西沙海域南部多边形断层的发现及其分布特征与控制因素     

杨涛涛  吕福亮  王彬  杨志力  李丽  张强 《海相油气地质》2017,22(1)

根据新采集的三维地震资料,在西沙海域南部发现了多边形断层,其发育分布具有层控特征明显、在富泥地层中发育、多方位走向、纵向断距小、平面延伸长度小且形态为不规则多边形等特征。由于研究区东西两侧应力条件的差异,导致多边形断层发育特征的差异明显。通过对多边形断层发育控制因素的分析,认为地层岩性(特别是西沙海域上构造层的远源细粒沉积物)是其发育的主控因素之一,同时水道砂岩、成岩作用及构造作用等也是影响其发育分布的因素。多边形断层可以作为流体运移的通道,它与下部构造断层连接可将深部烃源岩中的油气运移到上部储层中聚集,或继续向上运移到浅部地层中形成天然气水合物。  相似文献   

A 3D structural analysis of the Goliat field,Barents Sea,Norway     

《Marine and Petroleum Geology》2017

The Goliat field consists of Middle to Late Triassic reservoirs which exploit an elongate anticline (the Goliat anticline) in the hanging wall of the Troms-Finnmark Fault Complex (TFFC), offshore Norway. The area is affected by a dense network of multiple trending fault populations which historically have inhibited seismic resolution owing to persistent fault shadow. Seismic investigations utilising a multi-azimuth three-dimensional survey (EN0901) allow much crisper delineation of seismic features previously unattainable by vintage single-azimuth surveys. Three dominant fault populations are identified in the area, two of which parallel TFFC segments, the Alke–Goliat (WSW–ENE) and the Goliat–Tornerose (NNE–SSW) segments. The Goliat field is located within a zone of intersection between both segments. A third E–W trending fault population, the Hammerfest Regional population, is likely influenced by the offshore extension of the Trollfjord-Komagelv Fault Complex (TKFZ). A local NW–SE trending fault population, the Goliat Central, affects the Goliat anticline and partitions Alke–Goliat and Goliat–Tornerose subsidiary faults resulting in curvilinear traces. Several cross-cutting relationships between fault populations are observed and may provide fluid compartmentalisation in the reservoirs. Compilation of regional transects and the EN0901 survey provides new insight into the evolution of the Goliat anticline which is underlain by a fault-bound basement terrace that became established in the Late Palaeozoic. The structure is interpreted to have formed due to vertical segmentation of the TFFC and cores the overlying broad anticline. The western limb of the Goliat anticline likely formed by differential compaction, whereas the eastern limb is primarily a result of hanging wall roll-over linked to variable listric to ramp-flat-ramp fault geometry. Rifting took place in the Palaeozoic (Carboniferous to Permian?), and in the Mesozoic, possibly as early as the Late Triassic, with a major event in the Late Jurassic to Early Cretaceous. Minor reactivations continued into the Late Cretaceous, and possibly the Early Cenozoic. Mesozoic syn-kinematic geometries in the hanging wall of the Goliat–Tornerose TFFC segment are consistent with deposition during up section propagation of a blind fault, over which, a monocline was established and later breached. Jogs (abrupt orientation changes) in fault traces, transverse folds (associated with displacement maxima/minima) and vertical fault jogs suggest the TFFC existed as a greater number of segments prior to amalgamation during the Late Triassic to Jurassic. A phase of Barremian inversion created local compression structures above blind extensional faults, and deeper seated buttressing against large faults. Polygonal faults affect the Late Cretaceous to Early Cenozoic successions.  相似文献   

Examining fault architecture and strain distribution using geospatial and geomechanical modelling: An example from the Qaidam basin,NE Tibet     

