韦州-石沟驿拆离滑脱构造的确定及地质意义

以地震反射特征为依据，结合区域地质特征，确定了鄂尔多斯地块西部南北向基底拆离形成的韦州-石沟驿拆离滑脱构造。它在地震剖面上表现为：滑脱面以上有多层平行反射，不出现逆冲推覆前缘带复杂变形造成的杂乱反射；在平面上拆离滑脱构造与周边构造有明显的不协调性；它是在晚侏罗世地块西部大规模的东西向逆冲推覆所造成的南高北低的构造背景下，因重力作用沿T9界面附近的煤系地层由南至北拆离滑脱形成的，在东、西、北均以断层与周边相接，为一外来岩席构成的复武向斜，构造变形相对简单。在鄂尔多斯地块西部构造强烈变形区，因重力作用导致从南至北的拆离滑脱，形成了构造变形相对简单并且完整的石沟驿复向斜覆盖在原地岩席之上，这对该区构造演化史研究及油气勘探部署具有重要意义。     

复合陆内山前冲断构造转换类型及其成因

复合陆内山前厚皮构造向薄皮构造的转换类型决定了中国中西部地区山前复杂冲断结构的形成和发育，任何单一构造模式均不能完全概括和解释构造转换及其结构差异形成的机制。通过深-浅层结构联合对比分析，依据构造位移向前传递扩展的形式及其产生的地质结构特征，将山前厚皮向薄皮构造的转换划分为过渡Ⅰ带、过渡Ⅱ带、过渡Ⅰ+Ⅱ带、无过渡带4类。过渡Ⅰ带、过渡Ⅱ带、过渡Ⅰ+Ⅱ带型通过基底面拆离滑脱实现厚皮向薄皮构造的转换，并视深层次滑脱层与边界条件形成叠瓦逆冲、三角带、双重构造等不同结构样式；无过渡带型主要以大型逆掩断层实现两者之间的突变式转换，无明显的基底面拆离滑脱，形成以大型推覆构造为主的结构样式。构造转换及其冲断结构差异的形成主要源自"镶嵌式"复合大陆因不同的深部地质结构与边界条件在板缘俯冲、碰撞作用力下产生多种形式的构造响应。过渡Ⅱ带、过渡Ⅰ+Ⅱ带型山前冲断构造形成遵循"壳内俯冲与反向拆离冲断"构造模式，无过渡带、过渡Ⅰ带型则分别符合"壳内双向俯冲与均衡隆升冲断"和"多层次基底拆离滑脱冲断"构造模式。      

西昆仑北缘冲断带和田段的构造特征

通过对和田一带西昆仑北缘前陆冲断系地表地质构造和地震反射剖面的分析表明,和田前陆冲断系沿走向方向构造形态变化很大。在杜瓦河以东,冲断带的前锋主要发育向北的次级逆冲断层,后者向上消失于断层传播褶皱之中,地表出露的几排背斜就是这些褶皱向上传播的结果;杜瓦河以西,冲断带的前锋主要表现为向南的反冲断层,与整体向北逆冲的铁克里克北缘逆冲断裂构成一个三角带构造。滑脱面深度差异是造成东西方向不同构造形态的主要原因,西段主要沿中寒武统底面滑脱,东段主要沿下第三系底面(或二叠系顶面) 滑脱。     

褶皱—冲断体系双层滑脱构造变形物理模拟实验

褶皱冲断带是造山带—前陆盆地系统的重要组成部分,滑脱层在其形成和发展过程中起了显著作用。应用物理模拟实验方法,在模型中设置2套滑脱层,并改变其厚度和位置,研究了褶皱冲断带的几何学和运动学特征。实验结果表明,在双滑脱层褶皱冲断带中,主要形成自底部滑脱层向上传播的正向逆冲断层,断层以前展式发展,岩层在上部滑脱层以上弯曲形成断层相关褶皱。当2个滑脱层距离相近时,作为一个整体对断层起控制作用,形成的正向逆冲断层数目少,有利于反向逆冲断层形成;与2个滑脱层距离较远时,下部滑脱层对逆冲断层起主要控制作用,形成较多的正向逆冲断层和较少的反向逆冲断层。      

