准噶尔盆地西北缘下二叠统风城组喷流岩物质组分及地球化学特征

发布时间：2018-06-13 04:54

本文选题：喷流岩 + 物质组分特征　；参考：《成都理工大学》2017年硕士论文

【摘要】：喷流岩(即热水沉积岩),是当前地质学领域研究热点之一,目前研究多集中于海相环境,而湖相环境研究明显偏少,尤其是湖相“白烟型”喷流岩。同时,在与之类似的湖相“白烟型”喷流岩的致密油储层中已获得重要的油气勘探进展,显示了喷流岩作为良好的致密油储层,其具备的重大勘探开发潜力。因此,本文对湖相“白烟型”喷流岩的研究,不论是对于地学理论研究,还是对于勘探开发生产都具有重要意义。本文以准噶尔盆地西北缘乌尔禾地区下二叠统风城组为例,通过开展岩石学、矿物学及地球化学等研究,取得如下成果及认识:(1)研究区风城组沉积期具有前陆盆地性质,构造运动及火山喷发活动频繁,具有古地热背景高异常的特征,区内深大断裂系统发育,为热液运移提供良好的通道。(2)研究区风城组喷流岩物质组分以白云石和盐类矿物为主,可识别出含铁白云石、铁白云石、硅硼钠石、水硅硼钠石、碳钠钙石、氯碳钠镁石、碳钠镁石、苏打石、石盐及硬石膏等等,部分为硅酸盐或铝硅酸盐矿物,金属硫化物主要为黄铁矿。(4)风城组喷流岩中不同岩石类型在普遍强烈富集Li、Mo、W、U等微量元素,又表现为不同岩类具有各自不同的微量元素富集特征,其富集特征不仅明显区别于正常沉积,指示其沉积期有深部热流体的参与,也显示风城组白云岩类沉积期流体具有多源性的特点。(5)通过主量元素、微量元素以及碳、氧同位素、锶同位素、硼同位素和包裹体特征分析,表明风城组沉积期气候干燥炎热,蒸发量大,属于半封闭—封闭的还原环境,且成岩过程中,有来自于亏损幔源流体的参与。(6)研究区岩性类型以云质岩为主,白云岩中常有陆源碎屑、泥和火山灰物质的混入,其中陆源碎屑主要为细粒的粉砂,来源于浅湖区的扇三角洲前缘砂体,并受事件作用(风暴、洪水、地震、火山活动)等失稳形成重力流(砂质碎屑流、风暴流和浊流),带入的粉砂、泥和飘入湖盆内的火山灰一起与盆内的准同生期热液沉淀白云石混合、或与已固结的先期白云岩形成互层,共同构成具有典型的“间断-交叉”内外源混合沉积白云岩类。
[Abstract]:The exhalation rocks (i.e. hot water sedimentary rocks) are one of the research hotspots in the field of geology. At present, the researches are mostly focused on the marine environment, but the study on the lacustrine environment is obviously less, especially on the lacustrine "white smoke" jet rocks. At the same time, important oil and gas exploration progress has been obtained in the tight oil reservoir of the similar lacustrine "Baiyan" jet rock, which shows that the exhalation rock as a good tight oil reservoir has great potential for exploration and development. Therefore, the study of the lacustrine "white smoke" jet rock is of great significance for the study of geoscience theory as well as for exploration and production. Taking the Fengcheng formation of the Lower Permian in Wuerhe area on the northwestern margin of Junggar Basin as an example, through the study of petrology, mineralogy and geochemistry, the following results have been obtained and the understanding that the Fengcheng formation in the study area has the character of Foreland basin during the sedimentary period. The tectonic movements and volcanic eruptions are frequent, with the characteristics of high anomaly of paleogeothermal background, and the deep fault system is developed in this area, which provides a good channel for hydrothermal migration.) the material composition of the jet rock of Fengcheng formation in the study area is mainly dolomite and salt minerals. They can be identified as dolomite, sodium silicoborite, sodium silicate, sodium carbonate, sodium magnesium chloride, soda, rock salt and anhydrite, etc., some of which are silicate or aluminosilicate minerals, The metal sulfides are mainly pyrite. 4) the different rock types of the Fengcheng formation strongly enrich trace elements such as Liqimo WZU and other trace elements, and the different rocks have different characteristics of trace element enrichment. The enrichment characteristics are not only distinct from normal deposition, but also indicate that deep thermal fluids are involved in the sedimentary period. It also shows that the fluid of dolomite sedimentary period of Fengcheng formation has multi-source characteristics. 5) through major elements, trace elements, carbon and oxygen isotopes, The characteristics of strontium isotope, boron isotope and inclusions show that Fengcheng formation was characterized by dry and hot climate and large evaporation during the sedimentary period, which belongs to a semi-enclosed and closed reduction environment and is in the diagenetic process. The lithologic types in the study area are dominated by dolomite, and there is often a mixture of continental clastic materials, mud and volcanic ash in dolomite, in which the continental source debris is mainly fine silt. The fan delta front sand body originated from the shallow lake region is affected by events (storm, flood, earthquake, volcanic activity) and other instability to form gravity flow (sand debris flow, storm current and turbidity current) brought in silt, The mud and the volcanic ash floating into the lake basin are mixed with the quasi-syntectic hydrothermal precipitated dolomite in the basin, or interbedded with the preconsolidated dolomite, forming a typical "discontinuous-cross" mixed sedimentary dolomite from both internal and external sources.
【学位授予单位】：成都理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：P618.13

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