《Marine and Petroleum Geology》2017

The investigation of complex geological setting is still dominated by traditional geo-data collection and analytical techniques, e.g., stratigraphic logging, dip data measurements, structural ground mapping, seismic interpretation, balance section restoration, forward modelling, etc. Despite the advantages of improving our understanding in structural geometry and fault architecture, the geospatial modelling, applying computer-aided three-dimensional geometric design, visualization and interpretation, has rarely been applied to such complex geological setting. This study used the Lenghu fold-and-thrust belt (in Qaidam basin, NE Tibetan Plateau) to demonstrate that the application of geospatial and geomechanical modelling could improve our understanding and provide an effective technique for investigating the fault architecture and strain distribution. The three-dimensional configuration of the Lenghu fold-and-thrust belt was initially derived from traditional analysis techniques, such as regional stratigraphic logging, cross section construction, meso-scale ground mapping and landsat image interpretation. The high-resolution field data and landsat image were integrated to construct the geospatial model, which was subsequently used to quantitatively investigate the fault throw changes along the Lenghu thrust fault zone and to understand its control on the lateral structural variation. The geospatial model was then restored in three dimensions to reveal the kinematic evolution of the Lenghu fold-and-thrust belt. Geomechanical modelling, using a Mass-Spring algorithm, provided an effective three-dimensional tool for structural strain analysis, which was used to predict the strain distribution throughout the overall structure, e.g., normal faults with throws ranging from meters to tens of meters in the hanging-wall. The strain distribution predicted by geomechanical modelling was then validated by the natural normal faults in the hanging-wall. The high accordance between the strain prediction and statistics of natural normal faults demonstrates good applicability of geospatial and geomechanical modelling in the complex geological setting of the Lenghu fold-and-thrust belt. The geospatial models and geomechanical models, therefore, can provide a robust technique for analyzing and interpreting multi-source data within a three-dimensional environment. We anticipate that the application of three-dimensional geospatial modelling and geomechanical modelling, integrating both multi-source geologic data and three-dimensional analytical techniques, can provide an effective workflow for investigating the fault architecture and strain distribution at different scales (e.g., ranging from regional-to meso-scale).  相似文献   

New insights into the carbonate karstic fault system and reservoir formation in the Southern Tahe area of the Tarim Basin     

《Marine and Petroleum Geology》2017

As worldwide hydrocarbon exploration has extended from shallowly to deeply buried strata, reservoir quality has attracted substantial and persistent interest in petroleum geology. In particular, deeply buried strata (>5500 m) in the Tarim Basin have attracted considerable attention because carbonate reservoirs that have experienced fracture or dissolution have also been shown to demonstrate considerable hydrocarbon potential. Therefore, it is necessary to determine how these reservoirs are developed and distributed in detail from both scientific and practical standpoints.In this paper, we address this issue using a case study in the southern Tahe area, which is contained within the largest Palaeozoic marine oilfield in China. In the northern Tahe area, mega-paleokarst systems developed in the Ordovician strata; however, the reservoir quality in the southern part of the Tahe area is relatively poor because it is covered by insoluble formations during karstification. Observations of cores and analyses of images of well logging demonstrate that these reservoirs are dominated by caves, vugs and fractures that have developed near faults. We speculate that the faults penetrating insoluble formations represent the main dissolution passages that originally developed these karstic fault systems. Additionally, we analyse a series of outcrops, seismic data, and structures to characterize the spatial geometry of these major faults and their surrounding fractures in detail. Most of these are strike-slip faults, and their subsequent reservoirs can be divided into three categories based on their development, including dendritic, sandwich and slab reservoirs. Recent studies demonstrate that karstic fault reservoirs are most common traps in the study area. Although various types of carbonate karstic fault reservoirs are represented in this region, the dendritic karstic fault reservoir is the most hydrocarbon-rich.Guided by these initial results, 108 wells were drilled from 2013 to 2014, producing 485 thousand tons of oil and yielding success ratios greater than 89%. The average production of dendritic reservoirs is 37.4 tons per day (t/d), while those of sandwich and slab types are 20.2 t/d and 14.0 t/d, respectively. These results represent significant references for future hydrocarbon exploration and the development of similar deeply buried karstic fault reservoirs in the Tarim Basin and elsewhere.  相似文献   

Geochemistry and origin of organic-rich sediment veins in fractured granitic basement,Helmsdale, Sutherlandshire,UK     

《Marine and Petroleum Geology》2017

Black sediment veins up to 2 cm width penetrate the Caledonian Helmsdale Granite in the vicinity of the Helmsdale Fault, onshore Moray Firth. The black colour and geochemistry of the veins reflect a high content of organic carbon. Both Devonian and Jurassic shales are conceivable available sources, but sterane compositions relate the organic matter to the Jurassic shales. A content of extractable organic matter higher than in the shales suggests that the carbon in the veins represents oil rather than mechanically mobilized shale. The oil was present during sediment vein emplacement. The veins were emplaced forcefully, which may reflect high fluid pressure associated with post-Jurassic movement on the Helmsdale Fault.  相似文献   

