山东沂沭断裂显微构造及动力学分析

沂沭断裂是一条纵贯山东的深大断裂带。本文通过对该断裂带断裂构违岩显微变形研究,认为该断裂带在其发展演化过程中经历了塑性变形,塑脆性变形,脆性变形3个阶段。本文主要对其脆性变形阶段进行了研究,认为断裂带在该变形阶段至少经历了6次较为强烈的构造变动,进一步确定了造成这些变动的主压应力方位。     

山东沂沫断裂带成生时代探讨

郯庐断裂带成生时代，是当前研究郯庐断裂带的重大分歧点之一。虽众说不一，但基本上有两种观点，巨大平移说(1)否认其存在于中生代之前，认为它自侏罗纪以来，大致经历了巨大平移(达740公里之巨)、张裂(裂谷形成)、挤压(裂谷消亡)三个发展阶段，而垂直运动说(2)则认为该断裂成生于前震旦纪。两种截然相反的观点，都曾提出过不少的论据，这对提高人们对郯庐断裂带的认识，无疑是有益的。但就笔者对郯庐断裂带中段(山东地区的沂沭断裂带)所做的初步野外考察，认为前震旦纪成生观点，似有应再补充更多论据之必要，而中生代成生说在解释断裂两侧异地地质体相接方面，尚有许多难题。     

山东沂沭断裂带成生时代探讨

郯庐断裂带成生时代。是当前研究郯庐断裂带的重大分歧点之一。虽众说不一,但基本上有两种观点,巨大平移说否认其存在于中生代之前,认为它自侏罗纪以来,大致经历了巨大平移(达740公里之巨)、张裂(裂谷形成)、挤压(裂谷消亡)三个发展阶段;而垂直运动说则认为该断裂成生于前震旦纪。两种截然相反的观点,都曾提出过不少的论据,这对提高人们对郯庐断裂带的认识,无疑是有益的。但就笔者对郯庐断     

莱州湾地区郯庐断裂带的构造特征及其新生代演化

郯庐断裂带中段分东西两支从莱州湾进入渤海,在莱州湾地区的构造特征与演化历史一直鲜为人知。通过对横穿研究区的两条地震测线的解释和分析,揭示了该区郯庐断裂带中段在研究区的构造差异,研究表明郯庐断裂带东西两支在该研究区表现出不同的断裂性质,西支断裂表现为正断层,东支断裂表现为走滑断层。郯庐断裂是本研究区的主控断裂,通过对本地区地层形态及其组合、断层的剖面形态和空间展布规律的深入研究,揭示了郯庐断裂带在莱州湾地区新生代以来的构造演化历史:古新世—始新世的伸展阶段、渐新世—中新世早期的挤压和右行走滑阶段、中新世中晚期至今的稳定发展阶段,这几个不同时期的演化阶段主要受太平洋板块运动的方向和速度变化的控制。     

红河断裂带的新生代变形机制及莺歌海盆地的实验证据

红河断裂带是印藏碰撞过程中，印支地块被顺时针旋转挤出的走滑变形带。莺歌海盆地发育于红河断裂带海上延伸带上。根据莺歌海盆地和相邻的NE向琼东南盆地在晚中新世前(5．5Ma B．P．)独立的构造发育和差异的沉降特点，认为红河断裂不可能穿越莺琼盆地界限向北东延伸，而越东断裂和中建南断裂很可能是红河断裂的延续。莺歌海盆地成盆机制的物理模拟结合红河断裂带陆上的变形特征、年代学证据与青藏高原隆升过程的研究，参考莺歌海盆地模拟过程中不同应力场下沉降中心的长轴方向，我们推断红河断裂带新生代的演化大致分4个阶段：(1)50-38Ma B．P．期间的缓慢平移运动；(2)38—25MaB．P．期间的快速左行走滑运动；(3)25—5Ma B．P．期间的左行走滑逐渐停止阶段；(4)5Ma B．P．后的右行走滑阶段。     

渤海海域郯庐断裂带的地质构造特征

郯城-庐江断裂带纵贯我国东部,北起黑龙江省,南至安徽省并继续向南延伸,在我国境内长达三千余公里。本文主要讨论渤海海域中的一段,即北起辽宁营口,南至山东潍坊,长约五百公里。为了讨论的方便,我们将其称为营潍断裂带。该带完全被海水或第四纪地层复盖。对它的了解过去只是根据周边地质情况予以推断,自航磁工作开展以来,对此问题的认识有所深入,认为该断裂带自山东向北延入莱州湾属于深断裂性质,继续北延,虽仍为大断裂存在但由于无岩浆活动,而被认为属“干断裂”性质。随着海洋石油勘探事业的发展,近十几年来在渤海海域进行了重力、磁力、地震综合物探普查     

