Bioclastic sediment lobes on a supply dominated Upper Cretaceous carbonate platform margin, Montagna della Maiella, Italy

A thick bioclastic sediment wedge was deposited on the slope of the Maiella carbonate platform margin in the Late Campanian to Late Maastrichtian. The wedge consists of lobate depositional units (laterally and vertically convex structures). The complex internal geometries of the lobes combine characteristics of unidirectional sandwaves and the alternating point-sources of deltas. Excellent outcrop permits a detailed documentation and discussion of the depositional processes.
The sediment wedge constitutes a supersequence, which prograded along the platform margin as a result of high sediment supply and forced regression. Within the supersequence, a hierarchy of higher-order stratigraphic units (sequence sets and sequences) are developed. The individual bioclastic sediment lobes are interpreted as systems tracts and parasequences of the sequences within the sequence sets.     

塔里木盆地上新世晚期—更新世早期伸展构造:喜马拉雅碰撞造山远程效应的一个构造间歇期

受控于印度-亚洲碰撞的远程效应,中亚地区的晚新生代挤压冲断构造异常发育,同时发育少量区域挤压构造背景下派生的局部伸展构造。以往的研究没有发现晚新生代区域性伸展构造。我们通过认真、系统的地震资料解释,在塔里木盆地发现一系列上新世晚期-更新世早期的正断层。这些正断层主要分布于塔里木盆地西部的阿瓦提坳陷、巴楚隆起、麦盖提斜坡以及塘古孜巴斯坳陷。正断层走向NW-SE和NE-SW,剖面上组合成堑-垒构造,仅塔里木盆地西北缘沿沙井子断裂带分布的上新世晚期-更新世早期正断层带组合成负花状构造,显示出张扭性断层带的特征。根据生长指数计算,正断层活动的起始时间是上新世晚期（ca.3 Ma）,持续演化至更新世早期（ca.2 Ma）,然后停止活动。这些正断层形成于一个弱的区域性伸展构造背景;这期正断层活动代表印度-亚洲碰撞远程效应下,中亚地区脉动挤压冲断过程中的一个构造间歇期。     

Propagation of brittle failure triggered by magma in Iceland

The architectures of normal faults at a divergent plate boundary in Iceland are examined by combining surface fault observations with cross-sectional studies at different structural levels to constrain a model of failure propagation. The structures of Holocene faults defining graben are analyzed to characterize the upper-most parts of ruptures. The shapes of faults resulting from growth and interaction of separate segments are used to better understand failure propagation inferred to occur in the intervening stages of displacement accumulation and lateral propagation. Pleistocene faults in volcanic sequences exhumed from 800 to 1000 m are analyzed to characterize deeper portions of failure that occurred beneath the central rift zone. Tertiary dikes exhumed from depths of 1300–1500 m are studied to infer how magma controls the failure initiation. Field studies in combination with a literature review indicate that the planar ruptures are likely to initiate at depth as magma-filled vertical fractures and lengthen upward and laterally. As failures propagate to higher crustal levels, they are likely to change into inclined normal faults. At near-surface levels, faults link with cooling joints and dilational fractures propagating downward from the surface. It is suggested that the inferred stages of fault propagation are characteristic for normal faults developed at spreading ridges.     

An evaluation of models for the kinematic evolution of thrust and fold belts: structural analysis of a transverse fault zone in the Front Ranges of the Canadian Rockies north of Banff,Alberta

The prevailing ‘piggyback’ conceptual model for the kinematics of ‘thin-skinned’ thrust and fold belts maintains that the main faults develop sequentially from the hinterland to the foreland, and from the top to the bottom of the accretionary wedge. Moreover, it presumes that when younger thrust faults originate, overlying older thrust faults become inactive and are carried forward passively. This appears to contradict the prevailing mechanical model for the evolution of ‘thin-skinned’ thrust and fold belts, the critical Coulomb wedge model, which requires that lateral growth of the wedge must be accompanied by vertical thickening of the wedge. Crosscutting relationships along a transverse fault zone in the Front Ranges of the Canadian Rockies north of Banff, Alberta, and patterns of overprinting of thrust-related folding on pre-existing thrust sheets, demonstrate substantial overlap in the times of displacement on four major thrust faults in this part of the Front Ranges. The presumption that displacement on one major thrust fault ends when displacement on a younger underlying thrust begins is a fallacy. There is no contradiction between the ‘piggyback’ conceptual kinematic model and the critical Coulomb wedge mechanical model for the evolution of ‘thin-skinned’ foreland thrust and fold belts. The main faults do originate sequentially from the hinterland to the foreland, and from the top to the bottom of the evolving wedge; but displacement occurs simultaneously on several major faults.     

