川中地区上三叠统须家河组成岩层序地层学特征

充分利用薄片分析以及X-衍射等资料,结合元素俘获(ECS)测井解释所获得的岩石矿物组合特征,从层序界面对成岩特征的控制以及不同基准面旋回内的成岩作用发育规律两个方面分别对川中须家河组层序地层格架内的成岩作用特征进行探讨。结果表明,须家河组可划分为2个超长期和5个长期基准面旋回层序。须二段、须四段底部的层序界面之下碳酸盐胶结物含量普遍增加,而界面之上的砂体普遍见溶蚀现象,储层物性相对变好。须四段基准面上升半旋回时期形成的沉积物颗粒粒度较粗、泥质含量低、砂体厚度大、连通性好,在成岩过程中原生孔隙容易得到保存,再加上受到层序界面所控制的有机酸性水溶蚀作用的影响,有利于次生孔隙的产生。而基准面下降期,砂体的连通性变差、泥质夹层增多,在成岩过程中原生孔隙不易保留同时也不利于次生溶蚀孔隙的产生,因而物性最差。须二段总体也具此规律,但由于其埋藏更深,经历成岩作用更为复杂,因此并不如须四段明显。研究成果可为研究区优质储层追踪对比及预测提供依据,同时也能为成岩层序地层学的研究提供借鉴。     

Pleistocene stratigraphy in the Devils Hole Area,Central North Sea: Foraminiferal and amino-acid evidence

A detailed study of the foraminiferal assemblages from the 229.1-m-deep core 81/34 in the central North Sea has been combined with a series of measurements of the isoleucine epimerisation of foraminiferal tests. A total of 17 foraminiferal zones have been established and both the faunal compositions and the amino-acid values suggest that a major part of the sequence represents deposits of early and middle Pleistocene age. Only the uppermost zone is referred to the late Pleistocene. The sequence mainly comprises a series of marine zones from cold periods, but with some barren, possibly non-marine intervals in between. Only two of the foraminiferal zones can be referred to interglacial periods. The oldest one of these, defined here as the Devils Hole Interglacial, may belong to the latter part of the Cromerian Complex, while the upper warm interval is correlated with the Holsteinian of northwest Europe on the basis of its amino-acid values. A detailed stratigraphical correlation between core 81/34 and the neighbouring core 81/29 is suggested on the basis of their foraminiferal content, palaeomagnetic evidence and amino-acid measurements from both cores. A characteristic feature of both sequences is that most of the Quaternary record is missing. Similar episodic patterns of deposition and erosion have been reported previously from the North Sea area.     

黔南独山上泥盆统层序-海平面变化和成岩层序地层研究

贵州独山的上泥盆统由碳酸盐缓坡和碳酸盐台地两种沉积类型组成,包括13种沉积相和25种微相类型.它们构筑了6个层序,其中3个Ⅰ型层序和3个Ⅱ型层序.与6个层序对应的6个三级海平面升降旋回的速度、幅度和频率显示了不同的特征,第1和第2个旋回呈高幅、低频速进和高频缓退特征.第3个旋回为高幅、高频速进和高频缓退.第4个旋回为低幅、高频的中速进-退特征.第5、6个旋回具中、高幅高频缓进和低频速退特征.本文最后对不同沉积体系域和两种层序界面的成岩特征进行了探讨.     

川西邛崃县白马庙气田上侏罗统蓬莱镇组高分辨率层序地层分析

以高分辨率层序地层学理论及其技术方法为指导,通过地表露头、岩心、测井和地震资料的综合分析,在白马庙气田上侏罗统蓬莱镇组识别出3类不同成因类型和发育规模的层序界面、3个级别的湖泛面,划分出2个长期、6个中期、38～40个短期基准面旋回层序,并对不同级次旋回层序的特征进行了详细讨论.同时,发现中期基准面旋回层序近顶部的薄层灰岩和钙质泥岩也是识别中期基准面旋回的重要标志之一.在此基础上,运用旋回等时对比法则对各级次旋回层序进行对比,建立了3个不同时间尺度的等时地层格架,认为开展高分辨率层序地层分析对深化白马庙气田蓬莱镇组气藏的勘探开发工作具有重要意义.     