闽西南地区推覆构造特征

闽西南地区推覆(滑脱)构造广泛发育,可划分为5种类型:发育于上古生界—中生界下三叠统溪口组中的拆离(滑脱)构造;形成于印支期的拆离(滑脱)构造,后受燕山早期及后期的褶皱作用形成褶皱拆离构造;印支期及燕山早期的中深层次逆冲推覆构造;燕山早期和晚期的浅层次逆冲推覆构造;分布于燕山早期浅层次逆冲推覆构造原地岩系之中的浅层次褶皱逆冲推覆构造,其中燕山早期中深层次逆冲推覆构造规模最大。      

焦石坝地区中、古生界构造特征及其页岩气地质意义

通过二维、三维地震剖面解释和运用平衡剖面技术观点,对焦石坝地区基底结构、中、古生界构造特征及其构造演化进行了研究。研究结果表明,该区存在着基底卷入和盖层滑脱2种构造类型。基底卷入型有背冲背斜、对冲向斜、叠瓦逆冲、正花状扭动和多字形扭动5种构造样式。盖层滑脱型有断展或断弯、断滑、叠瓦逆冲、叠瓦反冲、冲断楔5种构造样式和组合。燕山早、中期是该区的2个主要构造变形期,在燕山早期,中、古生界与基底及其内幕之间近水平向西拆离滑脱推覆,形成了侏罗山隔挡式背-向斜交替褶皱。方斗山断裂与大天池背斜之间的焦石坝地区为挤压宽缓复向斜背景;在燕山中期,受东邻隔槽带中、深层基底拆离向西强烈冲断作用,焦石坝地区形成了仰冲-逆冲-掩冲构造格局,经历基底叠瓦冲断-盖层滑脱-左行压扭3个变形幕,形成了焦石坝双层背冲背斜及翼部的断褶带。石门断褶带具有多层滑脱褶皱特征,乌江断褶带具有滑脱与左行压扭的性质。构造变形性质与类型、龙马溪组-五峰组滑脱程度、层滑作用产生的构造缝是该区形成大型页岩气田重要的构造影响因素。     

塔里木盆地巴楚隆起吐木休克断裂带构造特征及形成演化

巴楚隆起是塔里木盆地重要的含油气构造单元,因其断裂构造特征与演化异常复杂,严重制约了对该区构造特征及演化的认识和油气勘探工作。基于地震剖面的精细地质解释,并结合塔里木盆地巴楚隆起构造演化背景及最新的钻井资料,利用断层相关褶皱理论,识别出吐木休克断裂带3段不同的冲断—褶皱构造样式。西段由一条单一的倾向巴楚隆起的基底卷入型高角度逆冲断层构成。中段除发育南西倾向的主冲断层外,还发育由巴楚隆起向阿瓦提凹陷方向的盖层滑脱构造。同时,断裂上盘褶皱核部发育第四纪正断层。东段为典型基底卷入型楔状冲断构造,冲断构造前锋位于中寒武统膏盐层,上寒武统以上发育低角度的盲冲断层为特征,主冲断层位移量为倾向阿瓦提凹陷的反冲断层吸收。根据地震剖面解释结果及构造演化恢复,认为由基底卷入型主冲断层和盖层滑脱型反冲断层及其相关褶皱构成的深部挤压冲断构造体系,定型于新近纪末。中段挤压隆起顶部中和面附近发育的小型张拱性正断层,形成于第四纪早中期。     

库车再生前陆逆冲带的构造特征与成因

库车再生前陆逆冲带自北而南分为以下５个构造速：①北部边缘冲断－隐伏构造楔;②斯的克背斜带;③北部线性背斜带;④拜城背驮凹陷;⑤丘里塔格前缘带。全体形成前锋向南的冲断变形楔。各构造带中发育多种型式的断坪／断坡台阶状逆断层相关褶皱：断层传播褶皱滑脱褶皱、断层传播－滑脱混生褶皱、双重逆冲构造。在不同构造带发不同时代的生长地层,批示了各构造带不的构造变形年代。斯的克背斜带变形时期最早,始于中新世带的亚肯变     

下扬子北缘前陆盆地构造变形样式

下扬子北缘前陆盆地经历了印支、燕山、喜山等多期构造改造,构造环境经开裂扩张—碰撞拼合—拉伸断陷等多次转换,最终形成了上部拉伸、中部逆冲推覆、下部拆离滑脱的"三层楼阁"式分层构造变形组合的构造几何学模式.其构造变形主要受中三叠世扬子地块与华北地块的陆—陆碰撞造山作用控制,具有横向上强弱分带、垂向上形变分层的特征.可划分为伸展变形、冲断褶皱变形、拆离滑脱变形等3种构造变形样式.      

