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Paola Vannucchi 《Journal of Structural Geology》1999,21(12):51
Meso- and micro-structural studies of the well-exposed Balduini Thrust (Northern Apennines, Italy) indicate that the structure formed during a single folding event, contemporaneous with diagenesis, and is a zone comprising curved, en-échelon fault segments. The geometry of each segment is arcuate with pure compression at one end and right-lateral displacement along the other. The thrust developed during the Tortonian within a single mud-rich formation, the Upper Eocene–Upper Oligocene Scaglia Cinerea, but rheological variations within the unit led to differences in deformation style; zones of scaly fabric are discontinuous and calcite veins vary in abundance. The mesoscopic morphology of the veins and the distribution of calcium carbonate along the formation indicate variations in the distribution of fluids at the time of deformation, which affected both diagenesis and the structural response of the material. Systematic variations of mechanical properties within the thickness of the Scaglia Cinerea Formation account for the curvature of the propagating thrust. Together with the heterogeneity of the stress field, the confinement of the arcing thrust to this single, weak unit lead to repeated initiation of new fractures and hence segmentation of the propagating thrust. Geometric analysis of the calcite veins and their microscopic characters suggests that hydrofracturing was involved, with the Scaglia Cinerea Formation experiencing high fluid pressure followed by rapid water expulsion. The Balduini Thrust is therefore an example of a fluid-driven, refracted compound shear zone. The analysis presented here provides insights into the three-dimensional arrangement of fault zones and fluid-migration patterns during regional faulting. 相似文献
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碳酸盐岩(台地)的消亡是沉积学研究的前沿和热点科学问题。南海东北部珠江口盆地东沙隆起所发育的下中新统珠江组碳酸盐岩是我国海相碳酸盐岩的最高层位,东沙台地珠江组碳酸盐岩的生长、繁盛和消亡过程提供了中国南海乃至世界范围内一个典型的受构造、海平面变化和物源共同控制的研究实例。依据采自钻井岩心钙质超微化石和浮游有孔虫化石带将珠江组的上界置于钙质超微化石带NN4与NN5的界线,即中、下中新统界线,下界置于浮游有孔虫N4的底部附近,即位于中新统与渐新统界线。有孔虫属为N4-N8带,钙质超微化石为NN2-NN4带,底界年龄为23.03Ma,顶界年龄为15.97Ma,地震反射上位于T40-T60之间。而其中碳酸盐岩地层最早于21Ma左右开始生长,最晚于16.5Ma被泥岩淹没。早期的东沙隆起北低南高,21Ma以后,东沙隆起沉降而丧失了向珠一凹陷提供物源的功能,沉降较快的东沙隆起北北部地区发育碳酸盐岩;初期为一套碳酸岩缓坡沉积,20Ma以后隆起整体被淹没,开始了大规模的碳酸盐岩建造,实现了由碳酸盐岩缓坡向台地的转变,随沉降向南推移,隆起逐渐转变为北高南低,整个碳酸盐岩台地持续向东南方向退缩,台地沉积逐渐萎缩为局部礁滩复合体,北部古地貌的高部位残存零星点礁;16.5Ma以后,沉降中心向珠二凹陷迁移,北部、北西部碎屑物质持续向东沙隆起前积导致台地消亡。结合珠江组沉积时期的地质事件的分析,本文认为早期碳酸盐岩的消亡是由于这一时期的全球海平面下降到最低位,引起区域上的物源供给加快,灰岩直接被北部沉积物退覆淹没所致;20±0.5Ma~18.3±0.5Ma的碳酸盐岩的消亡时间受制于沉降造成的相对海平面的变化,基底的火山作用及沉降中心的迁移等事件,最晚一期碳酸盐岩(流花地区碳酸盐岩)的消亡应该是构造反转后,北部物源对凹陷的持续填平补齐作用引起碳酸盐岩的生长环境变化所致。由此看,陆源碎屑的注入、沉降中心的迁移、相对海平面的升降及原始古地貌形态是碳酸盐岩生长发育及消亡的主要控制因素。 相似文献
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以中、下三叠统嘉陵江组(T1j)和雷口坡组(T2l)含膏盐碳酸盐岩层系为界,可以将川东北地区划分为3个构造-层序组合,盐下构造-层序组合由震旦系-下三叠统飞仙关组组成,属于一套海相碳酸盐岩层系为主的沉积;盐层构造-层序组合由下三叠统嘉陵江组和中三叠统雷口坡组组成,属于一套含厚层膏盐的海相碳酸盐岩层系;盐上构造-层序组合由上三叠统须家河组和侏罗系、白垩系组成,属于一套陆相碎屑岩沉积。川东北地区发育了一套独特的构造变形样式,主要有基底卷入叠瓦冲断强变形带、基底卷入与盐层滑脱叠合变形带、隐伏盐相关构造滑脱变形带、双重构造、堆垛式三角带构造和背冲断块构造等。由于该区盐岩层厚度相对较薄,盐岩层系总体作为一个大型滑脱层系,控制川东北地区的构造变形。川东北地区主要构造变形机制包括区域挤压缩短作用、盐岩层塑性流动和滑脱作用、构造隆升和剥蚀作用、重力滑动和重力扩展作用等。川东北地区与三叠系盐岩层系有关的构造变形控制该区油气圈闭样式,有利于油气聚集和保存。 相似文献
