渤海海域郯庐断裂带新生代活动方式与演化规律——以青东凹陷为例

青东凹陷东边界为郯庐断裂带在渤海海域内西支断裂所在,平面上由4条北北东向断裂呈左阶雁列式排列,剖面上以上盘下降为主,局部具有张扭性和压扭性花状构造现象。青东凹陷东界上的郯庐断裂新生代经历了古近纪右行平移正断层活动、古近纪末盆地挤压反转中的逆右行平移、新近纪的弱拉张活动和第四纪以来的逆右行平移4个演化阶段。古近纪断陷期,先存的郯庐断裂带由于具有较低的强度,在南北向伸展应力场作用下复活并表现为具有右行平移分量的斜向拉张活动,在浅部新生4条左阶雁列式断层,并与盆地内北西向基底断裂系统和东西向新生正断层共同控制了古近系的沉积格局。古近纪末发生了盆地反转,结束了断陷盆地发育阶段,在北东东-南西西向区域挤压应力作用下郯庐断裂表现为逆右行平移活动。新近纪坳陷阶段,盆地内构造活动较弱,主要受控于岩石圈热沉降作用,但郯庐断裂仍具有较弱的伸展活动。第四纪以来,郯庐断裂再次转变为逆右行平移活动。     

滇西北弥渡地区主要断裂晚新生代发育特征及其动力学机制

弥渡地区位于滇西北断陷带东南缘,红河断裂带尾端与程海断裂交汇部位,是揭示滇西北断陷带形成机制及其与红河断裂带间运动学关系的关键区域。综合利用遥感解译及野外调查发现,区内主要发育有北东向的毛栗坡断裂,北西—北北西向的凤仪-定西岭断裂、弥渡断裂、密祉断裂、寅街断裂。对断裂错动地质、地貌体及擦痕的统计分析结果表明,毛栗坡断裂第四纪以左旋走滑活动为主兼具有正断分量;弧形的弥渡断裂及北西向的寅街断裂第四纪期间均以正断活动为主;上新世期间凤仪-定西岭断裂以右旋走滑为主,密祉断裂主要为伸展正断,二者第四纪期间均无明显活动。据弥渡地区主要断裂的几何形态、运动学特征及红河断裂带晚新生代活动性变化过程推测,控制弥渡盆地展布的弥渡断裂、寅街断裂等主要第四纪活动断裂是在继承和改造红河断裂带原有断层行迹的基础上形成的。上新世或更早,弥渡地区及滇西北断陷带的断裂活动与地壳张扭变形可能与红河断裂带尾端伸展变形作用有关,但第四纪期间,程海断裂基本上完全控制了弥渡地区主要活动断裂的发育,这一时期区内张扭变形的动力可能来自于川滇内弧带的顺时针旋转以及周缘南汀河断裂、畹町断裂与理塘断裂等左旋走滑断裂引起的区域性走滑拉分的共同作用。      

遥感技术在断裂研究中的应用——以张家口—蓬莱断裂带为例

张家口一蓬莱断裂带是一条北西西向活动断裂带。本文选取ETM+光学影像和SRTM高程影像作为主要数据源,结合研究区已有地质资料研究发现该带断裂构造的北西西向线性特征明显。从水系分布和错断地形等地貌标志判断,该断裂具有左阶组合样式和左行走滑活动特征。据遥感影像综合特征,可将该带分为张家口段、延庆-怀来段和北京一天津段,影像特征分段性显著,并与断裂带的分段性一致。研究结果表明,张家口-蓬莱断裂具有左行走滑的运动学特征,限制或错断北北东或北东向断裂,并且控制该区域的左阶雁列式第四纪盆地群和第四纪冲洪积物的分布。该断裂带各段对不同规模的水系分布和形态影响比较大,且北京-天津地区的华北平原段断裂对第四纪冲洪积扇和沿海地区的贝壳堤的形态和分布有一定的控制作用。地球物理深部数据和野外地质考察资料也证实了遥感解泽的结果,证明遥感技术在探查断裂构造空间展布和活动性鉴定中有着广泛的应用前景。     