芦山地震前后龙门山断裂带西南段地应力状态对比分析   总被引：2，自引：0，他引：2       下载免费PDF全文

邱君  吴满路  范桃园  张重远  李冉  陈利忠 《地质学报》2017,91(5):969-978

2013年4月20日芦山Ms7.0级地震后,为研究龙门山断裂带西南段震后的地应力状态,应用水压致裂法和压磁应力解除法在该区开展了2个钻孔的原地应力测量工作。测量结果显示硗碛测点在128～188m深度范围内最小水平主应力的量值为10.47～18.47 MPa,最大水平主应力的量值为19.60～25.83 MPa,方向为N63°～85°W;天全测点在114～142m深度范围内最小水平主应力的量值为5.20～7.73 MPa,最大水平主应力的量值为8.21～9.31 MPa,方向为N59°W。两个测点水平主应力与垂直应力的关系均为σ_Hσ_hσ_v,其中硗碛测点最大、最小水平主应力与垂直应力比值的平均值分别为5.27和3.01,天全测点最大、最小水平主应力与垂直应力比值的平均值分别为2.60和1.76,表明有利于逆断层活动。通过比较该地区芦山地震前后实测地应力状态,发现芦山地震后,龙门山断裂带西南段的北段(即邛崃大邑西-宝兴北-汶川南一带)和南段(即天全-荥经-泸定-康定一带)应力积累量增加。相同深度范围内,北段硗碛测点震后的应力大小要比地震前有明显的提高,这也与硗碛测点地应力监测结果一致。实测应力方向与震前基本一致,都为NW-NWW。基于实测地应力资料,根据库伦破裂准则和Byerlee定律分析,位于北段的硗碛测点震前部分压裂段的最大水平主应力处于使断层滑动临界值的上下限之间,而地震后最大水平主应力则均已超过断层滑动临界值的上限。位于南段的飞仙关测点震前最大水平主应力均未达到断层滑动临界值的下限,而地震后天全测点的最大水平主应力则均处于使断层滑动临界值的上下限之间。采用最大剪应力(σ_1-σ_3)/2与平均应力(σ_1+σ_3)/2的比值μ_m(断层摩擦)参数评估研究区地应力的积累水平和地震危险性。震前硗碛测点μ_m的量值为0.16～0.72,平均为0.50,震后为0.71～0.81,平均为0.77。震前飞仙关测点μ_m的量值为0.31～0.35,平均值为0.32,震后天全测点μ_m的量值为0.53～0.57,平均值为0.55,两个研究区的μ_m的量值均变大。分析认为芦山地震后龙门山断裂带西南段的北段和南段的应力积累量增加,都有发生断层滑动的可能性,尤其是北段。  相似文献   

川滇黔地区铅锌矿床稳定同位素地球化学研究现状综合分析   总被引：2，自引：0，他引：2  

仲文斌  张均  王健  杨青  张哲坤  程元路 《矿床地质》2017,36(1):200-218

川滇黔接壤区是中国重要的铅锌多金属成矿区,目前已经发现了会泽、天宝山、大梁子等超大型-大型铅锌矿床。文章通过系统总结分析区域内铅锌矿床稳定同位素(C、H、O、S同位素)数据,结合区域构造控矿特征,表明成矿热液的碳、氧主要来源于碳酸盐岩围岩,个别矿床可能有有机碳或幔源碳参与成矿作用。黔西北地区从靠SE侧威宁-水城构造带上的铅锌矿床至NW侧垭都-蟒硐构造带上的铅锌矿床,方解石的δ~(13)CV-PDB值从0.6‰~2.5‰转变为-5.3‰~1.5‰,δ18OV-SMOW值从23.3‰~25.5‰转变为11.3‰~20.9‰,均显示出逐渐变小的趋势;SN向小江断裂带内各矿床表现出线性关系,并且具有向δ~(13)CV-PDB、δ~(18)OV-SMOW都亏损的方向偏移趋势,NE向断裂带内的各矿床C、O同位素则表现为集中一致的分布特征。H、O同位素显示成矿流体具有建造水(热卤水和油田卤水)特征,部分可能有大气降水、变质水和岩浆水参与成矿作用。矿床硫源主要为同时代海水硫酸盐的热化学还原(TRS)形成的还原硫,个别矿床细菌还原硫酸盐(BSR)形成的富含轻硫的油气藏中的H2S可能为成矿过程提供了部分硫来源。黔西北地区铅锌矿床S同位素组成具有从SE侧至NW侧向轻硫方向偏移的趋势,SN向小江断裂带内铅锌矿床S同位素组成较为集中一致,NE方向断裂带内铅锌矿床S同位素则具有从SW侧至NE侧向轻硫方向偏移的趋势,TSR的反应强度和反应速率降低可能是导致向轻硫方向偏移的重要原因之一。  相似文献   

