本文選題：新近系　切入點(diǎn)：三營(yíng)組　出處：《成都理工大學(xué)》2015年碩士論文　論文類型：學(xué)位論文

【摘要】：新近系三營(yíng)組是1959年由云南地質(zhì)局區(qū)調(diào)地質(zhì)調(diào)查大隊(duì)命名,其特征是由灰、深灰、褐灰、黃白等雜色泥巖(粘土巖)、粉砂巖、細(xì)-中粒砂巖與礫巖、砂礫巖及碳質(zhì)泥巖夾煤層及菱鐵礦小凸鏡體組成,并夾有紫紅色巖層。含哺乳動(dòng)物、腹足類、植物、介形類及孢粉等化石。其中植物有Acer,Quercus,Celtis,Pinus等化石。底部一般具礫巖。不整合覆于北衙組、三號(hào)溝組或雙河組等地層之上;上被第四系不整合覆蓋。厚49-1331米。云南省南澗縣三營(yíng)組盆地位于哀牢山斷裂帶兩側(cè),分別為南澗縣城的南澗盆地和德苴鄉(xiāng)至多依廠古建筑的德苴-多依廠盆地。經(jīng)過詳細(xì)的盆地實(shí)測(cè)地層剖面測(cè)制,得知南澗盆地主要發(fā)育為洪(沖)積扇-河流沉積相組合,其礫石組分不但有外來礫石,其礫石層中大的礫石很可能是其基底地層在外界條件下風(fēng)化剝蝕形成的原位礫石,德苴-多依廠盆地主要以洪(沖)積扇-辮狀河沉積相組合,其礫石風(fēng)化嚴(yán)重,磨圓不好,且含有很明顯的花崗巖礫石,其礫石物源很可能來自哀牢山構(gòu)造帶。通過對(duì)云南省南澗縣哀牢山斷裂帶兩側(cè)的兩個(gè)小型新近系三營(yíng)組盆地共計(jì)5個(gè)露頭測(cè)點(diǎn)的礫巖層礫性、礫度、礫態(tài)和礫向等的詳細(xì)研究與分析,結(jié)合盆地基巖地層特點(diǎn)和周邊構(gòu)造帶的巖性組合特征。對(duì)比了哀牢山斷裂帶兩側(cè)盆地的礫巖層組合特征,認(rèn)為兩者皆為半干旱-干旱古氣候條件下形成的沉積盆地,其中南澗盆地具有快速堆積的特點(diǎn),其礫石成分組合特征在盆地不同位置有較多的差異,反映了其物源供應(yīng)條件較復(fù)雜;而德苴-多依廠盆地礫巖組合特征表明水動(dòng)力條件相對(duì)南澗盆地弱,且礫石層礫石遭受了較強(qiáng)的物理化學(xué)作用。結(jié)合盆地基巖及周邊地層巖性特點(diǎn)和礫石扁平面傾向統(tǒng)計(jì),南澗盆地礫石主要來自盆地基底及周邊高山,而德苴-多依廠盆地則主要是盆地內(nèi)部的基底地層及其西緣的哀牢山構(gòu)造帶。為了進(jìn)一步探討兩盆地物源的異同之處,對(duì)兩盆地采集的碎屑鋯石樣品,分別進(jìn)行了LA-ICP-MS碎屑鋯石U-Pb測(cè)年,其中南澗盆地共得到碎屑鋯石年齡62個(gè),鋯石年齡跨度介于222-1093Ma之間,這表示其物源組分復(fù)雜。在鋯石U-Pb年齡諧和圖上,可見鋯石斷續(xù)存在多個(gè)集中區(qū),這個(gè)反映了鋯石的原巖年齡,對(duì)鋯石年齡進(jìn)行頻度統(tǒng)計(jì),鋯石年齡存在三個(gè)峰值,分別位于238Ma、436Ma、774Ma附近,在464-636Ma存在間斷,對(duì)比研究區(qū)碎屑鋯石測(cè)年數(shù)據(jù),推測(cè)該盆地很可能存在3個(gè)或者更多的可能物源區(qū)。,德苴-多依廠盆地共得到碎屑鋯石年齡80個(gè),其測(cè)年結(jié)果則與南澗盆地大相徑庭,其鋯石測(cè)年高度集中在一個(gè)極小的區(qū)間(32.3-40Ma),這不僅表明該盆地物源區(qū)單一,同時(shí)也表明了其形成時(shí)間極短,沉積物搬運(yùn)速度快速,在短時(shí)間內(nèi)形成了這個(gè)盆地,結(jié)合目前德苴-多依廠盆地沉積物風(fēng)化嚴(yán)重,且未見第四系沉積的現(xiàn)象,此盆地很可能經(jīng)歷了一個(gè)快速堆積而后急劇抬升的過程。
[Abstract]:The Sanying formation of the Neogene was named in 1959 by the Geological Survey Group of the Geological Bureau of Yunnan Province. It is characterized by mixed mudstone (clay rock, siltstone, fine to medium grained sandstone and conglomerate) with gray, deep ash, brown ash, yellow white, etc. Composed of gravelly and carbonaceous mudstone intercalated with coal seams and siderite, and intercalated with purplish red rocks, containing mammals, gastropods, plants, Ostracods and sporopollen fossils. Among them, there are Acera Quercus Celtis Pinus and other fossils. The bottom is usually conglomerate. The unconformity is on the formations of Beiya formation, No.3 Gou formation or Shuanghe formation. The basin of Sanying formation in Nanjian County, Yunnan Province is located on both sides of the Ailaoshan fault zone. The Nanjian basin in Nanjian county and the Deju-Duoyichang basin in Dejianxian in ancient buildings at most. Based on the detailed stratigraphic profiling of the basin, it is found that the Nanjian basin is mainly developed into a flood (alluvial) fan-river sedimentary facies association. There are not only foreign gravel in its gravel composition, but also the large gravel in its gravel layer is probably the in-situ gravel formed by weathering and denudation of its basement strata under external conditions. The Deju-Duichang basin is mainly composed of flood (alluvial) fan and braided river sedimentary facies. Its