酒泉盆地青西凹陷下白垩统下沟组湖相热水沉积岩中黄铁矿特征及成因研究
发布时间：2018-11-19 10:58
【摘要】：酒泉盆地青西凹陷下白垩统下沟组中所发育的湖相泥晶白云岩具有独特的复杂矿物组分和特殊的断陷湖盆沉积构造背景,完全不同于一般的热液交代白云石化或封闭环境下热液充填白云石(岩),是十分罕见的中生代湖泊环境中由热液喷流直接沉淀形成的泥晶原生含铁白云岩。凡此套热水沉积岩发育处,除了含有中-高温的矿物,还会含有黄铁矿,多呈极细碎屑状、多数无晶形,大部分以碎屑集合体的形式存在,这些碎屑状的黄铁矿或以条带状构造分布于泥质云岩条带中,亦或以角砾状构造和脉状构造分布于喷爆角砾岩格架间。本论文通过对该处黄铁矿及围岩进行深入和系统的岩石学、矿物学和地球化学的综合研究,包括对黄铁矿的结构构造研究、常量元素分析、微量元素分析和硫同位素分析,对围岩结构研究、碳-氧-锶同位素分析、微量元素分析和稀土元素分析等,首次对湖相“白烟型”热水沉积岩中的黄铁矿进行系统的研究,并获得以下结论和认识:1)酒泉盆地青西凹陷下沟组热水沉积岩中的黄铁矿主要为喷流沉积型和气水热液型两种成因类型。其中,喷流沉积型黄铁矿的标型构造为:团块状、角砾状、斑点状、洖状、侵染状、结核状、层状、层纹状和透镜状,其标型结构为:碎屑结构、自形粒状、镶边结构、格状结构、半自形粒状和它形结构;气水热液型黄铁矿的标型构造为:条带状和脉状,其标型结构为:侵蚀结构。2)黄铁矿的成矿流体来源主要为喷口内热液和湖底热卤水。湖底热卤水的特征为:富含Sb、Ba、Sr、Mn和V等热水沉积标型元素,LREE相对富集,具典型的负Eu异常稀土配分模式,氧同位素值明显负偏;锶同位素组成以少量幔源物质混入,主要受壳源物质影响最深为特征,反映纹层状泥晶含铁白云岩的沉积环境为受基底断裂控制的,和具备稳定、封闭和缺氧等条件的深湖底低洼热卤水池。喷口内热液的特征为:富硫、贫Ni,幔源锶较多混入(低87Sr/86Sr比值),温度高于黄铁矿的形成温度。3)微米级莓球状黄铁矿小而均一、由极细小晶粒组成的层状构造的黄铁矿反应成矿环境为静滞-缺氧的湖泊环境。4)黄铁矿因其成因类型的不同,有其特有赋存位置:与喷口热液有关的喷流沉积I型黄铁矿主要存在于热液喷口内和烟囱上;喷流沉积II型黄铁矿存在于受沉积作用更强的位置;气水-热液型黄铁矿主要存在于构造裂缝和沉积间隙中。5)建立湖相“白烟型”热水沉积岩中黄铁矿成因模式。
[Abstract]:The lacustrine mudstone developed in Xiagou formation of Lower Cretaceous in Qingxi Sag of Jiuquan Basin has unique complex mineral components and special sedimentary tectonic setting of faulted lacustrine basin. Completely different from the general hydrothermal metasomatism dolomitization or closed environment hydrothermal filling dolomite (rock) is a very rare Mesozoic lacustrine environment formed by hydrothermal jet direct precipitation of primary iron dolomite. Where the hot water sedimentary rocks are developed, in addition to the intermediate-high temperature minerals, they will also contain pyrite, most of which are very fine clastic, most of which are amorphous, and most of them are in the form of clastic aggregates. The clastic pyrite is distributed in the muddy dolomite belt or in the breccia framework by breccia structure and vein structure. In this paper, a comprehensive study of the petrology, mineralogy and geochemistry of pyrite and its surrounding rock is carried out, including the structural study of pyrite, the analysis of major elements, the analysis of trace elements and the analysis of sulfur isotopes. For the first time, the pyrite in the lacustrine "Baiyan" hot water sedimentary rock is systematically studied, including the study of surrounding rock structure, carbon-oxygen-strontium isotope analysis, trace element analysis and rare earth element analysis. The main conclusions are as follows: 1) Pyrite in the hydrothermal sedimentary rocks of Xiagou formation in Qingxi Sag Jiuquan Basin is mainly composed of two genetic types: jet sedimentary type and gas-water hydrothermal type. Among them, the typomorphic structure of jet sedimentary pyrite is: lump, breccia, speckled, filiform, infective, nodule, laminar and lenticular, its typomorphic structure is: clastic structure, self-shaped granular structure, edge structure. Lattice structure, hemiautomorphism granular structure and other shape structure; The typical structure of gas-hydrothermal-type pyrite is zonal and vein-like, and its typomorphic structure is erosion structure. 2) the ore-forming fluid of pyrite is mainly derived from hydrothermal solution in the nozzle and hot brine at the bottom of the lake. The characteristics of the hot brine at the bottom of the lake are as follows: rich in Sb,Ba,Sr,Mn and V, relatively enriched in LREE, typical negative Eu anomalous rare earth partitioning model, and obvious negative deviation of oxygen isotopic value; Sr isotopic composition is characterized by a small amount of mantle-derived materials, which is mainly influenced by crust-derived materials. It shows that the sedimentary environment of laminated mud-grained iron-bearing dolomite is controlled by basement faults and is stable. Deep lake bottom low-lying hot brine pool with closed and anoxic conditions. The characteristics of hydrothermal solution in the nozzle are: sulfur rich, rich in sulfur, rich in Ni, mantle source strontium (low 87Sr/86Sr ratio), and temperature higher than pyrite formation temperature. 3) micron raspberry globular pyrite is small and uniform. The ore-forming environment of pyrite reaction in stratified structure consisting of very fine grains is a lake environment of static hysteresis and anoxia. 4) pyrite is formed in different genetic types. It has its own location: I type pyrite which is related to nozzle hydrothermal deposition mainly exists in hydrothermal vent and chimney; The II type pyrite exists in the position where the sedimentary action is stronger, the gas-water hydrothermal type pyrite mainly exists in the structural fracture and the sedimentary gap. 5) the genetic model of pyrite in the lacustrine "Baiyan" hot water sedimentary rock is established.