岱崮地貌的基本特征、成因和演化          下载免费PDF全文

王 萌 李 理 周雄杰 王 博游远征  戴伊宁李 圯 辛 文 《地质科学》2017,(2):628-636

岱崮地貌是一种寒武系碎屑岩之上的平顶灰岩地貌,为中国五大地貌之一,对其研究具有地质学、古地理环境等科学意义。本文通过野外地质调查及室内研究,分析研究了岱崮地貌的特征、成因和演化,得出以下结论：1） 岱崮镇的崮主体呈NW向展布,由崮体和崮基组成。崮体包括崮顶、崮腰和崮底,崮顶为灰岩,崮腰和崮底以碎屑岩为主,崮基为前寒武系岩浆岩或太古宇泰山群;2） 近水平岩层是岱崮地貌发育的基础;3） NNW向、NW向和近EW向断层是岱崮地貌形成的根本因素,NW向和NE 向节理是主控因素,控制了岱崮地貌的走向、密度;4） 岱崮地貌古生代以来经历了多个时期的演化,经过加里东运动、海西运动和印支运动留存的寒武系-中奥陶统、上石炭统-二叠系是岱崮地貌形成的基础,燕山期中侏罗世末-晚侏罗世（162～149.8 Ma）、白垩纪（140～90 Ma）及喜马拉雅早期（65～43 Ma）产生的断层及节理是岱崮地。  相似文献   

Geomorphic appraisals of active tectonics associated with uplift of the Gohpur–Ganga section in Itanagar, Arunachal Pradesh, India     

R.K. Mrinalinee Devi   《Geomorphology》2008,99(1-4):76-89

The Gohpur–Ganga section is located southwest of Itanagar, India. The study area and its adjacent regions lie between the Main Boundary Thrust (MBT) and the Himalayan Front Fault (HFF) within the Sub-Himalaya of the Eastern Himalaya. The Senkhi stream, draining from the north, passes through the MBT and exhibits local meandering as it approaches the study area. Here, five levels of terraces are observed on the eastern part, whereas only four levels of terraces are observed on the western part. The Senkhi and Dokhoso streams show unpaired terraces consisting of very poorly sorted riverbed materials lacking stratification, indicating tectonic activity during deposition. Crude imbrications are also observed on the terrace deposits. A wind gap from an earlier active channel is observed at latitude 27°04′42.4″ N and longitude 93°35′22.4″ E at the height of about 35 m from the present active channel of Senkhi stream. Linear arrangements of ponds trending northeast–southwest on the western side of the study section may represent the paleochannel of Dokhoso stream meeting the Senkhi stream abruptly through this gap earlier. Major lineament trends are observed along NNE–SSW, NE–SW and ENE–WSW direction. The Gohpur–Ganga section is on Quaternary deposits, resting over the Siwaliks with angular contact. Climatic changes of Pleistocene–Holocene times seem to have affected the sedimentation pattern of this part of the Sub-Himalaya, in association with proximal tectonism associated with active tectonic activities, which uplifted the Quaternary deposits. Older and younger terrace deposits seem to mark the Pleistocene–Holocene boundary in the study area with the older terraces showing a well-oxidized and semi-consolidated nature compared to the unoxidized nature of the younger terraces.  相似文献   

The Relationship between Fe Mineralization and Magnetic Basement Faults using Multifractal Modeling in the Esfordi and Behabad Areas (BMD), Central Iran     

Masoumeh NABILOU  Peyman AFZAL  Mehran ARIAN  Ahmad ADIB  Hassan KHEYROLLAHI  Mohammad FOUDAZI  Parviz ANSARIRAD 《《地质学报》英文版》2022,96(2):591-606

Multifractal modeling is a mathematical method for the separation of a high potential mineralized background from a non-mineralized background. The Concentration-Distance to Fault structures (C-DF) fractal model and the distribution of the known iron (Fe) deposits/mines seen in the Esfordi and Behabad 1:100,000 sheets from the Bafq region of central Iran are used to distinguish Fe mineralization based on their distance to magnetic basement structures and surface faults, separately, using airborne geophysical data and field surveys. Application of the C-DF fractal model for the classification of Fe mineralizations in the Esfordi and Behabad areas reveals that the main ones show a correlation with their distance from magnetic basement structures. Accordingly, the distances of Fe mineralizations with grades of Fe higher than 55% )43% < Fe ≤ 60%) are located at a distance of less than 1 km, whereas for surfacial faults with grades of 43% ≤ Fe ≤ 60%, the distances are 3162< DF ≤ 4365 m from the faults. Thus, there is a positive relationship between Fe mineralization and magnetic basement structures. Also, the proximity evidence of Precambrian high-grade Fe mineralization related to magnetic basement structures indicates syn-rifting tectonic events. Finally, this C-DF fractal model can be used for exploration of magmatic and hydrothermal ore deposits.  相似文献