塔拉斯-费尔干纳断裂带南端构造转换及其新生代区域构造响应

塔拉斯费尔干纳断裂(TF)为中亚最大规模的断裂,其向南是否贯穿塔里木盆地西部研究较少,带来对其新生代运动性质的争论。研究表明,TF断裂在喀什凹陷以小规模的右旋走滑断裂逐渐消失,断层东盘以逆冲断层系的水平缩短变形,调节新生代右旋走滑位移,与巴楚隆起的阻挡作用相关。区域构造分析表明,随着帕米尔北缘逆冲断层系向北扩展,喀什凹陷中新生代沉积形成密集分布的线性褶皱和逆冲断层带。帕米尔高原向北仰冲触发TF不同区段在新生代差异性构造复活,发生大规模右旋位移及其南端构造转换(逆冲带隆升和前陆盆地发育)。新生代大断裂差异性复活及其构造调节,造成帕米尔构造节东西两侧不对称的构造样式。     

How Alpine or Himalayan are the Central Andes?

 Although non-collisional mountain belts, such as the Andes, and collisional mountain belts, such as the Alps and the Himalayas–Tibet, have been regarded as fundamentally different, the Central Andes share several features with the Himalayas–Tibet. The most important of these are extremely thickened (≥70 km) continental crustal roots supporting high plateaus and mountain fronts characterized by large basement thrusts. The main prerequisite for very thick crustal roots and extreme mountainous topography appears to be large-scale underthrusting of continental crust of normal thickness, irrespective of whether the crustal thrusts are antithetic with respect to subduction as in the Andes, or synthetic with respect to preceding subduction of oceanic lithosphere as in the Himalayas. In both cases sole thrusts near the base of the continental crust nucleated in thermally anomalous zones of the hinterland and then propagated across ramps into shallower detachments located within thick sedimentary or metasedimentary cover rocks. In contrast to the Central Andes and the Himalayas, the Alps are characterized by intracrustal detachment which allowed both the subduction of lower crust and a stacking of relatively thin upper crustal slivers, which make up a narrow mountain chain with a more subdued topography. Received: 10 August 1998 / Accepted: 1 March 1999     

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).     

Two Phases of Cenozoic Deformation in Northeastern Tibet: Thrusting Followed by Strike-Slip Faulting

TWO PHASES OF CENOZOIC DEFORMATION IN NORTHEASTERN TIBET: THRUSTING FOLLOWED BY STRIKE-SLIP FAULTING     

Spider impact structure,Kimberley Plateau,Western Australia: interpretations of formation mechanism and age based on integrated map-scale data

The centre of the 13?×?11 km Spider impact structure, Western Australia, displays an unusual system of eroded folds and imbricated thrusts surrounding a sandstone dome. As inferred from GIS-integrated remote sensing, geological and digital elevation data, the structural setting of the original crater was influenced by, and hence post-dates, the formation of the Mt Barnett Syncline, the east?–?west-oriented axis of which runs through the Spider structure. The syncline formed during the regional Yampi Orogeny (ca 900 Ma), thus constraining the maximum age of the impact event. The sandstone dome in the centre of Spider formed prior to the imbrication, as interpreted from the present setting that indicates a deflection of the southward moving material during the crater collapse. Two modes of formation are discussed in order to explain the south-directed shortening in the Spider impact structure: (i) impact into the bottom of a syncline-controlled palaeovalley leading to uplift of the central crater floor followed by gravity-driven asymmetric sliding preferentially from the northern crater wall and valley slope, respectively; and (ii) moderately oblique (～10?–?30°) impact from the north onto the axis of the syncline, producing a central uplift under the influence of downrange residual momentum and, thus, asymmetric deformation inside the uplift and farther downrange. Neither model alone explains all the observations, and only a combination of both may provide a satisfactory solution.     

