This note discusses the lithostratigraphic nomenclature used to characterise the Permian–Triassic transition at outcrop in the Oman Mountains, with emphasis on the position of the boundary between the Saiq and Mahil formations. Two inconsistent criteria for picking the Saiq/Mahil Boundary (SMB) prevail in the literature causing confusion regarding the correct position of the Permian/Triassic Boundary (PTB). The position of the PTB plays a central role in the correlation of these two formations from outcrop to the subsurface Khuff and overlying Sudair formations. The Khuff Formation contains one of the world’s greatest reserves of non-associated gas, and its outcrop equivalent in the Oman Mountains is increasingly being studied for the purposes of regional correlations, reservoir characterisation and exploration. Therefore an agreement on the position of the SMB is a pre-requisite for precise communication among geoscientists. In this note we review the historical source of the confusion and recommend applying stratigraphic rules to resolve the position of the Saiq/Mahil Boundary (SMB).
{"title":"Permian–Triassic Transition and the Saiq/Mahil Boundary in the Oman Mountains: Proposed correction for lithostratigraphic nomenclature","authors":"A. Baud, S. Richoz","doi":"10.2113/geoarabia180387","DOIUrl":"https://doi.org/10.2113/geoarabia180387","url":null,"abstract":"This note discusses the lithostratigraphic nomenclature used to characterise the Permian–Triassic transition at outcrop in the Oman Mountains, with emphasis on the position of the boundary between the Saiq and Mahil formations. Two inconsistent criteria for picking the Saiq/Mahil Boundary (SMB) prevail in the literature causing confusion regarding the correct position of the Permian/Triassic Boundary (PTB). The position of the PTB plays a central role in the correlation of these two formations from outcrop to the subsurface Khuff and overlying Sudair formations. The Khuff Formation contains one of the world’s greatest reserves of non-associated gas, and its outcrop equivalent in the Oman Mountains is increasingly being studied for the purposes of regional correlations, reservoir characterisation and exploration. Therefore an agreement on the position of the SMB is a pre-requisite for precise communication among geoscientists. In this note we review the historical source of the confusion and recommend applying stratigraphic rules to resolve the position of the Saiq/Mahil Boundary (SMB).","PeriodicalId":55118,"journal":{"name":"Geoarabia","volume":"50 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2013-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68186143","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2013-07-01DOI: 10.2113/geoarabia1803135
D. Bendias, B. Koehrer, M. Obermaier, T. Aigner
Khuff Sequence KS6 was studied in the Al Jabal al-Akhdar, Oman Mountains, in an area of 30 x 50 square kilometers by means of detailed sedimentological logging of five time-equivalent outcrop sections of the Saiq Formation. KS6 represents one transgressive-regressive, third-order sequence, and is composed of four facies associations each representing particular environments of deposition (backshoal, shoal, foreshoal and offshoal) with distinct sedimentological characteristics. Facies stack to form cycles and cycle sets that were used for correlation at a subregional scale and to reveal the KS6 stratigraphic architecture. During the initial phase of basin-fill, clastic sediments (“Basal Saiq Clastics”) were deposited in paleolows above the “Sub-Saiq Unconformity”. In contrast to younger Upper Khuff sequences KS4 to KS1, the underlying paleorelief strongly affects the thickness and facies composition of KS6. The correlation strategy to follow paleolandscape surfaces using all available sedimentological, biostratigraphic and lithostratigraphic data resulted in a stratigraphic architecture with subtle shingle geometries. Sequence KS6 shows a strong facies partitioning resulting in the necessity of two separate facies models for the transgressive (crinoidal ramp) versus regressive hemisequence (oolitic/peloidal carbonate ramp). This study revealed potential reservoir units in KS6, commonly regarded as non-reservoir in the subsurface of Oman and other parts of the Gulf region. The abundance, nature and lateral extent of reservoir facies strongly varies with stratigraphic position. In the transgressive part of KS6, crinoidal grainstones are concentrated around the margin of a gentle paleohigh. They might have the best reservoir potential, although early diagenetic cementation is common in most settings. Oolitic/peloidal grainstones in the upper regressive part have a much higher diagenetic reservoir potential and are laterally much more widespread. Thus, Khuff Sequence KS6 differs profoundly in its stratigraphic architecture from the more “layer-cake”-like KS4 to KS1 sequences. Facies and thickness patterns are controlled by a marked paleohigh to paleolow configuration, resulting from the antecedent uneven topography during the Neo-Tethyan syn-rift setting, in contrast to the post-rift setting with low tectonic activity during KS4 to KS1.
