凤滩水电站扩建工程进水口反倾层状结构边坡岩体特征与加固处理   总被引：1，自引：1，他引：0  

鲁显景  钟辉亚  李幸福 《工程地质学报》2005,13(4):557-567

凤滩水电站扩建工程进水口边坡为厚层反倾结构边坡,岩体完整性好,由于边坡及进水口段洞室开挖未及时支护,导致进水口段上部边坡岩体产生轻微倾倒变形。本文描述了该进水口部位的地质条件,分析了进水口隧洞上部厚层反倾岩体稳定性。研究了施工过程中岩体发生轻微倾倒变形的原因,并提出了相应的加固处理方案,通过现场监测证明处理后边坡岩体是稳定的。  相似文献   

Prerift and synrift sedimentation during early fault segmentation of a Tertiary carbonate platform, Indonesia     

Moyra E. J. Wilson   《Marine and Petroleum Geology》1999,16(8):262

Eocene carbonate deposits of the Barru area, Sulawesi, Indonesia, provide a rare insight into sedimentation prior to and during propagation of normal faults to the surface. Three main successions; late prerift, latest prerift/earliest synrift and synrift, are characterised by distinctive facies associations and sequence development. Shallow water foraminiferal shoals and intervening lower energy depositional environments occurred during the late prerift in areas which latter formed footwall highs and hangingwall depocentres, respectively. During the latest prerift/earliest synrift, shallow water shelves deepened laterally into slope environments in developing hangingwall depocentres. In both these sequences, sections in developing hangingwall areas are thickest, deepen up-section and thin laterally towards growing footwall highs. Active faulting resulted in rapid drowning of hangingwall depocentres and massive reworking of material derived from collapse of the platform margin and adjacent shallow water/emergent footwall highs.Differential subsidence, controlling water depths and accommodation space, types of carbonate producers and active faulting were the main factors affecting depositional environments and facies distributions. Carbonate producers are extremely sensitive indicators of depositional water depth and energy, hence rapid lateral and vertical facies variations in the Barru area provide quantifiable insight into environmental changes prior to and during active faulting.  相似文献   

Controlling factors on the morphology and spatial distribution of methane-related tubular concretions – Case study of an Early Eocene seep system     

Eva De Boever  Marijke Huysmans  Philippe Muchez  Lyubomir Dimitrov  Rudy Swennen   《Marine and Petroleum Geology》2009,26(8):1580-1591

Up to 10 m in length and >1 m in diameter tubular, calcite-cemented sandstone concretions are hosted by the faulted Dikilitash unconsolidated sands and sandstones. These structures document shallow subsurface pathways of Early Eocene methane seepage in the Balkan Mountains foreland (NE Bulgaria). Their exceptional exposure allowed a unique study of the factors governing the morphology and spatial distribution of such fossilized fluid conduits. The large dimensions and subvertical, cylindrical shape of the most common tube type primarily reflects the buoyancy-driven, vertical path of an ascending gas-bearing fluid through permeable, mainly unconsolidated sandy host sediments. Tube morphology was also influenced by local stratigraphic anisotropies and might as well document differences in former seepage conditions. Mapping of >800 tubular concretions showed the NNW–NNE elongation and alignment of tube clusters and massive cemented sandstone structures. This suggests that Paleogene fault systems played a major role in directing the movement of fluids. However, within a single tube cluster, tubes are preferentially aligned, over distances up to 50 m along directions at an angle between 10° and 36° with respect to the inferred NNW–NNE, cluster parallel fault traces. In addition, cylindrical tubes of analogue dimensions are aligned over distances >100 m along N15° to N25°-oriented directions. It is hypothesized that this spatial geometry of tubular concretions reflects the complex geometry of deformations structures in fault damage zones along which fluids were preferentially channelled.  相似文献   

Late quaternary seismic stratigraphy and active faults of the Gulf of İzmit (NE Marmara Sea)     

Mahmut Okyar  Ali Pinar  Devrim Tezcan  Züheyr Kamaci 《Marine Geophysical Researches》2008,29(2):89-107