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北京东部丰台顶一带地质构造特征 总被引：4，自引：6，他引：4
经过近期对燕山地区地质构造的调查研究 ,依据岩石、岩石组合、接触变质、矿化蚀变在空间上的展布、与燕山期侵入岩体的接触关系等证明 ,前人在丰台顶一带圈定的中生代潜 (次 )火山岩体 ,实际为陆相火山喷发 -沉积岩 ,属中生代早白垩世东岭台期酸性火山活动产物。在不足 4 0km2 面积中 ,发现了由多个构造推覆断片叠置而成的复杂构造堆叠体 ,卷入其中的既有太古宙片麻岩 ,也有中元古宙碳酸盐岩 ,还有中生代早白垩世东岭台期火山岩。其中 ,由东岭台组火山岩构成的 3个构造岩片夹于 4个由长城系、蓟县系碳酸盐岩构成的构造岩片之间。这些构造岩片具有不同的片内褶皱 (断片形成前的褶皱 )和岩片褶皱 (断片形成后的褶皱 )特征。以卷入叠覆构造的最高层位 -东岭台组为据判断 ,其为燕山晚期区域性收缩构造事件的产物。并由此预测 ,在北京东部大范围的中 -上元古宙沉积岩层中可能存在由碳酸盐岩构成的岩性相同产状相近的叠覆构造 ,亦可能在中 -上元古宙沉积层构成的推覆体下 ,隐伏有最高层位达下白垩统东岭台组的各时代地层和相关矿产。 相似文献
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随着油气二次创业的深入,海相地层已成为油气勘探领域的重点.下扬子沉积了巨厚的海相地层,其原型盆地经历了多期次的构造改造.通过对下扬子边界的讨论,对其进行系统的整体分析.在活动论构造历史观和盆地原型分析TSM工作程式的指导下,通过对下扬子晚震旦至中奥陶世残留地层分布状况以及该时期沉积充填过程的分析,确定了晚震旦至中奥陶世下扬子原型盆地的性质为被动大陆边缘,其特征主要表现在硅质碎屑沉积物、碳酸盐岩沉积物和同生断裂现象等方面.该时期碳酸盐岩台地发育成镶边台地,台地有侧向生长现象和向海盆输入沉积物的舌状凸起,以江南断裂为代表的同生断裂表明盆地沉积物的物源始终是从下扬子内部自西北向东南方向单向搬运,这些均表明晚震旦至中奥陶世为成熟的被动大陆边缘. 相似文献
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Tectonic Taphrogenesis and Paleoseismic Records from the Yishu Fault Zone in the Initial Stage of the Caledonian Movement 总被引：3，自引：0，他引：3
TIAN Hongshui ZHANG Zengqi ZHANG Banghu ZHU Jiewang SANG Zhongxi LI Hongkui 《《地质学报》英文版》2013,87(4):936-947
The Yishu fault zone (mid-segment of the Tanlu fault zone) was formed in the Presinian. Periodic tectonic activities and strong seismic events have occurred along the fault zone. During the initial stage of the Caledonian Movement, with the proceeding of the marine transgression from the Yishu paleo-channel to the western Shandong, uneven thick sediments, composed mainly of sand, mud and carbonates of littoral, lagoon, and neritic facies, were deposited in the Yishu fault zone and western Shandong, and constructed the bottom part of the Lower Cambrian consisting of the Liguan and Zhushadong formations. Through field observations and the lab-examinations, various paleoseismic records have been discovered in the Liguan Formation and the Zhushadong Formations of the Yishu fault zone and its vicinity, including some layers with syn-sedimentary deformation structures that were triggered by strong earthquakes (i.e. seismite, seismo-olistostrome, and seismo-turbidite). Paleoseismic records developed in the Zhushadong Formation are mainly seismites with soft-sediment deformation structures, such as liquefied diapir, small liquefied-carbonate lime-mud volcano, liquefied vein, liquefied breccia, convolute deformation (seismic fold), graded fault, soft siliceous vein, and deformation stromatolite, as well as seismites with brittle deformation structures of semiconsolidated sediments. Paleoseismic records preserved in the Liguan Formation are not only seismo-olistostrome with a slump fold, load structure, and ball-and-pillows, but also seismo-turbidite with convolution bedding, graded bedding and wavy-bedding. However, in the western Shandong area, the closer to the Yishu fault zone, the greater the thickness of the Liguan Formation and the Zhushadong Formation, the greater the number and type of layers with paleoseismic records, and the higher the earthquake intensity reflected by associations of seismic records. This evidence indicates that tectonic taphrogenesis accompanied by strong earthquake events occurred in the Yishu fault zone during the initial stage of the Caledonian Movement, which embodied the break-up of the Sino-Korean Plate along the Paleo-Tanlu fault zone at that time. 相似文献
