Differential Tectonic Deformation of the Longmen Mountain Thrust Belt,Western Sichuan Basin,China

Field investigation and seismic section explanation showed that the Longmen Mountain Thrust Belt has obvious differential deformation: zonation, segmentation and stratification. Zonation means that, from NW to NE, the Longmen Mountain Thrust Belt can be divided into the Songpan-Garzê Tectonic Belt, ductile deformation belt, base involved thrust belt, frontal fold-thrust belt, and foreland depression. Segmentation means that it can be divided into five segments from north to south: the northern segment, the Anxian Transfer Zone, the center segment, the Guanxian Transfer Zone and the southern segment. Stratification means that the detachment layers partition the structural styles in profile. The detachment layers in the Longmen Mountain Thrust Belt can be classified into three categories: the deep-level detachment layers, including the crust-mantle system detachment layer, intracrustal detachment layer, and Presinian system basal detachment layer; the middle-level detachment layers, including Cambrian-Ordovician detachment layer, Silurian detachment layer, etc.; and shallow-level detachment layers, including Upper Triassic Xujiahe Formation detachment layer and the Jurassic detachment layers. The multi-level detachment layers have a very important effect on the shaping and evolution of Longmen Mountain Thrust Belt.     

DEFORMATIONAL AND METAMORPHIC HISTORY OF THE CENTRAL LONGMEN MOUNTAINS, SICHUAN CHINA

DEFORMATIONAL AND METAMORPHIC HISTORY OF THE CENTRAL LONGMEN MOUNTAINS, SICHUAN CHINA1　ArneDC ,WorleyBA ,WilsonCJL ,etal.Differentialexhumationinresponsetoepisodicthrustingalongtheeasternmar ginoftheTibetanPlateau[J] .Tectonophysics,1997,2 80 :2 39～ 2 56 . 2　ChenSF ,WilsonCJL ,WorleyBA .TectonictransitionfromtheSongpan GarzeFoldBelttotheSichuanBasin,south westernChina[J] .BasinResearch ,1995,7:2 35～ 2 53. 3　ChenSF ,WilsonCJL .Emplaceme…     

川西龙门山冲断带构造油气藏类型及分布预测

野外地质考察和地震剖面解释表明川西龙门山冲断带具有复杂的构造地质特征,认为研究区发育类型众多的构造变形样式,主要有背冲断块、三角带构造、逆冲断层带和断块构造、断层相关褶皱构造以及双重构造等,不同类型的构造变形样式形成不同类型的构造油气藏。不同类型构造油气藏具有一定的分布规律,在平面上具有分带性,并与龙门山冲断带的主干断裂密切相关,如北川-映秀断裂与马角坝-通济场-双石断裂之间主要发育与断层相关的褶皱型油气藏;马角坝-通济场-双石断裂与广元-关口-大邑断裂之间主要发育三角带构造型油气藏以及一些断滑褶皱型油气藏,等等。在纵向上具有分层性,区域性滑脱层之上发育各种类型的构造油气藏,主要有背冲断块型油气藏、逆冲断裂带内的构造油气藏等,滑脱层之下发育双重构造型油气藏、断层相关及与背斜有关的构造油气藏。     

西昆仑山前冲断带的分段变形特征及控制因素

本文在精细地表构造地质学解析的基础上,利用塔里木油田公司在塔里木盆地西南缘完成的高分辨率地震资料、钻井资料,开展新生代构造变形的精细几何学解析,确定不同构造部位的变形几何学和运动学特征,分析不同构造部位构造变形特征的差异性及其变化规律,探讨构造变形分段性的控制因素。根据西昆仑山前冲断带的变形特征,可以将冲断带划分为5个构造段,自西北向东南分别为:乌泊尔段、苏盖特段、齐姆根段、柯东段与和田段,且各段又可分为1~4个的构造带。各段的构造样式存在较大差异,乌泊尔段表现为受主帕米尔断裂(MPT)和帕米尔北缘断裂(FPT)控制,帕米尔北缘断裂表现为地表突破和大规模的垂向位移,限定了冲断作用的往北传播,浅部发育了上新世以来的背驼盆地;苏盖特段表现为走滑逆冲作用导致的构造变形的特点,构造样式总体上靠近山前地区为堆垛构造,盆地内部为薄皮的叠瓦扇构造;齐姆根段受深部右行走滑断裂带控制,形成了向北东突出的走滑构造;柯东段则以逆冲作用为主,变形向盆地内部发生大规模的薄皮传播;和田构造段表现为南部发育高角度的铁克里克断裂及基底卷入构造,北部发育断层转折褶皱。北西向的喀什-叶城转换系统、北东向的库尔干右行压扭断裂带和齐姆根深部右行走滑断裂带、古近系的膏盐滑脱层、新近纪同构造沉积作用和乌拉根古隆起等对西昆山山前冲断带分段变形起到了重要的控制作用。     

