兰坪盆地古近纪沉积充填特征
发布时间：2018-10-29 18:47
【摘要】：本文以滇西兰坪盆地古近纪沉积充填为研究对象,利用岩石学、沉积学、沉积地球化学等理论知识,综合前人研究的地质成果,通过对盆地不同剖面古近纪砂岩样品的碎屑成分特征、地球化学特征以及粒度分布特征进行分析对比,研究古近纪兰坪盆地的充填特征及沉积环境。主要取得以下认识与结论:(1)研究区古近纪砂岩碎屑成分分析中石英类型主要为单晶石英,长石类型主要以稳定的钾长石为主,岩屑类型有沉积岩+变质岩+(偶见)火成岩岩屑,以沉积岩岩屑为主;盆地云龙组→果郎组→宝相寺组砂岩中的Q/(F+R)指数呈递减的特点;根据Qt-F-L、Qm-F-Lt和Qm-P-K三角图解可知,研究区物源主要来源于大陆块的沉积岩区;Qp-Lv-Ls三角图解显示出研究区碎屑物源成分主要落在了克拉通前缘的碰撞缝合线及褶皱-逆掩带物源区内。(2)研究区常量元素特征指出,研究区古近纪碎屑沉积物成熟度较高,岩石样品以长石砂岩为主;砂岩物源区呈现由中性火成岩物源区向大陆石英质物源区演化的趋势;云龙期物源以来自盆地东缘(大陆岛弧)为主,至果郎期和宝相寺期有盆地西缘(被动大陆边缘)物源的加入,而宝相寺期物源主要来自盆地西缘(被动大陆边缘)。(3)研究区微量元素特征显示物源区物质主要以长英质岩石为主,沉积环境为陆相氧化环境,源岩以沉积岩为主,母岩碎屑主要来自于大陆上地壳;物源具有多期多阶段的特点,早期(云龙期)以大陆岛弧构造背景为主,晚期(果郎组)逐渐过渡为大陆岛弧+被动大陆边缘构造背景,尤其是到了宝相寺期则主要由被动大陆边缘构造区域提供物源。(4)研究区古近纪砂岩粒度概率累积曲线主要包括:“一跳一悬夹过渡”式、“一跳一悬式”;古近纪砂岩粒度分布特征表明,研究区砂岩偏度值在正偏—很正偏范围之间,峰度属中等尖锐—尖锐范畴,分选好至很好;运用结构参数散点图投点以及判别函数计算确定云龙组和果郎组砂岩代表河流、三角洲、湖泊相沉积,为一套陆相沉积环境,宝相寺组砂岩为冲积扇相沉积环境。
[Abstract]:In this paper, Paleogene sedimentary filling in Lanping basin, western Yunnan, is taken as the research object, and the geological results of previous studies are synthesized by using the theoretical knowledge of petrology, sedimentary geochemistry and so on. By analyzing and comparing the characteristics of clastic composition, geochemistry and granularity distribution of Paleogene sandstone samples in different sections of the basin, the filling characteristics and sedimentary environment of Paleogene Jiilanping basin are studied. The main conclusions are as follows: (1) in the clastic composition analysis of Paleogene sandstone, the quartz type is mainly single crystal quartz, and the feldspar type is mainly composed of stable potassium feldspar. There are sedimentary rocks metamorphic rocks (occasionally) igneous rocks and cuttings mainly sedimentary lithoclasts. The Q / (F R) index in the sandstones of the Yunlong formation and the Yunguolang formation is decreasing. According to the Qt-F-L,Qm-F-Lt and Qm-P-K triangular diagrams, the source of the studied area is mainly derived from the sedimentary rock area of the continental block. The Qp-Lv-Ls triangulation shows that the clastic source materials in the study area are mainly located in the collision suture of the front edge of the craton and the source area of the fold-overthrust belt. (2) the characteristics of the major elements in the study area are pointed out. The Paleogene clastic sediments in the study area have a high maturity and the rock samples are mainly feldspathic sandstone. The sandstone provenance shows a trend of evolution from neutral igneous source to continental quartz provenance. The source of Yunlong period is mainly from the eastern margin of the basin (continental island arc), and to the Guolang period and Baoxangsi period there is the addition of the western margin of the basin (passive continental margin). The trace element characteristics of Baoxangsi period mainly came from the western margin of the basin (passive continental margin). (_ 3). The source area was mainly composed of felsic rocks, the sedimentary environment was continental oxidation environment, and the source rocks were mainly sedimentary rocks. The parent rock clastic mainly comes from the continental upper crust; The provenance is characterized by multi-period and multi-stage. In the early stage (Yunlong period), the continental island arc was the main tectonic background, and the late stage (Guolang formation) was gradually transitioned to the passive continental margin tectonic setting of the continental island arc. Especially in Baoxangsi period, the source is mainly supplied by the passive continental margin tectonic area. (4) the grain size probability accumulation curve of Paleogene sandstone in the study area mainly includes: "one jump and one suspension transition", "one jump and one suspension"; The grain size distribution characteristics of Paleogene sandstone show that the sandstone deviation value in the study area is between positive deviation and very positive deviation, and the kurtosis belongs to the category of medium sharp and sharp, and the sorting is very good. It is determined that the sandstone of Yunlong formation and Guolang formation represent fluvial, delta and lacustrine facies by using structural parameter scatter plot and discriminant function calculation, which is a set of continental sedimentary environment, and that of Baxiangsi formation sandstone is alluvial fan sedimentary environment.
