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Evaluation of the Lower Cretaceous Alam El Bueib Sandstone reservoirs in Shushan Basin, Egypt – Implications for tight hydrocarbon reservoir potential 埃及蜀山盆地下白垩统 Alam El Bueib 砂岩储层评估--对致密油气藏潜力的影响
IF 2.2 4区 地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY Pub Date : 2024-08-15 DOI: 10.1016/j.jafrearsci.2024.105386

This study presents the evaluation of the potential reservoir intervals in the early Cretaceous Alam El Bueib Formation of the Shushan Basin, Western Desert. Seismic 2D lines, and wireline logs (including image logs) were assessed to characterize the potential intervals. The study area is characterized by E-W to ENE-WSW striking parallel sets of steeply dipping normal faults. Based on the breakouts on image log, the regional maximum horizontal stress orientation is inferred as NE-SW. The AEB Formation, as observed on the image log, consists of massive sandstones, planar laminated siltstones, sandstone-siltstone heteroliths and laminated shales, deposited in a fluvial depositional environment. The bedding planes are WNW-ESE striking with a mean true dip of NNE (around 10°). Wireline log based quantitative petrophysical assessment identified multiple promising hydrocarbon-bearing reservoir intervals within the AEB Formation. The potential reservoir intervals are clean with shale content <10% with water saturation <50%. However, all these intervals are tight with effective porosity between 4 and 12%, dominantly ∼5%. Such tight effective porosity can be contributed by extensive silica cementation in the AEB Formation, as seen from the nearby fields in Western Desert. High porosity zones are observed to be water-bearing. The wells drilled in the north and northeastern area exhibit a cumulative net pay thickness between 70 and 150 ft, while south-southeastern region exhibits a very low cumulative net pay of 10–30 ft. Based on the breakout son image log, the regional minimum horizontal stress orientation is inferred as NW-SE, which can be preferred azimuth for placing highly deviated or horizontal wells to exploit such tight clastic reservoirs by optimizing hydraulic fracture propagation. The formation evaluation presented in this work shed critical insights into the tight hydrocarbon reservoir potential of the early Cretaceous AEB.

本研究对西部沙漠蜀山盆地早白垩世 Alam El Bueib 地层的潜在储层层段进行了评估。通过评估地震二维线和有线测井(包括图像测井),确定了潜在储层的特征。研究区域的特征是东-西至东-西-西走向的平行陡斜正断层。根据图像测井上的断裂,推断区域最大水平应力方向为 NE-SW。从图像测井仪上观察到的 AEB 地层由块状砂岩、平面层状粉砂岩、砂岩-粉砂岩杂岩和层状页岩组成,沉积于河流沉积环境中。基底面呈西西-东东走向,平均真实倾角为北北东(约 10°)。基于有线测井记录的定量岩石物理评估在 AEB 地层中发现了多个有潜力的含油气储层层段。这些潜在的储油层间很干净,页岩含量为 10%,含水饱和度为 50%。然而,所有这些区间都很致密,有效孔隙度介于 4% 与 12% 之间,主要为 5%。这种致密的有效孔隙度可能是由于 AEB 地层中广泛的二氧化硅胶结造成的,这一点从西部沙漠附近的油田可以看出。据观察,高孔隙度区域含水。在北部和东北部地区钻探的油井显示出的累计净付油厚度在 70 至 150 英尺之间,而东南部地区显示出的累计净付油厚度非常低,仅为 10 至 30 英尺。根据破裂子图像测井,推断出区域最小水平应力方位为西北-东南,这可能是通过优化水力裂缝传播来开采此类致密碎屑岩储层的高偏差或水平井的首选方位。这项工作中介绍的地层评估为了解早白垩世 AEB 的致密油气藏潜力提供了重要信息。
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引用次数: 0
Quantification of the effect of fracturing on heterogeneity and reservoir quality of deep-water carbonate reservoirs 量化压裂对深水碳酸盐岩储层异质性和储层质量的影响
IF 2.2 4区 地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY Pub Date : 2024-08-15 DOI: 10.1016/j.jafrearsci.2024.105383

