四川盆地川中地区走滑断裂的分布、类型与成因

近期研究发现四川克拉通盆地内存在大型走滑断裂带,是断控油气藏勘探开发的有利新领域,走滑断裂的分布与成因对油气目标评价具有重要意义。本文在三维结合二维地震资料解释的基础上,分析走滑断裂的分布与成因类型,并探讨走滑断裂的形成机制。结果表明,川中三维地震工区发育北西向走向为主的大型板内走滑断裂系统;走滑断裂呈雁列、斜列的不连续的带状分布,断裂发育成熟度低,具有断裂样式的多样性与分层分布的差异性;四川盆地存在川中克拉通内走滑断层、川东南帚状走滑构造、川东调节走滑带、川东北楔入走滑带、川西北斜向冲断走滑带等5个地区发育5种类型走滑断裂带;走滑断裂形成于震旦系灯影组沉积晚期,受控于原特提斯洋俯冲背景下的斜向伸展作用,基底北西向先存断裂构造复活,形成了调节斜向伸展裂陷槽的川中板内走滑断裂系统。结果揭示克拉通盆地可能发育大型的板内走滑断裂系统,不同于常规的板缘与板内调节走滑断裂系统。     

The Dihedral Angle and Intersection Processes of a Conjugate Strike‐Slip Fault System in the Tarim Basin,NW China

Recent studies, focused on dihedral angles and intersection processes, have increased understandings of conjugate fault mechanisms. We present new 3-D seismic data and microstructural core analysis in a case study of a large conjugate strike-slip fault system from the intracratonic Tarim Basin, NW China. Within our study area, "X" type NE and NW trending faults occur within CambrianOrdovician carbonates. The dihedral angles of these conjugate faults have narrow ranges, 19° to 62° in the Cambrian and 26° to 51° in the Ordovician, and their modes are 42° and 44° respectively. These data are significantly different from the ～60° predicted by the Coulomb fracture criterion. It is concluded that:(1) The dihedral angles of the conjugate faults were not controlled by confining pressure, which was low and associated with shallow burial;(2) As dihedral angles were not controlled by pressure they can be used to determine the shortening direction during faulting;(3) Sequential slip may have played an important role in forming conjugate fault intersections;(4) The conjugate fault system of the Tarim basin initiated as rhombic joints; these subsequently developed into sequentially active "X" type conjugate faults; followed by preferential development of the NW-trending faults; then reactivation of the NE trending faults. This intact rhombic conjugate fault system presents new insights into mechanisms of dihedral angle development, with particular relevance to intracratonic basins.     

Deep Structural Framework and Genetic Analysis of Gold Concentration Areas in the Northwestern Jiaodong Peninsula, China: A New Understanding based on High-Resolution Reflective Seismic Survey

The gold concentration areas in the northwestern Jiaodong Peninsula constituted an important gold metallogenetic region in Eastern China during the Mesozoic. The deep geological bodies’ texture characteristic is important for exploring the resources thoroughly and understanding the metallogenic process. The detailed textures were revealed using high-resolution seismic profiles through the three major ore-controlling structures-Sanshandao fault zone, Jiaojia fault zone and Zhaoping fault zone. This study aims to establish a deep structural framework of this area. Based on their formation mechanism, the fault structures developed in the area can be divided into regional and local fault structures. The structural styles are characterised by superimposing their compressional, strike-slip and extensional multi-stage activities. The crust is cut by vertical structures corresponding to a left-lateral strike-slip fault system on the surface. Nearby these structures are the arc-shape structures formed by multi-stage magma intrusions into the upper crust. Bounded by the Tancheng–Lujiang and Muping–Jimo fault zones, the current Jiaodong block, developed a series of NE-trending strike-slip fault systems, was probably formed by the assemblage of several obliquely aligned blocks. The intensive magmatism and hydrothermal activity between the blocks induced large-scale mineralisation. It provides a new angle of view for understanding the cratonic destruction and large ore-concentration formed during the Mesozoic.     

辽东湾坳陷新生代构造改造作用及演化

利用大量的渤海油气勘探资料与成果对辽东湾坳陷构造演化特点综合分析,揭示出辽东湾坳陷新生代构造改造作用主要表现在:断裂作用、地层抬升剥蚀及褶皱作用,对辽东湾坳陷构造演化过程具有重要的影响。其西部地区现今构造特征主要受前期伸展断层控制,构造改造作用较弱;而东部地区构造改造作用强烈,辽东凸起是在后期构造改造作用下形成的,分隔现今的辽中凹陷与辽东凹陷。郯庐断裂带辽东湾段新生代早期活动特征不明显,始新世末-渐新世主要以伸展作用叠加右旋走滑作用为主;渐新世末-新近纪晚期以右旋走滑作用为主,断裂带活动不控制辽东湾东部地区的沉积。辽东湾坳陷新生代的演化整体可划分为断陷期(孔店组沉积期-沙河街组三段沉积期)、断坳改造期(沙河街组二段沉积期-东营组沉积期)、走滑改造期(馆陶组沉积期至今)3个演化阶段。现今辽东湾坳陷构造格局与沙河街组三段沉积前古构造格局的差异性,对该区海域油气勘探具有重要意义。     

