龙门山北段唐王寨多期逆冲推覆构造结构与运动学解析
发布时间：2018-08-29 18:55
【摘要】：唐王寨逆冲推覆构造位于青藏高原东缘NE向龙门山逆冲构造带北段,一直被认为是青藏高原东缘前陆逆冲隆升的重要标志。然而,唐王寨逆冲推覆构造中的主逆冲断层及上盘褶皱样式的特殊几何结构和多期构造运动学特征表明,这是一个多期逆冲构造叠加的结果。本文以唐王寨逆冲推覆构造为研究对象,对推覆体中多期构造面理、线理,以及相关断层和褶皱的几何结构与运动学进行了精细的构造解析,分析了不同期次构造与变形样式的叠加关系。通过分期配套和初步变形时代限定,理清了构造变形序列,重新确定了推覆构造的演化过程。1、唐王寨逆冲推覆构造自中生代以来经历了三期构造变形:D1期由北向南包括三个推覆体,成叠瓦状组合形态,普遍发育了向NE倾斜的间隔劈理和局部千枚理(S1),构造面理主要沿NW向的膝折部位或倾向NE的倒转褶皱(f1)轴面发育,大体沿NW-SE走向并呈向SW凸出的弧形逆冲断层(F1)及对应的擦痕线理(L1)表明推覆体总体向SW逆冲,推覆构造的扩展方式为前展式,变形时代大致为中三叠世末-晚三叠世中期(~235-210Ma),与印支末期华北华南的碰撞造山有关。D2期的变形现象仅存在于唐王寨推覆体和甘竹垭推覆体中,在S1基础上发育的顺层掩卧褶皱(f2)及其倾向SE的轴面劈理、S-C组构、拉伸线理(L2)、褶劈理(S2)等均指示了向SE的正向韧性剪切变形。该期变形是由于D1期造山运动之后的区域性伸展垮塌,变形时代可能在早侏罗世(197Ma-183Ma)。D3期由西向东包括三个推覆体,亦呈叠瓦状组合的形态,沿宽缓褶皱(f3)的轴面发育了NE-SW走向的间隔劈理(S3),呈NE-SW走向的逆冲断层(F3)和对应的擦痕(L3)以及局部地区的脆-韧性剪切带均指示了推覆体向SE逆冲的特征,扩展方式为前展式,自早侏罗世晚期开始到新生代发生了多阶段的逆冲隆升,推测与中生代松潘-甘孜的侧向挤压和扬子板块的顺时针旋转俯冲以及新生代的印藏碰撞有关。2、唐王寨逆冲推覆构造在NW-SE方向上发生了强烈的收缩,缩短率为60.3%,其中四清池推覆体的推移距离至少为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.
【学位授予单位】：中国地质大学(北京)
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P542
本文编号：2212101
[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.
【学位授予单位】：中国地质大学(北京)
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P542
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