雪峰山早中生代构造演化:构造学和年代学分析木

雪峰山主体地处湖南省境内,位于华南板块的中心区域,是一条典型的陆内造山带.通过详细的野外地质观察,我们将其分为3个构造单元:西部外区,主要以大型箱状褶皱为主;中部区,与西部区以主逆冲断层相分隔,劈理发育呈扇状,是雪峰山构造带的核心区域,也是变质级别最深、变形最强的区域;东部区,变形集中在脆韧性区域之上,以极性北西构造为...     

青藏高原东缘数字高程剖面及其对晚新生代河流 下切深度和下切速率的约束*

文章利用数字高程剖面将青藏高原东缘分为4个大尺度地貌单元,即青藏高原地貌区、龙门山高山地貌区、山前冲积平原区(成都盆地)和四川盆地东部隆起区。根据数字高程剖面中的最高海拔高程点剖面与最低海拔高程点剖面之间的高差,定量计算了该地区河流下切深度;结合成都盆地岷江最古老冲积扇沉积物提供的青藏高原东缘河流形成的时间(3.6MaB.P.),定量计算了河流下切速率为1.29mm/a;在约束局部侵蚀基准面和气候变化对河流下切速率控制作用的基础上,建立了青藏高原东缘河流下切速率与表面隆升速率之间的定量关系,结果表明河流下切速率约为表面隆升速率的4倍。基于龙门山在表面隆升速率和下切速率等方面均大于青藏高原内部,认为青藏高原东缘的边缘山脉是剥蚀隆升和构造隆升两者叠加的产物。     

Carbonate Platform Margin Slope Characteristics of Cambrian Chefu Age in Baojing-Fenghuang and Adjacent Areas, Western Hunan, China

The Cambrian paleogeography in south China can be divided into Yangtze platform, plat-form margin slope (including upper slope and lower slope) and basin. The carbonate gravity deposits are well developed there, particularly in the Yangtze platform adjacent areas. This paper mainly deals with declivity fan characters of the Chefu age in Fenghuang acUacent areas, western Hunan Province. Accord-ing to their distribution and thickness, three main declivity fans have been divided in the study areas,namely, Dama ( ∈ c-dsf), Machong ( ∈ c-msf) and Huangheymm ( ∈ c-hsf) declivity fans. Each fan‘s characters are described in detail in this paper. Based on their distribution range, scale and fossiliferous layers, two peak periods (fair developmental period) are distinguished: (1) Linguagnostus reconditus Zone (time), and (2) Glyptagnostus reticulatus Zone (time). They were characterized by huge thickl imestone breccia layers (single layer 3--4 in thick) and dosely spaced spread. Besides, there are also two develolmaental periods: (1) Lej op yge laevigata- Proagnostus bulbus Zone (time), and (2) Agnos-ms inexpeetans-Proceratopyge protracta Zone (time) to Erixanium Zone (time) to Corynexochus plumula-Sinoproceratopyge cf. kiangshanensis Zone (time), while Glyptagnostus stolidotus Zone (time) was an interstitial period (without or rare limestone breccias). All these features may verify the relative movement of the earth crust and paleodimate variety of the Chefu age in the study areas.     