济阳坳陷东部长堤走滑断裂带构造特征及演化过程

济阳坳陷东部长堤断裂是一条特征明显的走滑断裂带,以T₂地震反射层（沙河街组二段底面反射层）为界,发育深层次和浅层次两套断裂系统。深层次断裂系统为长堤走滑断裂带的主体,发育R-P断层组合,剖面上呈丝带状构造样式,平面上呈发辫状构造样式;浅层次断裂系统由一组近南北向左阶羽状雁列带组成,雁列带中的每条断层为近南北向走滑断裂的T断层。Es₃-Es₂^下期,长堤走滑断裂带开始活动,发育深层次断裂系统,系由济阳坳陷和渤中坳陷之间的构造调节作用所造成;Es^上₂-Ed期,发育浅层次断裂系统,与长堤深层次断裂持续活动以及沉积盖层的逐渐增厚有关,同时,郯庐断裂带开始对研究区的构造格局产生影响;Ng-Nm期,研究区处在巨大的北东向走滑递进应变带中,长堤近南北向走滑断裂带让位于郯庐断裂带控制的北东向走滑体系。     

Unravelling the complexity of Apenninic extensional fault systems: A review of the 2009 L'Aquila earthquake (Central Apennines,Italy)

The 2009 L'Aquila sequence activated a normal fault system 50 km long in the Central Apennines, composed of two main NW-trending faults 12–16 km long: the main high angle L'Aquila segment and the Campotosto listric fault.The M_W 6.1 L'Aquila mainshock nucleated on the Paganica fault at a depth of ∼8.6 km and cut through the upper crust producing coseismic surface slip of up to 10 cm observed along a strike length of ∼13 km. Analysis of historical seismicity and data collected in paleo-seismological trenches suggest that this event filled a >500-year gap. In contrast, the blind Campotosto listric fault is composed of different fault segments displaying abrupt changes in dip at a depth where major events nucleate suggesting a rheological and geometrical control on stress concentration.A foreshock sequence that started around 4 months before the L'Aquila mainshock activated the deepest portion of the Paganica fault and marked the onset of large variations in elastic properties of the crustal volume. The variations have been modelled in terms of dilatancy and diffusion processes, corroborating the hypothesis that fluids play a key role in the nucleation process of extensional faults in the crust.     

Relationships between thrusts and normal faults in curved belts: New insight in the inversion tectonics of the Central-Northern Apennines (Italy)

The relationships between thrusts and normal faults represent primary constraints in the reconstruction of the modes and timing of pre-, syn- and post-orogenic deformation events in fold-and-thrust belts. Such relationships are well exposed in curved orogenic belts where the thrusts are oblique to the trend of normal faults.We study the NNE–SSW-trending Olevano-Antrodoco-Sibillini oblique thrust and its crosscutting relationships with NW–SE-trending normal faults in order to constrain the Neogene–Quaternary deformation history of the Central-Northern Apennine (Italy). The analysis of structural and geological data allowed us to reconstruct the geometric and kinematic constraints of two inversion events: 1 – During the Pliocene, positive inversion reactivated the NNE–SSW-trending pre-existing Ancona-Anzio normal fault as the Olevano-Antrodoco-Sibillini oblique thrust ramp and caused the shortcut of NW–SE-oriented normal faults; 2 – During the Quaternary, negative inversion reactivated NW–SE-trending pre-thrusting normal faults.The growth of the NW–SE Quaternary normal faults causes seismicity and is responsible of the development of wide Quaternary intramontane basins. Their distribution and the related seismicity have been controlled and compartmentalized by NNE–SSW-trending oblique thrusts. Thus, the crosscutting relationships between thrusts and normal faults are crucial in seismic hazard assessment.     