在阿曼山脉Al Jabal Al - akhdar地区，通过对Saiq组五个时间相等的露头剖面进行详细的沉积学测井，研究了Khuff层序KS6，面积为30 x 50平方公里。KS6为一个海侵-退退三级层序，由四个相组组成，每个相组代表不同的沉积环境(滩后、滩前、滩外)，具有不同的沉积学特征。相叠加形成旋回和旋回集，用于分区域尺度对比，揭示KS6地层构型。在盆地充填初期，碎屑沉积(“基底赛克碎屑”)沉积在“次赛克不整合面”上方的古岩浆岩中。与较年轻的上胡夫层序KS4 ~ KS1相比，下伏古隆起强烈影响KS6的厚度和相组成。利用所有可用的沉积学、生物地层学和岩石地层学数据跟踪古景观表面的对比策略导致了具有微妙的带状几何形状的地层结构。层序KS6表现出强烈的相划分，使得海侵半层序(海泥斜坡)和海侵半层序(鲕状/球粒状碳酸盐斜坡)需要两种独立的相模式。该研究揭示了KS6的潜在储层单元，通常被认为是阿曼和海湾地区其他地区地下的非储层。储层相的丰度、性质和横向程度随地层位置的不同而有很大差异。在KS6海侵区，深红色颗粒岩主要集中在古隆起边缘。尽管早期成岩胶结作用在大多数环境中都很常见，但它们可能具有最佳的储集潜力。上退段鲕粒/球粒岩具有更高的成岩储集潜力，横向分布也更为广泛。因此，KS6 Khuff层序的地层结构与KS4 - KS1层序的地层结构有很大的不同。相和厚度模式受明显的古高-古低构造控制，这是由新特提斯同裂谷背景下的不均匀地形造成的，而KS4 - KS1时期的后裂谷背景则是低构造活动。
{"title":"Mid-Permian Khuff Sequence KS6: Paleorelief-influenced facies and sequence patterns in the Lower Khuff time-equivalent strata, Oman Mountains, Sultanate of Oman","authors":"D. Bendias, B. Koehrer, M. Obermaier, T. Aigner","doi":"10.2113/geoarabia1803135","DOIUrl":"https://doi.org/10.2113/geoarabia1803135","url":null,"abstract":"\u0000 Khuff Sequence KS6 was studied in the Al Jabal al-Akhdar, Oman Mountains, in an area of 30 x 50 square kilometers by means of detailed sedimentological logging of five time-equivalent outcrop sections of the Saiq Formation. KS6 represents one transgressive-regressive, third-order sequence, and is composed of four facies associations each representing particular environments of deposition (backshoal, shoal, foreshoal and offshoal) with distinct sedimentological characteristics. Facies stack to form cycles and cycle sets that were used for correlation at a subregional scale and to reveal the KS6 stratigraphic architecture. During the initial phase of basin-fill, clastic sediments (“Basal Saiq Clastics”) were deposited in paleolows above the “Sub-Saiq Unconformity”. In contrast to younger Upper Khuff sequences KS4 to KS1, the underlying paleorelief strongly affects the thickness and facies composition of KS6. The correlation strategy to follow paleolandscape surfaces using all available sedimentological, biostratigraphic and lithostratigraphic data resulted in a stratigraphic architecture with subtle shingle geometries.\u0000 Sequence KS6 shows a strong facies partitioning resulting in the necessity of two separate facies models for the transgressive (crinoidal ramp) versus regressive hemisequence (oolitic/peloidal carbonate ramp). This study revealed potential reservoir units in KS6, commonly regarded as non-reservoir in the subsurface of Oman and other parts of the Gulf region. The abundance, nature and lateral extent of reservoir facies strongly varies with stratigraphic position. In the transgressive part of KS6, crinoidal grainstones are concentrated around the margin of a gentle paleohigh. They might have the best reservoir potential, although early diagenetic cementation is common in most settings. Oolitic/peloidal grainstones in the upper regressive part have a much higher diagenetic reservoir potential and are laterally much more widespread. Thus, Khuff Sequence KS6 differs profoundly in its stratigraphic architecture from the more “layer-cake”-like KS4 to KS1 sequences. Facies and thickness patterns are controlled by a marked paleohigh to paleolow configuration, resulting from the antecedent uneven topography during the Neo-Tethyan syn-rift setting, in contrast to the post-rift setting with low tectonic activity during KS4 to KS1.","PeriodicalId":55118,"journal":{"name":"Geoarabia","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2013-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68185873","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2013-04-01DOI: 10.2113/geoarabia1802219
K. Kelsch, Sukhdarshan Kumar, S. Al-Anazi, R. Corley, Mike Ye, P. Thompson, Y. A. Mohammad
{"title":"Structural and stratigraphic trapping of hydrocarbons within Late Jurassic to Early Cretaceous section as observed from drilling and 2-D/3-D seismic in Partitioned/Divided Zone of the Kingdom of Saudi Arabia/Kuwait","authors":"K. Kelsch, Sukhdarshan Kumar, S. Al-Anazi, R. Corley, Mike Ye, P. Thompson, Y. A. Mohammad","doi":"10.2113/geoarabia1802219","DOIUrl":"https://doi.org/10.2113/geoarabia1802219","url":null,"abstract":"","PeriodicalId":55118,"journal":{"name":"Geoarabia","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2013-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68185366","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
