新疆境内塔拉斯-费尔干纳断裂早侏罗世走滑的古地震证据   总被引：11，自引：2，他引：9  

乔秀夫  李海兵  王思恩  郭宪璞  司家亮  宗文明 《地质学报》2008,82(6)

在野外考察过程中,于新疆乌恰地区早侏罗世康苏组沼泽相砂岩层中,发现并识别出软沉积物液化变形层,变形包括负载构造,球-枕构造及卷曲变形构造。通过模拟试验的对比研究认为,该软沉积物变形机制与液化作用有关,触发沉积物液化的动力是古地震,并且根据地震震级与液化最大震中距的关系,推测出造成早侏罗世软沉积物变形的里氏地震震级为6相似文献   

Seal integrity and feasibility of CO<Subscript>2</Subscript> sequestration in the Teapot Dome EOR pilot: geomechanical site characterization     

Laura Chiaramonte  Mark D. Zoback  Julio Friedmann  Vicki Stamp 《Environmental Geology》2008,54(8):1667-1675

This paper reports a preliminary investigation of CO₂ sequestration and seal integrity at Teapot Dome oil field, Wyoming, USA, with the objective of predicting the potential risk of CO₂ leakage along reservoir-bounding faults. CO₂ injection into reservoirs creates anomalously high pore pressure at the top of the reservoir that could potentially hydraulically fracture the caprock or trigger slip on reservoir-bounding faults. The Tensleep Formation, a Pennsylvanian age eolian sandstone is evaluated as the target horizon for a pilot CO₂ EOR-carbon storage experiment, in a three-way closure trap against a bounding fault, termed the S1 fault. A preliminary geomechanical model of the Tensleep Formation has been developed to evaluate the potential for CO₂ injection inducing slip on the S1 fault and thus threatening seal integrity. Uncertainties in the stress tensor and fault geometry have been incorporated into the analysis using Monte Carlo simulation. The authors find that even the most pessimistic risk scenario would require ∼10 MPa of excess pressure to cause the S1 fault to reactivate and provide a potential leakage pathway. This would correspond to a CO₂ column height of ∼1,500 m, whereas the structural closure of the Tensleep Formation in the pilot injection area does not exceed 100 m. It is therefore apparent that CO₂ injection is not likely to compromise the S1 fault stability. Better constraint of the least principal stress is needed to establish a more reliable estimate of the maximum reservoir pressure required to hydrofracture the caprock.  相似文献   

Anthropogenic affects on lake sedimentation process: a case study from Lake Sapanca, NW Turkey     

Alper Gürbüz  Ömer Feyzi Gürer 《Environmental Geology》2008,56(2):299-307

Lake Sapanca in NW Turkey is a fault originated freshwater basin fed by seasonally variable flows of 15 streams. Considerations of lake–river interaction, supported by statistical measures of 47 bottom samples, suggest that sediment transport and deposition within the lake is controlled by two types of human constructed structures in addition to natural factors: (1) the dykes constructed in the front of streams, which feed the lake by strong flows, to prevent the filling of lakebed by coarse-grained sediments; (2) the constructed regulator on the outflowing Çarksuyu stream results in a higher sedimentation rate of clay-sized material on the NE corner of the lake, which is extraordinary in the shelf environment.  相似文献   

Structural elements of the Makran region, Oman sea and their potential relevance to tsunamigenisis     

Mohammad Mokhtari  Iraj Abdollahie Fard  Khaled Hessami 《Natural Hazards》2008,47(2):185-199