Structural architecture of the Owen Conglomerate,West Coast Range,western Tasmania: field evidence for Late Cambrian extension.

The Owen Conglomerate comprises coarse-grained siliciclastics that were deposited in response to Late Cambrian extension. The identification of normal faults that host thickened accumulations of siliciclastics is used here to support interpretation of syn-fill extension. Local mapping and section construction have identified a series of north-trending, en échelon, segmented normal faults that exhibit changes in along-strike polarity. The Late Cambrian faults are adjacent to sedimentary packages that define half-graben geometries, with an unconformity that defines basal contacts with underlying Mt Read Volcanics and onlap geometries onto the opposing basin margin. Faults that were active during deposition of the Owen Conglomerate were subsequently reversed during D₁ Middle Devonian deformation, with reverse displacement controlling the development of inversion structures defined by north-trending fold structures. Pervasive northwest-trending D₂ deformation extensively overprints earlier deformation features, and has led to the spectacular development of type 1 interference patterns that largely control outcrop distributions along the West Coast Range. Field evidence is documented in support for a simple structural history that accounts for geometries associated with Late Cambrian extension, prior to Middle Devonian inversion (D₁) and subsequent shortening (D₂).     

塔里木盆地顺托果勒地区早中志留世震积岩——高分辨构造事件的记录

在塔里木盆地塔中隆起与满加尔坳陷结合部——顺托果勒地区的深钻井岩心中,发现了大量早中志留世软沉积变形构造。其中主要包括液化砂岩脉、液化角砾岩、触变底劈构造、触变楔、负载构造、球-枕构造和复合混插构造等。通过系统地观察软沉积变形构造的岩石组成、构造形貌及样式、垂向分布的循环性、横向分布的延展性、沉积环境及与古活动断裂的关系,确定其为震积岩。结合该区断裂早中志留世的发育特征,推测发震断裂主要可能是塔中隆起与满加尔坳陷结合部的北东向走滑逆冲断裂以及北西向剪切拉张断裂。在早志留世柯坪塔格组沉积时约4 Ma中最少发生了26次古地震事件(震级M5)。这些古地震记录不仅反映了研究区志留纪构造的活动性,也是弥补主构造运动中高频次构造事件脉动性、循环性的重要证据,为重建中古生代的古构造提供新的线索。     

滇西北北衙斑岩型金多金属矿床万硐山矿段构造控岩控矿作用机制

滇西北北衙金多金属矿床是西南"三江"多金属成矿带新生代斑岩型矿床的典型代表,是近些年来取得找矿突破的超大型金多金属矿床。运用矿田地质力学的理论和方法,通过大比例尺构造剖面精测,进行典型控岩控矿构造力学性质的鉴定,分析构造对斑岩成岩和成矿作用的控制机制。认为北衙金多金属矿床万硐山矿段自燕山晚期–喜马拉雅早期以来主要经历了近EW向→近SN向→近EW向三期构造主压应力的转变,形成了典型的褶皱–断裂–节理控岩控矿构造系统。构造控岩控矿过程为:燕山晚期–喜马拉雅早期,在近EW向主压应力作用下,形成北衙矿区控岩控矿构造格架,为斑岩侵位和成矿作用发生提供了有利的成岩成矿构造环境,并伴有石英钠长斑岩的侵位;喜马拉雅中期,主压应力方向转变为近SN向,伴随构造活动发生石英正长斑岩的超浅成侵位和成岩作用,并发生斑岩型金成矿作用,在层间断裂破碎带、断裂带及节理构造内形成带状、"似层状"和脉状金矿体,在岩体内形成斑岩型浸染状金矿体,在斑岩与围岩接触带形成矽卡岩型金矿体;喜马拉雅晚期,本区再次经受近EW向挤压作用,主要对先期形成的斑岩和金矿体产生变形、变位,并造成风化剥蚀,成矿作用主要表现为氧化淋滤富集型金矿的形成。     

The Aosta–Ranzola extensional fault system and Oligocene–Present evolution of the Austroalpine–Penninic wedge in the northwestern Alps