The Shiranish Formation represents one of the most important fractured reservoirs in northern Iraq. In this work, the petrophysical properties of the formation have been fully characterised using microscopy, core analysis, and well log analysis using conventional methods as well as new quantitative diagenetic approaches. During this work we have developed methods to quantify a petrophysical heterogeneity index (χ), reservoir quality indicator (RQI), and fracture effect index (FEI) for each of the stratigraphic units of the formation. The FEI was calculated by dividing the difference between the mean permeability of the wireline log data and the mean permeability of the unfractured core plug samples by the difference between the mean porosity of the wireline log data and the mean porosity of the unfractured core plug samples. This study shows that the Shiranish Formation has a fracturing pore system in all the characterised units, but it is particularly well developed in U.4, which shows the best reservoir quality (A and B). The new methods developed in this study can be applied to any carbonate formation to provide a trustworthy way to obtain a reservoir quality indicator linked to the petrophysical heterogeneity of the studied formation.

希拉尼什地层是伊拉克北部最重要的断裂储层之一。在这项工作中,我们采用显微镜观察、岩心分析、测井分析等传统方法以及新的定量成岩方法,对该地层的岩石物理特性进行了全面描述。在这项工作中,我们为地层的每个地层单元开发了岩石物理异质性指数(χ)、储层质量指标(RQI)和裂缝效应指数(FEI)的量化方法。FEI 的计算方法是,用有线测井数据的平均渗透率与未压裂岩心塞样本的平均渗透率之差,除以有线测井数据的平均孔隙度与未压裂岩心塞样本的平均孔隙度之差。这项研究表明,Shiranish 地层在所有特征单元中都有压裂孔隙系统,但在储层质量(A 和 B)最好的 U.4 单元中尤为发达。本研究开发的新方法可应用于任何碳酸盐岩层,为获得与所研究岩层岩石物理异质性相关的储层质量指标提供了可靠的方法。
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引用次数: 0
Paleostress evolution of the Outer Kwanza basin (offshore Angola); comparison with the Congo basin and implications for the tectonic history of the Central segment of the West Africa passive margin 外宽扎盆地(安哥拉近海)的古应力演化;与刚果盆地的比较以及对西非被动边缘中部地段构造史的影响
IF 2.2 4区 地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY Pub Date : 2024-08-13 DOI: 10.1016/j.jafrearsci.2024.105382

This study aims at reconstructing the paleostress history of the Outer (offshore) Kwanza basin (West African passive margin) and at comparing it to stress results acquired further north in the Congo basin. Three oriented borehole cores provided by TotalEnergies and reaching the syn-rift, Barremian-Aptian pre-salt carbonates offshore Angola were investigated. Paleopiezometry based on the Stylolite Roughness Inversion Technique (SRIT) and Calcite Twin Inversion Technique (CSIT) was combined with fracture analysis, U–Pb geochronology of carbonates and burial modelling to unravel the orientations and magnitudes of horizontal and vertical stresses affecting the pre-salt carbonates over time. Calcite twins were measured from a primary sparite matrix, and the inversion process unravelled a polyphase stress history, comprising ∼ E-W and NE-SW extensional trends that we associate to the rifting (130-112 Ma) that led to the opening of the South Atlantic ocean. The ∼ E-W extension is consistent with the early occurrence of N-S striking normal faults which developed in relation to the reactivation of inherited basement structures. This ∼ E-W extension evolved during the Barremian-Aptian (?) into the dominant regional NE-SW extension marked by large-scale NW-SE striking normal faults. The stress history also comprises compressional and strike-slip stress regimes associated with a ∼N-S trending σ1 which can be related to the transfer of orogenic stresses from the distant Africa-Eurasia plate boundary at ∼67-60 Ma. Finally, compressional and strike-slip stress regimes associated with a ENE-WSW to ∼E-W trending σ1 dominated since at least ∼17-15 Ma (possibly ∼34 Ma); they are interpreted as the expression of the mid-Atlantic ridge push. These (paleo)stress results are compared and combined with earlier paleostress reconstructions in the northern offshore Lower Congo basin (also belonging to the Central segment of the margin) and in the onshore Congo basin in order to refine the stress record and the timing of tectonic events since the early Cretaceous, thus providing unprecedented constraints on the tectonic history of the West Africa passive margin. This tectonic history includes both extensional and compressional events, and was driven mainly by far-field stresses, either gravitational or tectonic in origin, which are related to interactions between the African plate and surrounding plates.