Differential exhumation in response to episodic thrusting along the eastern margin of the Tibetan Plateau

Thermochronological data from the Songpan-Ganze˛Fold Belt and Longmen Mountains Thrust-Nappe Belt, on the eastern margin of the Tibetan Plateau in central China, reveal several phases of differential cooling across major listric thrust faults since Early Cretaceous times. Differential cooling, indicated by distinct breaks in age data across discrete compressional structures, was superimposed upon a regional cooling pattern following the Late Triassic Indosinian Orogeny. ⁴⁰Ar/³⁹Ar data from muscovite from the central and southern Longmen Mountains Thrust-Nappe Belt suggest a phase of differential cooling across the Wenchuan-Maouwen Shear Zone during the Early Cretaceous. The zircon fission track data also indicate differential cooling across a zone of brittle re-activation on the eastern margin of the Wenchuan-Maouwen Shear Zone during the mid-Tertiary, between 38 and 10 Ma. Apatite fission track data from the central and southern Longmen Mountains Thrust-Nappe Belt reveal differential cooling across the Yingxiu-Beichuan and Erwangmiao faults during the Miocene. Forward modelling of apatite fission track data from the northern Longmen Mountains Thrust-Nappe Belt suggests relatively slow regional cooling through the Mesozoic and early Tertiary, followed by accelerated cooling during the Miocene, beginning at ca. 20 Ma, to present day.

Regional cooling is attributed to erosion during exhumation of the evolving Longmen Mountains Thrust-Nappe Belt (LMTNB) following the Indosinian Orogeny. Differential cooling across the Wenchuan-Maouwen Shear Zone and the Yingxiu-Beichuan and Erwangmiao faults is attributed to exhumation of the hanging walls of active listric thrust faults. Thermochronological data from the Longmen Mountains Thrust-Nappe Belt reveal a greater amount of differential exhumation across thrust faults from north to south. This observation is in accord with the prevalence of Proterozoic and Sinian basement in the hanging walls of thrust faults in the central and southern Longmen Mountains. The two most recent phases of reactivation occurred following the initial collision of India with Eurasia, suggesting that lateral extrusion of crustal material in response to this collision was focused along discrete structures in the LMTNB.     

通南巴背斜几何学、运动学与构造模型

通南巴背斜发育于四川盆地东北米仓山冲断构造带和大巴山弧形冲断构造带的构造叠合部位, 其形成与演化受到米仓山与大巴山的联合影响, 然而目前其变形特征以及变形机制认识尚且不清楚, 精细研究通南巴背斜构造几何学、运动学对于揭示背斜成因机制以及认识陆内构造变形具有积极作用.本文以覆盖通南巴背斜的三维地震资料为基础, 运用断层相关褶皱理论和平衡复原等方法, 精细刻画出通南巴背斜几何学与运动学特征, 并建立构造模型, 探讨其成因机制.研究表明, 通南巴背斜总体具有"东西分段、上下分层、早晚期构造叠加"的特征, 具体表现为: 1)受控于三叠系嘉陵江组膏盐滑脱层、志留系泥岩局部滑脱层以及前震旦系滑脱层, 通南巴背斜分为上、中、下、深4套构造层, 表现为多层滑脱变形特征, 其中, 中部构造层变形强度最大; 2)深部(前震旦系)构造楔发育于整个通南巴背斜, 其个数和几何学形态的变化直接影响了上覆背斜形态以及分段性背斜高点差异; 3)位移沿楔端点向前传递过程中, 受到川中刚性基底的阻挡, 背斜前翼旋转, 形成次级褶皱调节断层; 4)通南巴背斜晚期受大巴山向西南推覆挤压的叠加作用, 表现为中部构造层在东北段发育一系列双重构造和叠瓦构造, 并导致嘉陵江组以上地层被动变形褶皱.     

