青藏高原典型地区的地貌量化分析——兼对高原“夷平面”的讨论

尽管过去150年以来,人们对于喜马拉雅造山带有很长的一段研究历史,但是对其几何特征、运动方式、动力学演化仍然理解不深。这种情况的出现,主要是因为人们持续关注的是喜马拉雅造山带的二维构造空间特性,并将某些研究程度较高地区的地质关系向外推广到造山带其他地区。就地理、地层及构造划分而言,概念的混淆和误解在有关喜马拉雅的文章中也大量存在。为了阐明这些问题,并为那些有兴趣探究喜马拉雅造山带地质演化过程的人们提供一个新的平台,文中系统地综述了以前的基本观察。我的综述主要是强调沿走向变化的喜马拉雅地质格架在喜马拉雅剥露、变质和前陆沉积方面所起的作用。文章的主要目的是阐明占据造山带核部的大喜马拉雅结晶岩带(GHC)的侵位历史。因为喜马拉雅大部分地区是由主中央冲断层(MCT)和藏南拆离系(STD)之间的GHC所组成,所以在地图和剖面观察上确定这些一级喜马拉雅构造之间的关系是非常关键的。中喜马拉雅出露的平面模式表明,MCT具有断坪-断坡的逆断层的几何特征。南部的逆冲断坪携带了一个GHC的板片(Slab)叠置在小喜马拉雅层序之上(LHS),并形成了一个在MCT逆冲断层带之南延续100km的巨大上盘断弯褶皱。在西喜马拉雅造山带地区,东经约77°处,MCT呈现为横向逆冲断坡(Mandi倾向逆冲断坡)。在其西边,MCT将低级变质的特提斯喜马拉雅层序(THS)叠置到低级变质的小喜马拉雅之上;而在其东边,MCT将高级GHC叠置到低级LHS之上。这种沿走向变化的地层叠置和横穿MCT的变质等级表明,逆冲断层的断距向西减小,可能是由于地壳短缩总量沿着喜马拉雅造山带向西减小所致。在所有出露的地方,STD大致都沿着THS底部的同一地层面,呈现出一个长度>100km的上盘断坪。这种关系说明:STD可能沿着一个先期存在的岩石接触面,或者沿中部地壳近水平的脆性—韧性转换带而发生。虽然喜马拉雅造山带藏南拆离系的上盘都有THS发育,但是至今没有找到THS切断STD下盘的证据。这样使得估算STD的滑动距离非常困难。STD最南端地层或与MCT(即,Zanskar)相交,或者位于MCT前端1～2km的范围内(不丹),这两种可能都暗示MCT与STD在它们向南的上倾(up-dip)方向有可能结合。虽然这种几何特征在现有的模型中几乎被忽略,但对于整个喜马拉雅造山带的变形和剥露历史具有重要的指示作用。     

藏南错那拆离断层的活动时间限定及其构造意义

藏南拆离系(South Tibet Detachment System, STDS)是沿喜马拉雅造山带走向发育的一套伸展拆离系统，其形成过程与喜马拉雅造山带的隆升历史和演化过程密切相关，是研究印度-欧亚大陆碰撞造山过程中构造变形作用的重要对象。错那拆离断层(Cuona Detachment, CD)为STDS在错那地区的出露部分，其为一数千米宽的韧性剪切带，带内发育大量不同类型的淡色花岗岩，本文在野外大比例尺填图的基础上，在CD内识别出两期淡色花岗岩：早期同构造淡色花岗岩和晚期构造后淡色花岗岩，并分别对两期淡色花岗岩进行锆石LA MC-ICP-MS U-Pb分析测试。锆石U-Pb定年结果表明，CD在20Ma仍在持续活动，直到14.8～16.5Ma左右停止活动。同时结合前人研究结果，进一步探讨错那地区STDS演化过程以及其沿造山带走向上的差异性规律。沿着喜马拉雅造山带走向，不同地区的STDS的活动时间呈现出明显的差异性，本文认为STDS停止时间主要表现出由西构造结向东(如错那地区)逐渐变年轻的趋势。     