准噶尔盆地侏罗系八道湾组聚煤作用控制因素分析

从煤层厚度及其在层序地层格架中的平面展布特征入手,并在分析煤层在层序格架中的发育和分布规律的基础上,探讨了沉积环境、沉积体系演化和湖平面变化对陆相盆地---准噶尔盆地侏罗系层序Ⅰ(八道湾组的主体)聚煤作用的影响。河流泛滥平原、三角洲平原、湖湾等沉积环境的可容空间变化速率和泥炭堆积速率常能保持有利于泥炭沉积的平衡关系,从而成为富煤环境。实质上,沉积环境是聚煤作用控制因素的外在表现形式,而其最根本的控制因素则是可容空间变化速率。在本研究区,主要体现为湖平面变化对煤层分布的控制作用。     

Mesozoic (Late Jurassic) palynomorphs and charcoal from a sandstone pebble from Quaternary glacial deposits of the North Sea

The palynological contents as well as macroscopic charcoal fragments from a calcareous sandstone pebble from Quaternary glacial deposits of the North Sea (80 km SW of the Dogger Bank) are described. The taxonomic composition of the palynoflora points to a Late Jurassic (or Late Jurassic/Early Cretaceous) age of the sandstone. The charcoal is interpreted as direct evidence of palaeo‐wildfire occurring during this period in the source area of the sediments of this particular sandstone. This finding, together with already published data on Mesozoic deposits, allows to conclude that wildfires were obviously widespread during this period in the area of the modern day North Sea and adjacent areas. Copyright © 2012 John Wiley & Sons, Ltd.     

Coeval deposition of transgressive and normal regressive stratal packages in a structurally controlled area of the Viking Formation,central Alberta,Canada

Variability in accommodation and sedimentation rates within a basin generates significant deviations in the along-strike stratal stacking patterns of systems tracts. This variability can lead to coeval depositional units that record the juxtaposition of transgressive (retrogradational) and regressive (progradational) stratal stacking patterns. In scenarios where transgressive and regressive units are deposited concurrently, challenges arise when attempting to correlate and place systems tracts into a sequence stratigraphic framework. In these scenarios, the maximum flooding surface records a high level of diachroneity, with the position of the surface variable throughout the stratigraphic column. In this study, Viking Formation (late Albian) deposits in the Western Canada Sedimentary Basin, central Alberta, Canada, preserve significant along-strike variability of palaeoshorelines that developed in response to autogenic processes as well as allogenic controls that were active during deposition. Specifically, structural reactivation of Precambrian basement structures during Viking deposition led to significant variability in depositional environments along the palaeoshoreline. The incremental basement reactivation of the Precambrian Snowbird Tectonic Zone influenced sedimentation patterns and the creation of anomalous zones of accommodation in localized areas of the basin. Across fault boundaries and within the anomalously thick strata, both progradational and retrogradational stacking patterns occur within broadly contemporaneous deposits, complicating the correlation of stratigraphic units. While the concomitant deposition of transgressive and regressive units has been documented in a number of modern marine analogues, the concept is rarely applied to ancient successions. By identifying along-strike variabilities in shoreline geometries and incorporating the autogenic and allogenic controls that were active during deposition, a more accurate sequence stratigraphic framework can be proposed.     

北黄海盆地LV井侏罗系油砂抽提物地球化学特征

对北黄海盆地侏罗系两块含油砂岩的抽提物进行了常规的有机地球化学分析和碳同位素测试,结果表明它们具有不同的地球化学特征:埋藏较深的油砂抽提物属正常原油,饱和烃以正构烷烃为主,色谱图显示单峰型正态分布;而埋藏较浅的油砂抽提物,在饱和烃色谱图中有明显的UCM鼓包,同时含有完整的低碳数的正构烷烃、姥鲛烷和植烷,全油及族组成碳同位素分布范围广,为-24.7‰~-32.3‰,其中,全油及沥青质碳同位素偏重,饱和烃和芳烃碳同位素轻,反映出遭受了强烈的生物降解作用。与成熟度相关的生物标志物参数显示,原油已进入成熟—高成熟阶段。生物标志物和碳同位素组成表明,母质是在水体较浅的湖相环境下沉积的,受陆源高等植物和低等水生藻类的双源控制。综合判断,研究区存在两期油气充注。     

