复杂伸展盆地区平衡剖面的恢复方法

编制构造演化剖面可以对构造变形进行定量、半定量分析,对构造活动和演化研究具有重要意义。受伸展叠加走滑多期变形影响,复杂伸展盆地区断层、褶皱发育,为平衡剖面的恢复过程带来了一些困难和问题,影响了盆地演化分析的准确性。本文根据存在的问题,提出了一种利用Cdr（CorelDRAW）软件对复杂伸展盆地区变形进行恢复的新方法。该方法充分考虑变形、剥蚀和压实作用对恢复产生的影响,主要包括以下两个方面：1）地层恢复。如果浅部构造变形对深部影响不大,在恢复时采用层厚不变原则逐层进行回剥;若后期存在区域挤压作用,盆地整体发生构造反转形成褶皱,浅部每剥去一层,深部地层即相应消除该时期产生的应力叠加效应,此时需要对弯曲地层进行拉平处理。2）断层恢复。对生长断层而言,断层恢复就是消除上覆岩层产生的重力效应。对于深部早期生长断层而言,浅部地层对其只有压实作用而不影响其产状,此时应遵循深、浅部断层分开、独立恢复的原则。这种平衡剖面恢复的方法是基于地层及断层发育的构造部位、活动期次及其成因关系提出的,更加符合地质逻辑,能够更好地反演复杂伸展盆地区构造变形过程。运用该方法对渤海湾盆地济阳坳陷青西地区进行了平衡剖面反演,得出该区构造演化受控于伸展、构造反转和走滑影响。     

东海陆架盆地伸展率和压缩率及构造跃迁

东海陆架盆地位于欧亚板块的东南缘和西太平洋活动大陆边缘,本文选取了东海陆架盆地主要凹陷的17条地震剖面,采用平衡剖面技术,计算了主要凹陷新生代不同演化阶段的伸展率和压缩率。分析表明,东海陆架盆地构造演化总体由西向东跃迁。晚白垩世至晚古新世东海陆架盆地裂陷中心在西部坳陷带,始新世东迁至东部坳陷带,上新世东迁至东海陆架盆地东侧的冲绳海槽盆地。古新世中后期东海陆架盆地西部坳陷带北侧昆山凹陷反转; 中新世东部坳陷带的西湖凹陷反转。东海陆架盆地西部坳陷带与东部坳陷带构造演化不同,证明了东海陆架盆地的东西分带。西部坳陷带北部的长江坳陷和南部的台北坳陷构造演化不同,东部坳陷带北部的西湖凹陷和南部的钓北凹陷构造演化不同,证明了东海陆架盆地的南北分块.     

平衡剖面分析技术在松辽盆地构造演化恢复中的应用

平衡剖面分析技术是将计算机技术与新的地学思维方式相结合,对含油气盆地构造特征进行动态模拟,并快速、有效、合理地恢复盆地构造演化历史,它可为油气勘探提供可靠的依据.将平衡剖面分析技术应用于松辽盆地晚侏罗一下白垩统,使我们对其构造演化历史有了新认识.     

平衡剖面技术在龙门山中段构造解释中的应用

龙门山推覆冲断带地形条件恶劣,构造断裂复杂,阻碍了该区油气资源的勘探进程。为搞清龙门山推覆冲断带下的构造样式,验证其构造解释方案,应用平衡剖面技术,对龙门山中段具典型构造特征的地质、地震综合解释剖面进行平衡恢复。实例分析证明,平衡剖面技术可正确指导龙门山中段构造剧烈变形区的构造解释方案,并可定性、定量分析构造变形期次和变形程度,为下一步油气勘探提供可靠依据。     

伸展构造及其反转作用

伸展构造的演化主要发生在三个阶段：大陆裂谷阶段、大陆初始漂移和主要漂移阶段。伸展构造发育在不同构造层次：（１）在上地壳中，伸展构造呈现为位于拆离带之上脆性岩块的伸展，其周边为铲式断层、坡坪式断层或多米诺式断层所限；（２）在中地壳中，伸展构造呈现为变质透镜体，被不连续的韧性剪切带所分隔；（３）在下地壳中，伸展构造呈现为扩展变平的韧性流动和岩浆侵位。反转的伸展断层系常表现为冲断层、断弯背斜、生长断展褶皱、顶部塌陷地堑区的突隆构造和半地堑区的鱼叉构造等。     