喜马拉雅西部雅鲁藏布江缝合带地壳尺度的构造叠置

陆陆碰撞过程是板块构造缺失的链条。印度板块与亚洲板块的碰撞造就了喜马拉雅造山带和青藏高原的主体。然而,人们对印度板块在大陆碰撞过程中的行为尚不了解。如大陆碰撞及其碰撞后的大陆俯冲是如何进行的、印度板块是俯冲在青藏高原之下还是回转至板块上部(喜马拉雅造山带内)以及两者比例如何,这些仍是亟待解决的问题。印度板块低角度沿喜马拉雅主逆冲断裂(MHT)俯冲在低喜马拉雅和高喜马拉雅之下已经被反射地震图像很好地揭示。然而,关于MHT如何向北延伸,前人的研究仅获得了分辨率较低的接收函数图像。因而,MHT和雅鲁藏布江缝合带之间印度板块的俯冲行为仍是一个谜。喜马拉雅造山楔增生机制,也就是印度地壳前缘的变形机制,反映出物质被临界锥形逆冲断层作用转移到板块上部,或是以韧性管道流的样式向南溢出。在本次研究中,我们给出在喜马拉雅造山带西部地区横过雅鲁藏布江缝合带的沿东经81.5°展布的高分辨率深地震反射剖面,精细揭示了地壳尺度结构构造。剖面显示,MHT以大约20°的倾斜角度延伸至大约60 km深度,接近埋深为70~75 km的Moho面。越过雅鲁藏布江缝合带运移到北面的印度地壳厚度已经不足15 km。深地震反射剖面还显示中地壳逆冲构造反射发育。我们认为,伴随着印度板块俯冲,地壳尺度的多重构造叠置作用使物质自MHT下部的板块向其上部板块转移,这一过程使印度地壳厚度减薄了,同时加厚了喜马拉雅地壳。     

西藏冈底斯带石炭纪—二叠纪岛弧造山作用：火山岩及地球化学证据

系统研究了西藏冈底斯带石炭纪—二叠纪火山岩的时空分布、岩相学、元素及Sr、Nd、Pb 同位素地球化学和构造环境、源区性质,并与喜马拉雅带二叠纪火山岩进行了对比研究。冈底斯带石炭纪—二叠纪火山岩近东西向集中分布在冈底斯构造带中北部地带,空间上从东至西火山活动的强度和规模渐次减小,时间上从早至晚火山活动的强度和规模总体由弱到强。冈底斯带石炭纪—二叠纪火山岩形成于活动大陆边缘的岛弧构造环境,从早到晚岛弧造山作用经历了初始岛弧→早期岛弧→成熟岛弧的发展演变过程,火山岩浆来源于富集型地幔部分熔融作用,原始岩浆在形成和演化的过程中有俯冲洋壳及随带的深海沉积物和再循环进人地慢的地壳物质组分的强烈混染,明显不同于受地壳物质组分强烈混染的喜马拉雅带二叠纪陆缘裂陷型火山岩。综合研究冈底斯带及其邻区近年来的最新调查与研究成果,从北向南拟建了石炭纪—二叠纪冈底斯岛弧→雅鲁藏布江弧后裂谷盆地→喜马拉雅陆缘裂陷盆地的弧盆系时空结构演化模式,探讨了冈瓦纳大陆北缘石炭纪—二叠纪活动大陆边缘的岛弧造山作用与青藏高原古特提斯演化的耦合关系及其动力学机制,讨论了冈底斯带松多乡榴辉岩的形成过程。     