Combined tide and wave influence on sedimentation patterns in the Upper Jurassic Swift Formation, south-eastern Alberta

In south‐eastern Alberta, the Oxfordian Swift Formation comprises two unconformity‐bounded sequences. Sequence 1 consists of the shale member. It unconformably overlies Bathonian calcareous shale of the Rierdon Formation and consists dominantly of shale with uncommon hum‐ mocky cross‐stratified siltstone. The shale member comprises up to four parasequences that show a subtle upward‐fining stacking pattern, suggesting overall deepening in a storm‐dominated fully marine basin. Deposition of the shale member was terminated by a fall in relative sea‐level, which in turn initiated sequence 2. During lowstand, a network of north‐east‐ to south‐west‐trending meandering channels incised the top of sequence 1. Despite the preserved morphology of these channels, observations in core suggest that lowstand deposits are absent. These strata were most likely thoroughly reworked by ravinement processes associated with the ensuing transgression and are recorded only by a thin chert pebble lag. Also associated with transgression were significant changes in the physical and ecological conditions in the local Swift basin. These changes were related to modifications in basin configuration and the development of a low‐energy strait, which probably formed as a result of uplift of the Sweetgrass Arch. Within this newly configured basin, brackish‐water conditions prevailed, and sedimentation was dominated by suspension deposition of mud. Bed‐load sediment, composed mostly of very fine and fine sand, made up only a small part of the total sediment flux into the area and was transported principally by low‐energy combined flows with variable‐speed microtidal currents and a low‐energy oscillatory component related to storm waves. Sand was generally deposited in the form of small, discontinuous sand ridges that developed locally throughout the study area – it is these features that form the principal hydrocarbon reservoir bodies in the Swift Formation in the study area. After initiation, ridges built upwards and migrated laterally in response to transport and preferential local deposition of bed‐load sediment. Although common near the unconformity along the top of sequence 1, sand ridges also occur at several higher stratigraphic levels in sequence 2. These latter ridges, however, are not associated with regionally correlatable discontinuities but, instead, were initiated by local bed irregularities, possibly related to breaking internal waves, and were supplied with new sediment transported into the study area. The origin of these sand ridges is therefore not related to changes in relative sea‐level but, instead, to intrabasinal processes in a low‐energy strait.     

塔中地区石炭系生屑灰岩段成岩层序地层学

以塔中地区石炭系生屑灰岩段为研究对象,进行了成岩层序地层学研究.依据钻井、测井等多种资料将生屑灰岩段划分为1个三级层序,识别出了海侵体系域和高位体系域,低位体系域在研究区不发育,确定了海侵体系域为开阔碳酸盐岩台地沉积,高位体系域为带障壁海岸的潮坪沉积.分别从准同生白云岩化作用、大气淡水溶蚀作用和海底胶结作用3个方面对成...     

Microtextures of authigenic Or-rich feldspar in the Upper Jurassic Humber Group, UK North Sea

ABSTRACT Detrital alkali feldspars currently at burial depths of 3·2–3·5 km in the Upper Jurassic Humber Group of the Fulmar oilfield, UK North Sea, are overgrown and have been partially replaced by authigenic Or‐rich feldspar. Intracrystal microtextures suggest several different provenances for the detrital grains. The overgrowths are uniformly non‐cathodoluminescent and have occasional celsian‐rich zones. Transmission electron microscopy shows that they are composed of a microporous mosaic of subµm‐ to µm‐sized sub‐grains associated with barite, illite and pyrite. The subgrains are somewhat rounded but have an approximate {110} Adularia habit and display a faint modulated microtexture on the nanometre scale. They have triclinic symmetry, but the lattice angles depart only slightly from monoclinic symmetry. These features are characteristic of K‐feldspar precipitated relatively rapidly and at low temperature. Authigenic Or‐rich feldspar has also partially replaced microcline and perthitic albite within the detrital grains, often at a suboptical scale. Although, like diagenetic albitization, replacement by K‐feldspar is probably a very common diagenetic reaction, it has rarely been reported owing to difficulties in imaging the diagnostic textures with the scanning electron microscopy techniques used by most workers. The permeability of the subgrain microtexture may significantly hinder the use of feldspar overgrowths for K/Ar and ⁴⁰Ar/³⁹Ar dating of diagenesis, and the existence of suboptical, replacive authigenic K‐feldspar within detrital grains may significantly modify the apparent Ar ages of detrital grains. Similar subgrain microtextures in optically featureless quartz overgrowths are also illustrated.     