We present a high-resolution structural study on the dip slope of the southern flank of Jabal Shams in the central Oman Mountains. The objectives of the study were: (1) to test existing satellite-based interpretations of structural elements in the area; (2) prepare an accurate geological map; and (3) collect an extensive structural dataset of fault and bedding planes, fault throws, veins and joints. These data are compared with existing models of tectonic evolution in the Oman Mountains and the subsurface, and used to assess the applicability of these structures as analogs for fault and fracture systems in subsurface carbonate reservoirs in Oman. The complete exposure of clean rock incised by deep wadis allowed detailed mapping of the complex fault, vein and joint system hosted by Member 3 of the Cretaceous Kahmah Group. The member was divided into eight units for mapping purposes, in about 100 m of vertical stratigraphy. The map was almost exclusively based on direct field observations. It includes measurement of fault throw in many locations and the construction of profiles, which are accurate to within a few meters. Ground-truthing of existing satellite-based interpretations of structural elements showed that faults can be mapped with high confidence using remote-sensing data. The faults range into the subseismic scale with throws as little as a few decimeters. However, the existing interpretation of lineaments as cemented fractures was shown to be incorrect: the majority of these are open fractures formed along reactivated veins. The most prominent structure in the study area is a conjugate set of ESE-striking faults with throws resolvable from several centimeters to hundreds of meters. These faults contain bundles of coarse-grained calcite veins, which may be brecciated during reactivation. We interpret these faults to be a conjugate normal- to oblique fault set, which was rotated together with bedding during the folding of the Al Jabal al-Akhdar anticline. There are many generations of calcite veins with minor offset and at high-angle-to-bedding, sometimes in en-echelon sets. Analysis of clear overprinting relationships between veins at high-angle-to-bedding is consistent with the interpretations of Holland et al. (2009a); however we interpret the anticlockwise rotation of vein strike orientation to start before and end after the normal faulting. The normal faults post-date the bedding-parallel shear veins in the study area. Thus these faults formed after the emplacement of the Semail and Hawasina Nappes. They were previously interpreted to be of the same age as the regional normal- to oblique-slip faults in the subsurface of northern Oman and the United Arab Emirates, which evolved during the early deposition of the Campanian Fiqa Formation as proposed by Filbrandt et al. (2006). We interpret them also to be coeval with the Phase I extension of Fournier et al. (2006). The reactivation of these faults and the evolution of new veins was f
我们提出了一个高分辨率的构造研究，在阿曼山脉中部贾巴尔沙姆斯的南侧倾斜斜坡。这项研究的目的是:(1)测试该地区现有的基于卫星的结构要素解释;(二)编制准确的地质图;(3)收集了大量断层、层理面、断层抛射、脉、节理等构造数据。这些数据与阿曼山脉和地下构造演化的现有模型进行了比较，并用于评估这些构造作为阿曼地下碳酸盐岩储层断层和裂缝系统类比的适用性。被深溪谷切割的干净岩石完全暴露出来，可以详细绘制白垩纪Kahmah群3成员所处的复杂断层、脉和节理系统。在100米左右的垂直地层中，该成员被划分为8个单元进行制图。这张地图几乎完全是根据直接的实地观察绘制的。它包括在许多地点测量断层距离和构造剖面，其精度在几米以内。现有的基于卫星的构造元素解释的地面真实性表明，利用遥感数据可以高可信度地绘制断层图。这些断层的范围可达次地震级别，断层距小至几分米。然而，现有的将裂缝解释为胶结裂缝的解释是不正确的:这些裂缝大多数是沿着重新激活的静脉形成的开放裂缝。研究区最突出的构造是一套向东南方向的共轭断裂，其断层距离可分辨为几厘米至数百米。这些断层含有粗粒方解石脉束，可能在再活化过程中角化。我们将这些断层解释为一个共轭的正斜断层集，在Al Jabal Al - akhdar背斜褶皱期间，这些断层与层理一起旋转。方解石脉多代，偏置程度小，与层理呈大角度，有时呈阶梯形。分析表明，高角度与层理的脉体之间明显的叠印关系与Holland等人(2009a)的解释一致;然而，我们将脉走向的逆时针旋转解释为开始于正断层之前，结束于正断层之后。研究区内正断层的发育时间晚于顺层平行剪切脉。因此，这些断裂是在塞梅尔推覆体和哈瓦西纳推覆体侵位后形成的。它们之前被解释为与阿曼北部和阿拉伯联合酋长国地下的区域正斜滑断层年龄相同，后者是在Filbrandt等人(2006)提出的坎帕尼亚-菲卡组早期沉积期间演变而来的。我们将其解释为与Fournier等人(2006年)的第一阶段扩展相同。这些断裂的再活化和新脉的演化随后是Al Jabal Al - akhdar背斜的褶皱，最后是原有微脉的再活化引起的隆升和节理。因此，研究区内的断层与地下的断层具有相当的运动学和年龄。然而，它们是在更大的深度和流体压力下形成的，因此，直接将这些结构用作阿曼地下储层断层和裂缝系统的类似物时，应谨慎进行。