本研究旨在重建外(近海)宽扎盆地(西非被动边缘)的古应力历史,并将其与刚果盆地更北端获得的应力结果进行比较。由道达尔能源公司(TotalEnergies)提供的三个定向钻孔岩芯被用于研究安哥拉近海同步断裂的巴里米亚-中古前盐碳酸盐岩。基于苯乙烯岩粗糙度反演技术(SRIT)和方解石孪晶反演技术(CSIT)的古压强测量与断裂分析、碳酸盐岩的铀-铅地质年代和埋藏模型相结合,揭示了随着时间的推移影响盐前碳酸盐岩的水平和垂直应力的方向和大小。从原生榍石基质中测量了方解石孪晶,反演过程揭示了多相应力历史,包括东西向和东北-西南向延伸趋势,我们将其与导致南大西洋开辟的断裂(130-112 Ma)联系起来。东-西向延伸与早期出现的北-南走向正断层相一致,这些正断层的形成与继承的基底构造的重新激活有关。这种东西向延伸在巴里米亚-安普顿(?)时期演变为区域性的东北-西南向延伸,以大规模的西北-东南走向的正断层为标志。应力历史还包括与北-南走向σ1相关的压缩和走向滑动应力机制,这可能与67-60Ma∼时来自遥远的非洲-欧亚板块边界的造山应力转移有关。最后,与ENE-WSW至∼E-W走向的σ1有关的压缩和走向滑动应力机制至少从∼17-15 Ma(可能是∼34 Ma)起就占主导地位;它们被解释为大西洋中脊推力的表现形式。这些(古)应力结果与早先在下刚果盆地北部近海地区(也属于边缘中部地段)和刚果盆地陆上地区的古应力重建结果进行了比较和组合,以完善自早白垩世以来的应力记录和构造事件发生的时间,从而为西非被动边缘的构造历史提供了前所未有的制约因素。这一构造历史包括伸展和压缩事件,主要由远场应力驱动,无论是重力应力还是构造应力,都与非洲板块和周围板块之间的相互作用有关。
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引用次数: 0
New geological insights on the Palaeoproterozoic Sembé-Ouesso Basin in northern Congo-Brazzaville – Implications for the Kibaran orogeny, Neoproterozoic rifting and Pan-African overprint 刚果(布)北部古新生代森贝-韦索盆地的地质新发现--对基巴兰造山运动、新新生代断裂和泛非洲覆盖的影响
IF 2.2 4区 地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY Pub Date : 2024-08-10 DOI: 10.1016/j.jafrearsci.2024.105379
The Palaeoproterozoic Sembé-Ouesso Basin (SOB) is the northeasternmost of six foreland subbasins of the Eburnean orogen; it covers an area of about 64,000 km2 in the northern Republic of Congo, southeast Cameroun and the Central African Republic. The structural architecture and tectono-metamorphic history of the SOB have been studied in the Republic of Congo by airborne geophysical interpretation, geological mapping, and petrography, analysis of illite crystallinity and K-Ar geochronology.
The oldest tectono-metamorphic event (D1/M1), which caused the main structuring of the SOB, coincides in age with the last (1.0–1.07 Ga) stage of Kibaran orogeny. Metamorphic conditions decrease from greenschist facies in the east to upper diagenesis in the west. D1 deformation started with west-vergent folding followed by N-S sinistral transpression in discrete shear zones. The tectonic style characterises the SOB as foreland in the external zone of an eastern concealed orogen that either represents the continuation of the Kibaran Belt or forms a separate, as yet unidentified unit.
Subsequent Neoproterozoic extension is marked by two conjugate N-S/NNE-SSW and E-W/NW-SE fault systems and a local pull-apart structure (D2). Coeval mafic magmas were emplaced in the faults of both systems. At regional scale, the extension can be linked to Tonian rifting in the central part of the Congo Basin and within the West Congo Belt.
The influence of the Neoproterozoic (600 Ma) Central African orogeny is mainly restricted to the north-western part of the SOB where the Dja nappe was thrust from the north over the Palaeoproterozoic rocks (D3/M2). Elsewhere, the Pan-African event had no thermal and only minor structural effects on the SOB.
古近新生代的森贝-韦索盆地(SOB)是埃伯恩造山带六个前陆次盆地中最东北部的一个,面积约 64,000 平方公里,位于刚果共和国北部、喀麦隆东南部和中非共和国境内。刚果共和国通过机载地球物理解释、地质测绘、岩石学、伊利石结晶度分析和 K-Ar 地质年代学对 SOB 的构造结构和构造-变质历史进行了研究。变质条件从东部的绿泥石层向西部的上成岩层递减。D1变形始于西向褶皱,随后是在离散剪切带中的北-南正弦转位。这种构造风格使 SOB 成为东部隐伏造山带外部区域的前陆,该造山带或者是 Kibaran 带的延续,或者是一个尚未确定的独立单元。随后的新新生代延伸以两个 N-S/NNE-SSW 和 E-W/NW-SE 共轭断层系统以及一个局部拉开构造(D2)为标志。这两个断层系统的断层中都置入了同时期的钙质岩浆。新新生代(600Ma)中非造山运动的影响主要局限于 SOB 的西北部,那里的 Dja 断层从北部推覆在古新生代岩石上(D3/M2)。在其他地区,泛非事件对 SOB 没有产生热影响,仅有轻微的结构影响。
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引用次数: 0
Late Cenozoic mass transport deposits in the offshore Tanzania continental margin 坦桑尼亚近海大陆边缘的晚新生代大规模迁移沉积
IF 2.2 4区 地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY Pub Date : 2024-08-10 DOI: 10.1016/j.jafrearsci.2024.105377