雁列构造是走滑断层存在的充分判据?--来自平面砂箱模拟实验的启示

多年来 ,雁列构造被作为走滑作用的结果、并得到物理模拟实验模型的支持 ,通常作为走滑断层的判据加以运用。本文根据针对黄骅盆地所设计的曲折边界基底均匀伸展模型和针对焉耆盆地所设计的基底均匀收缩斜向挤压模型的砂箱实验结果 ,给出了雁列构造另外的成因解释。认为雁列构造的成因并非局限于基底走滑作用 ,基底均匀变形条件下的斜向伸展或斜向挤压作用均可形成雁列构造 ,因此雁列构造不能作为走滑断层存在的充分判据。     

深圳北西向断裂分布特征及其活动性研究

深圳地区断裂以北东向五华-深圳断裂带和北西向珠江口断裂带多条次级断裂相互切错的断裂空间分布特征为主,同时多组东西向断裂穿插其间组成复杂的"棋盘格子状"断裂系统。北东向和北西向断裂是现今活动的发震构造,自有地震记录以来在深圳市及其周边发生的多起微震事件表明北西向和北东向断裂活动仍在持续,尤其是近百年来珠江口断裂带发生的多起中强震更是佐证了这一观点。针对深圳南山区及周边北西向断裂的第四纪活动性研究,从露头区实地断层追索、断层特征的考察以及已有钻孔和地球物理资料收集等方法入手分析总结了深圳地区北西向主要断裂的分布特征和活动性:深圳地区北西向断裂在空间上控制了珠江口断陷,区域上切割北东向断裂,空间分布连续性较差;北西向断裂最新活动于晚、中更新世,部分断裂表现为老断裂新活动,最新活动时间存在明显分段特征。全新世以来活动性明显减弱,部分次级断裂属于弱活动或不活动断裂。      

Neotectonics of the Eastern Margin of the Tibetan Plateau: New Geological Evidence for the Change from Early Pleistocene Transpression to Late Pleistocene-Holocene Strike-slip Faulting

We present in this paper some new evidence for the change during the Quaternary in kinematics of faults cutting the eastern margin of the Tibetan Plateau. It shows that significant shortening deformation occurred during the Early Pleistocene, evidenced by eastward thrusting of Mesozoic carbonates on the Pliocene lacustrine deposits along the Minjiang upstream fault zone and by development of the transpressional ridges of basement rocks along the Anninghe river valley. The Middle Pleistocene seems to be a relaxant stage with local development of the intra-mountain basins particularly prominent along the Minjiang Upstream and along the southern segment of the Anninghe River Valley. This relaxation may have been duo to a local collapse of the thickened crust attained during the late Neogene to early Pleistocene across this marginal zone. Fault kinematics has been changed since the late Pleistocene, and was predominated by reverse sinistral strike-slip along the Minshan Uplift, reverse dextral strike-slip on the Longmenshan fault zone and pure sinistral strike-slip on the Anninghe fault. This change in fault kinematics during the Quaternary allows a better understanding of the mechanism by which the marginal ranges of the plateau has been built through episodic activities.     

Active right-lateral strike-slip fault zone along the southern margin of the Japan Sea

We describe an active right-lateral strike-slip fault zone along the southern margin of the Japan Sea, named the Southern Japan Sea Fault Zone (SJSFZ). Onshore segments of the fault zone are delineated on the basis of aerial photograph interpretations and field observations of tectonic geomorphic features, whereas the offshore parts are interpreted from single-/multichannel seismic data combined with borehole information. In an effort to evaluate late Quaternary activity along the fault zone, four active segments separated by uplifting structures are identified in this study. The east–northeast-trending SJSFZ constitutes paired arc-parallel strike-slip faults together with the Median Tectonic Line (MTL), both of which have been activated by oblique subduction of the Philippine Sea plate during the Quaternary. They act as the boundaries of three neotectonic stress domains around the eastern margin of the Eurasian plate: the near-trench Outer zone and NW–SE compressive Inner zone of southwest Japan arc, and the southern Japan Sea deformed under E–W compression from south to north.     