The character of convergence along the Arabian–Iranian plate boundary changes radically eastward from the Zagros ranges to the Makran region. This appears to be due to collision of continental crust in the west, in contrast to subduction of oceanic crust in the east. The Makran subduction zone with a length of about 900 km display progressively older and highly deformed sedimentary units northward from the coast, together with an increase in elevation of the ranges. North of the Makran ranges are large subsiding basins, flanked to the north by active volcanoes. Based on 2D seismic reflection data obtained in this study, the main structural provinces and elements in the Gulf of Oman include: (i) the structural elements on the northeastern part of the Arabian Plate and, (ii) the Offshore Makran Accretionary Complex. Based on detailed analysis of these data on the northeastern part of the Arabian Plate five structural provinces and elements—the Musendam High, the Musendam Peneplain, the Musendam Slope, the Dibba Zone, and the Abyssal Plain have been identified. Further, the Offshore Makran Accretionary Complex shown is to consist Accretionary Prism and the For-Arc Basin, while the Accretionary Prism has been subdivided into the Accretionary Wedge and the Accreted/Colored Mélange. Lastly, it is important to note that the Makran subduction zone lacks the trench. The identification of these structural elements should help in better understanding the seismicity of the Makran region in general and the subduction zone in particular. The 1945 magnitude 8.1 tsunamigenic earthquake of the Makran and some other historical events are illustrative of the coastal region’s vulnerability to future tsunami in the area, and such data should be of value to the developing Indian Ocean Tsunami Warning System.  相似文献   

南太平洋辐合带(SPCZ)的特征分析   总被引：1，自引：0，他引：1  

吴增茂  陈登俊  温之平 《中国海洋大学学报(自然科学版)》1993,(Z2)

根据热带西太平洋卫星云图资料及流场特征分析,讨论了南太平洋辐合带(SPCZ)的演变特征和形成机理。提出SPCZ是反映西太暖池同东太冷舌海气耦合系统以及暖池大气同相邻陆区大气间相互作用的重要特征。主要表现为在12～2月的热带西太平洋上的NW/SE辐合带,其形成原因主要应归因于西太暖池本身,以及暖池与东太赤道冷水舌强度与相对位置改变引发的Walker环流位置与走向的变动,另外,新几内亚岛及澳洲大陆也有重要影响。  相似文献   

The Agulhas Ridge, South Atlantic: The Peculiar Structure of a Fracture Zone     

Gabriele Uenzelmann-Neben  Karsten Gohl 《Marine Geophysical Researches》2004,25(3-4):305-319

The Agulhas Ridge is a prominent topographic feature that parallels the Agulhas-Falkland Fracture Zone (AFFZ). Seismic reflection and wide angle/refraction data have led to the classification of this feature as a transverse ridge. Changes in spreading rate and direction associated with ridge jumps, combined with asymmetric spreading within the Agulhas Basin, modified the stress field across the fracture zone. Moreover, passing the Agulhas Ridge’s location between 80 and 69 Ma, the Bouvet and Shona Hotspots may have supplied excess material to this part of the AFFZ thus altering the ridge’s structure. The low crustal velocities and overthickened crust of the northern Agulhas Ridge segment indicate a possible continental affinity that suggests it may be formed by a small continental sliver, which was severed off the Maurice Ewing Bank during the opening of the South Atlantic. In early Oligocene times the Agulhas Ridge was tectono-magmatically reactivated, as documented by the presence of basement highs disturbing and disrupting the sedimentary column in the Cape Basin. We consider the Discovery Hotspot, which distributes plume material southwards across the AAFZ, as a source for the magmatic material.  相似文献   

Seismic structure and tectonics of the Shackleton Fracture Zone (Drake Passage,Scotia Sea)     

Riccardo?Geletti  Emanuele?LodoloEmail author  Anatoly?A.?Schreider  Alina?Polonia 《Marine Geophysical Researches》2005,26(1):17-28

