陕西省富县直罗组沉积环境分析

发布时间：2018-05-23 10:59

本文选题：直罗组 + 七里镇砂岩　；参考：《长安大学》2015年硕士论文

【摘要】：直罗组是李德生于1951年创名于陕西省富县直罗镇,标准剖面为富县葫芦河直罗组剖面,指位于延安组之上、安定组之下的以块状长石砂岩和杂色泥岩、粉砂岩为主的粗碎屑岩组合,以富含砂岩为特征。下以一层块状中、粗粒长石砂岩与延安组分界,为平行不整合,上以一层灰绿色泥岩夹砂质长石砂岩与安定组分界,为整合接触。直罗组的研究成果丰富但缺少分类整理,一些基本问题还存有疑问,如七里镇砂岩的命名地点等问题。通过本次研究,解决了以上问题,并取得相应成果:1.收集了直罗组自创名(1951)以来的多个研究成果,根据研究程度对资料进行分类,归纳出直罗组的命名、沿革、地质年代、地质特征等方面的材料,选择直罗组底部七里镇砂岩、延安组煤线,中部高桥砂岩,顶部安定组底部砂岩为标志层,对直罗组进行划分。考证早期文献并结合实际资料认为,七里镇砂岩命名地位于建庄川汇入沮水河处,即现今店头镇。2.研究认为直罗组底部以七里镇砂岩或延安组煤线与延安组分界,顶部以紫红色巨厚层状中粒含泥砾长石石英砂岩与安定组为界,内部可以划分为两个旋回。下旋回起始于刘家砭东侧至杜家砭西侧结束,下部为黄绿色巨厚层状含砾中粗粒砂岩,即“七里镇砂岩”,区域上分布较为稳定,从南向北厚度逐渐变薄,底部常含泥砾,可见到树干化石;上部为黄绿色泥岩、粉砂岩与黄绿色中层状砂岩互层。上旋回起始于草子沟至安家川结束,下部岩性为黄绿色块状中细粒砂岩,底部含树干化石;上部为黄绿、蓝灰、紫红等杂色泥岩、粉砂岩夹黄绿色中层状砂岩。3.研究区砂岩十分发育,概率累积曲线与河道亚相相似,结合其它沉积相标志,如沉积构造、古生物特征等,认为研究区杜家砭附近发育辫状河相、草子沟发育曲流河相和宝塔山附近发育湖泊相,河流相可进一步划分为河道亚相和河漫滩亚相,湖泊相主要发育滨浅湖相。直罗组早期处于半干旱气候的辫状河沉积环境,中期气候逐渐向炎热干旱转变,为曲流河沉积环境,晚期气候更加干旱炎热,在河漫滩上或更低洼处形成小型湖泊。4.直罗组下段岩性主要为中、粗粒含泥砾长石砂岩,长石胶结;孔隙类型有粒间孔隙、溶蚀孔隙等;平均孔隙度56.71%,平均渗透率49.16 x10-3μm2,其储层主要为IIb类低渗透层。
[Abstract]:The Zhiluo formation was founded in 1951 by Li Desheng in Zhiluo Town, Fuxian County, Shaanxi Province. The standard section is the Hulu River Zhiluo formation section of Fuxian County, which refers to the massive feldspathic sandstone and mixed color mudstone located above the Yan'an formation and under the Anding formation. The coarse clastic rock assemblage of siltstone is characterized by rich sandstone. Under a layer of block, the boundary between coarse feldspar sandstone and Yan'an formation is parallel unconformity, and the upper layer of gray-green mudstone with sandy feldspathic sandstone is integrated contact. The research results of Zhiluo formation are rich but lack of classification, and some basic problems, such as the naming location of sandstone in Qili Town, are still in doubt. Through this research, has solved the above question, and obtained the corresponding achievement: 1. This paper has collected many research results since Zhiluo formation since its inception in 1951), classified the data according to the degree of research, summed up the names, evolution, geological age and geological characteristics of the Zhiluo formation, and selected the sandstone in Qili Town at the bottom of the Zhiluo formation. The Yanan formation coal line, the middle Gaoqiao sandstone, the top Anding formation bottom sandstone as the mark layer, carries on the division to the Zhiluo formation. According to the early literature and actual data, the named place of sandstone in Qili Town is located in Jianzhuang River into Jushui River, that is, Dianshang Town. 2. It is considered that the bottom of Zhiluo formation is separated by Qilizhen sandstone or Yan'an formation coal line and Yan'an formation, and the top of Zhiluo formation is divided into two cycles by fuchsia thick layer medium grained gravel-bearing feldspar quartz sandstone and diazepam formation. The lower cycle started from the east side of Liujiabian to the end of the west side of du Jiabian, and the lower part was the coarse sandstone with yellowish green and very thick layers, that is, the "Qili town sandstone". The distribution in the area was relatively stable, the thickness gradually thinned from south to north, and the bottom often contained mud gravel. The upper part is yellowish green mudstone with siltstone interbedded with yellowish-green mesostratified sandstone. The upper cycle originated from Caozigou to the end of Anjiachuan, the lower lithology was yellowish green block medium fine grained sandstone, the bottom contained trunk fossils, the upper part was yellowish green, blue gray, purple red mixed mudstone, siltstone intercalated yellow green medium layer sandstone. The sandstone is well developed in the study area, and the probability accumulation curve is similar to the channel subfacies. Combined with other sedimentary facies markers, such as sedimentary structure and paleontological characteristics, it is considered that braided river facies are developed near du Jiabian in the study area. The lacustrine facies developed in Caozigou and the lacustrine facies in the vicinity of Baotashan. The fluvial facies can be further divided into channel subfacies and floodplain subfacies, and the lacustrine facies mainly developed shallow-shore lacustrine facies. In the early period of Zhiluo formation, the braided river sedimentary environment was in the semi-arid climate, and the middle climate gradually changed to hot and dry climate. The late climate was more arid and hot, and the small lake .4 was formed on the floodplain or lower lying area. The lithology of the lower member of Zhiluo formation is mainly medium, coarse grained shaly feldspar sandstone, feldspar cementation, pore types such as intergranular pores and dissolution pores, average porosity 56.71 and average permeability 49.16 x 10-3 渭 m2. The reservoir is mainly IIb type low permeability layer.
【学位授予单位】：长安大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P618.13

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