下扬子区新生代伸展构造变形及其区域构造意义

下扬子区是中国东部重要的含油气盆地区之一,其新生代伸展构造变形一直是下扬子新生代构造动力学的核心问题.通过对下扬子海陆全区新生代断陷盆地结构与构造格局分析,明确了下扬子区伸展构造变形特征,探讨了变形成因机制及其区域构造意义.区域构造分析表明,下扬子区伸展变形构造由一系列NNE-NE-NEE走向的总体呈弧形展布的正断层构成,表现为受伸展断裂系统控制的断陷结构,具有多向伸展特征,自南向北可分为江南、沿江-苏北-南黄海和南黄海北部3个构造伸展区.有限元数值与构造物理模拟表明,受控于太平洋板块俯冲推挤传递至陆内的侧向构造作用力,下扬子块体南向蠕移,区域上近南北向伸展变形,郯庐断裂右旋走滑,两者共同构成一个"右旋侧向扩展变形"系统.在区域构造上,大兴安岭-太行山-武陵山重力梯度带以东的中国东部新生代伸展变形构造和盆地成因与古太平洋板缘边界条件密切相关.      

构造高差分析原理及其在地学研究中的应用

构造高差分析是构造解析及平衡剖面制作与恢复的基础.长期以来,构造高差并没有一个严格的定义,也缺乏原理性描述;构造高差分析也主要局限在构造地貌和地形高差的分析.本文在分析前人有关构造解析、地貌高差和构造高差研究的基础上,提出构造高程概念,将构造高差定义为构造高程之差,拓展了构造高差的内涵;并将构造高程定义为地质点所在构造...     

东营凹陷伸展断弯褶皱的构造几何学分析

东营凹陷是渤海湾盆地南部一个典型的中新生代半地堑盆地。本文通过对横穿东营凹陷的地震反射剖面进行精细的构造解析,发现这个半地堑盆地的伸展构造具有明显的膝折变形特征,基本上符合伸展断弯褶皱模型。由此运用伸展断弯褶皱理论,同时按照平衡剖面原理,详细恢复了东营凹陷伸展构造的发育过程。经过对盆地内部构造变形的反复拟合和测算,我们确定了东营凹陷伸展断弯褶皱的构造几何学特征及其运动学过程,揭示出东营凹陷各主要裂谷阶段的地壳水平伸展量,并且将其中的背斜解释为上凹与上凸断层转折组合所形成的一个伸展背斜构造。同时采用构造几何学方法推断在白垩纪末期该地区曾经历过大约1750m厚的剥蚀作用,总伸展量可达25km。     

川鄂湘边区褶皱构造样式及其成因机制分析

川鄂湘边区从西向东由隔槽式褶皱向隔档式褶皱的变化反映在深部构造样式上 ,其卷入的构造层次逐渐变深 ,至湘西带已由侏罗山式薄皮构造转为基底卷入式的厚皮构造 ,构造样式也更趋复杂 ;但由地表向下构造样式却普遍表现为由复杂向简单的变化。平衡剖面分析揭示了上述规律性。区域构造分析表明 ,上述构造是燕山期由南东向北西不断推进的挤压力作用的结果。     

Late Mesozoic rift evolution and crustal extension in the central Songliao Basin,northeastern China: constraints from cross-section restoration and implications for lithospheric thinning

The Songliao Basin, the largest oil-producing basin in China, was the centre of late Mesozoic rifting and lithospheric thinning in northeastern China. However, the rifts are still poorly revealed due to a thick cover of subsidence successions. By structural interpretation and sequential restoration of cross-sections based on new 2D seismic data and well data, this study presents the structural style, basin evolution, and horizontal crustal extension of the central Songliao Basin. We have developed a novel method to retrieve the regional extension principal strains. The results enable an assignment of rifting into two episodes. The earlier episode (ca. 157–130 Ma) was dominated by distributed faulting of numerous planar normal faults trending NNE–SSW, NNW–SSE, or near NS, probably reflecting pre-existing basement fabrics; in contrast, the later episode (ca. 130–102 Ma) was controlled by localized extension along several major listric faults. Horizontal crustal extension during rifting is estimated to have been 11–28 km (10.6%–25.5%), with the long-term average rate varying from 0.20 to 0.51 mm yr^–1. Regional horizontal strains show a gradual evolution from biaxial extension at the beginning of rifting to WNW–ESE uniaxial stretching during the later rifting episode. Brittle crustal extension is interpreted to have been associated with vertical strain due to tectonic stretching, which is estimated to have contributed more in thinning the lower crust than the mantle lithosphere. Accordingly, a two-episode dynamic model is proposed to explain rifting in the Songliao Basin. We suggest that the earlier event was dominated by delamination of the thickened continental lithosphere, whereas the later event was probably controlled by regional crustal detachment due to slab subduction and stagnancy of the Izanagi lithospheric plate.     