The Upper Quaternary seismic stratigraphy and active faults of the Gulf of İzmit were investigated by means of high-resolution shallow seismic profiling data in the source region of 1999 İzmit earthquake. High-resolution seismic reflection data correlated with borehole data indicate that the stratigraphy of İzmit Bay consists of three distinct depositional sequences formed in response to middle Pleistocene-Holocene sea-level changes. Reflector R, separating the pre-Holocene sequences (1 and 2) from the Holocene sequence (3), represents an erosional unconformity produced by the subaerial fluvial erosion of the continental shelves at the time of the last glacial maximum. Occasional, anomalous reflections (acoustic turbidity) observed within the Holocene sequence are interpreted as gas accumulations. The maximum thickness of the Holocene sediments is found to be about 25 m. The isopach map of Holocene sediment implies that the thickness of the Holocene decreases from the east towards the central and western basins of İzmit Bay. Two distinct fault systems are interpreted in İzmit Bay. The main fault system extending roughly in an E-W direction along the Gulf of İzmit is an active right lateral strike slip fault with a normal component. The secondary faults are normal faults striking in different directions and these are identified as being both active and inactive. In addition, prominent compressive features are identified in the seismic cross-sections of some profiles acquired to the east of Hersek Peninsula where the focal mechanisms of the aftershocks of the 1999 İzmit earthquake also reveal predominantly reverse faulting mechanisms, as identified by a local dense seismic network.  相似文献   

松南十屋断陷深层油气成藏条件与模式研究     

赵勇刚  张树林 《海洋地质译丛》2009,(1):21-25

十屋断陷是断坳叠置的复合盆地，充填了巨厚的断陷地层。其深部地层包括登娄库组、营城组、沙河子组以及火石岭组。在十屋断陷深部沉积了沙河子组-营城组和登娄库组两套烃源岩和良好的储盖层组合；由于断陷构造运动，形成大量的断裂构造和不整合面，构成了油气运移的有效通道，同时还形成有效断裂、断鼻构造圈闭以及不整合圈闭。综合分析认为，十屋断陷深部具有有利油气成藏生储盖组合。主要有下生上储式、自生自储式和上生下储式三种成藏模式。  相似文献   

南海东北部新构造运动及其动力学机制     

孙金龙  徐辉龙  李亚敏 《海洋地质与第四纪地质》2009,(3)

南海东北部地处欧亚板块与菲律宾海板块的交汇区,新构造运动活跃。根据地震活动性、震源机制解和GPS资料对该区的新构造活动特征进行分析,在此基础上讨论该区新构造运动的动力学机制。分析发现,菲律宾海板块NW向俯冲对该区的影响最为显著,导致了该区较强的地震活动性以及与俯冲方向一致的构造应力场。而印藏碰撞产生的侧向应力传递也影响到该区,控制华南地块向SE方向运动,并与菲律宾海板块的NW向俯冲共同作用,使华南地块在SE向运动的同时伴有逆时针旋转。印藏碰撞的SE向应力传递对俯冲产生的NW向水平挤压的抵消作用,使得地震活动性自东向西减弱以及构造应力场P轴方位角顺时针旋转。在这一背景下,区内滨海断裂带的活动控制了该区的地震、海岸带构造升降等新构造运动。  相似文献   

廊固凹陷近岸水下扇特征及控制因素   总被引：2，自引：0，他引：2  

宋荣彩  张哨楠  董树义  周文 《地球科学与环境学报》2007,29(2):145-148,157

通过对廊固凹陷18口井541 m岩心的系统观察、156口井测井序列的建立、1km×1 km三维地震测网密度的地震相识别,分析了该沉积体系的相带展布特征。该砂砾岩层总体趋势为向上厚度减薄、层数减少,共识别出5期扇体,多呈条带状沿大兴断层断面分布,每期之间发育稳定的暗色泥岩段。该近岸水下扇的形成受3级层序、大兴断层、古构造、古气候、古地形以及物源供给等多种因素的控制。3级层序的发育特点、大兴断层的分段活动以及特殊的物源供给背景因素的匹配对近岸水下扇形成起到决定性作用。2~3期扇体扇中分布范围广,储集条件好,是凹陷下一步开发工作的有利目标。  相似文献   