{"title":"Development of fault and vein networks in a carbonate sequence near Hayl al-Shaz, Oman Mountains","authors":"S. Virgo, M. Arndt, Zoé Sobisch, J. Urai","doi":"10.2113/geoarabia180299","DOIUrl":"https://doi.org/10.2113/geoarabia180299","url":null,"abstract":"\u0000 We present a high-resolution structural study on the dip slope of the southern flank of Jabal Shams in the central Oman Mountains. The objectives of the study were: (1) to test existing satellite-based interpretations of structural elements in the area; (2) prepare an accurate geological map; and (3) collect an extensive structural dataset of fault and bedding planes, fault throws, veins and joints. These data are compared with existing models of tectonic evolution in the Oman Mountains and the subsurface, and used to assess the applicability of these structures as analogs for fault and fracture systems in subsurface carbonate reservoirs in Oman. The complete exposure of clean rock incised by deep wadis allowed detailed mapping of the complex fault, vein and joint system hosted by Member 3 of the Cretaceous Kahmah Group. The member was divided into eight units for mapping purposes, in about 100 m of vertical stratigraphy. The map was almost exclusively based on direct field observations. It includes measurement of fault throw in many locations and the construction of profiles, which are accurate to within a few meters. Ground-truthing of existing satellite-based interpretations of structural elements showed that faults can be mapped with high confidence using remote-sensing data. The faults range into the subseismic scale with throws as little as a few decimeters. However, the existing interpretation of lineaments as cemented fractures was shown to be incorrect: the majority of these are open fractures formed along reactivated veins.\u0000 The most prominent structure in the study area is a conjugate set of ESE-striking faults with throws resolvable from several centimeters to hundreds of meters. These faults contain bundles of coarse-grained calcite veins, which may be brecciated during reactivation. We interpret these faults to be a conjugate normal- to oblique fault set, which was rotated together with bedding during the folding of the Al Jabal al-Akhdar anticline. There are many generations of calcite veins with minor offset and at high-angle-to-bedding, sometimes in en-echelon sets. Analysis of clear overprinting relationships between veins at high-angle-to-bedding is consistent with the interpretations of Holland et al. (2009a); however we interpret the anticlockwise rotation of vein strike orientation to start before and end after the normal faulting. The normal faults post-date the bedding-parallel shear veins in the study area. Thus these faults formed after the emplacement of the Semail and Hawasina Nappes. They were previously interpreted to be of the same age as the regional normal- to oblique-slip faults in the subsurface of northern Oman and the United Arab Emirates, which evolved during the early deposition of the Campanian Fiqa Formation as proposed by Filbrandt et al. (2006). We interpret them also to be coeval with the Phase I extension of Fournier et al. (2006). The reactivation of these faults and the evolution of new veins was f","PeriodicalId":55118,"journal":{"name":"Geoarabia","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2013-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68185390","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2013-04-01DOI: 10.2113/geoarabia1802141
D. Cooper, Mohammed Y. Ali, M. Searle, A. Al-Lazki
The Jabal Qumayrah area, 50 km ESE of Al Ain and Buraimi, preserves a culmination of Jurassic and Cretaceous continental slope deposits (Sumeini Group) that was emplaced during the Late Cretaceous onto the Oman margin with other Neo-Tethyan units and the Semail Ophiolite. Almost uniquely in the Oman Mountains, Jabal Qumayrah also contains outcrops of gypsum and anhydrite that occur as a central complex from which laterally discontinuous linear and arcuate outcrops extend up to 4 km to the northwest and south. The gypsum and anhydrite bodies contain sedimentary clasts and rafts, which show close affinities with the local Sumeini Group host rock. There are no sedimentary features that indicate the evaporites were deposited in situ, either as part of, or unconformably overlying the Sumeini Group. Boundaries with the host rock are either high-angle faults or steep and intrusive, with significant dissolution of host rock