短基线InSAR探测龙门山主断裂带两侧震后雨期的滑坡空间分布特征

为探测汶川震后龙门山主断裂带两侧滑坡灾害的空间分布特征,使用雨期前后的两幅超短基线PALSAR影像开展雷达干涉测量,提出三维空间因子SAR大气长波相位建模方法,利用雷达视线方向形变阈值扣除大气短波相位,联合地形坡度因子综合提取主断裂带两侧强降雨期的滑坡空间分布。计算结果表明,震后滑坡灾害基本沿映秀-北川主断裂带两侧呈条带状密集分布,其中90%滑坡分布于高程为（1000~3000）m区间,地形坡度因子则集中于(15~35)°范围,多数滑坡距离发震断层约为（3~15）km,70%滑坡分布于断层上盘区,上下盘滑坡数量和面积存在明显差异,表明震后滑坡受发震断层上盘逆冲运动特性的滞后效应较为显著。     

塔里木盆地西部巴楚断隆南界断裂带的主要特征 和构造演化

塔里木西部巴楚断隆的南界断裂带晚中生代开始形成,内部结构十分复杂。在逐条介绍各断裂特征的基础上综述了该断裂带的主要几何学和运动学特征。该断裂带经历了白垩纪、中新(—上新)世和更新(—全新)世3期重大的冲断,前者与巴楚断隆北界断裂的演化不同步,后两者则与北界断裂带同步发育。白垩纪、更新(—全新)世的向北冲断与西昆仑山前褶皱冲断系的向北扩展有关,中新(—上新)世的向南(西)冲断受南天山褶皱冲断系向南扩展的制约。这3期冲断都伴有剪切变换构造发育,尤其是白垩纪的北西向右行走滑断裂,在造就南界断裂带的分段性和复杂面貌中起了重要作用。     

淮南煤田罗园井田地质特征及勘查工程布置

淮南煤田罗园井田构造是以阜凤逆冲推覆断层为主要断层组成的逆冲推覆构造系统。针对推覆体内含煤地层急倾斜、倒转以及总体呈"L"形构造形态特征,在二维地震勘查手段效果不理想的情况下,根据构造发育特征选择以钻探为主,布置了垂直钻孔、定向斜孔、分叉孔,并结合测井、采样测试等手段,取得了良好的地质效果。     

Simulation of the Subsidence and Deposition Processes of the Foreland Basin in the Southwestern Margin of Ordos

Characteristics of deformation in the thrust belt and sequence stratigraphic framework in the foreland basin, structural features of the basin margin, and the episodic thrusting are studied in this paper by combining the eastern Qilian thrust belt and the Late Triassic foreland basin on the southwestern margin of Ordos. On this basis, a geological model and a mechanical model of coupling mechanism were established for the pair of thrust belt and foreland basin, and the subsidence and deposition process of the foreland basin were simulated on given parameters.     

下扬子地区古生代盆地的改造变形

包括苏北-南黄海地区在内的下扬子区海相古生界盆地,在中三叠世末以来的构造演化过程中,经历了3期不同性质构造作用的改造变形。(1)在中三叠世末-早、中侏罗世的印支运动期,发生了江南-雪峰基底拆离体由南东向北西方向(同时派生由南向北,由东向西方向)的逆冲推覆,以及后缘弹性松弛断陷构造作用的改造,使海相古生界盆地发生了第Ⅰ期的由强及弱、递进衰减的逆冲 褶皱变形。(2)在晚侏罗-早白垩世的燕山运动期,叠加了第Ⅱ期以郯庐断裂带为代表的NNE向大陆平移走滑构造的左行简单剪切,以及拉分断陷构造作用的改造变形。(3)在晚白垩世-古近纪的喜马拉雅运动期,下扬子区在由南向北的伸展拆离与多米诺式拉张断陷构造作用下,受到了第Ⅲ期的变形改造。这3期构造变形作用促使扬子板块海相油气的早期聚集、晚期热演化和再分配。文中将重点讨论下扬子区板内海相古生界盆地自中三叠世末以来所经历的3期不同性质构造作用的改造变形。