Kinematic History and Changes in the Tectonic StressRegime during the Cenozoic along the Qinling andSouthern Tanlu Fault Zones

Since the mid-late Eocene, North China has been subjected to extensional stress, resulting in the formation and development of basins. The dynamic origin of this crustal extension has long been an issue of debate. This paper presents the results of kinematic analyses of faults obtained from two seperated areas in North China. In the Weihe graben situated on the southernmost margin of the Ordos block, analyses of fault kinematics were coupled with an analysis of the basin's subsidence history. Three successive extensional tectonic phases accompaning the basin's formation and development have been distinguished. The Palaeogene extension was oriented in a WNW-ESE direction; the Neogene extension in a NE-SW direction and the Pliocene-Quaternary extension in a NW-SE direction. Such changes have also been recorded by fault kinematics along the southern Tanlu fault zone. This has been demonstrated by three successive sets of fault striations indicating normal dip slip resulting from NW-SE extension, then left-     

渤海海域渤南地区新生代断裂体系与盆地演化

利用现今丰富的三维地震资料,将地震剖面解释与相干切片分析相结合,对渤海海域渤南地区断裂发育与盆地结构 进行研究,明确了断裂体系及构造演化特征。结果表明：新生代郯庐断裂渤南段可分为东、中、西三支,并与受郯庐走滑 断裂影响的近EW向、NW向和NE向主干断裂体系共同组成了渤南地区网格状的构造格局;而区域应力背景的改变导致渤 南地区走滑和伸展作用的强弱发生了变化,使得构造演化可划分为左旋走滑-强伸展、右旋走滑-强伸展和弱走滑-弱伸展 三个阶段,第一阶段孔店组~沙四段郯庐断裂东支强烈活动,中支和西支活动微弱,NW向和近EW向大断裂活动形成了黄 河口凹陷和莱州湾凹陷的盆地格局;第二阶段沙三段~东营组走滑断裂三支及其他方向主干断裂均活动,NE向和近EW向 次级断裂开始发育,各盆地持续性伸展断陷;第三阶段馆陶组-明化镇组右旋走滑减弱,郯庐断裂中支和西支发育呈一系 列NE向雁列断层,东支及其他方向主干断裂附近次级小断层继续增多,各盆地转为了整体的坳陷。     

Late Quaternary Activity of the Huashan Piedmont Fault and Associated Hazards in the Southeastern Weihe Graben, Central China

The Weihe Graben is not only an important Cenozoic fault basin in China but also a significant active seismic zone. The Huashan piedmont fault is an important active fault on the southeast side of the Weihe Graben and has been highly active since the Cenozoic. The well–known Great Huaxian County Earthquake of 1556 occurred on the Huashan piedmont fault. This earthquake, which claimed the lives of approximately 830000 people, is one of the few large earthquakes known to have occurred on a high–angle normal fault. The Huashan piedmont fault is a typical active normal fault that can be used to study tectonic activity and the associated hazards. In this study, the types and characteristics of late Quaternary deformation along this fault are discussed from geological investigations, historical research and comprehensive analysis. On the basis of its characteristics and activity, the fault can be divided into three sections, namely eastern, central and western. The eastern and western sections display normal slip. Intense deformation has occurred along the two sections during the Quaternary; however, no deformation has occurred during the Holocene. The central section has experienced significant high–angle normal fault activity during the Quaternary, including the Holocene. Holocene alluvial fans and loess cut by the fault have been identified at the mouths of many stream valleys of the Huashan Mountains along the central section of the Huashan piedmont fault zone. Of the three sections of the Huashan piedmont fault, the central section is the most active and was very active during the late Quaternary. The rate of normal dip–slip was 1.67–2.71±0.11 mm/a in the Holocene and 0.61±0.15 mm/a during the Mid–Late Pleistocene. As is typical of normal faults, the late Quaternary activity of the Huashan piedmont fault has produced a set of disasters, which include frequent earthquakes, collapses, landslides, mudslides and ground fissures. Ground fissures mainly occur on the hanging–wall of the Huashan piedmont fault, with landslides, collapses and mudslides occurring on the footwall.     