Sediment mass movements and their associated Mass Transport Deposits (MTDs) have been widely studied due to their economic and geohazard potentials. This study combines 2D and 3D seismic reflection data with a seismic facies approach and attribute analysis to reveal the presence and distribution of different MTDs in the southernmost region offshore Tanzania. Results of seismic facies analysis show that the study area contains different Late Cenozoic MTDs. The MTDs have limited petroleum reservoir potential and include slides, slumps, debris flow deposits and occasional turbidites. The formation of these MTDs was caused by tectonic events associated with the development of the East African Rift System. Seismic attribute maps have shown the locations of channels, remnant blocks, headwall scars, and grooves confirming downslope sediment mass mobilization. The seabed attribute maps have shown areas where recent mass mobilizations were initiated. Some of these areas coincide with faults which have dissected the seabed, forming potential future gravity failure sites. Other future gravity failure sites include channel banks and slope edges, which may be present over the whole Tanzania continental margin. Sediment mass movements may be catastrophic, and therefore future infrastructure installations in the area must involve detailed mapping of the seabed to assess geohazard risks and act accordingly.

由于其经济和地质灾害潜力,沉积物大规模移动及其相关的大规模迁移矿床(MTDs)已被广泛研究。本研究将二维和三维地震反射数据与地震剖面方法和属性分析相结合,揭示了坦桑尼亚近海最南端地区不同 MTD 的存在和分布情况。地震剖面分析结果表明,研究区域包含不同的晚新生代 MTD。这些 MTD 的石油储藏潜力有限,包括滑坡、坍塌、泥石流沉积和偶尔出现的浊积岩。这些 MTD 的形成是与东非大裂谷系统发展相关的构造事件造成的。地震属性图显示了河道、残留块体、顶壁疤痕和沟槽的位置,证实了下坡沉积物的移动。海底属性图显示了最近开始大规模移动的区域。其中一些区域与剖开海床的断层相吻合,形成了潜在的未来重力破坏点。其他未来的重力崩塌点包括河道堤岸和斜坡边缘,可能存在于整个坦桑尼亚大陆边缘。沉积物的移动可能会造成灾难性后果,因此该地区未来的基础设施建设必须对海底进行详细测绘,以评估地质灾害风险并采取相应行动。
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引用次数: 0
New insights on the stratigraphy of the Upper Cretaceous-lower Paleogene successions at Esh-ElMellaha half-graben, Gulf of Suez, Egypt 埃及苏伊士湾 Esh-ElMellaha 半地堑上白垩世-下古近纪地层的新见解
IF 2.2 4区 地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY Pub Date : 2024-08-10 DOI: 10.1016/j.jafrearsci.2024.105381

