發(fā)布時(shí)間：2019-05-29 16:05

【摘要】：川西盆地位于揚(yáng)子板塊西緣,現(xiàn)今東以龍泉山隆起與川中地區(qū)分隔,西以龍門山北川-映秀斷層為邊界。中三疊以前,川西盆地作為揚(yáng)子板塊被動大陸邊緣沉積了巨厚的海相碳酸鹽巖地層。自晚三疊世以來,伴隨印支運(yùn)動,川西盆地逐漸過渡為陸相沉積盆地,沉積馬鞍塘組和須家河組。從現(xiàn)今構(gòu)造格架分析,龍門山逆沖構(gòu)造帶、川西盆地與龍泉山隆起均呈NE走向,似乎具有盆-山配套關(guān)系,因此晚三疊世的川西盆地長期被認(rèn)為是現(xiàn)今龍門山逆沖推覆帶控制形成的前陸盆地,以須家河組(T3x)為代表的晚三疊世沉積為前陸盆地沉積。然而在川西盆地發(fā)育的上三疊統(tǒng)在盆地的西南段明顯為北川-映秀斷層截切,在斷層西側(cè)上盤仍發(fā)育有須家河組等地層,位于龍門山腹陸帶內(nèi)的探井也鉆遇須家河組,表明晚三疊世盆地西緣并非現(xiàn)今的北川-映秀斷層。因此,重建晚三疊世川西原型盆地是深入理解這一時(shí)期盆地-山脈關(guān)系,乃至重新認(rèn)識川西地區(qū)晚三疊世構(gòu)造格局的關(guān)鍵。原型盆地分析的關(guān)鍵是盆地沉積物的特征,我們綜合研究了川西盆地野外露頭資料及鉆井資料,分析上三疊統(tǒng)的沉積特征及展布特點(diǎn)。結(jié)果表明從早到晚須家河組沉降中心具有從北東向南西遷移的規(guī)律,其中的礫巖沉積物從T3x2~T3x4分布范圍逐漸擴(kuò)大,具有從盆地北段向中段進(jìn)積的規(guī)律。運(yùn)用碎屑鋯石測年方法,分析確定須家河組初始沉積年齡為222Ma,碎屑鋯石指示其物源主要來自西秦嶺。綜合分析以上成果,表明晚三疊世從早到晚以粗碎屑為代表的盆地邊緣相和盆地沉降中心從北向南西遷移,邊緣沉積相帶走向可能從近東西向逐漸轉(zhuǎn)變?yōu)镹E向,從而在此基礎(chǔ)上建立了晚三疊世川西盆地演化模式,認(rèn)為其主要受西秦嶺南緣逐漸向南西擴(kuò)展的前陸逆沖構(gòu)造控制。
[Abstract]:The western Sichuan basin is located in the western margin of the Yangtze plate. At present, the Longquan Mountain uplift is separated from the central Sichuan area in the east, and the Beichuan-Yingxiu fault in the west is the boundary in the west. Before the Middle Triassic, the western Sichuan Basin, as the passive continental margin of the Yangtze plate, deposited a very thick marine carbonate strata. Since the late Triassic, with the Indochina movement, the western Sichuan basin has gradually transitioned into a continental sedimentary basin, sedimentary Maantang formation and Xujiahe formation. From the analysis of the present tectonic framework, the Longmenshan thrust tectonic belt, the western Sichuan basin and the Longquanshan uplift show NE strike, which seems to have a basin-mountain matching relationship. Therefore, the western Sichuan basin in the late Triassic has long been considered to be a Foreland basin controlled by the Longmenshan thrust nappe belt, and the late Triassic deposits represented by the Xujiahe formation (T3x) are the Foreland basin deposits. However, the Upper Triassic developed in the western Sichuan basin is obviously cut by Beichuan-Yingxiu fault in the southwest section of the basin, and there are still Xujiahe formation and other strata in the upper plate on the west side of the fault, and the exploration wells located in the Longmenshan ventral continental belt are also drilled into the Xujiahe formation. It shows that the western margin of the late Triassic basin is not the present Beichuan-Yingxiu fault. Therefore, the reconstruction of the late Triassic prototype basin in western Sichuan is the key to deeply understand the basin-mountain relationship in this period, and even to re-understand the late Triassic tectonic pattern in western Sichuan. The key to the analysis of the prototype basin is the characteristics of basin sediments. We comprehensively study the outcrop data and drilling data in the western Sichuan basin, and analyze the sedimentary characteristics and distribution characteristics of the Upper Triassic. The results show that the subsidence center of Xujiahe formation has the law of migration from north east to south west from morning to night, and the distribution range of gravel sediments is gradually expanded from T3x2~T3x4, and it has the regularity of accumulation from the north section of the basin to the middle part of the basin. By using the clastic zircon dating method, it is determined that the initial sedimentary age of Xujiahe formation is 222 Ma, and the clastic zircon indicates that its provenance mainly comes from the West Qinling Mountains. The comprehensive analysis of the above results shows that the basin margin facies and basin subsidence center represented by crude clastic migrated from north to south and the marginal sedimentary facies belt may gradually change from near east to west to NE from early to late Triassic. On this basis, the evolution model of the late Triassic western Sichuan basin is established, and it is considered that it is mainly controlled by the Foreland thrust structure which gradually extends to the south west of the southern margin of the western Qinling Mountains.
【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】：P534.51