Post-nappe brittle structures across the Austroalpine-Penninic wedge are representative of two principal deformation stages. The former (D1) developed during the Late Oligocene, the latter (D2) from the Miocene to the Present. Major D1 features are the E-W Aosta-Ranzola half-graben and the NE-SW Ospizio Sottile subvertical normal fault system. Oligocene extension was also characterized by hydrothermal activity and intrusion of calc-alkaline to ultra-potassic dikes. From the Miocene onwards (D2), the Ospizio Sottile system was re-activated as a SE sinistral boundary of the Pennine-Graian Alps block of nappes, bodily moving away from the Simplon detachment to the SW. Inside the escaping block, a number of D2 slightly diverging sublatitudinal splays (Aosta-Piccolo San Bernardo system) was generated, as well as a regular set of NW-trending normal faults from the Simplon to the Gran Paradiso massif. Instead, the Aosta-Ranzola system was poorly reworked in that time. More generally, the short-lived Oligocene extension (D1) was associated to slab break-off of lower plate, wedge rebound, rapid uplift and thermal perturbation. From the Early Miocene onwards the Oligocene extension was replaced by renewed compression, allowing the vertical extrusion of the Lepontine dome and lateral escape of the overlying Pennine-Graian Alps block.     

Coarse-grained sediment gravity flow facies in a large supraglacial lake

Near Williams Lake, in the central interior of British Columbia, the Fraser River exposes long sections of late Pleistocene glaciolacustrine sediments selectively preserved within a bedrock trough. The dominant facies types are thick, normally graded gravels and sands that occupy steeply dipping multistorey channels up to 300 m wide and several tens of metres deep. Channels appear to have been simultaneously cut and filled by high density turbidity currents in a glacial lake floored by stagnant ice. Fining upward sediment gravity flow sequences up to 50 m thick may be the product of quasi-continuous ‘surging’ turbidity flows triggered by catastrophic meltwater discharges into the trough or retrogressive failure of ice-cored sediments. Large-scale post-depositional deformation structures, such as synclinal folds, normal faults, sedimentary dyke swarms and dewatering structures, record gravitational foundering of sediment and pore-water expulsion caused by the melt of underlying glacier ice. Melting of buried ice masses along the floor of the trough appears to have controlled the flow paths of turbidity currents by producing sub-basins within the overlying sediment pile. An idealized model of ‘supraglacial’ lacustrine sedimentation is developed that may be applicable to other glaciated areas with similar bedrock topography.     

Opposed shear senses inferred from neotectonic mesofracture systems in the North Anatolian fault zone

The 1200-km long North Anatolian fault zone is a right-lateral, intracontinental transform boundary which was initiated in the Late Neogene. Sediments of Pliocene to Holocene age in basins between Cerkes and Erbaa, within the convex-northwards arc of the fault zone, are deformed by syn-sedimentary and post-depositional mesoscopic faults and joints. The mesofractures, which strike obliquely to the fault zone, include reverse faults, normal faults, normal shear joints, conjugate vertical joints and strike-slip faults. Each type of structure occurs in two geometrical groups, one comprises four systems of fractures, the other is made up of five systems. The directions of secondary compression and/or extension inferred from the first group of mesofractures, which are restricted to sediments of Pliocene to Early Pleistocene age, are interpreted as being related to left-lateral shear along the North Anatolian fault zone. The directions of compression and/or extension inferred from the second group of mesofractures, which cut sediments of Pliocene to late Holocene age, were generated during right-lateral shear.The presence of the second group of mesofractures is understandable because they are related to the shear sense which operates at the present-day, but those interpreted as being related to left-lateral shear are more puzzling: their development implies one or more reversals of the dominant sense of displacement. Several tentative models to explain such reversals are proposed, including regional and local influences, the latter related to mechanical constraints and/or the effects of other fault systems.     

塔里木盆地晚志留世-石炭纪伸展构造的发现及其地质意义

通过精细的地震资料解释,在塔里木盆地中部的满西地区发现晚志留世-石炭纪伸展构造。伸展构造由一系列规模不大的正断层组成,平面上组成两条北东-南西向的左行雁列状正断层带,剖面上构成负花状构造和堑垒构造。根据生长系数计算结果,正断层形成于晚志留世,在泥盆纪和石炭纪持续活动,于石炭纪末停止活动。正断层活动的高峰期为晚志留世。该期伸展构造在塔中和塔北地区也有发育,反映当时塔里木盆地处于区域性伸展构造背景。塔里木盆地晚志留世-石炭纪的伸展构造,是昆仑早古生代晚期（晚奥陶世-中志留世）碰撞造山后构造应力松弛作用的产物。     