莺歌海盆地反转构造变形特征及其动力学演化

莺歌海盆地位于印支半岛与南海北部大陆边缘交接区,复杂的地质构造背景使其形成演化的动力学机制成为国内外研究的焦点。综合新的区域资料,对影响莺歌海盆地发育的区域构造演化特征进行了系统分析,认为新生代以来印度板块与欧亚板块的碰撞造成印支板块的逃逸构造,以及印支板块的顺时针旋转,红河断裂带新生代的变形机制,直接或间接地控制了莺歌海盆地的形成与演化。在此背景条件下,莺歌海盆地新生代以来的构造演化经历了3个阶段,即左旋走滑-伸展裂陷阶段、地壳韧性伸展-热沉降阶段和加速沉降阶段。     

莱州湾凹陷东部新生代走滑构造特征及油气勘探意义

莱州湾凹陷位于渤海南部海域,为中生界基底之上发育的新生代半地堑.郯庐断裂带分东西两支穿过莱州湾凹陷东部,在新生代盖层中表现出渤海最复杂最典型的为NNE向的右旋走滑断裂特征.其中东支断裂在渐新世以后活动强烈,发育多条NNE向走滑断层及NE向伴生断层组成的复杂断裂带.走滑断裂带内断层展布符合右旋单剪作用下的脆性走滑剪切模式,地震方差切片存在右旋运动拖拽断裂证据.通过对主断裂活动期次分析表明,研究区主要有三期大的构造活动,同时形成了三期构造反转.应力分布的局域性导致了形变特征的差异性,产生了褶皱、挤压反转、掀斜断块、花状构造等典型的构造类型.研究区首次利用三维地震资料对本区构造特征进行了分析,研究认为走滑活动形成了良好的构造背景、优越的油源及运移等成藏条件,具有较大的油气勘探潜力.     

厦门篔筜港一钟宅断裂带的活动性

本文根据野外地质、地貌与第四纪地质调查,结合卫片和航片影象分析等,论述了筼筜港—钟宅断裂带的存在,并从地貌面、沉积物、风化层的变形、断裂物质、地形、水系及微地震等方面分析了该断裂带自距今30k—40ka以来的活动性问题。     

东海西湖凹陷平湖斜坡带断层特征及其封闭性

在对西湖凹陷平湖斜坡带断裂系统特征定性分析的基础上,结合断层封闭性的半定量研究,总结了平湖斜坡带断层的封闭性特征。依据主干断裂及伴生断裂的平面组合样式、剖面组合关系等特征,将平湖斜坡带断裂系统划分为4个断裂带,由北至南依次为"K"同向断裂带、"W"反向断裂带、"P"同向断裂带和"N"堑式断裂带。断层封闭性研究认为平湖斜坡带中部断层封闭性要好于南部和北部。"K"同向断裂带和"W"反向断裂带多数断层封闭性较好,但由于平湖主断裂的长时间活动,使得整体封闭性一般。"P"同向断裂带由于受中新世末龙井运动的弱挤压反转作用,断层的封闭性较好。"N"堑式断裂带由于平湖主断裂的长期活动和沉降期断裂的存在,断层封闭性较差。     

浅层地震在复杂断裂带探测中的应用研究

拟建中的潍河特大桥地处沂沭大断裂边缘。区内断裂发育,构造复杂,直接会影响大桥基础的稳定性,因而查清区内断裂带的准确位置与分布是大桥工程的关键。探测应用浅层地震折射波方法和选用追逐与相遇观测系统和大小排列相结合的工作方法,准确地查明了区内断裂的准确位置和特征,与钻井资料对比,十分吻合。     

新构造期鲁南地区地壳垂向运动特征

本文主要介绍了新构造期以来鲁南地区的地层、层状地貌及断陷盆地的演化,并以此分析讨论了本区地壳垂向运动及其强度的时空变化特征。     

Quantification of mass transfers and mineralogical transformations in a thrust fault (Monte Perdido thrust unit,southern Pyrenees,Spain)