塔里木盆地西部鸟山-古董山地区断裂构造分析

鸟山-古董山地区位于塔里木盆地西部, 巴楚隆起与麦盖提斜坡之间, 鸟山、玛南、玛扎塔格、古董山和罗斯塔格构造带在此交汇, 附近还发育与之密切相关的沙陇断裂, 十分引人注目。鸟山-古董山地区的主干断裂形成于晚白垩世, 包括鸟山、罗斯塔格和玛扎塔格晚白垩世冲断构造带和玛南晚白垩世走滑断裂带, 玛南断裂是玛扎塔格构造带与鸟山和罗斯塔格构造带之间的调节断层。该期构造变形受控于南羌塘和拉萨地块与亚洲大陆之间的碰撞造山作用。鸟山-古董山地区的断裂构造于中新世末基本定型。因帕米尔突刺楔入于塔里木和卡拉库姆之间, 在塔西南地区形成一系列走滑断裂, 包括玛扎塔格-罗斯塔格中新世末走滑断裂, 古董山断裂是其派生断层。晚白垩世是研究区构造和圈闭的关键形成期, 上新世晚期-全新世早期以古近系底部膏盐层为主滑脱面的滑脱-冲断构造保护早期形成的圈闭和油气藏。鸟山和玛扎塔格构造带是研究区最有利的油气勘探区带, 玛南构造带是重要的油气运移通道。     

New paleomagnetic evidences of paleogene tectonic rotation of the Qaidam Basin and adjacent region： mechanism and its tectonic implication

In order to better understand the tectonic evolution of the Qaidam Basin. The authors carried out a paleomagnetic study on 39 samples of 7 sites from Hongsanhan section, northwest Qaidam Basin. Stepwise thermo-demagnefizafion isolated a high-temperature component （HTC）, which passes the fold and reversal tests at 95 % confidence level. It suggests that the HTC should be primary. Unblocking temperature （about 685℃ ） and the experiment of isothermal remanence indicate that hematite is the mainly carrier of the remanence. A tilt-corrected mean direction is： Ds= 7.1°, Is= 38.5°, α95 = 7.4°. Corresponding to a palaeopole at, φ= 250. 1°E, λ= 72.0°N, A95 = 6.8°, Compared with the reference APWP of Eurasia, the sampling area occurred a non-significant rotation （3.4° ± 5.5°） relative to Eurasia since Eocene due to the affect of left-lateral Altyn fault, Based on the paleomagnetic results of early Cretaceous and Teritary within the Qaidam block, we can obtained the mean clockwise rotations from the samples deposited from 160 Ma to 45 Ma is 24.5° ± 9.0°, and from 38 Ma to present is - 0.5° ± 7.5° relative to present geomagnetism respectively. During the Mid Eocene （45 -38 Ma） rotation phase, there should existing an important early tectonic event in northern part of the present-day Tibetan Plateau, which probably represents one of large-scale strike-slip events of the Altyn strike-slip fault.     

Structural deformation and evolution of right-lateral strike-slip tectonics of the Liaohe western depression during the early Cenozoic

The Tan-Lu fault zone (TLFZ) traverses the Liaohe western depression (LHWD), affords an exceptional opportunity to reveal the structural deformation and evolution of a major strike-slip fault of the LHWD using three dimensional seismic data and well data. In this paper, based on structural interpretations of the 3-D seismic data of the LHWD, combined with depth slice and seismic coherency, a variety of structural features in relation to right-lateral strike-slip fault (the western branch of the Tan-Lu fault) have been revealed presence in the depression, such as thrust faults (Xinlongtai, Taian-Dawa, and Chenjia faults), structural wedges, positive flower structures, and en echelon normal faults. Fault cutoffs, growth strata and the Neogene unconformity developed in the LHWD verify that the activity of right-lateral strike-slip from the late Eocene to Neogene (ca. 43–23 Ma). The study indicates that the right-lateral strike-slip played an important role in controlling the structural deformation and evolution of the LHWD in the early Cenozoic. Moreover, the front structural wedge generated the gross morphology of the Xinlongtai anticline and developed the Lengdong faulted anticline during the late Eocene, and the back structural wedge refolded the Lengdong faulted anticline zone in the late Eocene to the early Oligocene. Wrench-related structures (the Chenjia thrust fault and the en echelon normal faults) were developed during the late Oligocene. Uniform subsidence in the Neogene to Quaternary. Furthermore, the driving force of the right-lateral strike-slip deformation was originated from N–S extension stress related to the opening of the Japan Sea and NE–SW compression, as the far-field effect of India–Eurasia convergence.     

滇西南地区汉母坝-澜沧断裂晚第四纪构造活动的地质地貌证据

通过对汗母坝-澜沧断裂晚第四纪地质、地貌实地调查与测量,并结合前人研究成果,讨论了该断裂晚第四纪最新构造活动特征。综合分析认为,汗母坝-澜沧断裂为一条以右旋走滑为主的全新世活动断裂,长约120 km,整体走向NNW。该断裂活动习性具有明显的分段特征,北段称为汗母坝断裂,是1988年耿马7.2级地震的发震断裂;南段称为澜沧断裂,是1988年澜沧7.6级地震的发震断裂之一。晚第四纪以来其新活动形成了丰富的断错地貌现象,如冲沟和山脊右旋位错、断层沟槽、断层垭口、断层陡坎、断陷凹坑等。根据断裂断错地貌特征的相应资料估计,该断裂晚第四纪右旋走滑速率约为(4.7±0.5) mm/a。     

走滑构造在地震剖面上的展布特征和研究方法 以准噶尔盆地西北缘车浅6井区断裂特征解析为例

走滑构造是一个普遍存在的构造形式,具有三维空间特征,研究走滑构造一直是一个难点。实际上,拉张构造和推覆构造中都可以存在走滑分量,而具有走滑分量的构造样式极具油气成藏的特性,因此研究构造是否具有走滑特征对寻找潜在油气藏具有广泛的现实意义。以准噶尔盆地西北缘车浅6井区三维地震资料为基础,通过总结对该区走滑构造在地震剖面上的展布特征和研究思路,试图找到一套研究走滑构造空间展布的通用方法。