西藏冈底斯带石炭纪—二叠纪岛弧造山作用：火山岩和地球化学证据

系统地研究了西藏冈底斯带石炭纪-二叠纪火山岩的时空分布,岩相学,元素及Sr、Nd、Pb同位素地球化学,以及构造环境、源区性质,并与喜马拉雅带二叠纪火山岩进行了对比研究.冈底斯带石炭纪-二叠纪火山岩近东西向集中分布在冈底斯构造带的中北部,空间上从东至西火山活动的强度和规模渐次减小,时间上从早至晚火山活动的强度和规模总体由弱到强.冈底斯带石炭纪-二叠纪火山岩形成于活动大陆边缘的岛弧构造环境,从早到晚岛弧造山作用经历了初始岛弧→早期岛弧→成熟岛弧的发展演变过程,火山岩浆来源于富集型地幔的部分熔融物质,原始岩浆在形成和演化的过程中有俯冲洋壳、随带的深海沉积物和再循环进入地慢的地壳物质组分的强烈混染,明显不同于受地壳物质组分强烈混染的喜马拉雅带二叠纪陆缘裂陷型火山岩.综合分析冈底斯带及其邻区近年来的最新调查与研究成果,从北向南拟建了石炭纪-二叠纪冈底斯岛弧→雅鲁藏布江弧后裂谷盆地→喜马拉雅陆缘裂陷盆地的弧盆系时空结构演化模式,探讨了冈瓦纳大陆北缘石炭纪-二叠纪活动大陆边缘的岛弧造山作用与青藏高原古特提斯演化的耦合关系及其动力学机制,讨论了冈底斯带松多乡榴辉岩的形成过程.     

藏南洛扎地区洛扎断裂构造特征及其地质意义

藏南洛扎地区洛扎断裂属于区域上定日—洛扎断裂的东段部分,是喜马拉雅造山带中一条重要的断裂,但其总体研究程度较低。运用地质填图和构造解析的方法研究了洛扎断裂的几何形态、运动表现和活动历史等,讨论其在喜马拉雅造山带构造格局形成中的意义。主要认识如下:(1)洛扎断裂现今主要表现为一条规模大的脆性-脆韧性断层,SWW—NEE走向,高角度倾向NNW。断层带内发育劈理带、断层泥、构造角砾岩等。运动性质主体表现为正断层。(2)洛扎断裂的南北两侧地块具有显著不同的变形特征,南侧为平缓的大型背斜-向斜构造,北侧为近NWW—SEE走向的倒转褶皱-断层构造。(3)洛扎断裂经历了多期活动,中生代正断活动,古近纪逆冲活动,中新世韧性伸展,中新世晚期逆冲活动以及上新世—第四纪正断活动。现今断层展示的更多是最后一期活动的形迹。(4)依据其规模大、多期活动性、两盘构造变形与沉积的系统差异性等肯定了其作为构造分区断层而存在。(5)洛扎断裂和藏南拆离断层(STD)在研究区均有出露,局部二者出露线近于重合,但洛扎断裂以高角度断面切割了平缓的STD。洛扎断裂是比STD具有更悠久地质历史的区域性断层,只是后者中新世以来的活动性更多受到关注。     

郯庐断裂带渤海湾北段早新生代逆冲推覆的生长褶皱证据

高分辨率的地震剖面显示辽河盆地西部凹陷深部存在一生长断层转折褶皱。本文对地震剖面的构造变形以及褶皱两翼的生长前、生长和生长后地层的变形几何关系进行详细构造解析;利用断层转折褶皱几何变形的计算机模拟技术分别对西部凹陷南段、北段的生长断层转折褶皱进行几何变形过程的模拟,提取构造特征并与实际地震反射剖面进行对比。研究结果表明,郯庐断裂带渤海湾北段分支断层台安 大洼断层在早新生代就存在逆冲推覆过程,构造活动主要发生在沙河街组三段下至馆陶组沉积前(E2s3下～N1g前),其逆冲推覆速率为 0.116 mm/a。     

断层相关褶皱的几何学模型及其应用

在前陆盆地逆冲带中发育两种主要的断层相关褶皱构造样式：断层转折褶皱和断层传播褶皱。利用断层相关褶皱的下伏断层和上覆褶皱之间的角度参数存在的函数关系,可以对自然构造横剖面的构造解释进行检验。由于在时间地震剖面下的构造图形由于产生变形而与实际的自然构造有一定的偏差,这会影响几何学模型检验的有效性,因此在应用的过程中需要进行校正。通过地震速度谱将时问地震剖面转化为深度地震剖面,然后利用几何学关系对断层相关褶皱的构造剖面进行了检验。     

塔里木盆地东部古生代中期伸展构造的发现及其地质意义

通过地震资料解释,首次在塔里木盆地东部发现了古生代中期的伸展构造。它们是一系列正断层,以及由这些正断层组合成的雁列状张扭性断层带。正断层走向近N-S;雁列状张扭性断层带分两组,走向分别是NE-SW和NW-SE,构成一个共轭体系,显示近E-W向的拉张作用。根据断层生长指数、断层断开的地层单元和断层断距变化的解析,这些伸展构造的形成时间是中志留世—中泥盆世。它们是原特提斯阿尔金早古生代碰撞造山带的碰撞后构造,是判定塔里木地块—柴达木地块碰撞造山作用结束时间的重要证据。     