南北构造带北部香山地区中-新生代构造抬升事件

南北构造带北部位于鄂尔多斯地块和阿拉善地块,秦祁褶皱造山带和兴蒙褶皱带四大构造单元的结合交汇部位,演化历史复杂。本文以南北构造带北部香山地区为研究对象,探讨该区中-新生代的隆升过程和阶段。对采自香山地区的9件样品分别进行了锆石、磷灰石裂变径迹测年及热历史模拟分析。香山地区的裂变径迹年龄主要分布在4个区间,对应地质时代分别为晚三叠世末-早侏罗世、晚侏罗世末-早白垩世初、晚白垩世和始新世,反映出香山地区在这4个时期内发生了明显的冷却事件。而这4期冷却抬升事件与区域构造背景及野外地质特征均有很好的响应关系。同时热历史模拟表明,香山地区晚白垩世以来整体上经历了2期快速隆升事件,其中始新世的快速隆升主要是该区对鄂尔多斯地块新生代周缘裂陷解体事件的响应。值得注意的是,香山地区并未反映出8Ma左右的快速隆升,说明青藏高原隆升对该区的影响是较为有限的。     

Geochemistry and Tectonic Setting of Mafic Igneous Units in the Neoproterozoic Katangan Basin, Central Africa: Implications for Rodinia Break-up

Geochemical compositions of mafic igneous rocks in the Katangan basin in Central Africa (Democratic Republic of Congo, hereafter Congo, and Zambia) provide the basis for the geodynamic interpretation of the evolution of this Neoproterozoic basin located between the Congo and Kalahari cratons. The Katangan basin is subdivided into five major tectonic units: the Katangan Aulacogen, the External Fold and Thrust Belt, the Domes Region, the Synclinorial Belt and the Katangan High. The metamorphosed mafic igneous rocks investigated occur in the Katangan Aulacogen, the External Fold and Thrust Belt and the Domes Region. The earliest magmatic activity produced continental tholeiites emplaced on Paleoproterozoic crust during the early stages of intraplate break-up. This continental tholeiite magmatism was followed by an association of alkaline and tholeiitic basalts emplaced in the Katangan continental rift and then by tholeiitic basalts with E-MORB affinity marking a young oceanic crust. These volcanic associations mark different stages of evolution from pre-rift continental break-up up to a continental rift similar to the East African rift system and then to a Red Sea type incipient oceanic rift. A similar evolution occurs in the Damaran basin in southwestern Africa, although no pre-rift continental tholeiites have been recorded in this segment of the Pan-African belt system.     

Deformation, Stratigraphy, Structures and Shortening of the Zagros Fold-Thrust Belt in Southwest Iran Analysis by Restoration

A structural cross-section constructed across the Zagros Fold-Thrust Belt covering the Abadan Plain, Dezful Embayment, and Izeh Zone applied 2D and 3D seismic data, well data, surface and subsurface geological maps, satellite images and field reconnaissance. Besides validation and modification of the cross-section, restoration allows better understanding of the geology, structural style and stratigraphy of the Zagros basin. In the area of interest, the Hormuz basal decollement and the Gachsaran detachment play the most significant roles in the structural style and deformation of the Zagros belt. More complexity is associated with interval decollements such as Triassic evaporites, Albian shales and Eocene marls. A variety of lithotectonic units and detachment surfaces confound any estimation of shortening, which generally decreases with increasing depth. Deformation completely differs in the Abadan Plain, Dezful Embayment and Izeh Zone because of different sedimentation histories and tectonic evolution; gentle and young structures can be interpreted as pre-collisional structures of the Dezful Embayment before the Late Cretaceous. After the Late Cretaceous, the Mountain Front Fault is the main control of sedimentation and deformation in the Zagros Basin, and this completely characterizes fold style and geometry within the Dezful Embayment and the Izeh Zone.     

中－新生代龙门山的差异隆升

通过对采自龙门山南段、中段和北段花岗岩与砂岩样品中的磷灰石、锆石的裂变径迹年龄的分析,发现中生代以来龙门山的隆升在走向上存在分段性,在近东西方向上存在分带性。从松潘－甘孜褶皱带→龙门山冲断带→川西前陆盆地：松潘－甘孜褶皱带整体发生区域隆升,裂变径迹年龄与高程呈正相关关系;在龙门山冲断带,裂变径迹年龄与高程呈负相关关系或无关,说明冲断层在隆升过程中起主导作用;在川西前陆盆地,样品随埋深发生部分或全部退火。茂县－汶川断裂两侧锆石裂变径迹年龄差异明显而磷灰石裂变径迹年龄无明显差异,显示茂县－汶川断裂以西地区在38～10 Ma发生过更为快速的隆升;北川断裂两侧磷灰石裂变径迹年龄差异明显,表明北川断裂以西地区在10～0 Ma发生过快速隆升。从走向上看,从龙门山北段向南段,锆石裂变径迹年龄呈逐渐增大的趋势,这可能意味着印支末期或燕山早期,龙门山北段发生了更快的隆升;而磷灰石裂变径迹年龄总体上从龙门山北段向中段和南段呈递减趋势,反映新生代期间龙门山中、南段隆升更快。     