limestones. Two gravity transects across the area indicate the areas of gypsum and anhydrite lie on a gravity low, compatible with an elongated, high-level body concentrated along the main N-S axis of the Jabal Qumayrah dome. Taken together, these features point towards an intrusive origin for the evaporite bodies in Jabal Qumayrah. While the sub-surface is poorly constrained, the central complex is interpreted as representing the deeply weathered top of a salt diapir, whose emplacement had a strong tectonic fault-driven component. The smaller, discontinuous exposures to the northwest and south are interpreted as pods of gypsum and anhydrite that were injected along faults. The absence of other evaporite minerals, in particular halite, is attributed to deep weathering and dissolution similar to that seen at the surface-piercing salt domes of the Ghaba Salt Basin in central Oman. In the absence of unequivocal dating evidence, the regional context suggests the intrusion may be derived from evaporites within the Ediacaran–Early Cambrian Ara Group. These form large deposits in the Fahud and Ghaba salt basins to the southwest of the Oman Mountains and the Hormuz Salt Basin to the north. The Jabal Qumayrah area may represent another, smaller basin or an extension to the Fahud Basin. The Jabal Qumayrah intrusion does not contain rafts of Ara Group limestones, which characterise the salt diapirs of the Ghaba Salt Basin, but this is not considered diagnostic. Other regional evaporite units of Permian to Jurassic ages do not extend into the area of the Oman Mountains and are thus unlikely potential sources. There is no evidence to suggest the Jabal Qumayrah culmination was thrust over Cenozoic evaporites and this potential source is also discounted. The timing of intrusion is constrained by the boundary faults, which cut across and thus post-date structures related to the Late Cretaceous emplacement of the Sumeini Group of Jabal Qumayrah. There is no evidence of any movement since the unroofing and exposure of the salt intrusion, which began
{"title":"Salt intrusions in Jabal Qumayrah, northern Oman Mountains: Implications from structural and gravity investigations","authors":"D. Cooper, Mohammed Y. Ali, M. Searle, A. Al-Lazki","doi":"10.2113/geoarabia1802141","DOIUrl":"https://doi.org/10.2113/geoarabia1802141","url":null,"abstract":"\u0000 The Jabal Qumayrah area, 50 km ESE of Al Ain and Buraimi, preserves a culmination of Jurassic and Cretaceous continental slope deposits (Sumeini Group) that was emplaced during the Late Cretaceous onto the Oman margin with other Neo-Tethyan units and the Semail Ophiolite. Almost uniquely in the Oman Mountains, Jabal Qumayrah also contains outcrops of gypsum and anhydrite that occur as a central complex from which laterally discontinuous linear and arcuate outcrops extend up to 4 km to the northwest and south. The gypsum and anhydrite bodies contain sedimentary clasts and rafts, which show close affinities with the local Sumeini Group host rock. There are no sedimentary features that indicate the evaporites were deposited in situ, either as part of, or unconformably overlying the Sumeini Group. Boundaries with the host rock are either high-angle faults or steep and intrusive, with significant dissolution of host rock limestones. Two gravity transects across the area indicate the areas of gypsum and anhydrite lie on a gravity low, compatible with an elongated, high-level body concentrated along the main N-S axis of the Jabal Qumayrah dome. Taken together, these features point towards an intrusive origin for the evaporite bodies in Jabal Qumayrah. While the sub-surface is poorly constrained, the central complex is interpreted as representing the deeply weathered top of a salt diapir, whose emplacement had a strong tectonic fault-driven component. The smaller, discontinuous exposures to the northwest and south are interpreted as pods of gypsum and anhydrite that were injected along faults. The absence of other evaporite minerals, in particular halite, is attributed to deep weathering and dissolution similar to that seen at the surface-piercing salt domes of the Ghaba Salt Basin in central Oman.