东喜马拉雅缺口的地质与地貌成因

东喜马拉雅缺口位于西藏东南部米林地区,平均海拔高度只有4500m,远远低于喜马拉雅山其它地段。我们的研究揭示,它的形成是由一条规模很大的,称之为米林韧性正断层的活动造成的。断层带的宽度至少有20km,大体倾向西,主要由眼球状糜棱岩组成,岩石中的拉伸线理以及眼球旋转的方式表明位于其东西两侧的高喜马拉雅深变质岩系和特提斯喜马拉雅中浅变质岩系之间发生过大规模的拆离运动,导致了东喜马拉雅构造结的最高峰——南迦巴瓦(7756m)的早期抬升以及特提斯喜马拉雅的重力垮塌。该断裂的南西端和藏南拆离系(STDS)相交,因此,它很可能是藏南拆离系的东翼断裂,同样形成于中新世。拆离构造的发生表明喜马拉雅山在中新世发生南北向构造缩短的同时还伴随着近东西向的拉伸。米林断裂的北东端和派区断裂相接。后者在中新世呈左旋剪切,构成东喜马拉雅挤入构造的西边界。米林断裂和上述两个断裂的衔接关系表明该断裂是一个协调高喜马拉雅和特提斯喜马拉雅之间斜向拆离运动的转换断层。     

A brief account of the continuum from Karakoram and Himalayan ranges to foreland and ocean basins

Himalayan orogeny in relation to Global Tectonics is a hotly debated subject. Orogeny can result either from collision of continental plates or by an endogenic process of mantle upwelling along pre-existing fracture zones in the crust. This paper describes a new technique of frequency analysis of radiometric ages of crystalline rocks in the mountain ranges straddling the Indus-Tsangpo Suture Zone (ITSZ), the supposed line of collision between India and Asia, and shows that all the ranges from Karakoram to Lesser Himalaya across the ITSZ got uplifted simultaneously in a particular sequence. This contradicts the concept of suturing, places the ITSZ in the category of one of the intracrustal thrusts of the Himalayan orogenic system and establishes the family affinity between the Karakoram and the Himalaya. Analysis of stratigraphic and structural data points out that this family affinity is not confined to the ranges only but extends beyond into the foreland and oceanic basins as well. This paper also explains a number of apparent contradictions in terrain geomorphology, ophiolites in suture zones, thickness anomaly of Himalaya-derived sediments in eastern and western wings of terrestrial and oceanic basins to the south of the ranges, the status of Mid-oceanic Ridges in global tectonics, convergence aspect between Himalaya and India, nature of Foothills Fault and metamorphism of early Tertiary sediments in the Himalayan foreland basin.     

南海西部晚渐新世主要断裂活动特征及与红河断裂之关系

南海的形成演化是众多被动型边缘海中最复杂的,而南海西部的断裂带构造活动特征又是南海中最复杂的构造之一。本文针对前人提出的红河断裂带出莺歌海盆地后的东延、南延以及东南延问题,通过晚渐新世-早中新世琼东南盆地受到南北向挤压的区域应力场分析,认为这期的应力主要来自南海西部近南北向断裂带的右旋剪切活动,结合红河断裂带的构造运动特征,提出晚渐新世末南海西部发生断裂构造置换,红河断裂带17°30′N以南近SN走向部分被南海西缘断裂带所置换,并且构造活动特征与北部红河断裂带明显不同,南海西部晚渐新世前后两个时期不同的断裂构造活动特征反映了印度板块与欧亚板块碰撞造成的两种不同影响效应。     