In fold-and-thrust belts, shortening is mainly accommodated by thrust faults which are preferential zones for recrystallisation and mass transfer. This study focuses on a detachment fault related to the emplacement of the Monte Perdido thrust unit in the southern Pyrenees. The studied fault zone consists of a 10 m thick intensively foliated phyllonite developed within the Millaris marls, of Eocene age. The lithological homogeneity of the hanging wall and footwall allows us to compare the Millaris marls outside the fault zone with the highly deformed marls located in the fault zone and to quantify the chemical, mineralogical and volumetric changes related to deformation processes along the fault.The Millaris marls are composed of detrital quartz, illite, chlorite, minor albite and pyrite, in a micritic calcite matrix. In the fault zone, the cleavage planes are marked by clay minerals and calcite ± chlorite veins attest to fluid–mineral interactions during deformation.The mineral proportions in all samples from both the fault zone and Millaris marls have been quantified by two methods: (1) X-ray diffraction and Rietveld refinement, and (2) bulk chemical analyses as well as microprobe analyses to calculate modal composition. The excellent agreement between the results of these two methods allows us to estimate mineralogical variations using a modification of the Gresens' equation. During fault activation, up to 45 wt% of calcite was lost while the amounts of quartz and chlorite remained unchanged. Illite content remained constant to slightly enriched. The mineralogical variations were coupled with a significant volume loss (up to 45%) mostly due to the dissolution of micritic calcite grains. Deformation was accompanied by pressure solution and phyllosilicates recrystallisation. These processes accommodated slip along the fault. They required fluids as catalyst, but they did not necessitate major chemical transfers.     

Geometries and mechanism of folds in sediments on the southern Huanghai Sea shelf

1Intraduction Foldsinconsolidatedstrataareoftendocumen ted.Butfoldsinloosely consolidatedsedimentsare rarelydiscussed,probablybecauseofthefollowings:(1)folddeformationsinloosely consolidatedsedi mentsareweakortheyhavebeendestroyed;(2)tectonicactivityhasbe…     

Recent structures in the Alboran Ridge and Yusuf fault zones based on swath bathymetry and sub-bottom profiling: evidence of active tectonics

The seafloor of the Alboran Sea in the western Mediterranean is disrupted by deformations resulting from convergence between the African and Eurasian plates. Based on a compilation of existing and new multibeam bathymetry data and high-resolution seismic profiles, our main objective was to characterize the most recent structures in the central sector, which depicts an abrupt morphology and was chosen to investigate how active tectonic processes are shaping the seafloor. The Alboran Ridge is the most prominent feature in the Alboran Sea (>130 km in length), and a key element in the Gibraltar Arc System. Recent uplift and deformation in this ridge have been caused by sub-vertical, strike-slip and reverse faults with associated folding in the most recent sediments, their trend shifting progressively from SW–NE to WNW–ESE towards the Yusuf Lineament. Present-day transtensive deformation induces faulting and subsidence in the Yusuf pull-apart basin. The Alboran Ridge and Yusuf fault zones are connected, and both constitute a wide zone of deformation reaching tens of kilometres in width and showing a complex geometry, including different active fault segments and in-relay folds. These findings demonstrate that Recent deformation is more heterogeneously distributed than commonly considered. A narrow SSW–NNE zone with folding and reverse faulting cuts across the western end of the Alboran Ridge and concentrates most of the upper crustal seismicity in the region. This zone of deformation defines a seismogenic, left-lateral fault zone connected to the south with the Al Hoceima seismic swarm, and representing a potential seismic hazard. Newly detected buried and active submarine slides along the Alboran Ridge and the Yusuf Lineament are clear signs of submarine slope instability in this seismically active region.     

Geodynamic Evolution of the Eastern Segment of the Azores-Gibraltar Zone: The Gorringe Bank and the Gulf of Cadiz Region

Detailed structural interpretation of the recently acquired deep seismic multichannel profiles along the Iberian Atlantic Margins (IAM Project) provides new results on the geodynamic evolution of the eastern part of the Azores-Gibraltar plate boundary. Thrusting and folding of the oceanic basement and of Mesozoic and Cenozoic sedimentary cover of the Gorringe Bank region are consistent with the N–S convergence of Iberia and Africa. Compressive structures in the Gorringe Bank region are spread over a wide area. Deformation under compression took place mainly in Tertiary times, as is evidenced by a basal unconformity and several discontinuities in Tertiary sediments, although some deformation has also been recorded in Quaternary sediments. The compressive structures in the Gulf of Cadiz are E–W oriented thrusts, folds and related diapiric structures. N–S oriented transpressive deformation is likely to occur in the western Portuguese platform. There is no continuity of structures from the oceanic to the continental domain, suggesting that deformation transfers from one side to the other through a transcurrent fault zone. The fault contact between the two domains is located in the ocean-continent transition zone.     