\u0000 In the absence of unequivocal dating evidence, the regional context suggests the intrusion may be derived from evaporites within the Ediacaran–Early Cambrian Ara Group. These form large deposits in the Fahud and Ghaba salt basins to the southwest of the Oman Mountains and the Hormuz Salt Basin to the north. The Jabal Qumayrah area may represent another, smaller basin or an extension to the Fahud Basin. The Jabal Qumayrah intrusion does not contain rafts of Ara Group limestones, which characterise the salt diapirs of the Ghaba Salt Basin, but this is not considered diagnostic. Other regional evaporite units of Permian to Jurassic ages do not extend into the area of the Oman Mountains and are thus unlikely potential sources. There is no evidence to suggest the Jabal Qumayrah culmination was thrust over Cenozoic evaporites and this potential source is also discounted. The timing of intrusion is constrained by the boundary faults, which cut across and thus post-date structures related to the Late Cretaceous emplacement of the Sumeini Group of Jabal Qumayrah. There is no evidence of any movement since the unroofing and exposure of the salt intrusion, which began","PeriodicalId":55118,"journal":{"name":"Geoarabia","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2013-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68185585","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The Middle–Upper Permian (Guadalupian–Lopingian) Dalan Basin was part of a very large carbonate ramp/platform along the passive margin of the Arabian Plate, located at mid-latitude Neo-Tethys Ocean. As shown in the modern world the mid-latitudes are areas where climatic fluctuations and velocity of climate change are most significant. Consequently, the most significant variations in foraminiferal diversity occur at higher latitudes as already noted for the Middle Permian (Guadalupian) foraminifers’ record. The fusulinids as a large, warm-water foraminifera were quite sensitive to water temperature. The optimal water temperature for recent warm-water benthic foraminifera with living symbionts, and consequently for fusulinids, is 20–30°C, while the lower limit is 14–16°C. Three climatically-determined assemblages were distinguished in Zagros and the surrounding areas. The first assemblage is characteristic of temperate, cool-water environments and contains smaller foraminifera with no symbionts, which possess resistance to such environments. Fusulinid staffellids, schubertellids, Chusenella, Eopolydiexodina and Monodiexodina can be found in the warmer water environments in a second climatic assemblage, transitional from temperate- to warm-water state. The third assemblage is characterized by the presence of verbeekinids in warm-water conditions in Zagros and appeared where surface-water temperature exceeded approximately 25°C. The proposed model of climate fluctuations and paleogeography in the Neo-Tethys is based on analyses of temporal and spatial distribution of fusulinids. Also, a temperate cool-water Monodiexodina is recorded in this area for the first time. Three new species of fusulinids are described.
{"title":"Middle Permian (Guadalupian) fusulinid taxonomy and biostratigraphy of the mid-latitude Dalan Basin, Zagros, Iran and their applications in paleoclimate dynamics and paleogeography","authors":"V. Davydov, S. Arefifard","doi":"10.2113/geoarabia180217","DOIUrl":"https://doi.org/10.2113/geoarabia180217","url":null,"abstract":"\u0000 The Middle–Upper Permian (Guadalupian–Lopingian) Dalan Basin was part of a very large carbonate ramp/platform along the passive margin of the Arabian Plate, located at mid-latitude Neo-Tethys Ocean. As shown in the modern world the mid-latitudes are areas where climatic fluctuations and velocity of climate change are most significant. Consequently, the most significant variations in foraminiferal diversity occur at higher latitudes as already noted for the Middle Permian (Guadalupian) foraminifers’ record. The fusulinids as a large, warm-water foraminifera were quite sensitive to water temperature. The optimal water temperature for recent warm-water benthic foraminifera with living symbionts, and consequently for fusulinids, is 20–30°C, while the lower limit is 14–16°C. Three climatically-determined assemblages were distinguished in Zagros and the surrounding areas. The first assemblage is characteristic of