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The Aínsa Basin of northern Spain contains a deep‐marine succession comprising up to 24 sandstone bodies separated by thick marl‐rich units. A detailed analysis of nine outcrops (>900 m of sediment profiles) from the Morillo Formation of the San Vicente Group, from the upper part of the basin succession, has enabled a reappraisal of the unit. Within the Morillo Formation, sediment transport was to the NW, and a range of environments are recognized including channels, lobes and pelagic deposits. The overlying Coscojuela Formation, which partly cuts into the Morillo Formation, shows W‐directed palaeocurrents in its proximal reaches, with flows being deflected to the N along an adjacent slope. Destabilization of the adjacent carbonate platform resulted in a significant input of carbonate material into the flow. The final phases of sedimentation within the Aínsa Basin were more complex than previously suspected, probably as a result of a combination of factors, including tectonic activity, resulting in basin narrowing due to anticlinal growth, as well as encroachment and/or destabilization of the adjacent regional carbonate platforms. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
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通过野外观察,发现贺兰山中段长城系黄旗口组中发育大量的软沉积变形构造,主要包括液化砂岩墙（脉）、液化水压破碎构造和液化角砾岩、负荷构造、砂岩球和砂岩枕构造、砂岩串珠状构造、包卷层理（液化卷曲变形）、阶梯状微断层等。室内显微镜下观察发现,石英砂岩成分成熟度相对较高,但结构成熟度较低,颗粒多呈次圆状-圆状,粒径大小不等,碎屑颗粒间有泥质混入,泥质多呈不规则脉状穿插在砂岩中,显微镜下也见微逆断层切过纹层。沉积环境分析结果显示,黄旗口组发育脊状波痕、小型交错层理、水平层理、泥裂等沉积构造,指示沉积时水体较浅,沉积环境为滨-浅海。认为黄旗口组中的软沉积变形构造不是由上覆重荷引起,可能为古地震成因。在黄旗口组中第一段下部识别出4个地震事件层,推测黄旗口组沉积时早期地壳运动相对活跃,晚期渐趋稳定。地震岩的出现可能与贺兰裂陷槽拉张-裂陷的构造背景有关。 相似文献
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<正>The Outangdi Formation in Jiangshan,Zhejiang,is the mixing deposit of terrigenous clastics and carbonates in Weiningian of the late Carboniferous.The mixing deposits include interbeddings, which constitute a series of alternated clastic and carbonate beds and mixing within the same bed which forms"hunji rock".The Outangdi Formation has the features of intercalated marine and terrestrial deposits with the progradational sequences,which are lower fine and upper coarse sedimentary granularity in the section.Hunji rock is formed in a seashore environment.It is a mixed carbonate sediment found in beaches or tideland facies with quartz sand taken from a bayou or beach by coastwise flow and circumfluence.There are two kinds of hunji sequences:(1) interbeds of sandstone and carbonate rock in seashore environments;and(2) interbeds of clastics in river facies and carbonate rock in ocean facies.It is indicated that mixing depositions belong to"facies mixing",affected mainly by regional tectonic uplift,rise of the global sea level,and the dynamics of water medium in