【摘要】：唐王寨逆沖推覆構(gòu)造位于青藏高原東緣NE向龍門山逆沖構(gòu)造帶北段,一直被認(rèn)為是青藏高原東緣前陸逆沖隆升的重要標(biāo)志。然而,唐王寨逆沖推覆構(gòu)造中的主逆沖斷層及上盤褶皺樣式的特殊幾何結(jié)構(gòu)和多期構(gòu)造運(yùn)動(dòng)學(xué)特征表明,這是一個(gè)多期逆沖構(gòu)造疊加的結(jié)果。本文以唐王寨逆沖推覆構(gòu)造為研究對(duì)象,對(duì)推覆體中多期構(gòu)造面理、線理,以及相關(guān)斷層和褶皺的幾何結(jié)構(gòu)與運(yùn)動(dòng)學(xué)進(jìn)行了精細(xì)的構(gòu)造解析,分析了不同期次構(gòu)造與變形樣式的疊加關(guān)系。通過分期配套和初步變形時(shí)代限定,理清了構(gòu)造變形序列,重新確定了推覆構(gòu)造的演化過程。1、唐王寨逆沖推覆構(gòu)造自中生代以來經(jīng)歷了三期構(gòu)造變形:D1期由北向南包括三個(gè)推覆體,成疊瓦狀組合形態(tài),普遍發(fā)育了向NE傾斜的間隔劈理和局部千枚理(S1),構(gòu)造面理主要沿NW向的膝折部位或傾向NE的倒轉(zhuǎn)褶皺(f1)軸面發(fā)育,大體沿NW-SE走向并呈向SW凸出的弧形逆沖斷層(F1)及對(duì)應(yīng)的擦痕線理(L1)表明推覆體總體向SW逆沖,推覆構(gòu)造的擴(kuò)展方式為前展式,變形時(shí)代大致為中三疊世末-晚三疊世中期(~235-210Ma),與印支末期華北華南的碰撞造山有關(guān)。D2期的變形現(xiàn)象僅存在于唐王寨推覆體和甘竹埡推覆體中,在S1基礎(chǔ)上發(fā)育的順層掩臥褶皺(f2)及其傾向SE的軸面劈理、S-C組構(gòu)、拉伸線理(L2)、褶劈理(S2)等均指示了向SE的正向韌性剪切變形。該期變形是由于D1期造山運(yùn)動(dòng)之后的區(qū)域性伸展垮塌,變形時(shí)代可能在早侏羅世(197Ma-183Ma)。D3期由西向東包括三個(gè)推覆體,亦呈疊瓦狀組合的形態(tài),沿寬緩褶皺(f3)的軸面發(fā)育了NE-SW走向的間隔劈理(S3),呈NE-SW走向的逆沖斷層(F3)和對(duì)應(yīng)的擦痕(L3)以及局部地區(qū)的脆-韌性剪切帶均指示了推覆體向SE逆沖的特征,擴(kuò)展方式為前展式,自早侏羅世晚期開始到新生代發(fā)生了多階段的逆沖隆升,推測(cè)與中生代松潘-甘孜的側(cè)向擠壓和揚(yáng)子板塊的順時(shí)針旋轉(zhuǎn)俯沖以及新生代的印藏碰撞有關(guān)。2、唐王寨逆沖推覆構(gòu)造在NW-SE方向上發(fā)生了強(qiáng)烈的收縮,縮短率為60.3%,其中四清池推覆體的推移距離至少為21.6km。
[Abstract]:The Tangwangzhai thrust nappe structure is located in the northern section of the Longmenshan thrust belt in the eastern margin of the Qinghai-Xizang Plateau, and has been regarded as an important symbol of the Foreland thrust uplift in the eastern margin of the Qinghai-Xizang Plateau. However, the special geometric structure and multi-stage tectonic kinematics of the main thrust fault and the upper plate fold pattern in the thrust nappe structure of Wangzhai in the Tang Dynasty indicate that this is the result of the superposition of a multi-stage thrust structure. Taking the thrust and nappe structure of the Tangwangzhai thrust as the object of study, this paper makes a detailed structural analysis of the multi-stage tectonic plane, alignment, and the geometric structure and kinematics of the related faults and folds in the nappe. The superposition relationship between different times structure and deformation style is analyzed. By stages matching and preliminary deformation times, the tectonic deformation sequence is sorted out. The evolution process of nappe structure has been redefined. The thrusting nappe structure of Tangwangzhai has undergone three stages of tectonic deformation since Mesozoic, including three nappe bodies from north to south, and imbricate assemblage. The interval cleavage and local Qianmili (S1) inclined to NE are generally developed, and the tectonic plane is mainly developed along the knee fold in the direction of NW or the inverted fold (F1) axial plane which inclines to NE. The arc thrust fault (F1) and the corresponding trace lineage (L1) along the NW-SE strike and protruding toward SW indicate that the nappe thrust toward SW in general and the extension of the nappe structure is forward expansion. The deformation epoch is approximately from the end of the Middle Triassic to the middle of the late Triassic (235-210Ma). The deformation phenomenon of the D 2 period related to the collision orogeny in South China during the late Indosinian period exists only in the Tangwangzhai nappe and the Ganzhuya nappe. The horizontal fold (f _ 2) developed on the basis of S1 and the axial cleavage S-C fabric of SE, tensile line (L _ 2), fold cleavage (S _ 2) all indicate the forward ductile shear deformation of SE. The deformation is due to the regional extensional collapse after the D1 orogenic movement. The deformation age may include three nappe from west to east in the early Jurassic (197Ma-183Ma) .D3, and also show the shape of imbricate assemblage. Along the axial plane of wide and slow fold (f3), NE-SW strike spacer cleavage (S3), NE-SW strike thrust fault (F3) and corresponding scratch (L3), as well as brittle ductile shear zone in local area, all indicate the characteristics of SE thrust towards the nappe, and the expansion mode is forward expansion. From the late early Jurassic to the Cenozoic, multiple stages of thrusting uplift occurred. It is inferred that it is related to the lateral compression of Songpan-Ganzi in the Mesozoic, the clockwise rotational subduction of the Yangtze plate and the Sea-Tibet collision of the Cenozoic. The Tangwangzhai thrust nappe structure shrank strongly in the direction of NW-SE. The shortening rate was 60.3, in which the distance of the nappe of Siqingchi was at least 21.6km.
【學(xué)位授予單位】：中國地質(zhì)大學(xué)(北京)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類號(hào)】：P542

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本文編號(hào)：2212101