藏北羌塘盆地西部查桑地区结构及构造特征

通过对近年新获得的航磁、重力、大地电磁测深和地质等资料的综合研究揭示,羌塘西部隆起查桑段具有明显的南北分带、东西分块和垂向分层的结构、构造特征。该区总体由两(东部)、三(西部)个东西向展布的大型南倾构造块体推覆叠置而成,其间又被数条近南北向断裂分割为若干个断块。各块带出露地层时代、结构构造和地球物理场特征有较大差别。在查桑段及邻区,地壳中上部有两个低阻层,所在的深度分别为15±5km和约40km之下。壳内上部低阻层主要分布在查桑段及其以南,为各块体总体向北运动和逆掩叠覆之底部主拆离推覆面,该区各南倾大断裂均向下收敛并交会到该层。下部低阻层的展布超出了查桑段,向北已达北羌塘坳陷,其影响的范围可能更为广阔。此南北分带、多块叠置的结构和复杂多变的地球物理场特征,仅孤零零地出现在双湖—绒马之间,不具区域意义。其形成与该区东、西两侧中生代始存在的近南北向转换断层和晚古生代可能曾发育有裂谷之背景密切相关。该区段挤压变形和叠覆隆升,始于早白垩世羌塘盆地反转期;始新世以来,印度板块碰撞遂继续向北推挤,又得到进一步的发展、加强及改造。     

古地貌恢复方法及应用——以济阳坳陷桩西地区沙二段为例

济阳坳陷桩西地区沙二段埋深较大,应用残留厚度进行古地貌恢复存在较多问题。介绍了用压实法进行古地貌恢复的原理及方法。该方法分为视厚度校正、压实方程建立、单井压实厚度恢复、原始厚度图和古地貌图编制4个步骤。根据沙二段顶面构造图计算的真厚度校正系数最小可达0.83。压实结果表明压实率一般大于30%。结合视厚度校正、压实恢复结果和古水深,编制了沙二段基准面上升期和下降期的古地貌图,桩西地区沙二段古地貌中间高、东西两侧低。滩坝主要分布在孤北古隆起东西两侧,滩坝的发育明显受古隆起的控制。     

渤海湾盆地黄骅坳陷中北区新生代幕式沉降过程

黄骅坳陷中北区是位于渤海湾盆地中部的一个重要新生代构造单元.构造层序界面分析、同生断裂活动和盆地沉降史回剥分析表明该区经历了幕式沉降过程,沉降中心显示出规律性的迁移演化特征.馆陶组底界面为区域性裂后不整合界面,将研究区的演化划分为裂陷期和裂后期.在裂陷期的充填序列中,沙一段底界面为整个研究区都可以识别的显著的角度不整合界面,以此界面为界,盆地的裂陷期进一步划分为裂陷Ⅰ幕和裂陷Ⅱ幕.裂陷Ⅰ幕发育了Es₃-Es₂地层,断裂几何学和断裂的性质表明该幕构造活动为北西南东向伸展作用所致,而裂陷Ⅱ幕发育了Es₁-Ed地层,为近南北向拉伸作用的结果.裂后期,从早到晚则表现为由稳定热沉降到加速沉降的过程.分析认为上述盆地的幕式沉降过程与区域应力场的转变密切相关,受控于周缘板块的动力学事件,尤其是晚始新世之后,太平洋板块对欧亚大陆向西的加速俯冲,促使了郯庐断裂右旋活动向南延伸和穿过黄骅坳陷的兰聊断裂北段的活化,形成了位于渤海海域的南北向伸展叠加区,从根本上改变了黄骅坳陷中北区应力场的分布,由此导致了盆地同裂陷阶段的幕式演化.      

塔里木盆地熟化有机质成烃动力学模型原始参数的恢复及意义

针对塔里木盆地主力源岩层大多埋深较大、成熟度较高,对这些源岩所进行的模拟实验不能反映或描述样品在达到现今埋深这前所经历的成烃演化过程的难题,本文先由模拟实验数据出发,建立和标定各样品的化学动力模型,在此基础上,推导和建立了恢复化学动力的始参数的方法并利用塔里木盆地的样品进行了应用。结果表明,深埋样品有机质中有相当部分的低活化能组分已在其前期演化过程中被成烃反应所消耗。因此,要客观描述样品的全部成烃     