阿尔伯达山脚地区东倾俯冲断层下的石油与天然气

在阿尔伯达地区,科迪勒拉造山带前陆边缘的大部分地区是以一系列东倾俯冲断层为标志的,这些俯冲断层上覆于人们更为熟识的西倾山脚叠瓦逆冲断裂构造。13000km~2的山脚地区,包括很多主要的油气田在内,都封闭于俯冲断层带之下,这个俯冲断层带是曾经覆盖着科迪勒拉东部更广大地区的一个硕部滑脱带经剥蚀后的残迹。沿顶部滑脱带的两边相对出露的东倾和西倾地层并排延伸便形成了一个长达数百千米、被称之为“前缘褶皱”或“三角带”的伪背斜。“三角带”的地下地质看起来很混乱,其实它可以看成是由叠覆的逆掩冲断席的系统排列而成。这些逆掩冲断席由于阶梯断裂而被褶皱并与顶部滑脱带合并,项部滑脱带本身又由于其下的构造增厚而被褶皱。 众所周知,落基山山脚地带和前缘山岭的西倾叠瓦逆冲断层是以一底部断层或称底部滑脱断层为根的。“三角带”的几何形态证明还存在一顶部滑脱带。顸部和底部滑脱带在阿尔伯达向斜的轴部合并,从而标志了山脚地区构造形变的东部边界。其他逆掩冲断带的前陆边缘的横剖面也表明俯冲边缘是普遍的,而且“三角带”几何形态和地质原理可以解释一些普遍的构造异常。     

THE CONFIGURATION OF THE BASEMENT BENEATH THE ZAGROS BASIN

It has long been recognised that the deposition and deformation of the Phanerozoic cover in the Zagros Basin (mountains plus foreland) was strongly influenced by the reactivation of old tectonic fabrics in its basement. Facies boundaries and structures trending north-south and NW-SE can be attributed to the reactivation of Pan-African sutures and Najd faults which are exposed in the Nubian-Arabian Shield. However, to the east of a projection of the Oman line SWwards into the Rhub Al Khali Basin, cover structures have a NE-SW trend which is not seen in Arabia. This boundary may overlie a Pan-African suture between Arabia and India (Somalia or Pakistan).
Data including magnetic intensities, geothermal gradients and isopach maps are used here to distinguish old faults which were reactivated in the basement from more recent faults formed in the cover by Zagros shortening. Old faults trending NW-SE are interpreted as having reactivated episodically since the Permo-Triassic opening of Neo-Tethys; perhaps more significantly, the basement faults that reactivated in the East Arabian Block since then trend north-south. The basement configuration is clarified by extending a modified East Arabian Block across the Zagros to an "East Arabian-Zagros block" in which the NW trend of the Zagros lies between two syntaxes. This suggests a new tectonic framework for the region. The repeated reactivation of basement faults throughout the East Arabian-Zagros Block controlled source rocks, traps and seals for the supergiant and giant oil and gas reserves which are present at various stratigraphic levels in different areas.     

走滑构造变形量估算方法探讨

走滑构造属基底卷入型构造，由基底走滑断层控制沉积盖层的变形，且走滑断层的位移量与盖层的变形量间有定量关系。岩石在地壳浅部的永久变形以破裂变形为主，其变形量在一定层位可测量，可据此求得其底走滑断层的移量，即走滑构造的走滑量，并进一步求得沉积盖层中各层位于移断层的位移量。     

THE FORMATION AND DISTRIBUTION OF MESOZOIC-CENOZOIC SEDIMENTARY BASINS IN CHINA

Numerous intraplate, fault-bounded basins have been developed on the Chinese landmass as a result of interactions between the Pacific, Asian and Indian Plates since Mesozoic-Cenozoic times. In Eastern China, continental-rift basins were formed in a geodynamic regime during which the continental crust was stretched and thinned, and moved slowly towards the Pacific Ocean. These rift basins may be distinguished from those in NE, Northern and Southern China, due to differences in basement configuration and evolution.
In Central China, cratonic subsidence depressions exist, with thin-skinned décollement tectonics, fold belts and minor fore-deeps. These include the Ordos, Sichuan and Chuxiong Basins, which can be differentiated according to their stage of development.
In Western China, crustal compression resulted in horizontal shortening and vertical thickening; thus, fore-deep and intermontane basins were developed, usually associated with basement thrust-faulting.     

