【摘要】：研究區(qū)位于青海省南祁連地區(qū)天峻縣,隸屬于南祁連地塊,主要涉及祁連山造山帶,屬于青藏高原泛華夏大陸秦祁昆構(gòu)造區(qū)。泛華夏古陸塊群在晚古生代是介于岡瓦納大陸與勞亞大陸的陸鏈,分隔了古特提斯大洋和古亞洲洋,秦祁昆造山帶早古生代造山作用受控于原特提斯洋向泛華夏大陸西部陸塊群俯沖和消減,屬于特提斯構(gòu)造域的重要組成部分。本文主要對青海省南祁連地區(qū)二疊系及其沉積相進行研究。主要涉及二疊系勒門溝組、草地溝組、哈吉爾組、忠什公組、巖石地層、生物地層、年代地層及沉積組合相等方面。勒門溝組由西向東沉積逐漸減薄,至剛察大寺剖面尖滅。草地溝組分布于中祁連山以南,花海于-大柴旦-德令哈-剛察大寺一線以北的廣大地域,呈紡錘形展布。草地溝組下部為一套厚層泥晶灰?guī)r夾生物碎屑泥晶灰?guī)r,富含雙殼類、腕足類、蜓類及有孔蟲化石。忠什公組分布于盆地沉積中心一帶,主要出露于忠什公剖面,向東厚度逐漸減薄�？傮w上,二疊系由西向東灰?guī)r、礫巖沉積逐漸減薄,砂巖沉積逐漸增多,沉降中心可能在忠什公一帶。本次研究在草地溝剖面草地溝組底部生物碎屑灰?guī)r中,及莫力克東溝剖面下伏地層哈吉爾組中,發(fā)現(xiàn)了蜓類及有孔蟲化石15屬,牙形石化石2屬3種。研究區(qū)二疊系砂巖石英含量較高,主要為石英砂巖及長石石英砂巖,分選良好,近次圓狀—次棱狀,結(jié)構(gòu)成熟度較高。且野外露頭上,砂體形態(tài)多為透鏡狀,具有頂平底凸,向兩側(cè)尖滅的特點。研究區(qū)內(nèi)原生沉積構(gòu)造發(fā)育,常見平行層理、交錯層理、槽狀交錯層理、浪成交錯層理、波痕、泥裂,偶見沖刷充填構(gòu)造。綜合巖性組合特征,沉積構(gòu)造,野外沉積形態(tài)等因素,認為研究區(qū)二疊系碎屑巖主要為三角洲沉積。草地溝組底部泥晶灰?guī)r及生物碎屑泥晶灰?guī)r沉積為碳酸鹽局限臺地沉積相。
[Abstract]:The study area is located in Tianjun County, South Qilian area, Qinghai Province, and belongs to the South Qilian block, which mainly involves the Qilian Mountain orogenic belt and belongs to the Qinghai-Xizang Plateau pan-Chinese continental Qinqi-Kun tectonic area. In the late Paleozoic, the Pan-Cathaysian ancient continental block group was a continental chain between Gondwana and Laoya, separating the Paleotertes Ocean from the Paleo-Asian Ocean. The early Paleozoic orogeny of the Qinqi-Kun orogenic belt is controlled by the subduction and subduction of the primitive Tethys ocean to the western continental block group of Pan-China, which is an important part of the Tethyan tectonic domain. The Permian system and its sedimentary facies in South Qilian area of Qinghai Province are studied in this paper. It mainly involves the Permian Lemengou formation, Caogou formation, Hajier formation, Zhongshigong formation, lithostratigraphy, biostratigraphy, chronostratigraphy and sedimentary assemblages. The Lemengou formation gradually thinned from west to east to the tip of Gangcha Dasi section. The Caogou formation is distributed in the south of the Middle Qilian Mountains, and the Huahai is distributed in a wide area north of the first line of Dachaidan-Delingha-Gangcha Temple, with a spindle-shaped distribution. The lower part of the Caogou formation is a set of thick layer mudstone with bioclastic mudstone, which is rich in bivalves, brachiopods, flies and foraminifera fossils. The Zhongshigong formation is distributed in the sedimentary center of the basin and is mainly exposed to the Zhongshigong section and gradually thinned eastward. On the whole, the Permian limestone is from west to east, the conglomerate deposit is thinning, the sandstone deposit is increasing, and the subsidence center may be in the area of Zhongshi Gong. In this study, 15 genera and 3 species of conodont fossils have been found in 15 genera and 2 genera of conodont fossils in the bottom bioclastic limestone of the grassland gully formation in the Laogou section and in the underlying formation of the Hagil formation in the Molek Donggou section. The content of quartz in Permian sandstone is high, mainly quartz sandstone and feldspar quartz sandstone. In the field outcrop, the sand body is mostly lenticular, which has the characteristics of top and flat bottom convex and pointed out to both sides. In the study area, the primary sedimentary structures are developed, such as parallel bedding, interlaced bedding, trough interlaced bedding, wave interlaced bedding, ripples, mud cracks, and occasionally scour and filling structures. According to the characteristics of lithologic assemblage, sedimentary structure and field sedimentary morphology, it is considered that the Permian clastic rocks in the study area are mainly delta deposits. At the bottom of Caogou formation, mudstone and bioclastic mudstone are deposited into carbonate confined platform sedimentary facies.
【學(xué)位授予單位】：中國地質(zhì)大學(xué)(北京)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：P534.46

【相似文獻】

相關(guān)碩士學(xué)位論文 前2條

1 姚暢;青海省南祁連二疊及其沉積相研究[D];中國地質(zhì)大學(xué)(北京);2015年

2 羅凱;中祁連北緣托來河地區(qū)石炭紀(jì)—三疊紀(jì)盆地演化研究[D];中國地質(zhì)大學(xué)(北京);2015年

，

本文編號：2185036