【学位授予单位】：东华理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P512.2
本文编号：2298497
[Abstract]:In this paper, Paleogene sedimentary filling in Lanping basin, western Yunnan, is taken as the research object, and the geological results of previous studies are synthesized by using the theoretical knowledge of petrology, sedimentary geochemistry and so on. By analyzing and comparing the characteristics of clastic composition, geochemistry and granularity distribution of Paleogene sandstone samples in different sections of the basin, the filling characteristics and sedimentary environment of Paleogene Jiilanping basin are studied. The main conclusions are as follows: (1) in the clastic composition analysis of Paleogene sandstone, the quartz type is mainly single crystal quartz, and the feldspar type is mainly composed of stable potassium feldspar. There are sedimentary rocks metamorphic rocks (occasionally) igneous rocks and cuttings mainly sedimentary lithoclasts. The Q / (F R) index in the sandstones of the Yunlong formation and the Yunguolang formation is decreasing. According to the Qt-F-L,Qm-F-Lt and Qm-P-K triangular diagrams, the source of the studied area is mainly derived from the sedimentary rock area of the continental block. The Qp-Lv-Ls triangulation shows that the clastic source materials in the study area are mainly located in the collision suture of the front edge of the craton and the source area of the fold-overthrust belt. (2) the characteristics of the major elements in the study area are pointed out. The Paleogene clastic sediments in the study area have a high maturity and the rock samples are mainly feldspathic sandstone. The sandstone provenance shows a trend of evolution from neutral igneous source to continental quartz provenance. The source of Yunlong period is mainly from the eastern margin of the basin (continental island arc), and to the Guolang period and Baoxangsi period there is the addition of the western margin of the basin (passive continental margin). The trace element characteristics of Baoxangsi period mainly came from the western margin of the basin (passive continental margin). (_ 3). The source area was mainly composed of felsic rocks, the sedimentary environment was continental oxidation environment, and the source rocks were mainly sedimentary rocks. The parent rock clastic mainly comes from the continental upper crust; The provenance is characterized by multi-period and multi-stage. In the early stage (Yunlong period), the continental island arc was the main tectonic background, and the late stage (Guolang formation) was gradually transitioned to the passive continental margin tectonic setting of the continental island arc. Especially in Baoxangsi period, the source is mainly supplied by the passive continental margin tectonic area. (4) the grain size probability accumulation curve of Paleogene sandstone in the study area mainly includes: "one jump and one suspension transition", "one jump and one suspension"; The grain size distribution characteristics of Paleogene sandstone show that the sandstone deviation value in the study area is between positive deviation and very positive deviation, and the kurtosis belongs to the category of medium sharp and sharp, and the sorting is very good. It is determined that the sandstone of Yunlong formation and Guolang formation represent fluvial, delta and lacustrine facies by using structural parameter scatter plot and discriminant function calculation, which is a set of continental sedimentary environment, and that of Baxiangsi formation sandstone is alluvial fan sedimentary environment.
【学位授予单位】：东华理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P512.2
【参考文献】
相关期刊论文 前1条
1 王鸿祯;关于国际(年代)地层表与中国地层区划[J];现代地质;1999年02期
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