THE SIGNIFICANCE OF STRIKE-SLIP FAULTING IN THE BASEMENT OF THE ZAGROS FOLD AND THRUST BELT

Lateral offsets in the pattern of seismicity along the Zagros fold and thrust belt indicate that transverse faults segmenting the Arabian basement are active deep‐seated strike‐slip faults. The dominant NW‐SE trending features of the belt have undergone repeated horizontal displacements along these transverse faults. These reactivated basement faults, which are inherited from the Pan‐African construction phase, controlled both deposition of the Phanerozoic cover before Tertiary‐Recent deformation of the Zagros and probably the entrapment of hydrocarbons on the NE margin of Arabia and in the Zagros area. We have used observations of faulting recognized on Landsat satellite images, in conjunction with the spatial distribution of earthquakes and their focal mechanism solutions, to infer a tectonic model for the Zagros basement. Deformation in the NW Zagros appears to be concentrated on basement thrusts and a few widely‐spaced north‐south trending strike‐slip faults which separate major structural segments. In the SE Zagros, two main structural domains can be distinguished. A domain of NNW‐trending right‐lateral faults in the northern part of the SE Zagros implies that fault‐bounded blocks are likely to have rotated anticlockwise about vertical axes relative to both Arabia and Central Iran. In contrast, the predominance of NNE‐trending left‐lateral faults in the southern part of the SE Zagros implies that fault‐bounded blocks may have rotated clockwise about vertical axes. We propose a tectonic model in which crustal blocks bounded by strike‐slip faults in a zone of simple shear rotate about vertical axes relative to both Arabia and Central Iran. The presence of domains of strike‐slip and thrust faulting in the Zagros basement suggest that some of the convergence between Arabia and Central Iran is accommodated by rotation and possible lateral movement of crust along the belt by strike‐slip faults, as well as by obvious crustal shortening and thickening along thrust faults.     

分形理论在剖面缩短量研究中的应用

总缩短量的确定对岩层变形的定量研究有着重要意义.复杂构造地区的层面在二维平面内可看作为一条曲线,从而可运用分形几何学的方法由分数维来定量描述.利用自相似分形和自仿射分形的概念,建立了计算缩短量的数学模型,以川东大池干构造的85-D362剖面为例,进行了缩短量和剖面应变计算,分形分析结果表明,T_0顶层曲面的分维值为1.0897,缩短量达11km,表现出47.844%的应变.要正确地平衡地质剖面,必须对小尺度范围的应变进行分析.     

THE EFFECT OF BASEMENT FAULTING ON DIAPIRISM

Experimental and natural examples illustrate the influence of sub-salt horizon basement faults on diapirism. In a series of experimental models, viscous diapirs were observed to form above or close to basement faults. In all the models, basement faults initiated a half-graben, where thicker overburden units enhanced differential loading on an underlying buoyant layer. The buoyant material flowed updip to the low-pressure zones in the uplifted block, and updip along the tilted upper boundary of the hanging-wall. Basement faulting extended the overburden, and provided the space through which the buoyant layer could rise. Subsidence and faulting of overburden layers allowed diapirism along the faulted zones. In all cases, the deformation in the overburden was accommodated within a wider zone of faulting than the discrete basement fault which initiated the deformation. Differential compaction enhances differential loading and accumulation of thicker overburden on the downthrown sides of basement faults.
Seismic profiles from the Danish Basin, Dutch Central Graben, Gulf of Mexico and North Sea show that diapirs are spatially associated with basement faults. However, model results show that diapirs triggered by basement faults are not necessarily located directly above the faults.
Basement faults extend the cover sequences. If detached from the cover by a ductile layer, thick-skinned extension is accompanied by thin-skinned extension and decoupling of the cover. The influence of basement faults on diapirs depends on: the thickness and effective viscosity of the ductile layer (e.g. rock salt); the thickness ratio between the buoyant layer and the overburden; the mechanical properties of the brittle cover in the case of clastic sediments; the rate of sedimentation; the displacement rate throw and the dip of the basement faults.     