the basin. Regional sea level periodic changes and progradational sequences probably resulted from the intense uplift of the old land called Cathaysia.The classification and name of mixed sediments are also discussed in the present study.Interbeds and alternated beds of clastic and carbonate beds are named"hunji sequence",a new genetic term.It is suggested that hunji rock means a special sediment event of mixing terrigenous clastics and carbonates instead of a name of a specific rock. 相似文献
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地质名山馒头山及其附近早寒武世古地震沉积事件研究 总被引：1，自引：0，他引：1
蜚声中外的地质名山馒头山处在济南南部山区。通过野外调查和室内研究,从馒头山及其附近的青杨村东山、红叶谷、滚球山等地的下寒武统中,鉴别出了许多地震引起的同沉积变形构造（震积岩）,主要有卷曲变形（震褶岩）、粒序微断层、滑移构造、滑塌褶曲、负载构造、枕状体、混插沉积、软硅质脉、软硅质层底辟构造、硅藻叠层石变形、沉陷构造、触变楔、布丁、震裂缝、震裂角砾岩及震碎角砾岩等。本文较详细地阐述了它们的特征和形成机理。触变楔属国内首次发现。触变楔和沉陷构造发育在夹软硅质层的白云岩中,其原始沉积物是含软硅质层的白云质灰泥。受强震触动,因软硅质沉积物(SiO2·nH2O)的粘度变小,软硅质层的粘度变小而变得更软,灰泥同时发生液化;在竖向震动力作用下,软硅质层被断开、继而沉陷形成了沉陷构造;沉陷构造向下延伸,结果使断开的硅质层汇聚,形成了触变楔。根据早寒武世古构造板块与地震带的分布,认为这些地震沉积遗迹是早寒武世板内地震记录,推测由古郯庐带的构造活动的响应。这些古地震事件记录的发现,丰富了济南南部山区、尤其是馒头山的地质科学内涵。 相似文献
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Mixed carbonate-siliciclastic sediment gravity flow deposits of Late Pennsylvanian to Early Permian age are exposed in the Death Valley - Owens Valley region of east-central California. The Mexican Spring unit constitutes the upper part of the Keeler Canyon Formation and is characterized by turbidites, debris flow deposits and megabreccias, all of mixed carbonate-siliciclastic composition. The mixed composition of the Keeler Canyon Formation provides an opportunity to link facies architecture to controls on depositional system development. Depositional relationships indicate that the deposits represent a non-channellized base of slope carbonate apron system with inner, outer and basinal facies associations. These gravity flow deposits are characterized by repeated stacked, small scale (<15 m) coarsening and thickening upward cycles with superimposed medium scale (>100 m) coarsening and thickening upward cycles. Contemporaneous outer shelf and upper slope deposits of the Tippipah Limestone are exposed at Syncline Ridge on the Nevada Test Site. The deposits consist of carbonate buildups directly overlain by cross bedded, quartz-rich sandstone and conglomerate which filled channels that traversed across the previously existing carbonate shelf. Detritus was transported to the west, down the upper slope by gully systems that fed the temporally persistent base of slope apron of the upper part of the Keeler Canyon Formation. This style of deposition differs from point-sourced siliciclastic submarine fan depositional systems. However, the Keeler Canyon system has lithofacies similar to some sandy siliciclastic turbidite systems, such as the delta-fed submarine ramp facies model, which is a line-sourced, shelf-fed system that is not supply limited. The mixed clastic apron systems of the Keeler Canyon Formation differ from classical carbonate aprons in that the former is characterized by an abundance of sedimentary cycles. Controls on the development of these cycles and of the facies distribution may have resulted from changes in type and