Detailed field and stratigraphic (lithostratigraphy & biostratigraphy) studies were carried out on the Upper Cretaceous–lower Paleogene successions at Esh-ElMellaha half-graben, Gulf of Suez, Egypt. Four stratigraphic sections were investigated and arranged in a geologic profile extends from south to north as follow: Gabal El-Mellaha, Wadi Abu Had, Wadi Dib and Gabal Tarbul. The field work led to recognize four lithostratigraphic units (formations): Sudr (upper part), Dib, Esna and Thebes (top). The distinctive Dababiya Quarry Member (DQM) which characterizes the Paleocene Eocene Thermal Maximum (PETM) was initially recorded at Esh-ElMellaha region. Sudr Formation is stratigraphically differentiated into two distinctive informal rock units, argillaceous bedded limestone unit and calcareous shale unit. The Dib Formation is here reviewed and correlates with the Dakhla Formation (upper part) in the different geographic neighborhoods of Egypt. It consists of glauconitic carbonate rocks (bioclastic limestone) embracing reworked gravelly and pebbly extra-clasts and broken exhumed mega-fossils (e.g. cephalopods, gastropods and bivalves, corals). Dib Formation is assigned to thelower Paleocene (Danian Stage) according to the occurrence of praemuricids taxa (e.g. Praemurica inconstans and P. uncinata) index fossils. Esna and Thebes formations are assigned to the Ypresian Stage. Dib Formation is bounded by two regional unconformity surfaces (erosional surfaces) as a result of two tectonic events (I and II) linked to Syrian Tectonic Event.

对埃及苏伊士湾 Esh-ElMellaha 半格拉本的上白垩世-下古生代地层进行了详细的实地和地层学(岩石地层学 & 生物地层学)研究。对四个地层剖面进行了调查,并按地质剖面由南向北排列如下:Gabal El-Mellaha、Wadi Abu Had、Wadi Dib 和 Gabal Tarbul。通过实地考察,确定了四个岩石地层单元(构造):Sudr(上部)、Dib、Esna 和 Thebes(顶部)。独特的 Dababiya Quarry Member(DQM)是古新世始新世热量最高期(PETM)的特征,最初记录于 Esh-ElMellaha 地区。Sudr Formation 在地层上分为两个独特的非正式岩石单元,即砾质层状石灰岩单元和钙质页岩单元。本文回顾了迪卜地层,它与埃及不同地理区域的达赫拉地层(上部)相互关联。该地层由釉质碳酸盐岩(生物碎屑灰岩)组成,包含再加工的砾石和鹅卵石碎屑以及破碎的大型化石(如头足类、腹足类和双壳类动物、珊瑚)。Dib Formation(迪布地层)被归入下古新世(Danian Stage),这是根据出现的Praemuricids类群(如Praemurica inconstans和P. uncinata)索引化石确定的。埃斯纳地层和底比斯地层被归入伊普雷希安期。迪布地层以两个区域性不整合面(侵蚀面)为界,这是与叙利亚构造事件相关的两个构造事件(I 和 II)的结果。
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引用次数: 0
Experimental characterization of two clay deposits blended with feldspar and quartz for building services and refractory applications 两种与长石和石英混合的粘土沉积物在建筑服务和耐火材料应用中的实验特性分析
IF 2.2 4区 地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY Pub Date : 2024-08-10 DOI: 10.1016/j.jafrearsci.2024.105373

Clay deposits across the globe have variations in mineralogical compositions that elicit their use in numerous applications. In this study, two clay deposits were identified and blended with feldspar and quartz in various amounts to produce different samples of composites that could be used for applications in building services and refractories. Chemical analysis, mineralogical composition, microstructure, physical properties, and thermal behaviours were characterized. The X-ray fluorescence (XRF) analysis results show that the clays belong to the aluminosilicate group containing traces of other oxides which enhance strength and the crystallization of thermally stable phases. The XRD patterns confirmed the presence of dominant quartz with moderate to minor presence of kaolin, orthoclase, and albite. The texture of the clays showed particles of different sizes and shapes with uneven distribution. The EDX characteristic spectrum showed x-ray characteristic peaks of Si, Al, Fe, K, and O which affirmed their major oxide compositions. Physical properties results show that firing at various temperatures and blending resulted to increase in Bulk density and flexural strength while apparent porosity and water absorption decreased. The TGA, DTA, and DSC results show that the two clay minerals are thermally stable. This can be attributed to the nucleation and crystallization of refractory phases like cristobalite and mullite. Addition of feldspar and quartz was found to contribute significantly to improve the overall properties of the investigated clays. A comparison of the various results from the two clay deposits suggests that they could be suitable for building services and refractory applications.