龙门山中段山前带浅层冲断系统的结构、形成与演化

本文依据断层相关褶皱几何学原理,对龙门山中段地震剖面进行了精细解释。研究发现,龙门山中段山前带浅层冲断系统存在多套滑脱层,具有上下分层变形特征。浅层滑脱层为上三叠统须家河组三段(T_3~x3)的碳质页岩夹煤层,其上发育双重构造和叠瓦构造;下三叠统嘉陵江组四、五段(T_1j~(4-5))的膏岩层,发育断层传播褶皱、冲起构造和构造楔;深层为下寒武统的泥页岩层,发育断层转折褶皱和滑脱褶皱。该区滑脱断层所控制的地层变形和缩短量各不相同,其中三叠系上统缩短量最大,大于30 km;三叠系下统至古生界地层缩短量约为14.5 km;侏罗系以上的地层缩短量则较小。研究区内的通济场断裂(F_3)为印支末期形成的一套逆冲断层组,其下部交于下寒武统滑脱层,深度约为10 km;关口断层(F_4)和彭县断裂(F_5)为晚侏罗世一早白垩世形成的逆冲断层,下部交与下三叠统嘉陵江组滑脱层,深度大约为8～10 km。这些断层以前展的方式破裂,并且长期活动。龙门山中段自中生代以来存在多期构造事件,主要发生诺利末期、印支晚幕、燕山期和喜马拉雅期。其中,燕山期和喜马拉雅期是龙门山活动最强烈的两个阶段,在龙门山中段山前带表现为大量断裂的长期活动,地壳缩短和龙门山快速隆升,并形成多种构造样式。     

塔里木盆地库车坳陷中部构造变形样式及分布特征

库车坳陷是塔里木盆地北部一个次级构造单元,受晚新生代陆内造山作用控制,发育典型的挤压冲断构造; 同时,由于古近系和新近系盐层的存在,发育丰富的盐相关构造; 另外,冲断构造各段之间的调节作用还形成了一系列的走滑构造。本文利用最新的2D、3D 地震资料及钻井资料,分析总结了库车坳陷中部的变形样式及分布特征。研究结果表明: 1)根据变形的成因机制,将库车坳陷的构造变形划分为收缩构造、盐构造及走滑构造。2)收缩构造以逆冲断层及褶皱样式为主,盐上构造层可划分为断层相关褶皱和褶皱相关断层,其中断层多在盐层内滑脱。盐下构造层根据断层组合方式可划分为叠瓦状冲断构造、楔形冲断构造及滑脱冲断构造。盐构造可以划分为盐席、盐墙、盐楔入、盐刺穿及盐拱构造。走滑构造在剖面上可见花状构造及不协调变形,平面上则可见雁列褶皱、马尾断层及海豚效应。3)收缩构造及盐构造主要分布于克拉苏构造带及秋里塔格构造带内,自南天山至盆地中心,盐下构造层由叠瓦状冲断构造过渡至滑脱冲断构造,过渡带内则发育楔形冲断构造; 走滑构造集中于坳陷西部的阿瓦特-却勒构造段以及东部的克拉3-东秋8构造段。     

米仓山构造转换带特征及转换模式

米仓山构造带被北东走向的龙门山陆内复合造山带及北北西走向的大巴山前陆冲断带夹持于其间,两个构造带平面上组成一个“八”字形构造,空间上为一个向北收敛,向南发散背倾型的Ⅰ型三角带构造.在两大构造带前展式扩展变形晚期的过程中,米仓山则起到调节这两大构造带构造平衡的作用,因此为一构造转换带.米仓山构造转换带由北向南可以分为基底...     