甘肃疏勒河冲积扇发育特征及其对构造活动的响应   总被引：7，自引：2，他引：5  

王萍  卢演俦  丁国瑜  陈杰 《第四纪研究》2004,24(1):74-81

甘肃疏勒河冲积扇是面积达2400km²的一个巨型冲积扇,位于青藏高原北缘阿尔金断裂带东端。区域构造上该扇发育在阿尔金主断裂、三危山断裂和南截山断裂组成的阿尔金断裂带左旋走滑构造域。根据野外调查获得的沉积层序、地貌形态和构造变形等资料,该冲积扇可划分为老冲积扇和新冲积扇。老冲积扇扇顶紧靠阿尔金主断裂,由已显著构造变形的早更新统玉门砾岩组成;新冲积扇是在老冲积扇基础上发育的,扇顶已向下游移动到大坝附近,距阿尔金主断裂4km,主要由中更新统酒泉砾石和晚更新统戈壁砾石组成。疏勒河冲积扇发育对区域构造活动的响应主要表现为:1)在第四纪早期,阿尔金断裂的左旋走滑兼逆冲运动,导致了由玉门砾岩组成的疏勒河老冲积扇扇头被左旋错动约8km,同时扇体,尤其扇头明显褶皱隆升,扇顶向山外移动;2)此后随着阿尔金断裂继续作左旋走滑兼逆冲运动,老冲积扇扇头又被左旋错动了约2km,总共左旋位移了约10km,并且扇顶下移了约4km,形成新的冲积扇;3)在冲积扇内从早更新世至晚更新世沉积中心不断向下游移动,呈现向下游超覆沉积的特征,这也一定程度上反映了祁连山隆升、向外扩展和侵蚀作用显著  相似文献   

湖泊沉积有机质的地球化学记录与古气候古环境重建   总被引：6，自引：1，他引：5  

卢粤晗  孙永革  翁焕新 《地球化学》2004,33(1):20-28

与深海沉积与冰芯记录相比,湖泊沉积主要反映区域气候变迁史,可以揭示百年、甚至十年尺度的古气候事件,是高分辨率古环境、古气候重建的理想场所.传统的地质地球化学方法主要侧重于宏观物理 /化学特性描述和孢粉学的研究,近 10年来,沉积有机质分子碳、氢同位素地球化学技术的渗入,使研究工作从传统的宏观、微观层次向分子级水平发展,对诸如古生产率估算、C3/C4植被演替史、古二氧化碳分压及古温度计算等深层次问题解决提供了强有力支持.本文评述了湖泊沉积有机质分子与碳、氢同位素地球化学记录及其在区域古环境、古气候研究中的应用前景.  相似文献   

辽宁鞍山－本溪地区铁矿床流体包裹体和硫、氢、氧同位素特征研究   总被引：2，自引：0，他引：2  

杨秀清  李厚民  李立兴  马玉波  陈靖  刘明军  姚通  陈伟十  姚良德 《地质学报》2014,88(10):1917-1931

鞍山-本溪地区是我国最大的铁矿集区,分布有诸多大型、特大型铁矿床,并且产出有弓长岭二矿区大型和齐大山、南芬中型磁铁富矿床。贫铁矿体与变质沉积岩和火山碎屑岩等围岩呈层状或似层状产于太古宙花岗岩中,富铁矿体(TFe50%)呈层状或透镜体状产于贫铁矿体和围岩及其附近的断裂带中,并可见明显的热液蚀变现象。为了探讨鞍本地区富铁矿的成因,为指导找富矿提供依据,本文主要对比研究了鞍本地区贫铁矿石和富铁矿石中流体包裹体、硫同位素和氢氧同位素特征。贫铁矿石(磁铁石英岩和假象赤铁石英岩)石英中含有大量的孤立分布负晶形气体包裹体(Ⅰc类包裹体),富铁矿石石英中主要以液体包裹体(Ⅰb类包裹体)为主,可见含子矿物的流体包裹体;贫铁矿石中黄铁矿的δ34S变化范围为-6.5‰~11.8‰,平均值为0.4‰,富铁矿石中黄铁矿的δ34S变化范围较大,为-7‰~14.4‰,平均值为2.0‰;贫铁矿石中磁铁矿δ18 O变化范围为3.4‰~10.4‰,平均值为7.1‰,石英δ18 O变化范围为11.8‰~15.1‰,平均值为13.4‰,富铁矿石中磁铁矿δ18 O变化范围为-1.4‰~6.5‰,平均值为2.3‰,富铁矿石中石英δ18 O变化范围为9.6‰~15.8‰,平均值为13.6‰,δD变化范围为-129‰~-75‰,平均值为-104‰。富铁矿石中石英流体包裹体、黄铁矿δ34S和磁铁矿δ18 O部分继承了贫铁矿石的特征,但是显示更多的后期热液特征,暗示鞍本地区富铁矿石是在贫铁矿石的基础上受后期热液改造形成的。富铁矿石中石英的氢氧同位素特征表明其热液流体主要为混合岩化热液,富铁矿的形成可能为去硅富铁模式,同时也可能有铁质活化再转移模式。  相似文献