全球各地的粘土矿藏的矿物成分各不相同,因此可用于多种用途。在这项研究中,我们确定了两种粘土矿床,并将其与长石和石英以不同的量混合,生产出不同的复合材料样品,这些样品可用于建筑服务和耐火材料领域。对样品的化学分析、矿物成分、微观结构、物理性质和热行为进行了表征。X 射线荧光(XRF)分析结果表明,粘土属于铝硅酸盐类,含有微量的其他氧化物,这些氧化物可增强强度和热稳定相的结晶。XRD 图谱证实,粘土中主要存在石英,少量存在高岭土、正长石和白云石。粘土的纹理显示出不同大小和形状的颗粒,且分布不均。电子衍射X特征光谱显示出Si、Al、Fe、K和O的X射线特征峰,证实了它们的主要氧化物成分。物理性质结果表明,在不同温度下焙烧和混合会导致体积密度和抗折强度增加,而表观孔隙率和吸水率降低。TGA、DTA 和 DSC 结果表明,这两种粘土矿物具有热稳定性。这可归因于钙钛矿和莫来石等难熔相的成核和结晶。添加长石和石英可显著改善所研究粘土的整体性能。对这两种粘土沉积物的各种结果进行比较后发现,它们可适用于建筑服务和耐火材料应用。
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引用次数: 0
Sedimentology and stratigraphy of lower Cretaceous fluvial to shallow marine deposits on the central Atlantic passive margin: The Aaiun-Tarfaya Basin, Morocco 大西洋中部被动边缘下白垩世河道至浅海沉积的沉积学和地层学:摩洛哥 Aaiun-Tarfaya 盆地
IF 2.2 4区 地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY Pub Date : 2024-08-09 DOI: 10.1016/j.jafrearsci.2024.105380

This paper presents the first integrated regional outcrop-based sedimentological study of the northern Aaiun-Tarfaya Basin located in Morocco (NW Africa). The Lower Cretaceous Tan-Tan Formation has been subdivided into six new members and placed within a sequence stratigraphic framework that includes two incomplete depositional sequences. Strong thickness variations of individual lithostratigraphic units from north to south suggest differential subsidence during sedimentation and/or the existence of major topography on the basal unconformity that the succession onlaps. The results provide valuable insights into the timing of local tectonics in the Western Anti-Atlas and the control on the evolution of the sedimentary system. Deposition of each of these six units is interpreted to be the result of a complex interplay between an overall eustatic sea-level rise during the early Cretaceous, sediment delivery controlled by tectonic movements in the Western Anti-Atlas and Reguibat Shield and periods of differential subsidence in the basin. The results document the style of evolution of a back-stepping wave-dominated system feeding into the Central Atlantic during the passive margin phase. The improved facies and depositional models together with improved understanding of the evolution of the delta have significant implication for exploring the deep-water equivalents offshore.

本文首次对位于摩洛哥(西北非)的阿尤恩-塔尔法亚盆地北部进行了基于露头的区域沉积学综合研究。下白垩统坦坦地层被细分为六个新成员,并被置于一个包含两个不完整沉积序列的层序地层框架中。各个岩层单位从北到南的厚度变化很大,这表明沉积过程中存在不同的沉降和/或在该层序所叠加的基底不整合面上存在主要地形。这些结果为了解西反阿特拉斯地区的局部构造时间及其对沉积系统演化的控制提供了宝贵的信息。据解释,这六个单元中每一个单元的沉积都是白垩纪早期海平面总体上升、西反阿特拉斯和雷吉巴特盾构运动控制的沉积物输送以及盆地不同时期沉降之间复杂相互作用的结果。研究结果记录了在被动边缘阶段注入中大西洋的以波浪为主的后步式系统的演化过程。改进后的岩相和沉积模型以及对三角洲演变的进一步了解,对探索近海深水等效区域具有重要意义。
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引用次数: 0
Comment on: Structural analysis of the central Tunisian Atlas: Implications for salt-related structures and conjugate strike-slip faults by Haji et al. (2024) 评论突尼斯阿特拉斯中部的构造分析:与盐有关的结构和共轭走向滑动断层的影响》,Haji 等人 (2024)
IF 2.2 4区 地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY Pub Date : 2024-08-09 DOI: 10.1016/j.jafrearsci.2024.105372
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引用次数: 0
Insights into Afikpo Synclinorium structures: Subsurface analysis and intrusion outlining from airborne magnetic data 洞察阿菲克波合生构造:根据机载磁数据进行地下分析和侵入勾勒
IF 2.2 4区 地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY Pub Date : 2024-08-08 DOI: 10.1016/j.jafrearsci.2024.105374