GPS-derived deformation rates in northwestern Himalaya and Ladakh

Deformation rates derived from GPS measurements made at two continuously operating stations at Leh (34.1°N, 77.6°E) and Hanle (32.7°N, 78.9°E), and eight campaign sites in the trans-Himalayan Ladakh spanning 11 years (1997–2008), provide a clear picture of the kinematics of this region as well as the convergence rate across northwestern Himalaya. All the Ladakh sites move 32–34 mm/year NE in the ITRF2005 reference frame, and their relative velocities are 13–16 mm/year SW in the Indian reference frame and ~19 mm/year W with reference to the Lhasa IGS station in southeastern Tibet. The results indicate that there is no statistically significant deformation in the 200-km stretch between the continuous sites Leh and Hanle as well as between Leh and Nubra valley sites along the Karakoram fault, whereas the sites in and around the splayed Karakoram fault region indicate surface deformation of 2.5 mm/year. Campaign sites along the Karakoram fault zone indicate a fault parallel surface motion of 1.4–2.5 mm/year in the Tangste and western Panamik segment of the Karakoram fault, which quantifies the best possible GPS-derived dextral slip rate of 3 mm/year along this fault during this 11-year period. Baselines of Ladakh sites show convergence rates of 15–18 mm/year with respect to south India and 12–15 mm/year with respect to Delhi in north India and Almora in the Himalaya ~400 km north-northeast of Delhi. These constitute an arc normal convergence of 12–15 mm/year across the western Himalaya, which is consistent with arc normal convergence all along the Himalayan arc from west to east. Baseline extension rates of 14–16 mm/year between Lhasa and Ladakh sites are consistent with the east–west extension rate of Tibetan Plateau.     

济阳坳陷孤西负反转断层形成演化定量研究及其油气地质意义

以高精度三维地震资料和钻井资料为基础,对研究区断裂构造进行精细解释,确定孤西断层为"薄底型"的、且表现为北段缓而南段陡、并向西倾的负反转构造;通过回剥技术和平衡剖面等定量分析技术对垂直穿越孤西断层的典型地震剖面研究揭示,孤西断层在J3-K1时期断层性质发生改变,由逆断层反转变为正断层,且在印支、J3-K1和Ek-Es4时期剖面拉伸率分别为-4%,17.2%和18.5%;沿孤西断层走向方向不同位置计算其断层活动速率表明该断层整体经历了负反转运动。以上述分析为基础,论文从烃源岩、圈闭、储集岩和油气运移角度,探讨了孤西负反转断层在孤岛潜山油气成藏方面的重要意义。     

The geometry of the active strike-slip El Tigre Fault,Precordillera of San Juan,Central–Western Argentina: integrating resistivity surveys with structural and geomorphological data

The geometry and related geomorphological features of the right-lateral strike-slip El Tigre Fault, one of the main morphostructural discontinuities in the Central–Western Precordillera of Argentina, were investigated. Achievements of this survey include: recognition of structural and geometrical discontinuities along the fault trace, identification and classification of landforms associated with local transpressional and transtensional sectors, observation of significant changes in the fault strike and detection of right and left bends of different wavelength. In the Central Segment of the El Tigre Fault, 2D electrical resistivity tomography surveys were carried out across the fault zone. The resistivity imaging permitted to infer the orientation of the main fault surface, the presence of blind fault branches along the fault zone, tectonic tilting of the Quaternary sedimentary cover, subsurface structure of pressure ridges and depth to the water table. Based on this information, it is possible to characterize the El Tigre Fault also as an important hydro-geological barrier. Our survey shows that the main fault surface changes along different segments from a high-angle to a subvertical setting whilst the vertical-slip component is either reverse or normal, depending on the local transpressive or transtensive regime induced by major bends along the trace. These local variations are expressed as sections of a few kilometres in length with relatively homogeneous behaviour and frequently separated by oblique or transversal structures.     

Geometry and kinematics of the Mosha Fault, south central Alborz Range, Iran: An example of basement involved thrusting

Field investigation of the western part of the Mosha Fault in several structural sections in the south central Alborz Range showed that the fault has a high angle of dip to the north, and emplaces Precambrian to Cenozoic rocks over the Eocene Karaj Formation. Study of the kinematics of the Mosha Fault in this area, based on S–C fabric and microstructures, demonstrates that it is a deep-seated semi-ductile thrust. Strain analysis on rock samples from different sections across the Mosha Fault shows a flattening pattern of deformation in which the long axis of the strain ellipsoid is aligned in the fault shear sense. The Mosha Fault is associated with a large hanging-wall anticline, cored by Precambrian rocks, and series of footwall synclines, formed of late Tertiary rocks. This geometry, together with several low angle short-cut thrusts in the fault footwall, implies that the Mosha Fault is an inverted normal fault which has been reactivated since the late Tertiary. In the study area, the reverse fault mechanism was associated with the rapid uplift and igneous activity in the central Alborz Range during the late Tertiary, unlike in the eastern portion of the fault, where the fault kinematics was replaced by a strike-slip mechanism in the Late Miocene.     