temperate, cool-water environments and contains smaller foraminifera with no symbionts, which possess resistance to such environments. Fusulinid staffellids, schubertellids, Chusenella, Eopolydiexodina and Monodiexodina can be found in the warmer water environments in a second climatic assemblage, transitional from temperate- to warm-water state. The third assemblage is characterized by the presence of verbeekinids in warm-water conditions in Zagros and appeared where surface-water temperature exceeded approximately 25°C. The proposed model of climate fluctuations and paleogeography in the Neo-Tethys is based on analyses of temporal and spatial distribution of fusulinids. Also, a temperate cool-water Monodiexodina is recorded in this area for the first time. Three new species of fusulinids are described.","PeriodicalId":55118,"journal":{"name":"Geoarabia","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2013-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68185777","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2013-04-01DOI: 10.2113/geoarabia1802241
P. Razin, C. Grélaud, E. Dujoncquoy, A. Lebec
{"title":"Latest Jurassic to Early Barremian carbonate systems from the United Arab Emirates to Oman: Regional stratigraphic architecture and controlling factors","authors":"P. Razin, C. Grélaud, E. Dujoncquoy, A. Lebec","doi":"10.2113/geoarabia1802241","DOIUrl":"https://doi.org/10.2113/geoarabia1802241","url":null,"abstract":"","PeriodicalId":55118,"journal":{"name":"Geoarabia","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2013-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68185484","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
About 20 billion tonnes of world-class, high-grade phosphorite resources occur in a small area of the eastern Mediterranean region, including Jordan, northern Negev (Palestine), northwestern Saudi Arabia, western Iraq, and southeastern Syria. Major deposits were formed during Campanian to Eocene times and contribute significantly to the economic development of these countries, particularly Jordan and Syria. The phosphorite deposits consist mainly of reworked granular material. The phosphate particles are peloids, such as pellets, intraclasts, nodules, coated grains and coprolites, and vertebrate fragments (bone and teeth). The phosphorite sequences are associated with extensive bedded chert, porcelanite, and organic-rich marls. The main phosphate mineral is francolite, a carbonate-rich variety of fluorapatite that has a relatively enhanced uranium content as a result of substitution for calcium in its crystal structure. Two factors are deemed responsible for the deposition of the phosphorites and their associated chert, porcelanite, and marl within this relatively restricted area. The first was a compressional event associated with the initial collision of the oceanic forefront of the Afro-Arabian Plate with the subduction trench of Eurasia that began in Turonian times and continued into the Eocene. This event resulted in gentle folding that produced the Syrian Arc, the Ha’il, Rutba, and Sirhan paleohighs and the Ga’ara Dome, which were loci for the deposition of phosphorites. The second factor was the obstruction and consequent upwelling of oceanic currents by these tectonic highs, enhanced by winds blowing from east to west along the southern platform margin of the Neo-Tethys Ocean. The intense upwelling was associated with the Tethyan Circumglobal Current that flowed along the Afro-Arabian platform on the southern margin of the Neo-Tethys Ocean. In contrast, relatively minor phosphorite deposition took place to the north in southern Europe. The upwelling spread cold, nutrient-rich oceanic water from the deep Neo-Tethys Ocean to the surface, thereby enhancing bioproductivity to produce organic-rich sediments. The subsequent authigenesis of phosphorites, their diagenesis and the reworking and winnowing of the phosphorite-rich sediments, concentrated the materials into economic deposits. Phosphorite deposition ended in the Late Eocene following the final collision of the Afro-Arabian Plate with Eurasia. The sub-aerial exposure of this formerly productive shallow-marine platform was the result of the separation of the Arabian Plate from the African Plate during the mid-Miocene.