北黄海盆地东部坳陷侏罗纪北部物源--沉积体系的岩矿特征

以北黄海盆地东部坳陷北部侏罗系为目的层,探讨侏罗纪北部物源-沉积体系的岩矿特征、物源区构造背景和物源方向。研究区侏罗系是一套陆相碎屑岩沉积,主要岩石类型为岩屑石英砂岩和岩屑砂岩。通过对北黄海盆地东部坳陷侏罗系沉积序列的研究,识别出三角洲、扇三角洲和湖泊等3类沉积环境。根据碎屑组分和灰岩丰度可知,北部物源-沉积体系为风化物源,并存在附加的火山物源,物源区为再旋回造山带,沉积体系为自北向南方向的扇三角洲沉积体系。对岩石样品进行微观特征及粒度特征研究,识别出沉积微相类型有扇三角洲前缘亚相的远砂坝、河口坝、水下河道和重力水下河道4种微相。     

An example of a highly bioturbated,storm‐influenced shoreface deposit: Upper Jurassic Ula Formation,Norwegian North Sea

Integrated ichnological and sedimentological analyses of core samples from the Upper Jurassic Ula Formation in the Norwegian Central Graben were undertaken to quantify the influence of storm waves on sedimentation. Two main facies associations (offshore and shoreface) that form a progradational coarsening upward succession are recognizable within the cores. The offshore deposits are characterized by massive to finely laminated mudstones and fine‐grained sandstones, within a moderately to highly bioturbated complex. The trace fossil assemblage is dominated by deposit‐feeding structures (for example, Planolites, Phycosiphon and Rosselia) and constitutes an expression of the proximal Zoophycos to distal Cruziana ichnofacies. The absence of grazing behaviours and dominance of deposit‐feeding ichnofossils is a reflection of the increased wave energies present (i.e. storm‐generated currents) within an offshore setting. The shoreface succession is represented by highly bioturbated fine‐grained to medium‐grained sandstones, with intervals of planar and trough cross‐bedding, thin pebble lags and bivalve‐rich shell layers. The ichnofossil assemblage, forming part of the Skolithos ichnofacies, is dominated by higher energy Ophiomorpha nodosa ichnofossils and lower energy Ophiomorpha irregulaire and Siphonichnus ichnofossils. The presence of sporadic wave‐generated sedimentary structures and variability in ichnofossil diversity and abundance attests to the influence of storm‐generated currents during deposition. As a whole, the Ula Formation strongly reflects the influence of storm deposits on sediment deposition; consequently, storm‐influenced shoreface most accurately describes these depositional environments.     

勘探早—中期的沉积盆地有效烃源岩综合预测方法探讨——以北黄海某盆地为例

针对勘探程度较低的地区,提出了一套有效烃源岩的综合预测方法。其基本思路是,从钻井出发,井震结合,按由点到面、由剖面到平面的顺序分五步进行:确定有利沉积相带;确定烃源岩平面分布;划分区域沉积相分布;确定平面热演化分布;有效烃源岩分布预测。利用该方法,对北黄海某盆地侏罗系SQ1层序进行了有效烃源岩预测。     

北羌塘盆地中部上侏罗统研究新进展

北羌塘盆地腹地自然条件恶劣 ,地层研究难度极大。经在北羌塘盆地腹地东湖、河湾山、长水河及半岛湖等地进行了详细的岩石地层及生物地层研究工作 ,依据岩石特征和生物化石特征 ,将上侏罗统二分 :下部灰岩层为索瓦组 ,含 L acunosella triobatiformis- Pentithyris vulgaris、Radulopecten fibrosus- Gervillella aviculoides组合 ,其时限为牛津期 ;上部灰岩、碎屑岩互层为白龙冰河组 ,具 Radulopecten scarburgensis、R.moondanensis、Cladophylliaqeibulaensis、Stylosmilia chaputi化石 ,其主体时限为基默里奇期—提塘期 ,顶部可能跨入早白垩世。白龙冰河组的确立 ,是北羌塘盆地上侏罗统岩石地层与生物地层研究上一个新进展     