龙门山大地电磁深部结构及汶川地震(MS 8.0)

2008年5月12日汶川发生的MS 8.0地震使四川、甘肃和陕西等省遭受重大人员伤亡及财产损失,本文通过震前完成的穿过龙门山构造带中段的松潘中江大地电磁测深剖面的反演解释,揭示了龙门山构造带及其两侧松潘甘孜褶皱带、川西前陆盆地地壳内部30 km深处电性结构。龙门山构造带东侧四川盆地为上部较厚低阻沉积盖层之下存在连续稳定高阻的扬子基底特征,而以西的松潘甘孜褶皱带分上部和下部两部分,上部为高阻古生界夹低阻中新生界,下部（中下地壳）呈连续低阻层,推测可能存在一个连续稳定的壳内高导层。而龙门山恰好是青藏高原与扬子地台联合作用的结果,形成了上部高阻及下部基底高阻,中间夹西倾低阻带,低阻带最厚10 km,其深度从地表10 km连续向西延伸至20 km深处,与松潘甘孜褶皱带15～20 km的低阻层相连。这个异常低阻带可能是松潘甘孜地块向东向上移动的传输带,北川映秀断层逆冲分量显然大于右行走滑分量,因此汶川地震属于右行平移-逆冲断裂型地震。     

A balanced cross section across the Himalayan foreland belt, the Punjab and Himachal foothills: A reinterpretation of structural styles and evolution

The Siwaliks in the foothills of the Himalayas, containing molasse sediments derived from the rising mountain front, represent a foreland fold-thrust belt which was deformed during the continued northward convergence of the Indian plate following the continent-continent collision. In this contribution we present balanced and restored cross sections along a line from Adampur through Jawalamukhi to Palampur in the foothills of the Punjab and Himachal Himalayas using published surface/subsurface data. The cross section incorporates all the rock units of the Sub-Himalaya Zone as well as that of the northern Lesser Himalaya Zone. The structural geometry of the fold-thrust belt in this section is largely controlled by three buried thrusts within the Sundernagar Formation of the Lesser Himalaya Zone. Two of these buried thrusts splay from the basal detachment and delineate a buried horse. Three thrusts towards foreland, including the Main Frontal Thrust (inferred to be a blind thrust in this sector), splay from these buried thrusts. In the hinterland, an anticlinal fault-bend fold was breached by a sequence of break-back thrusts, one of which is the Main Boundary Thrust. A foreland propagating thrust system is inadequate to explain the evolution of the fold-thrust-belt in this section. We show that a “synchronous thrusting” model in whichin-sequence initiation of thrusts at depth combined with continued motion on all the thrusts leading toout-of-sequence imbrication at the upper structural levels better explains the evolution of the fold-thrust belt in the Jawalamukhi section. The estimated shortening between the two chosen pin lines is about 36% (about 72 km).     

GEOLOGICAL EVOLUTION AND OROGENY OF EAST KUNLUN TERRAIN ON THE NORTHERN QINGHAI—TIBET PLATEAU

GEOLOGICAL EVOLUTION AND OROGENY OF EAST KUNLUN TERRAIN ON THE NORTHERN QINGHAI—TIBET PLATEAU1　XuZQ ,YangJS ,ZhangJX ,etal.AcomparisonbetweenthetectonicunitsonthesidesoftheAltunsinistralstrike slipfaultandthemechanismoflithosphericshearing[J] :ActaGeologicaSinica,1999,73:193～ 2 0 5(inChinesewithEnglishabstract) . 2　YangJS ,XuZQ ,LiHB ,Wu ,etal.DiscoveryofeclogiteatthenorthernmarginofQaidambasin,NWChina[J] .Chi neseScienceBulletin,1998,4 3…     

TECTONIC EVOLUTION OF THE YANGTZE PASSIVE MARGIN AND SONGPAN GARZ? FOLD BELT, CHINA

TECTONIC EVOLUTION OF THE YANGTZE PASSIVE MARGIN AND SONGPAN GARZ? FOLD BELT, CHINA