Tracing the middle strand of the North Anatolian Fault Zone through the southern Sea of Marmara based on seismic reflection studies

We studied the active deformation zone of the middle strand of the North Anatolian Fault Zone through the southern part of the Sea of Marmara by means of high-resolution as well as deep seismic reflection data. Our main objective was to investigate the active deformation within the uppermost sedimentary layers at high resolution as well as deeper sedimentary layers, focusing on the tectonic and stratigraphic setting between Gemlik and Bandırma. The middle strand of the North Anatolian Fault reaching the Gulf of Gemlik is a main fault which has a lazy-S shape in the Gulf of Gemlik, and extends westwards to Bandırma as a main fault which is an E–W-trending single right-lateral fault controlling the zone along the Gemlik and Bandırma sub-basins. Small-scale faults, consistent with a dextral shear regime, are present in the vicinity of the main fault. Several oblique fault groups parallel to the main fault were detected. The deformation in the Gulf of Gemlik is characterized by a series of synthetic and antithetic faults emanating from the main fault. The boundary faults in the Gulf of Gemlik have a compressive component, which indicates the sill areas of the gulfs of Gemlik and Bandırma to be push-up structures. Four seismic stratigraphic units were identified in the sediments of the gulfs of Gemlik and Bandırma, providing evidence of tectonic influence. The present tectonic structure between Gemlik and Bandırma is not a pull-apart structure. The microseismic study in this area has shown that fault planes are either strike-slip or compressional, and that the stress tensor is compatible with pure strike-slip in the E–W fault system.     

南黄海陆架沉积物中褶皱的形态及成因

更新世以来南黄海陆架具有构造活动性强、沉积厚度大(100~300m)、褶皱变形保存完整等特点,是研究未固结沉积物中褶皱变形的理想“实验室”.高分辨率单道地震剖面揭示了南黄海陆架沉积物中具有不同几何形态的三种褶皱:(1)断层相关褶皱(包括断层扩展褶皱和断层牵引褶皱);(2)横向弯曲褶皱;(3)复合作用褶皱.对褶皱的成因和几何形态的研究表明,控制未固结沉积物中褶皱形成的因素是基底断层及其形成的断块,而不是区域应力场.大量孔隙水可能对沉积物的几何形变具有重要的影响作用.沉积物中断层扩展褶皱和牵引褶皱在形变程度上具有连续性,说明两者在成因上存在联系.断层扩展褶皱可能引发的地震活动和变形带在海洋工程地质评估中应受到重视.     

海州湾地区新构造运动及其水系变化

一、海州湾地区新构造 运动特征 本区系沂沭断裂带与黄海断陷所夹持的楔形断块,南隔响水断裂带,濒临下杨子断块,北接山东文登—日照断隆与胶东断块构成一体。其间又有芎海隆起作东西穿过。 盱眙—响水深断裂,在海州湾南侧经灌南县田楼至燕尾港灌河口作北东向延伸,将海州湾沿岸及其邻近地区分成截然不同的两部分,     

Cover deformation above steep, basement normal faults: Insights from 2D discrete element modeling

A discrete element model is used to investigate progressive cover deformation above a steep (70°), basement normal fault. The cover materials are homogenous with frictional material behavior. In the model shown here both normal and reverse faults in the cover accommodate displacement on the underlying basement fault. The earliest faults are curved, reverse faults which propagate upwards from the basement fault tip into the proto hanging wall. These are replaced, progressively towards the footwall, by subvertical to steep normal faults and finally by a normal fault which dips at an angle predicted by Mohr-Coulomb theory. Thus, most early, secondary structures are located in the hanging-wall of the final, through-going, fault. This structural evolution produces an asymmetric, triangular zone of deformation above the basement fault tip which superficially resembles that associated with trishear; however, its progressive development is quite different. Results also emphasize that the occurrence of reverse faults in extensional settings is not diagnostic of inversion.