations and flows into the southern part of the Moreton Bay. The formation of sedimentary pyrite associated with the mid-Holocene transgression is an important feature of this coastal setting. The oxidation and hydrolysis of pyrite and the consequent production of sulfuric acid are controlled by the amount and seasonality of rainfall and influenced locally by landuse activities. The acid production and the leaching of dissolved metals from river alluvium and estuarine sediments impact substantially on land and aquatic habitats. The water quality of the Pimpama River and its tributaries reflects the lithology of the bedrock and can vary largely depending on season, tidal regimes, sediment lithology, local topography and agricultural activities. Monitoring of river water for several seasons revealed four types of events, each with a different response in terms of water quality: (a) occasional showers during the dry season cause low pH and high amounts of dissolved metals in the water, (b) the first heavy rain of the wet season can produce very toxic conditions (low pH and high concentrations of metals) that can result in a fish kill, (c) towards the end of the wet season, prolonged flushing of pyrite oxidation products leads to short-term recovery of the aquatic system (neutral pH and lower amounts of dissolved metals in the water) and (d) a flood event can produce low pH, salinity and high concentrations of metals, which can represent lethal conditions for aquatic life. Assessment of saturation indexes for representative weathering and oxidation products such as clays, goethite, gibbsite and jarosite shows that these mineral phases can precipitate only when the water reaches neutral pH. Received: 21 September 1998 · Accepted: 1 December 1998  相似文献   

Au-Sb association and fractionation in micro-disseminated gold deposits,southwestern Guizhou--geochemistry and thermodynamics     

ZHU Laimin  HU Ruizhong 《中国科学D辑(英文版)》2000,43(2)

The dual geochemical character of paragenesis and fractionation between gold,arsenic and antimony in micro-disseminated gold deposits in southwestern Guizhou is discussed in terms of spatial distribution of independent deposits,lateral and vertical enrichment,mineralization stage and factor and correlation analyses.Thermodynamic calculations of solubility and speciation of gold and antimony minerals indicate that gold is transported in hydrothermal solution as Au(HS)-2 and antimony is mainly as Sb(OH)03 although HSb2S-4 may be of increasing importance in acid environment at low temperatures during the late stage of mineralization.Changes in physicochemical conditions hold the key to the association and fractionation between gold and antimony.Gold and antimony response differently to physicochemical variations because they are distinct from each other in soluble speciation and mineral solubility,leading to precipitation at different times and localities during hydrothermal evolution.  相似文献   

Inherent heterogeneity of sediments in Dhahran, Saudi Arabia — a case study     

Naser A. Al-Shayea   《Engineering Geology》2000,56(3-4):305-323

The behavior and properties of sediments depend on their compositional characteristics and formation processes, as well as the environmental conditions during their geological history, i.e. post-formation processes. A vertical cut made in a hill in Dhahran, Saudi Arabia, reveals a vivid picture of the inherent heterogeneity of sediments that have been deposited at different geological ages. A review of the geology of the area, as well as laboratory tests, help to determine the possible causes of the variability of soil types and properties in the area. Laboratory tests include basic geotechnical tests, chemical tests, X-ray diffraction analysis, scanning electron microscopy, and thermal analysis. These tests are used to identify different rock types and soils from the face of the cut. The results of this study indicate that the material from this cut varies from clayey shale and limestone rock (Tertiary, lower Eocene) formed some 52 M.Y. to calcite-cemented sand and pure calcite rock formed in the Quaternary age.  相似文献   

Factors controlling the major ion chemistry of streams in the blue ridge and valley and ridge physiographic provinces of Virginia and Maryland     

Larry J. Puckett  Owen P. Bricker 《水文研究》1992,6(1):79-97

The factors controlling the chemistry of 69 low-order streams in the Blue Ridge and Valley and Ridge physiographic provinces of Virginia and Maryland were studied over a 13-month period. Principal component analysis was used to examine regional patterns in stream chemistry and to examine the degree to which the chemistry of low-order streams is controlled by the bedrock upon which they flow. Streams clustered into regionally isolated groups, strongly related to bedrock type, with SO^2?₄ and HCO^?₃ the chemical variables of most importance. Sulphate concentrations appear to be strongly controlled by climate and hydrology, and sorption in the soils within the watershed. Much of the atmospherically derived SO^2?₄ accumulates in watersheds during the growing season and is later flushed out. Weathering reactions were found to be particularly important in the production of HCO^?₃, accounting for 91 per cent on an annual basis, and export of divalent cations from these watersheds, accounting for 48–50 per cent on an annual basis. About half of non-anthropogenic Na⁺ was derived from weathering of silicates, whereas nearly all K⁺ was identified with leaching by SO^2?₄. Water chemistry was strongly related to the rock type in the watershed and the weatherability of the component minerals. Rock type is not a randomly distributed function; instead, it is controlled by geologic factors that result in clusters of similar rock types in a given region. When planning large synoptic studies, it is extremely important to consider that a sampling scheme based on random sampling of a non-randomly distributed function May, not provide the most accurate representation of the variables of interest. Instead, a hierarchical sampling scheme May, be indicated. Our results also suggest that, although one sample in time May, be sufficient to characterize the primary geochemical factors controlling stream chemistry throughout the year, it May, not be sufficient to detect subtle, flow-related alterations in chemistry.  相似文献   

原子荧光法测定天然矿泉水及地下水中的痕量锡     

赵辉  马欣 《国土资源》1993,(4)

将天然矿泉水或地下水水样蒸发浓缩后,于XDY—Ⅱ型原子荧光光度计上测定锡的荧光强度。此法操作简单、快速、灵敏度高、检出限低。其相对标准偏差为2.34％,最低检出限为0.49μg/L,锡的回收率为97％—104％。  相似文献