Lower Jurassic Sequence Stratigraphy and Sedimentary Facies on the North Slope of Mount Qomolangma

The Lower Jurassic is subdivided in ascending order into the Wulong, Kangdui and Yongjia Formations on the north slope of Mount Qomolangma, with a total thickness of 1362 m. They are thought to have been deposited respectively in the environments of the carbonate ramp fault-bounded basins and carbonate platform, with six sedimentary facies and six sub-facies. During the Early Jurassic, the Qomolangma area experienced strong faulting and subsidence, and was of a matured rift basin. The Lower Jurassic consists of eleven 3rd-order sequences, which can be grouped into three 2nd-order sequences and form a large transgressive-regressive cycle. The 3rd-order sequences and the corresponding sea-level changes recognized in the area can be correlated quite well with those set up in the western Tethys, and may have been caused by the eustatic fluctuations, while the 2nd-order sequences seem to be more closely related to the basement subsidence and the variation in sedimentary influx, indicating the evolution of th     

鄂尔多斯盆地甘泉地区下侏罗统高分辨率层序地层学分析

根据层序沉积时限以及基准面旋回界面识别标志,运用高分辨率层序地层学理论和方法,对鄂尔多斯盆地中南部甘泉地区下侏罗统进行了划分。识别出下侏罗统各级旋回层序界面,并将其划分为1个超长期、8个长期、32个中期、86个短期旋回层序。应用地层等时对比技术,以长期旋回层序为地层对比框架、中期旋回层序为地层对比单元,建立了研究区下侏罗统等时地层格架。下侏罗统沉积于盆地基底快速沉降、缓慢抬升的构造环境,在基底抬升速度周期性变化过程中,盆地边缘沉积了数层可采煤层,成为划分层序的重要依据。     

Facies Analysis and Sequence Stratigraphy of the Qal’eh Dokhtar Formation (Middle–Upper Jurassic) in the West of Boshrouyeh, East Central Iran

The study area is located in the east Tabas Block in Central Iran. Facies analysis of the Qal’eh Dokhtar Formation (middle Callovian to late Oxfordian) was carried out on two stratigraphic sections and applied to depositional environment and sequence stratigraphy interpretation. This formation conformably overlies and underlies the marly-silty Baghamshah and the calcareous Esfandiar formations, respectively. Lateral and vertical facies changes documents low- to high energy environments, including tidal-flat, beach to intertidal, lagoon, barrier, and open-marine. According to these facies associations and absence of resedimentation deposits a depositional model of a mixed carbonate–siliciclastic ramp was proposed for the Qal’eh Dokhtar Formation. Seven third-order depositional sequences were identified in each two measured stratigraphic sections. Transgressive systems tracts (TSTs) show deepening upward trends, i.e. shallow water beach to intertidal and lagoonal facies, while highstand systems tracts (HST) show shallowing upward trends in which deep water facies are overlain by shallow water facies. All sequence boundaries (except at the base of the stratigraphic column) are of the no erosional (SB2) types. We conclude eustatic rather than tectonic factors played a dominant role in controlling carbonate depositional environments in the study area.     

浅析准噶尔盆地侏罗系煤层在层序地层中的意义

准噶尔盆地侏罗系主要发育了三套煤层组合,分别位于八道湾组下段、八道湾组上段下部和西山窑组底部。在准噶尔盆地侏罗系层序地层学划分的方案中sb1、sb2、sb4界面则分别位于八道湾组下段、八道湾组上段下部和西山窑组底部三套煤层组合附近。由于在不同层序的不同体系域及同一体系域的不同时期可供煤层堆积所需要的可容空问和容纳快速堆积的煤层 (泥炭 )的发育程度以及沉积环境的不同,其聚煤情况也有较大差异,因而准噶尔盆地侏罗系煤层具有穿时现象,在层序的各个体系域中都有可能发育。经分析发现侏罗系煤层主要发育于 :⑴层序I的低位和高位域;⑵层序II的低位域;⑶层序III的高位域和 (4)局部发育于层序IV的低位域