MSS和TM遥感图像在修水地区找金中的应用

本文通过对MSS和TM图像的分析与研究,结合其它地质资料,指出修水地区的金成矿主要受高湖-蕉溪岭断裂和幽居-船滩断裂控制,二者是郯-庐断裂带西侧一支在本区的散开部分。高湖-蕉溪岭断裂既控岩又控盆。本区金矿床、矿田的定位模式为控金断裂与北东东向断裂相交,发育与岩浆活动有关的环状构造,并有金源层分布的地段。与该定位模式相似的地段有7处。模式地段的构造条件提供有利的成矿环境,如存在其它矿源层(体),也可形成相应的金属矿产。在模式地段应用TM图像对含矿构造及蚀变进行研究,可有效地为找矿服务。     

Evolution of the Himalaya

The compression and attendant deformation of a thick and vast sedimentary prism formed since Early Riphean times on the northern continental margin of the Indian craton gave rise to the Himalaya mountains as a result of convergence and collision of the Indian and Asian plates. The oceanic trench-sediments, tectonically implanted with sea-floor material and intimately associated with calc-al-kaline volcanics in the narrow Sindhu-Tsangpo belt extending from Kohistan through Dras, Leh, Darchen (Mansarovar) to Shigatse and beyond, represent the subduction-island arc complex which developed south of the dynamic southern margin of the Asian continent and was welded to the colliding Indian plate during the late Eocene to Oligocene period. This complex is fringed to the north by a wide zone of Andean-type granitic bodies. The evolution of the Himalayan orogen is closely connected with the development of the present-day Andaman-Nicobar-Indonesia island arc-subduction system in the southeast and the Makran Ranges-Oman Trench in the southwest.The evolution of the Himalaya was accomplished in four major phases of tectonic upheaval during the late Cretaceous to Palaeocene (Karakoram phase), late Eocene to Oligocene (Malla Johar phase), middle Miocene to Pontian (Sirmurian phase), and late Pliocene to middle Pleistocene (Siwalik phase). While the Karakoram phase marks the convergence of continents and the Malla Johar phase represents the collision and subduction, it was during the Sirmurian upheaval that the main tectonic features developed and the Himalaya acquired its distinctive structural complexion     

渤海海域辽中南洼压扭构造带成因演化及其控藏作用

在三维地震资料详细分析解释的基础上,利用水平相干切片和不同方向地震测线对辽中南洼压扭构造带的发育特征 进行了分析,进一步结合地层发育及应力场特征对压扭构造带的成因演化进行了研究,在此基础上探讨了其对油气成藏的 控制作用。结果表明：辽中南洼压扭构造带的形成演化受控于NNE向展布的辽中1号和中央走滑断裂,两条断裂主要表现 为伸展-走滑性质,平面上表现为弯曲的“S”形,且构成左阶排列。辽中南洼的古近纪早期的伸展沉降与后期走滑断裂派 生的挤压应力是压扭构造带形成演化的主要控制因素,古近纪孔店-沙三期辽中南洼伸展沉降,沙三末期的构造变革使得 压扭构造带开始形成,古近纪晚期（Ed） 辽中1号和中央走滑断裂表现为强烈的右旋走滑,两条断裂的左阶排列以及中央 走滑断裂的“S”形弯曲在压扭构造带派生出构造挤压应力。此后,古近纪末期东营运动以及新近纪末期渤海运动的构造挤 压对其进行了改造,压扭构造带下凹上凸,古近系东营组和新近系地层弯曲上拱。压扭构造带成藏条件优越,作为主要封 堵断层的中央走滑断裂“S”形外凸增压部位断裂带紧闭、封堵能力强,有利于形成大中型油气藏。