Structure of a normal seismogenic fault zone in carbonates: The Vado di Corno Fault,Campo Imperatore,Central Apennines (Italy)

The Vado di Corno Fault Zone (VCFZ) is an active extensional fault cutting through carbonates in the Italian Central Apennines. The fault zone was exhumed from ∼2 km depth and accommodated a normal throw of ∼2 km since Early-Pleistocene. In the studied area, the master fault of the VCFZ dips N210/54° and juxtaposes Quaternary colluvial deposits in the hangingwall with cataclastic dolostones in the footwall. Detailed mapping of the fault zone rocks within the ∼300 m thick footwall-block evidenced the presence of five main structural units (Low Strain Damage Zone, High Strain Damage Zone, Breccia Unit, Cataclastic Unit 1 and Cataclastic Unit 2). The Breccia Unit results from the Pleistocene extensional reactivation of a pre-existing Pliocene thrust. The Cataclastic Unit 1 forms a ∼40 m thick band lining the master fault and recording in-situ shattering due to the propagation of multiple seismic ruptures. Seismic faulting is suggested also by the occurrence of mirror-like slip surfaces, highly localized sheared calcite-bearing veins and fluidized cataclasites. The VCFZ architecture compares well with seismological studies of the L'Aquila 2009 seismic sequence (mainshock M_W 6.1), which imaged the reactivation of shallow-seated low-angle normal faults (Breccia Unit) cut by major high-angle normal faults (Cataclastic Units).     

Left-lateral active deformation along the Mosha–North Tehran fault system (Iran): Morphotectonics and paleoseismological investigations

The Mosha and North Tehran faults correspond to the nearest seismic sources for the northern part of the Tehran megacity. The present-day structural relationships and the kinematics of these two faults, especially at their junction in Lavasanat region, is still a matter of debate. In this paper, we present the results of a morphotectonic analysis (aerial photos and field investigations) within the central part of the Mosha and eastern part of the North Tehran faults between the Mosha valley and Tehran City. Our investigations show that, generally, the traces of activity do not follow the older traces corresponding to previous long-term dip–slip thrusting movements. The recent faulting mainly occurs on new traces trending E–W to ENE–WSW affecting Quaternary features (streams, ridges, risers, and young glacial markers) and cutting straight through the topography. Often defining en-echelon patterns (right- and left-stepping), these new traces correspond to steep faults with either north- or south-dipping directions, along which clear evidences for left-lateral strike–slip motion are found. At their junction zone, the two sinistral faults display a left-stepping en-echelon pattern defining a positive flower structure system clearly visible near Ira village. Further west, the left-lateral strike–slip motion is transferred along the ENE–WSW trending Niavaran fault and other faults. The cumulative offsets associated with this left-lateral deformation is small compared with the topography associated with the previous Late Tertiary thrusting motion, showing that it corresponds to a recent change of kinematics.     

青岛即墨温泉盆地第四纪以来活断层及其地质背景

根据野外地质观察和第四系的断错,在青岛即墨温泉盆地发现第四纪以来活断层。笔者在阐述了温泉盆地第四纪以来活断层的几何特征、构造特征的基础上,阐述了活断层产生的地质背景。用地震预测整体观的视角,认为盆地中第四纪以来活断层是与沧口—温泉活动断裂、温泉地热异常、地震异常、地球化学异常具有密切的成因联系。     