rate of sediment supply, relative sea level changes and/or tectonic events. Interpretation of the data is focused on relative changes in sea level as the most significant control on development of the depositional system. Relative sea level changes serve two important functions: (1) they provide a mechanism for bringing coarse siliciclastic and bioclastic grains together on the outer shelf, and (2) shelf margin collapse may be initiated during relative lowstands allowing for transport of the sediment to the deep basin and development of deep basinal cycles. Therefore, an abundance of mixed clastic gravity flow deposits such as these in the rock record may be an indicator of periods of high frequency changes in relative sea level, which is a characteristic of Late Palaeozoic sea level history. 相似文献
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华北古陆北缘中元古代串岭沟组是整个华北古陆沉积环境从以滨浅海陆源碎屑岩为主体的沉积体系向以碳酸盐岩为主体的陆表海沉积体系的转折点。串岭沟组发育了大量的软沉积物变形构造:水塑性变形构造,液化构造,流化构造,均是与地震驱动相适配的变形构造,它们赋存于特定的层内,并在空间上呈规律变化,为典型震积岩。地震中心主要为蓟县—兴隆区域,东西向展布的断裂控制相带分布,南北向控制沉积类型。软沉积变形构造可以作为重要沉积标志来限定大陆裂解引发的伸展构造运动时间。因此综合研究串岭沟组发育的软沉积物变形构造类型、特征、层位和空间位置对于认识原型盆地的断裂构造活动特征具有重要意义。 相似文献
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《Journal of African Earth Sciences》2007,47(3):121-134
The Neoproterozoic Zerrissene Turbidite Complex of central-western Namibia comprises five turbiditic units. From the base to the top they are the Zebrapüts Formation (greywacke and pelite), Brandberg West Formation (marble and pelite), Brak River Formation (greywacke and pelite with dropstones), Gemsbok River Formation (marble and pelite) and Amis River Formation (greywacke and pelites with rare carbonates and quartz-wacke).In the Lower Ugab River valley, five siliciclastic facies were recognised in the Brak River Formation. These are massive and laminated sandstones, classical turbidites (thick- and thin-bedded), mudrock, rare conglomerate and breccia. For the carbonate Gemsbok River Formation four facies were identified including massive non-graded and graded calcarenite, fine grained evenly bedded blue marble and calcareous mudrock. Most of these facies are also present in the other siliciclastic units of the Zerrissene Turbidite Complex as observed in other areas.The vertical facies association of the siliciclastic Brak River Formation is interpreted as representing sheet sand lobe to lobe-fringe palaeoenvironment with the abandonment of siliciclastic deposition at the top of the succession. The vertical facies association of the carbonate Gemsbok Formation is interpreted as the slope apron succession overlain by periplatform facies, suggesting a carbonate slope sedimentation of a prograding depositional shelf margin.If the siliciclastic–carbonate paired succession would represent a lowstand relative sea-level and highstand relative sea-level, respectively, the entire turbidite succession of the Zerrissene Turbidite Complex can be interpreted as three depositional sequences including two paired siliciclastic–carbonate units (Zebrapüts-Brandberg West formations; Brak River–Gemsbok formations) and an incomplete succession without carbonate at the top (Amis River Formation). 相似文献
17.