The structural framework of the southern part of the Shackleton Fracture Zone has been investigated through the analysis of a 130-km-long multichannel seismic reflection profile acquired orthogonally to the fracture zone near 60° S. The Shackleton Fracture Zone is a 800-km-long, mostly rectilinear and pronounced bathymetric lineation joining the westernmost South Scotia Ridge to southern South America south of Cape Horn, separating the western Scotia Sea plate from the Antarctic plate. Conventional processing applied to the seismic data outlines the main structures of the Shackleton Fracture Zone, but only the use of enhanced techniques, such as accurate velocity analyses and pre-stack depth migration, provides a good definition of the acoustic basement and the architecture of the sedimentary sequences. In particular, a strong and mostly continuous reflector found at about 8.0 s two-way traveltime is very clear across the entire section and is interpreted as the Moho discontinuity. Data show a complex system of troughs developed along the eastern flank of the crustal ridge, containing tilted and rotated blocks, and the presence of a prominent listric normal fault developed within the oceanic crust. Positive flower structures developed within the oceanic basement indicate strike-slip tectonism and partial reactivation of pre-existing faults. Present-day tectonic activity is found mostly in correspondence to the relief, whereas fault-induced deformation is negligible across the entire trough system. This indicates that the E–W-directed stress regime present in the Drake Passage region is mainly dissipated along a narrow zone within the Shackleton Ridge axis. A reappraisal of all available magnetic anomaly identifications in the western Scotia Sea and in the former Phoenix plate, in conjunction with new magnetic profiles acquired to the east of the Shackleton Fracture Zone off the Tierra del Fuego continental margin, has allowed us to propose a simple reconstruction of Shackleton Fracture Zone development in the general context of the Drake Passage opening.  相似文献   

山东省虎（Panthera tigris）化石的首次发现及其意义     

张祖陆 《海洋地质与第四纪地质》1994,14(1):69-74

本文祥详细记述了山东省首次发现的虎化石的特征及出土地点和剖面的基本情况，论证了化石出土地层剖面的时代，应当属于晚更新世，并阐明了该化石发现的意义。  相似文献   

从山羊寨哺乳动物化石看柳江盆地洞穴堆积的时代与环境   总被引：3，自引：0，他引：3  

牛平山  张燕君  法蕾 《海洋地质与第四纪地质》2003,23(2):117-122

山羊寨洞穴堆积是河北省秦皇岛“柳江盆地地质遗迹自然保护区”众多溶洞的洞穴堆积之一，其中含有大量的哺乳动物化石。经发掘整理与鉴定，采用生物地层学和哺乳动物生活习性对比分析方法，确定其时代为Qp^2.3，晚于辽宁营口“金牛山下组动物群”，早于河北“迁安爪村动物群”和内蒙古“萨拉乌苏动物群”，其特征反映了中国华北与东北过渡地带中更新世晚期至晚更新世早期的哺乳动物面貌，并反映出当时区内森林、森林草原、草原和水域条件等生态环境的多次时空变化。如此众多哺乳动物化石的发现增加了保护区遗迹资源的多样性和保护价值；为该区洞穴堆积的时代与沉积环境研究提供了依据；改变了区内洞穴堆积仅为中更新世地层的认识。  相似文献   

The permeability of faults within siliciclastic petroleum reservoirs of the North Sea and Norwegian Continental Shelf   总被引：1，自引：0，他引：1  

Q. J. Fisher  R. J. Knipe 《Marine and Petroleum Geology》2001,18(10):1315

Faulting in Middle Jurassic reservoirs occurred at shallow depth during regional extension. Clean sandstones (<15% clay) deformed without significant grain fracturing and permeability reduction. Faults in impure sandstones (15–40% clay) experienced significant syn-deformation compaction and permeability reduction. Enhanced compaction during deeper burial reduced their permeabilities further from an average of 0.05 mD at <2.5 km to 0.001 mD at >4 km. Clay-rich sediments (>40% clay) deformed to produce clay smears with very low permeabilities (<0.001 mD). Faulting in the Rotliegendes occurred at greater depth during both basin extension and inversion. Extensional faulting produced cataclasites with permeability reductions of <10–>10⁶; their permeabilities range from 0.2 to 0.0001 mD and are inversely related to their maximum burial depth. Faults formed or reactivated during inversion experienced permeability increase. These results can be extrapolated to other hydrocarbon reservoirs if differences in stress and temperature history are taken into account.The permeability of most (>80%) faults is not sufficiently low, compared to their wallrock, to retard single-phase fluid flow on a km-scale. Nevertheless, most faults could retard the flow of a non-wetting phase if present at low saturations. It may be necessary to incorporate the two-phase fluid flow properties of fault rocks into reservoir simulators using upscaling or pseudoisation techniques. Fault property data should be calibrated against production data before it can be used confidently.  相似文献