The airborne magnetic data over Afikpo Synclinorium were used to highlight subsurface structures and establish the orientations of tectonic features and their influence on the hydrocarbon play of the area. The characteristic trends of the lineaments were achieved through the center for exploration targeting of grid data analysis. The results of the TMI, residual magnetic field, first vertical, horizontal derivative, Analytic signal, and Tilt angle derivative classified the area into regions of high magnetic intensity observed around the northeastern, southwestern, and central portions of the study area. These areas characterized by anomalous signatures of short magnetic wavelengths delineate shallow magnetic sources. Conversely, regions with medium to low magnetic intensities are characterized by long magnetic wavelengths which indicates deep-seated magnetic source(s) and prospect for hydrocarbon (if other play concepts are emplace); due the thick sediment cover at the southern portion of the area (around, southern part of Nguzu, Ohafia, Biakpan, Abriba and Bende areas). The sediment thickness decreases towards north, west, North-east and north-west (dominated by Benue Trough deposit). Depth to the anomaly sources is of two categories, namely, shallow <1.0 km (dominated by NE trending structures) and deep ≥2.5 km. Ground-truthing confirmed the anomalous zone of high magnetic sources in the northeastern and central regions as Tertiary related tectonic-magmatic intrusion. The most prominent intrusion cuts across Amangwu Edda in Afikpo South through Amaeta-Oziza to Cross River State in a fissure form. This intrusion occurrence conformed to the high magnetic signature identified as a dolerite sill within the Afikpo Sub-basin. It stretches over 16 km in length with an average width of about 1.2 km, having its widest part in the northern parts of Mata Hospital Afikpo. The subsurface topographic model indicated that no fewer than 50% of the study area is characterized by sporadically distributed intrusive rocks. The result revealed several structural lineaments with high lineament density at the northcentral corner of the area trending NE-SW with fault lines (slip fault) perpendicular to it, offsetting the Akpoha, Ibii, Amasiri. and Ozara-ukwu ridges. The major drainage systems across the area followed major structural trends perpendicular to the identified major lineaments, passing through the major regional structural displacement pattern of the Basin. The emplacement of these intrusions might have impacted the hydrocarbon potential of the basin.

阿菲克波 Synclinorium 上的机载磁数据用于突出地下结构,确定构造特征的方向及其对该地区油气开采的影响。通过网格数据分析的勘探目标中心,确定了线状构造的特征趋势。TMI、残余磁场、第一垂直导数、水平导数、分析信号和倾斜角导数的结果将该地区划分为在研究区东北部、西南部和中部观察到的高磁场强度区域。这些区域以短磁波长的异常信号为特征,划定了浅层磁源。相反,中低磁场强度区域的特点是磁波长长,这表明该区域有深层磁源和油气前景(如果有其他开采概念的话);这是因为该区域南部(恩古祖、奥哈菲亚、比阿克潘、阿布里巴和本德地区南部周围)的沉积物覆盖层较厚。沉积厚度向北部、西部、东北部和西北部(以贝努埃槽沉积为主)递减。异常源深度分为两类,即浅层 1.0 千米(以东北走向结构为主)和深层 ≥2.5 千米。地面实况调查证实,东北部和中部地区的高磁源异常区与第三纪构造-岩浆侵入有关。最突出的侵入体以裂隙形式穿过阿菲克波南部的 Amangwu Edda,通过 Amaeta-Oziza 到达克罗斯河州。这种侵入现象与阿菲克波次盆地内被确定为辉绿岩山体的高磁性特征相吻合。其长度超过 16 千米,平均宽度约为 1.2 千米,最宽的部分位于马塔医院阿菲克波北部。地下地形模型显示,不少于 50%的研究区域为零星分布的侵入岩。研究结果表明,在该地区的中北部有几条构造线,线状密度很高,呈东北-西南走向,断层线(滑动断层)与之垂直,与阿克波哈、伊比、阿马西里和奥扎拉-乌库山脊相抵。整个地区的主要排水系统沿垂直于已确定的主要构造线的主要构造趋势发展,穿过盆地的主要区域构造位移模式。这些侵入体的形成可能对盆地的碳氢化合物潜力产生了影响。
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Journal of African Earth Sciences
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