The Impact of the Linked Factors of Provenance, Tectonics and Climate on Potash Formation: An Example from the Potash Deposits of Lop Nur Depression in Tarim Basin, Xinjiang, Western China

Potash deposits commonly accumulate in highly restricted settings at the final stage of brine evaporation. This does not mean that potash deposits are formed simply as a result of the evaporation concentration of seawater or lake water, but rather as a coupling result of particular provenance, tectonics and climate activities. In this paper, we focus on the formative mechanism of the potash deposits of Lop Nur depression in Tarim Basin to interpret the detailed coupling mechanism among provenance, tectonics and climate. In terms of the provenance of Lop Nur Lake, the water of the Tarim River which displays “potassium-rich” characteristics play an important role. In addition, the Pliocene and Lower-Middle Pleistocene clastic beds surrounding Lop Nur Lake host a certain amount of soluble potassium and thus serves as “source beds” for potash formation. During the late Pliocene, the Lop Nur region has declined and evolved into a great lake from the previous piedmont and diluvial fan area. Since the mid Pleistocene, the great-united Lop Nur Lake has been separated and has generated a chain system consisting of Taitema Lake, Big Ear Lake and Luobei Lake which has turned into the deepest sag in Lop Nur Lake. Dry climate in Lop Nur region has increased since the Pliocene, and became extreme at the late Pleistocene. The study implies that potash formation in Lop Nur Lake depends on the optimal combination of extreme components of provenance, tectonics and climate during a shorter-term period. The optimal patterns of three factors are generally characterized by the long-term accumulation and preliminary enrichment of potassium, the occurrence of the deepest sub-depression and the appearance of an extremely arid climate in Lop Nur region. These factors have been interacting synergistically since the forming of the saline lake and in the later stages strong “vapor extraction” caused by extremely arid climate is needed to trigger large scale mineralization of potash deposits.     

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.     

断裂对断陷盆地火山岩天然气的成藏与控制作用——以松辽盆地徐家围子断陷为例

通过断裂发育及分布特征、火山岩中天然气分布规律和二者之间时空匹配关系研究得到,徐家围子断陷主要发育徐西早期走滑伸展断裂系统、徐中走滑长期活动断裂系统、徐东走滑断裂系统、早期伸展晚期张扭长期活动断裂系统以及晚期张扭断裂系统。断裂的主要活动时期为火石岭组至营三段沉积时期和泉头组沉积晚期至青山口组沉积时期。火山岩中天然气分布具有纵向分布层位多、深度范围大和平面上分布于生气凹陷内或附近,且沿断裂带分布的特征。断裂对火山岩天然气成藏与分布的控制作用表现在:火山岩天然气源岩的形成与分布,火山岩体和其内部裂缝形成与分布,火山岩天然气藏形成的层位及火山岩圈闭的形成与分布。     

The Earlier Spreading of South China Sea Basin due to the Late Mesozoic to Early Cenozoic Extension of South China Block： Structural Styles and Chronological Evidence from the Dulong-Song Chay Metamorphic Dome, Southwest China

INTRODUCTION Whatmechanismresultedinthespreadingof SouthChinaSeabasin(SCSB)?Wasitreallypro ducedbytheinteractionofperipheralplatesofthe SCSBorAilaoshan RedRiversinistralfault(Fig.1)? Figure1.AnoutlinetectonicmapofSouthChinablockandIndochinablock(modified…     

太古宙克拉通型下地壳剖面：华北怀安－丰镇－尚义的麻粒岩－角闪岩系

华北克拉通北缘晋冀内蒙交界地区有变质程度连续变化、从高压基性麻粒岩、麻粒岩到角闪岩相的变质岩系出露。它们的古变质压力由＞１．４ＧＰａ（５０ｋｍ）变化到０．５ＧＰａ（１５ｋｍ）；岩石类型从变辉长岩、中酸性正片麻岩到表壳岩变化；变质矿物组合由不含水的耐火组合变为富含云母和角闪石的组合；地球化学性质表现出从贫Ｓｉ和Ａｌ、轻度亏损生热元素到具有正常的化学成分的连续变化；包裹体流体性质在轻度亏损生热元素的麻粒岩中均为ＣＯ２流体，而在麻粒岩相的表壳岩和角闪岩系中Ｈ２Ｏ流体逐渐增加。上述变质岩系剖面的组成和特点符合大陆下地壳的定义，可能代表了包括最下部地壳在内的华北地块太古宙克拉通型大陆下地壳。据此本文建立了我国第一条克拉通型大陆下地壳剖面，并讨论其地质意义以及相关的问题