关于碎屑岩层的去压实校正方法的讨论——兼讨论李绍虎等提出的压实校正法

碎屑岩层的去压实校正的主要问题是建立一个能正确反映岩层压实规律的孔隙度深度函数或密度深度函数。通常用单井或多井中实测的不同岩层在不同深度的孔隙度资料并不能真正代表某一特定岩层的压实曲线。利用单井或多井中观测到的同一岩层的孔隙度深度数据来建立该岩层的孔隙度深度函数,或许可以得到更加理想的去压实校正结果。由于岩层骨架密度与深度无关,同一岩层的孔隙度深度函数与密度深度函数呈线性互补相关,因此也可以利用少数几组可靠的观测数据解析出Athy孔隙度深度函数中的初始孔隙度值和压实系数。      

Using the aeromagnetic data for mapping the basement depth and contact locations,at southern part of Tihamah region,western Yemen

The present study aims to produce an excellent picture for the basement depth and contact locations, deduced from the available aeromagnetic data. The total intensity aeromagnetic map was first corrected by the application of the reduction to the magnetic pole (for low latitude areas) technique. On the other hand, this map shows different anomalies of varying frequencies and amplitudes that reveal various causative sources, as well as varying compositions and depths. So, the fast Fourier transform is applied on the RTP map to show the regional and residual sources and their depths, using the radial averaged power spectrum which divided into three segments, according to the slope,: the maximum depth is 12,500 m that probably reflect the crustal thickness at this place, depths of deep sources which reflect the maximum depth to the basement complex is found to be 10,388 m and the shallow sources and noise (near-surface geological structures), its depth will be 2410 m. This slope probably represents the minimum depth to the basement, especially at the eastern part of the study area (along the great escarpment). At the western part, the basement will be deeper than the eastern part. Different edge detection processes, for example, tilt angle derivative (TDR) and its total horizontal derivative (HD_TDR) as well as 3D-Euler deconvolution; can determine the edges of these sources. These techniques were carried out on the aeromagnetic data of Tihamah region (the study area). The estimated Euler solutions were plotted on the tilt angle derivative map. An excellent correlation was noticed between these techniques indicating that both of them can be attributed in delineating the general structural framework of the area. These techniques indicated that the southern part of Tihamah region was highly affected by Red Sea–Gulf of Aden rift system, that represent two legs of Afar Triple Junction. Moreover that, two depth methods were applied, analytic signal (AS) and source parameter imaging (SPI). They reflected similar results for estimating the basement depths. From both of them the depth ranges from 2050 to 10,885 m. On the other hand, all the methods used in this study gave a similar results to the depth of the basement rocks, ranging in depth between 2250and 10,400 m.     

渭河盆地基底三维变密度重力反演

渭河盆地前寒武系变质基底深度反演对于盆地古生界油气勘探具有重要意义,但目前对于基底深度认识不足。盆地内各沉积层密度随深度变化且横向上亦有差异,因此采用常密度模式的重力反演不能准确得到盆地基底深度。本文根据渭河盆地综合地球物理剖面解释结果,结合不同构造单元内各地层密度,在不同水平位置利用6种密度-深度函数拟合实际地层密度。不同函数拟合误差统计结果表明,指数变密度函数更符合渭河盆地沉积层密度变化规律。利用不同位置的指数变密度函数中地表密度差及密度随深度的变化系数进行插值,进而得到了全区的地表密度差及密度随深度变化因子,据此建立了渭河盆地及邻区三维密度模型,并利用该变密度模型反演了前寒武系结晶基底深度。与常密度模式重力反演结果对比表明,三维变密度反演结果更加准确,能为盆地油气勘探提供基础数据支撑,该方法亦可为解决类似地质-地球物理问题提供研究思路。     

东海陆架盆地海礁凸起南块基底性质研究

通过对东海陆架盆地海礁凸起重磁资料的处理,结合周边的地质情况及各种地球物理资料,对海礁凸起的基底深度和岩性进行了研究,在基底岩性推断的基础上,求取了中生界厚度和古生界厚度,为东海陆架盆地油气资源的进一步开发提供了依据。