【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】：P618.31
本文编号：2342096
[Abstract]:The lacustrine mudstone developed in Xiagou formation of Lower Cretaceous in Qingxi Sag of Jiuquan Basin has unique complex mineral components and special sedimentary tectonic setting of faulted lacustrine basin. Completely different from the general hydrothermal metasomatism dolomitization or closed environment hydrothermal filling dolomite (rock) is a very rare Mesozoic lacustrine environment formed by hydrothermal jet direct precipitation of primary iron dolomite. Where the hot water sedimentary rocks are developed, in addition to the intermediate-high temperature minerals, they will also contain pyrite, most of which are very fine clastic, most of which are amorphous, and most of them are in the form of clastic aggregates. The clastic pyrite is distributed in the muddy dolomite belt or in the breccia framework by breccia structure and vein structure. In this paper, a comprehensive study of the petrology, mineralogy and geochemistry of pyrite and its surrounding rock is carried out, including the structural study of pyrite, the analysis of major elements, the analysis of trace elements and the analysis of sulfur isotopes. For the first time, the pyrite in the lacustrine "Baiyan" hot water sedimentary rock is systematically studied, including the study of surrounding rock structure, carbon-oxygen-strontium isotope analysis, trace element analysis and rare earth element analysis. The main conclusions are as follows: 1) Pyrite in the hydrothermal sedimentary rocks of Xiagou formation in Qingxi Sag Jiuquan Basin is mainly composed of two genetic types: jet sedimentary type and gas-water hydrothermal type. Among them, the typomorphic structure of jet sedimentary pyrite is: lump, breccia, speckled, filiform, infective, nodule, laminar and lenticular, its typomorphic structure is: clastic structure, self-shaped granular structure, edge structure. Lattice structure, hemiautomorphism granular structure and other shape structure; The typical structure of gas-hydrothermal-type pyrite is zonal and vein-like, and its typomorphic structure is erosion structure. 2) the ore-forming fluid of pyrite is mainly derived from hydrothermal solution in the nozzle and hot brine at the bottom of the lake. The characteristics of the hot brine at the bottom of the lake are as follows: rich in Sb,Ba,Sr,Mn and V, relatively enriched in LREE, typical negative Eu anomalous rare earth partitioning model, and obvious negative deviation of oxygen isotopic value; Sr isotopic composition is characterized by a small amount of mantle-derived materials, which is mainly influenced by crust-derived materials. It shows that the sedimentary environment of laminated mud-grained iron-bearing dolomite is controlled by basement faults and is stable. Deep lake bottom low-lying hot brine pool with closed and anoxic conditions. The characteristics of hydrothermal solution in the nozzle are: sulfur rich, rich in sulfur, rich in Ni, mantle source strontium (low 87Sr/86Sr ratio), and temperature higher than pyrite formation temperature. 3) micron raspberry globular pyrite is small and uniform. The ore-forming environment of pyrite reaction in stratified structure consisting of very fine grains is a lake environment of static hysteresis and anoxia. 4) pyrite is formed in different genetic types. It has its own location: I type pyrite which is related to nozzle hydrothermal deposition mainly exists in hydrothermal vent and chimney; The II type pyrite exists in the position where the sedimentary action is stronger, the gas-water hydrothermal type pyrite mainly exists in the structural fracture and the sedimentary gap. 5) the genetic model of pyrite in the lacustrine "Baiyan" hot water sedimentary rock is established.
【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】：P618.31
【参考文献】
相关期刊论文 前5条
1 周涛发;张乐骏;袁峰;范裕;David R.Cooke;;安徽铜陵新桥Cu-Au-S矿床黄铁矿微量元素LA-ICP-MS原位测定及其对矿床成因的制约[J];地学前缘;2010年02期
2 寇大明;黄菲;姚玉增;彭艳东;金成洙;;黄铁矿晶体形貌学研究进展[J];矿物学报;2009年03期
3 李志国;曾祥涛;王军平;;隐爆角砾岩型金矿床中黄铁矿的标型特征[J];黄金;2012年10期
4 张文正;杨华;解丽琴;杨奕华;;湖底热水活动及其对优质烃源岩发育的影响——以鄂尔多斯盆地长7烃源岩为例[J];石油勘探与开发;2010年04期
5 黎应书;秦德先;程细音;郭宁宁;罗曦;谢阳;邹滔;;个旧锡矿区印支期喷流热水沉积成矿的证据[J];有色金属;2009年03期
相关博士学位论文 前1条
1 杨雪英;华南泥盆纪地层与化石中的莓状黄铁矿研究[D];中国地质大学;2013年
，本文编号：2342096
本文链接：https://www.wllwen.com/kejilunwen/diqiudizhi/2342096.html