河南南召盆地上三叠统太山庙组软沉积物变形构造及其古地理意义*

河南南召盆地上三叠统太山庙组中发现的软沉积物变形构造包括同沉积断层、液化均一层与泄水脉、底劈构造、塑性变形层、碎裂岩及大型负载构造。它们集中保存在太山庙组中段深湖环境中,以该层段为界,其下水体渐深,其上水体渐浅。多数软沉积物变形构造与浊流沉积砂体相伴生,也可保存在泥岩层中,其形成可能与浊流沉积过程相关,但古地震活动是主要的触发机制。软沉积物变形的类型包括液化变形、塑性变形和脆性变形,指示了高强度的古地震活动,记录了秦岭造山带印支期一次强烈的造山活动。造山带逆冲推覆作用造成南召盆地的抬升,代表了前陆盆地系统中的楔顶沉积。     

海南抱伦矿区构造变形、成矿时代与金矿化关系研究

抱伦金矿床位于海南岛西南部乐东县境内,是一个以石英脉型为主的大型金矿床。野外地质调查表明,矿区大致经历了三期构造变形:早期(D1)NE向褶皱,中期(D2)NNW向褶皱和剪切变形,晚期(D3)脆性断层和节理。其中,中期的NNW向右行剪切变形为金矿体的赋存提供了主要空间,金矿化主要发生于三个不同的阶段,以第一阶段(自然金-Q2石英阶段)最为重要,形成了大量自然金,为主要矿化阶段。对切割矿体的细晶岩脉中锆石的定年研究表明,抱伦金矿化主要与印支期尖峰岭花岗岩浆活动有关,而与燕山晚期岩浆活动关系不大。     

Appinite suites and their genetic relationship with coeval voluminous granitoid batholiths

ABSTRACT

Appinite complexes preserve evidence of mantle processes that produce voluminous granitoid batholiths. These plutonic complexes range from ultramafic to felsic in composition, deep to shallow emplacement, and from Neo-Archean to Recent in age. Appinites are a textural family characterized by idiomorphic hornblende in all lithologies, and spectacular textures including coarse-grained mafic pegmatites, fine-grained ‘salt-and-pepper’ gabbros, as well as planar and linear fabrics. Magmas are bimodal (mafic-felsic) in composition; ultramafic rocks are cumulates, intermediate rocks are hybrids. Their geochemistry is profoundly influenced by a mantle wedge extensively metasomatized by fluids/magmas produced by subduction. Melting of spinel peridotite sub-continental lithospheric mantle (SCLM) produces appinites whose geochemistry is indistinguishable from coeval low-K calc-alkalic arc magmatism. Coeval felsic rocks within appinite complexes and adjacent granitoid batholiths are crustal magmas. When subduction terminates, asthenospheric upwelling (e.g. in a slab window, or in the aftermath of slab failure) induces melting of metasomatized garnet SCLM to produce K-rich sho shonitic magmas enriched in large ionic lithophile and light relative to heavy rare earth elements, whose asthenospheric component can be identified by Sm-Nd isotopic signatures. Coeval late-stage Ba-Sr granitoid magmas have a ‘slab failure’ geochemistry, resemble TTG and adakitic suites, and are formed either by fractionation of an enriched (shoshonitic) mafic magma, or high pressure melting of a meta-basaltic protolith either at the base of the crust or along the upper portion of the subducted slab. Appinite complexes may be the crustal representation of mafic magma that underplated the crust for the duration of arc magmatism. They were preferentially emplaced along fault zones around the periphery of the granitoid batholiths (where their ascent is not blocked by overlying felsic magma), and as enclaves within granitoid batholiths. When subduction ceases, appinite complexes with a more pronounced asthenospheric component are preferentially emplaced along active faults that bound the periphery of the batholiths.     

Formation and growth of normal faults at the divergent plate boundary in Iceland

The divergent plate boundary in Iceland is characterized by 40–80 km long and 5–10 km wide swarms of tension fractures (∼10² m long) and normal faults (∼10³ m long). The upper part of the crust is mainly composed of lava flows, with abundant columnar joints that are mostly perpendicular to the lava contacts. The lava flows are horizontal at the surface of the rift zone but become tilted at the rate of 1° for every 150 m depth in the crust. At the surface of the rift zone the joints are vertical and parallel to the vertical principal stress. Because of tilting of the lava pile, the columnar joints become oblique to this stress, hence becoming potential shear fractures, and form echelon sets at greater depths in the crust. Theoretical considerations suggest that normal faults start to nucleate on sets of en echelon columnar joints and/or large-scale tension fractures at crustal depths of 0.5–1.5 km. The width (depth) must be the smallest (controlling) dimension of many faults. Nevertheless, there is a positive linear relation (r = 0.91) between maximum throw and length of the Holocene faults. If the faults grow as self-similar structures, the throw-length relationship can be explained by a similar relation between fault length and width.     