【相似文獻(xiàn)】

相關(guān)期刊論文 前10條

1 李產(chǎn)林;四川晚三疊世煤變質(zhì)問題的研究[J];現(xiàn)代地質(zhì);1990年02期

2 馮少南;席運(yùn)宏;;華南晚三疊世生物地質(zhì)事件[J];河南地質(zhì);1991年02期

3 王運(yùn)生;龍門山晚三疊世早期菊石[J];成都地質(zhì)學(xué)院學(xué)報(bào);1992年04期

4 王喜富;川陜地區(qū)晚三疊世輪葉狀植物一新屬[J];古生物學(xué)報(bào);1977年02期

5 雷作淇;四川寶鼎龍硐晚三疊世的孢粉組合[J];古生物學(xué)報(bào);1986年02期

6 孟繁松;鄂西晚三疊世植物化石的兩個新種[J];古生物學(xué)報(bào);1986年02期

7 川波 ,春林;《中國環(huán)太平洋帶北段晚三疊世地層古生物及古地理》專著通過評審[J];長春地質(zhì)學(xué)院學(xué)報(bào);1989年02期

8 吳熙純;川西北晚三疊世的燈海綿動物群[J];古生物學(xué)報(bào);1990年03期

9 林啟彬;新疆托克遜晚三疊世昆蟲[J];古生物學(xué)報(bào);1992年03期

10 陳金華;楊勝秋;;西藏康馬地區(qū)晚三疊世的雙殼類[J];古生物學(xué)報(bào);1983年03期

相關(guān)會議論文 前5條

1 馮明;劉化清;王宏波;白云來;;鄂爾多斯盆地西緣晚三疊世存在“古陸梁”嗎?[A];中國石油勘探開發(fā)研究院西北分院建院20周年論文專集[C];2005年

2 姚華舟;張仁杰;牛志軍;趙小明;王健雄;段其發(fā);;青藏高原地區(qū)晚三疊世偉齒蛤類[A];中國古生物學(xué)會第十次全國會員代表大會暨第25屆學(xué)術(shù)年會——紀(jì)念中國古生物學(xué)會成立80周年論文摘要集[C];2009年

3 陳應(yīng)明;侯世云;;西藏怒江西松尼地區(qū)晚三疊世植物化石的發(fā)現(xiàn)[A];新世紀(jì) 新機(jī)遇 新挑戰(zhàn)——知識創(chuàng)新和高新技術(shù)產(chǎn)業(yè)發(fā)展（上冊）[C];2001年

4 姚華舟;沙金庚;張仁杰;;關(guān)于晚三疊世偉齒蛤類Neomegalodon Gümbel,1862[A];中國古生物學(xué)會第九屆全國會員代表大會暨中國古生物學(xué)會第二十三次學(xué)術(shù)年會論文摘要集[C];2005年

5 尹恭正;羅永明;喻懸，

本文編號：2488046