南海西缘断裂带走滑特征及其形成机理初步研究

南海西缘断裂带是南海西部最主要的构造要素,从北到南贯穿了该区主要的沉积盆地,具有走滑断裂的性质。由于不同地质时期走滑方向的不同,形成了不同的断层组合,主要表现为负花状构造和北东向、北西向两组雁列断层以及平面上双马尾状构造组合。主体断裂带以单条式为主,区段式活动特征明显。在南北盆地之间的构造转换带表现为负花状构造-犁式断裂-多米诺式反向调节正断层的组合。综合分析认为,南海西缘断裂是一组长期活动的断裂带,大规模走滑活动从中始新世至第四纪时期,主要为右旋走滑,应力以张扭作用为主;但是在中中新世末期,走滑方向曾经发生转变,为左旋走滑,转为压扭应力,造成区域隆升,导致地层被剥蚀,南海西部盆地现今沉积-构造格局基本形成。     

辽东湾坳陷东部地区新生代断裂体系与构造演化

断裂体系发育特征是辽东湾坳陷东部地区新生代构造演化的重要表现形式,运用丰富的三维地震资料,详细刻画了 研究区断裂体系平面和剖面特征。断裂体系特征分析表明: 研究区古新世-渐新世的断裂体系主要由NNE向的拉张正断层组 成;渐新世时期的断裂体系则表现出走滑断裂的性质,主干断裂附近出现走滑效应产生的增压区和释压区,同时发育似花 状构造和多级“y”字型构造,次级断裂多表现为雁列状的NEE向断裂;新近纪时期断裂体系仍以雁列状断裂为主,发育 共轭状剪切破裂以及“背形负花”状构造。断裂体系的研究明确了研究区新生代走滑构造系统与伸展构造系统的叠加改造 过程,结合研究区构造动力学背景,将辽东湾坳陷东部地区的构造演化阶段划分为古新世-始新世的弱走滑强拉张期、渐 新世的弱拉张强走滑期以及新近纪的弱挤压弱走滑期。     

中国中新生代盐盆地的构造控制

中国中新生代盐盆地分布于东部沿海的裂陷裂谷、滇西的撞击裂谷、西北的多旋回褶皱山脉的山前带以及中部的陆内裂谷和断块的一侧,四种不同构造环境中盐类矿床也各有特点.盐盆地构造控制影响了盆地的活动性和盐类物质的多源性,而这些情况在时间和空间上并不限于本文所讨论的范围。     

Evidence of positive tectonic inversion in the north-central sector of the Sicily Channel (Central Mediterranean)

In order to unravel the tectonic evolution of the north-central sector of the Sicily Channel (Central Mediterranean), a seismo-stratigraphic analysis of single- and multi-channel seismic reflection profiles has been carried out. This allowed to identify, between 20 and 50 km offshore the central-southern coast of Sicily, a ~80-km-long deformation belt, characterized by a set of WNW–ESE to NW–SE fault segments showing a poly-phasic activity. Within this belt, we observed: i) Miocene normal faults reactivated during Zanclean–Piacenzian time by dextral strike-slip motion, as a consequence of the Africa–Europe convergence; ii) releasing and restraining bend geometries forming well-developed pull-apart basins and compressive structures. In the central and western sectors of the belt, we identified local transpressional reactivations of Piacenzian time, attested by well-defined compressive features like push-up structures and fault-bend anticlines. The reconstruction of timing and style of tectonic deformation suggest a strike-slip reactivation of inherited normal faults and the local subsequent positive tectonic inversion, often documented along oblique thrust ramps. This pattern represents a key for an improved knowledge of the structural style of foreland fold-and-thrust belts propagating in a preexisting extensional domain. With regard to active tectonics and seismic hazards, recent GPS data and local seismicity events suggest that this deformation process could be still active and accomplished through deep-buried structures; moreover, several normal faults showing moderate displacements have been identified on top of the Madrepore Bank and Malta High, offsetting the Late Quaternary deposits. Finally, inside the northern part of the Gela Basin, multiple slope failures, originated during Pleistocene by the further advancing of the Gela Nappe, reveal tectonically induced potential instability processes.