Structural geometry of orogenic gold deposits: Implications for exploration of world-class and giant deposits

With very few exceptions, orogenic gold deposits formed in subduction-related tectonic settings in accretionary to collisional orogenic belts from Archean to Tertiary times. Their genesis, including metal and fluid source, fluid pathways, depositional mechanisms, and timing relative to regional structural and metamorphic events, continues to be controversial. However, there is now general agreement that these deposits formed from metamorphic fluids, either from metamorphism of intra-basinal rock sequences or de-volatilization of a subducted sediment wedge, during a change from a compressional to transpressional, less commonly transtensional, stress regime, prior to orogenic collapse. In the case of Archean and Paleoproterozoic deposits, the formation of orogenic gold deposits was one of the last events prior to cratonization. The late timing of orogenic gold deposits within the structural evolution of the host orogen implies that any earlier structures may be mineralized and that the current structural geometry of the gold deposits is equivalent to that at the time of their formation provided that there has been no significant post-gold orogenic overprint. Within the host volcano-sedimentary sequences at the province scale, world-class orogenic gold deposits are most commonly located in second-order structures adjacent to crustal scale faults and shear zones, representing the first-order ore-forming fluid pathways, and whose deep lithospheric connection is marked by lamprophyre intrusions which, however, have no direct genetic association with gold deposition. More specifically, the gold deposits are located adjacent to ～10°-25° district-scale jogs in these crustal-scale faults. These jogs are commonly the site of arrays of ～70° cross faults that accommodate the bending of the more rigid components, for example volcanic rocks and intrusive sills, of the host belts. Rotation of blocks between these accommodation faults causes failure of more competent units and/or reactivation and dilation of pre-existing structures, leading to deposit-scale focussing of ore-fluid and gold deposition.Anticlinal or antiformal fold hinges, particularly those of 'locked-up' folds with ～30° apical angles and overturned back limbs, represent sites of brittle-ductile rock failure and provide one of the more robust parameters for location of orogenic gold deposits.In orogenic belts with abundant pre-gold granitic intrusions, particularly Precambrian granitegreenstone terranes, the boundaries between the rigid granitic bodies and more ductile greenstone sequences are commonly sites of heterogeneous stress and inhomogeneous strain. Thus, contacts between granitic intrusions and volcano-sedimentary sequences are common sites of ore-fluid infiltration and gold deposition. For orogenic gold deposits at deeper crustal levels, ore-forming fluids are commonly focused along strain gradients between more compressional zones where volcano-sedimentary sequences are thinned and relatively more extensional zones where they are thickened. World-class orogenic gold deposits are commonly located in the deformed volcano-sedimentary sequences in such strain gradients adjacent to triple-point junctions defined by the granitic intrusions, or along the zones of assembly of micro-blocks on a regional scale. These repetitive province to district-scale geometrical patterns of structures within the orogenic belts are clearly critical parameters in geology-based exploration targeting for orogenic gold deposits.     

塔里木盆地顺南地区走滑断裂发育特征及演化

顺南地区位于塔里木盆地塔中隆起北部.受多期构造应力影响,该地区以走滑断裂大量发育为典型特征.对三维地震资料的精细解释和深入分析结果表明,研究区走滑断裂具有垂向分层、平面分段、多期次构造叠加的特征.顺南地区主要发育北东、北东东和北西向3组走滑断裂.北东向断裂活动性强,平面上发育雁列式断层及马尾状构造,剖面上主要发育对称花状、正花状与负花状上下分层叠置的复合花状构造.北东东和北西向断裂活动性较弱,剖面上以单条直立走滑断裂为主,平面上呈线性延伸或由多段同向走滑断层连接而成.根据断层构造样式和受力性质,将顺南1断裂沿走向划分为4段：2个复合花状-拉张段和2个简单花状-挤压段,拉张段和挤压段沿走向交替出现.顺南走滑断裂的形成主要经历了5期构造运动：加里东早期、加里东中期Ⅰ幕、加里东中期Ⅲ幕、加里东晚期-海西早期和海西晚期.其中,加里东中期Ⅰ幕和加里东中期Ⅲ幕为该区主要断层活动期.     