gravel weathered seriously, the grinding round is not good, and contains very obvious granite gravel, The gravel source is probably from the Ailaoshan structural belt. The gravel properties and graveliness of the two small Neogene Sanying formation basins on both sides of the Ailaoshan fault zone, Nanjian County, Yunnan Province, were measured at 5 outcrop sites. The characteristics of conglomerate assemblage on both sides of the Ailaoshan fault zone are compared by the detailed study and analysis of the gravel-state and gravel-direction, combined with the characteristics of the basement strata and the lithologic assemblages of the surrounding structural zones. It is considered that both of them are sedimentary basins formed under semi-arid and arid paleoclimate conditions, in which Nanjian basin is characterized by rapid accumulation, and the characteristics of gravel composition combination are different in different locations of the basin. The characteristics of conglomerate assemblage show that the hydrodynamic conditions are weaker than those in Nanjian basin. Combined with the lithologic characteristics of the basement and surrounding strata of the basin and the statistical analysis of the flat surface of the gravel, the gravel in the Nanjian basin mainly comes from the basement of the basin and the surrounding high mountains. The Deju-Duoyichang basin is mainly composed of the basement strata and the Ailaoshan tectonic belt in the western margin of the basin. In order to further explore the similarities and differences between the two basins, the samples of the detrital zircons collected from the two basins are studied. The U-Pb dating of LA-ICP-MS detrital zircons has been carried out respectively. A total of 62 zircon ages have been obtained in Nanjian Basin, and the zircon age span is between 222-1093 Ma, which indicates that its provenance components are complex. It can be seen that there are several concentration zones in zircon intermittently, which reflects the age of zircon. According to the frequency statistics of zircon age, there are three peaks of zircon age, located at about 238Ma-436Ma-774Ma, and discontinuous at 464-636Ma. By comparing the data of detrital zircon dating in the study area, it is inferred that there are probably three or more possible provenances in the basin. 80 zircon ages have been obtained in the Deju-Duichang basin, and the results are quite different from those in the Nanjian basin. The zircon dating height is concentrated in a very small interval of 32.3-40 Ma, which not only indicates that the source area of the basin is single, but also indicates that the basin was formed in a short time, with a very short time of formation and a rapid speed of sediment transport, resulting in the formation of the basin in a short period of time. Combined with the serious weathering of sediments in the Deju-Duoyichang basin and the absence of Quaternary sediments, the basin probably experienced a rapid accumulation and then a sharp uplift.
【學(xué)位授予單位】：成都理工大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類號(hào)】：P534.6

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