【摘要】：米倉山隆起區(qū)屬于上揚(yáng)子地臺(tái)北緣的一部分,位于四川盆地北部川陜交界地區(qū)。米倉山區(qū)內(nèi)寒武紀(jì)地層出露,巖性變化大。下寒武統(tǒng)由寬川鋪組、郭家壩組、仙女洞組、閻王碥組和孔明洞組組成,主要為碎屑巖、碳酸鹽巖和混積巖類,其中仙女洞組及相鄰地層包括泥晶灰?guī)r、多種類型鮞�；�?guī)r、(微)生物灰?guī)r、礫屑灰?guī)r和鈣質(zhì)砂泥巖等。根據(jù)實(shí)測(cè)剖面沉積物幾何形態(tài)、沉積構(gòu)造和粒度變化等宏微觀特征,本文將米倉山區(qū)仙女洞組及相鄰地層劃分出11類沉積巖相,并通過各類沉積巖相代表的沉積環(huán)境以及各巖相之間的位置關(guān)系,進(jìn)一步總結(jié)為4類沉積巖相組合,分別代表淺海陸棚、臺(tái)緣斜坡、臺(tái)緣丘灘和局限臺(tái)地等沉積環(huán)境,再對(duì)其中的縱向序列進(jìn)行研究,劃分出多種沉積亞環(huán)境。米倉山區(qū)早寒武世仙女洞期的沉積環(huán)境總體可歸結(jié)為毗鄰古陸的連陸混積碳酸鹽巖鑲邊臺(tái)地—斜坡—陸棚沉積環(huán)境。 本文通過區(qū)域背景研究,認(rèn)為仙女洞組底部為臺(tái)地邊緣斜坡沉積,并擬出4種沉積巖相表征斜坡不同深度的沉積環(huán)境,后以變形條帶、崩坍巖塊和斜坡灰泥丘為特征,探討出米倉山西南緣臺(tái)緣斜坡變形構(gòu)造形成機(jī)制,即同沉積斷裂大背景之下由于重力因素等引發(fā)的滑塌變形,形成獨(dú)具特色的似瘤狀礫屑灰?guī)r與滑塌角礫。通過對(duì)比分析全球早寒武世微生物及其分布規(guī)律,總結(jié)出米倉山區(qū)仙女洞組海相碳酸鹽巖不同沉積環(huán)境、水體深度發(fā)育的三期不同類型的生物巖�。盒逼略迩�、臺(tái)緣藻丘和臺(tái)緣灘后古杯丘,探討微生物生存繁殖的水體環(huán)境差異,并歸納出不同灰泥丘各自的營造模式。
[Abstract]:The Mecang Mountain uplift is a part of the Taipei margin of the Upper Yangtze platform and is located in the northern Sichuan Basin at the junction of Sichuan and Shaanxi. The Cambrian strata are exposed and the lithology changes greatly in the Micang Mountain area. The Lower Cambrian is composed of the Kuanchuanpu formation, the Guojiaba formation, the Xiandong formation, the Yan Wangbin formation and the Kongming Cave formation, and is mainly composed of clastic rocks, carbonate rocks and migmatite, among which the Andromedan formation and adjacent strata include mudstone. Many types of oolitic limestone, (micro) biolimestone, gravel limestone and calcareous sand mudstone. According to the macro and micro characteristics of sediment geometry, sedimentary structure and grain size change in the measured section, 11 types of sedimentary lithofacies have been classified into the Xiandong formation and adjacent strata in Micang Mountain area in this paper. And through the sedimentary environment represented by various sedimentary lithofacies and the position relationship between each lithofacies, it is further summarized as four types of sedimentary lithofacies assemblages, representing the shallow sea shelf, the platform margin slope, the platform margin hill beach and the limited platform, respectively. Then the longitudinal sequence is studied and a variety of sedimentary subenvironments are divided. The sedimentary environment of the early Cambrian Fairy Cave in Micang Mountain area can be attributed to the rimmed platform slope shelf sedimentary environment adjacent to the ancient land. Based on the study of the regional background, it is considered that the bottom of the Xiadong formation is a platform margin slope deposit, and four sedimentary lithofacies are proposed to characterize the sedimentary environment of the slope at different depths, followed by a deformed strip, a collapsing rock block and a sloping mud mound. The forming mechanism of deformation structure of the slope in the southwestern margin of Mecang Mountain is discussed, that is, the landslide deformation caused by gravity factors under the background of the synsedimentary fault, forms unique nodular conglomerate limestone and sloughing breccia. By comparing and analyzing the microbes and their distribution in the global early Cambrian, three different types of biolith uplift in the Xiandong formation of Xiandong formation in Micang Mountain area, which are formed in different sedimentary environments and deep water bodies, are summarized, which are algae-dune on slopes. In this paper, the difference of water environment between algal dune of platform margin and ancient cup mound of backside beach of platform margin is discussed, and the construction mode of different plaster mound is concluded.
【學(xué)位授予單位】：西南石油大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類號(hào)】：P618.13

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本文編號(hào)：2176448