【摘要】：研究區(qū)位于內(nèi)蒙古中部，大地構(gòu)造位置位于華北板塊北緣，緊鄰華北板塊與西伯利亞板塊的拼合帶。依徐尼烏蘇斷裂帶研究區(qū)分為北部的華北地層大區(qū)和南部的北疆—興安地層大區(qū)，同時(shí)該條斷裂也被認(rèn)為是槽臺(tái)界線，即該斷裂以南為華北地臺(tái)區(qū)，以北為地槽區(qū)。出露的地層主要有太古界色爾騰山巖群，中新元古界長城-薊縣-青白口系白云鄂博群，下古生界寒武-奧陶系溫都爾廟群和白乃廟群、下寒武統(tǒng)西井子組以及下中奧陶統(tǒng)五道灣組、志留系徐尼烏蘇組和西別河組，上古生界石炭系本巴圖組和阿木山組、下二疊統(tǒng)三面井組和額里圖組及少量中生界和新生界。 經(jīng)野外觀察并結(jié)合前人研究，在研究區(qū)多處見有白云鄂博群覆蓋在古生界之上，白云鄂博群出露不連續(xù)，東西向延伸約160km，因其大致沿徐尼烏蘇斷裂分布，故稱該帶為“徐尼烏蘇逆沖推覆構(gòu)造帶”，本文首次對徐尼烏蘇逆沖推覆構(gòu)造的分布范圍、分帶特征、構(gòu)造變形特征、推覆方向、推覆距離以及推覆時(shí)代進(jìn)行了系統(tǒng)研究，補(bǔ)充了前人對于徐尼烏蘇逆沖推覆構(gòu)造中帶研究的不足，并結(jié)合徐尼烏蘇斷裂的性質(zhì)，合理推斷徐尼烏蘇斷層并非研究區(qū)的槽臺(tái)邊界。 按分布范圍和構(gòu)造特征，將徐尼烏蘇逆沖推覆構(gòu)造進(jìn)一步劃分：鋒帶主要沿補(bǔ)力太—徐尼烏蘇—白乃廟—博日和—章毛烏蘇—化德縣北一帶分布，呈疊瓦狀逆沖推覆構(gòu)造；中帶主要沿東、西烏素—愛國村—章蓋營—西井子鄉(xiāng)一線分布，以發(fā)育大量大小不一的飛來峰和構(gòu)造窗為特征，斷層角礫巖發(fā)育，推覆構(gòu)造界面發(fā)生褶皺變形；研究中未能識(shí)別出根帶，逆沖推覆構(gòu)造根帶很可能已經(jīng)被后期的巖漿活動(dòng)和構(gòu)造運(yùn)動(dòng)破壞。 徐尼烏蘇逆沖推覆構(gòu)造大致可以分為兩期：第一期以大規(guī)模的水平運(yùn)動(dòng)為主，該期為逆沖推覆構(gòu)造主期次；第二期以擠壓變形為主。從研究區(qū)中帶測得的產(chǎn)狀數(shù)據(jù)進(jìn)行分析，可以判斷該逆沖推覆構(gòu)造主要受區(qū)域上南北向擠壓作用，整體的推覆的方向?yàn)閺哪舷虮保桓鶕?jù)飛來峰前緣至構(gòu)造窗后緣之間的距離，初步確定推覆距離不小于52km；從逆沖推覆構(gòu)造涉及的地層和侵入構(gòu)造界面的巖體形成時(shí)代兩個(gè)方面進(jìn)行限定，確定了該逆沖推覆構(gòu)造發(fā)生的大致時(shí)間為早二疊世末期。 研究區(qū)的徐尼烏蘇斷裂被認(rèn)為是傳統(tǒng)的槽臺(tái)界線，但通過本次研究認(rèn)為該斷裂帶是由于逆沖推覆構(gòu)造形成的一系列逆斷層組合，斷層傾角較小，影響深度較淺，并非區(qū)域上的槽臺(tái)界線，推斷真正的槽臺(tái)界線在該斷裂以南約10~20km處。 結(jié)合區(qū)域構(gòu)造演化背景，暗示本次逆沖推覆構(gòu)造與中二疊世華北板塊與西伯利亞板塊的對接碰撞、古亞洲洋的閉合有關(guān)。
[Abstract]:The study area is located in the central part of Inner Mongolia, the tectonic position is located in the northern margin of the North China Plate, close to the convergence zone of the North China Plate and the Siberian Plate. The North China Platform is a geosynclinal area to the north. The strata are mainly Archaeozoic Seltenshan Group, Mesoproterozoic Changcheng-Jixian-Qingbaikou Bayan Obo Group, Lower Palaeozoic Cambrian-Ordovician Wenduermiao Group and Bainaimiao Group, Lower Cambrian Xijingzi Formation and Lower-Middle Ordovician Wudaowan Formation, Silurian Xuniwusu Formation and Xibiehe Formation. Formation, Upper Paleozoic Carboniferous Benbatu Formation and Amushan Formation, Lower Permian Sanmianjing Formation and Erlitu Formation, and a few Mesozoic and Cenozoic.
According to field observation and predecessors'research, the Bayan Obo Group is found to cover the Paleozoic in many places in the study area. The Bayan Obo Group is not continuous and extends about 160km in the East-West direction. Because it is distributed along the Xuniwusu fault, it is called the Xuniwusu thrust nappe structure belt. This paper is the first time to study the Xuniwusu thrust nappe structure. Distribution range, zoning characteristics, structural deformation characteristics, nappe direction, nappe distance and nappe age have been systematically studied, which complements previous studies on the middle zone of Xuniwusu thrust nappe structure and reasonably infers that Xuniwusu fault is not the trough-platform boundary of the study area.
According to the distribution and structural characteristics, the Xuniwusu thrust nappe structure is further divided into the following parts: the front belt is mainly distributed along the northern part of Buli Tai-Xuniwusu-Bainaimiao-Bori and Zhangmaowusu-Huade County, showing imbricate thrust nappe structure; the middle belt is mainly along the east, Xiwusu-Aiguo Village-Zhanggaiying-Xijingzi Township. Fault breccia developed and folding deformation occurred at the nappe structure interface. Root zone could not be identified in the study, and the thrust nappe structure root zone may have been destroyed by later magmatic activity and tectonic movement.
Xuniwusu thrust nappe structure can be roughly divided into two stages: the first stage is dominated by large-scale horizontal movement, and the second stage is dominated by compression deformation. According to the distance between the front edge of Feilai peak and the rear edge of the structural window, the nappe distance is not less than 52 km, and the time of the formation of the strata involved in the thrust nappe structure and the rock mass at the intrusive tectonic interface is limited, and the time of the occurrence of the thrust nappe structure is approximately two years earlier. The end of the world.
The Xuniwusu fault in the study area is considered to be the traditional trough-platform boundary. However, this study suggests that the fault zone is a series of thrust faults formed by thrusting nappe structure. The fault dip angle is small and the influence depth is shallow. It is not the trough-platform boundary in the region. It is inferred that the true trough-platform boundary is about 10-20 km south of the fault.
Combining with the regional tectonic evolution background, it is suggested that the thrust nappe structure is related to the collision between the North China plate and the Siberian plate in the Middle Permian and the closure of the Paleo-Asian Ocean.
【學(xué)位授予單位】：吉林大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：P542

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