Stratigraphic and structural characteristics of the Romanian Black Sea shelf

The Western Black Sea basin opened during Cretaceous times by back-arc rifting in association with a north dipping subduction at the rear of the Cretaceous–Early Tertiary Pontide volcanic arc. The sedimentary wedge developed on the shelf of the Romanian Black Sea sector reflects a complex interplay between large scale rifting, uplift of the orogenic flanks, large-scale post-rift subsidence and sea level changes. We examine the detailed structural configuration of this sector for a regional correlation with the adjacent offshore in Ukraine and Bulgaria. The evolution of the western Black Sea basin started in the Albian–Cenomanian times, when two extensional phases with significantly different directions (N–S and subsequently E–W) lead to the formation of a complex interplay between isolated blocks organised in horsts and grabens generally deepening eastwards. Superposition of normal faults footwall blocks from the two extensional episodes generated a deeply subsided area with enhanced accommodation space, i.e., the Histria Depression, and, consequently, recorded a larger thickness of Paleogene sediments in the post-rift stage. (Re)activation of faults and associated folding reflects repeated inversion during the Late Cretaceous–Oligocene times, associated with subsequent periods of non-deposition and/or erosion during moments of basin fill exposure. These periods of inversion recorded in the Black Sea are controlled by coeval orogenic deformations taking place in the Balkans, Pontides and the Crimean thrust belt. Sea level fluctuations during the Neogene and late Alpine tectonics in the neighbouring orogens caused massive sedimentation followed by sediment starvation and/or significant erosion. Large thicknesses of sediments accumulated during the Pontian, presumably associated with an extensional episode deepening the distal parts of the basin and with differential compaction structures. The interpretation of a high-quality seismic dataset combined with published data allowed the correlation of major structural units and lineaments defined onshore towards the Carpathians with the ones deeply buried below the western Black Sea basin sediments. Unit correlations are furthermore used to derive an integrated tectonic image of the western Black Sea area.     

柴达木盆地西南缘新近系与地震沉积有关的软沉积物变形构造及其地质意义

在区域构造背景研究和岩心观察的基础上,在柴达木盆地西南缘新近纪地层中识别出与地震沉积有关的软沉积物变形构造。软沉积物变形构造包括液化砂岩脉、泄水构造、重荷模、火焰构造、震积砂枕、砂球构造、枕状层、层内错断、地裂缝、串珠状构造、震褶层、混合层及地震角砾状构造等。液化砂岩脉有喉道状、脉络状、飘带状、尖突状及“V”字形五种,主要是由振动流体化作用、振动液化挤压作用和振动拉张裂缝充填作用形成的;重荷模、火焰构造、枕状构造、球状构造是受地震颤动在砂、泥岩界面上由于砂层下沉、泥层上穿形成的;地裂缝、层内错断、震褶层是地震颤动直接引起的断裂、错断和褶皱;枕状层是地震振动引起的砂层脱水、下沉、变形形成的;混合层构造的完整性取决于地震强度和地震持续时间;地震角砾状构造是由地震振动使原始沉积层断裂形成的自碎屑角砾、脆性角砾和塑性角砾组成。该成果从沉积学角度证明了新近纪是昆仑山造山带北侧断裂活动较强烈时期,也为柴达木盆地新生代构造演化研究提供了依据。地震作用极大地提高了储层的渗透率,改善了油气储层的储集物性。     

鄯善油田裂缝特征及构造应力场

通过野外节理裂缝的观测,钻井岩心裂缝的古地磁定向与倾角测井裂缝解释,分析了鄯善油田构造应力场,得出鄯善油田储层构造裂缝发育方位主要为N30°-40°E,N30°-50°W,为一对NE、NW向共轭断裂.高角度缝和垂直缝为主.鄯善构造带是近南北挤压作用下形成的,侏罗纪末期燕山期构造运动为近SN向的主压应力模式,形成油田内一系列近SN向正断层,以及测量的NE、NW向共轭断裂.鄯善油田储层断裂是侏罗纪末期燕山期构造运动形成的.通过倾角测井椭圆井径曲线分析等方法判别的鄯善油田现今最大水平主应力方向约140°.人工压裂的裂缝方位理论上当为140°,它与320°方位的构造缝如果匹配,可能对压裂产生影响.