混合沉积具有碎屑岩类与碳酸盐岩类的双重特征,国内外尚未建立有效的混和沉积储层识别方法.通过对辽东湾北部地区混合沉积发育背景、岩石学特征分析,将混合沉积分为陆源碎屑型、生物成因碳酸盐型、化学沉淀碳酸盐型3种.明确了3种类型混合沉积的发育相带与模式.通过对不同类型的岩石物理参数交会分析认为:生物成因碳酸盐型具有中低-中高纵波速度、低密度、低纵波阻抗特征,化学沉淀碳酸盐型及陆源碎屑型具有中高纵波速度、高密度、高阻抗特征,纵波阻抗与密度是区分不同类型混合沉积的敏感参数;通过地震正演模拟与实际地震资料响应对比,发现辽北地区沙河街组混合沉积地层受到下伏潜山地层低频强能量的屏蔽,创新采用匹配追踪方法对潜山顶面强反射进行压制,并在此基础上进行岩性敏感参数预测,有效地提高了沙河街组混合沉积储层的识别能力. 相似文献
18.
The growth and subsequent dissolution of salts on or within sediment may alter sedimentary structures and textures to such an extent that it is difficult to identify the depositional origin of that sediment and, as a result, the sediment may be misinterpreted. To help to overcome such problems with investigating ancient successions, results are presented from a comprehensive study of the morphology and fabrics of three large areas of modern salt flats in SE Arabia: the Sabkhat Matti inland region and the At Taf coastal region, both in the Emirate of Abu Dhabi, and the Umm as Samim region in Oman. These salt flats are affected by tidal‐marine, alluvial and aeolian depositional processes and include both clastic‐ and carbonate‐dominated surficial sediments. The efflorescent and precipitated salt crusts in these areas can be grouped into two main types: thick crusts, with high relief (>10 cm) and a polygonal or blocky morphology; or thin crusts, with low relief (<10 cm) and a polygonal or blister‐like appearance. The thin crusts may assume the surface morphology of underlying features, such as ripples or biogenic mats. A variety of small‐scale textures were observed: pustular growths, hair‐like spikes and irregular wrinkles. Evolution of these crusts over time results in a variety of distinctive sedimentary fabrics produced by salt‐growth sediment deformation, salt‐solution sediment collapse, sediment aggradation and compound mixtures of these processes. Salt‐crust processes produce features that may be confused with aeolian adhesion structures. An example from the Lower Triassic Ormskirk Sandstone Formation of the Irish Sea Basin demonstrates how this knowledge of modern environments improves the interpretation of the rock record. A distinctive wavy‐laminated facies in this formation had previously been interpreted as the product of fluvial sheetfloods modified by soft‐sediment deformation and bioturbation. Close inspection of laminations seen in core reveals many of the same sedimentary fabrics seen in SE Arabia associated with salt crusts. This facies is the product of salt growth on aeolian sediment and is not of fluvial origin. 相似文献
19.
巴彦浩特盆地东缘中奥陶统混合型深水重力流沉积层序及其旋回 总被引：5，自引：1，他引：5
作者在巴彦浩特盆地东缘中奥陶统樱桃沟组中识别出一套巨厚的混合型深水重力流沉积岩,包括碳酸盐滑塌角砾岩?递变细砾岩?砂质砾岩?经典浊积岩?灰绿色泥页岩等岩相类型?作者认为碳酸盐滑塌角砾岩是近源海底断裂陡崖下形成的碎屑裙的产物,而陆源碎屑-浊积岩是基岩古风化壳剥蚀而形成的一系列碎屑流-浊流沉积物?对其纵向序列进行分析后作者认为,该套岩层总体上相当于一个Ⅱ级旋回,代表拗拉槽强烈沉陷阶段的产物,为次一级的地壳升降旋回,主要受古构造因素控制,而每一陆源与内源沉积物混合体则相当于一个Ⅲ级旋回,代表一个低级次的海平面升降旋回? 相似文献