{"title":"The eastern Mediterranean phosphorite giants: An interplay between tectonics and upwelling","authors":"A. Abed","doi":"10.2113/geoarabia180267","DOIUrl":"https://doi.org/10.2113/geoarabia180267","url":null,"abstract":"\u0000 About 20 billion tonnes of world-class, high-grade phosphorite resources occur in a small area of the eastern Mediterranean region, including Jordan, northern Negev (Palestine), northwestern Saudi Arabia, western Iraq, and southeastern Syria. Major deposits were formed during Campanian to Eocene times and contribute significantly to the economic development of these countries, particularly Jordan and Syria. The phosphorite deposits consist mainly of reworked granular material. The phosphate particles are peloids, such as pellets, intraclasts, nodules, coated grains and coprolites, and vertebrate fragments (bone and teeth). The phosphorite sequences are associated with extensive bedded chert, porcelanite, and organic-rich marls. The main phosphate mineral is francolite, a carbonate-rich variety of fluorapatite that has a relatively enhanced uranium content as a result of substitution for calcium in its crystal structure.\u0000 Two factors are deemed responsible for the deposition of the phosphorites and their associated chert, porcelanite, and marl within this relatively restricted area. The first was a compressional event associated with the initial collision of the oceanic forefront of the Afro-Arabian Plate with the subduction trench of Eurasia that began in Turonian times and continued into the Eocene. This event resulted in gentle folding that produced the Syrian Arc, the Ha’il, Rutba, and Sirhan paleohighs and the Ga’ara Dome, which were loci for the deposition of phosphorites. The second factor was the obstruction and consequent upwelling of oceanic currents by these tectonic highs, enhanced by winds blowing from east to west along the southern platform margin of the Neo-Tethys Ocean. The intense upwelling was associated with the Tethyan Circumglobal Current that flowed along the Afro-Arabian platform on the southern margin of the Neo-Tethys Ocean. In contrast, relatively minor phosphorite deposition took place to the north in southern Europe.\u0000 The upwelling spread cold, nutrient-rich oceanic water from the deep Neo-Tethys Ocean to the surface, thereby enhancing bioproductivity to produce organic-rich sediments. The subsequent authigenesis of phosphorites, their diagenesis and the reworking and winnowing of the phosphorite-rich sediments, concentrated the materials into economic deposits. Phosphorite deposition ended in the Late Eocene following the final collision of the Afro-Arabian Plate with Eurasia. The sub-aerial exposure of this formerly productive shallow-marine platform was the result of the separation of the Arabian Plate from the African Plate during the mid-Miocene.","PeriodicalId":55118,"journal":{"name":"Geoarabia","volume":"8 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2013-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68185601","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
During the Aptian 28 to possibly 34 transgressive-regressive “fourth-order” sequences were deposited on the Arabian Plate. The sequences were controlled by sea-level fluctuations with a relative amplitude of 5–20 m. The fluctuations are interpreted as the glacio-eustatic response to orbital-forcing and assumed to have an average duration of 405 Kyr corresponding to the long-eccentricity orbital cycle. The sequences are referred to as “stratons” and calibrated in the orbital time scale of Matthews and Al-Husseini (2010, abbreviated M&H-2010). An independent study by Huang et al. (2010) counted nearly 33 cycles of 405-Kyr in a deep-marine Aptian succession in the Piobicco core in central Italy. The Italian cycles and Arabian stratons can be correlated in GTS 2004 by the position and age of the oceanic anoxic event OAE1a (Selli Interval, ca. 124.5–123.1 Ma). Two lowermost Aptian stratons and at least nine upper Aptian ones show stratigraphic geometries that imply 40–50 m box-like drops in relative sea level. They provide evidence for the formation of an ice sheet, mainly in Antarctica, that held several 10s of meters sea-level equivalent. The ca. 5-Myr-long late Aptian drop started at Global SB Apt 5 (ca. 117.9 Ma), which correlates to a major eccentricity minimum predicted at 118.2 Ma in the M&H-2010 scale. Similar minima are predicted to recur every 14.58 Myr (36 × 405 Kyr), and to cause major glacio-eustatic drops and regional sequence boundaries (SB). The youngest SB 0 is predicted at 1.586 Ma, and SB 8 (118.2 = 1.586 + 8 × 14.58 Ma) is interpreted to have triggered the late Aptian glaciation. The M&H-2010 scale was tested against the high-resolution sea-level curve derived from benthic foraminiferal δ18O isotopes for the late Miocene to Holocene (9.25– 0.0 Ma, Miller et al., 2005, abbreviated Metal-2005). Antarctica’s glacio-eustatic signature is interpreted as high-frequency sea-level fluctuations with a period of 41 Kyr (obliquity) above -20 m relative to present-day sea level. The fluctuations ride up-and-down on longer-period sea-level cycles (transgression-regression) with amplitudes of 20–40 m. The cycles are bounded by prominent lowstands, have durations of 325–545 Kyr, and an average duration of 405 Kyr. Sequence Boundary SB 0 (predicted at 1.586 Ma) is interpreted at 1.54 Ma, and correlated to Calabrian Global sequence boundary Cala1 (1.54 Ma).
{"title":"MIDDLE EAST GEOLOGIC TIME SCALE 2013","authors":"M. Al-Husseini","doi":"10.2113/geoarabia180117","DOIUrl":"https://doi.org/10.2113/geoarabia180117","url":null,"abstract":"\u0000 During the Aptian 28 to possibly 34 transgressive-regressive “fourth-order” sequences were deposited on the Arabian Plate. The sequences were controlled by sea-level fluctuations with a relative amplitude of 5–20 m. The fluctuations are interpreted as the glacio-eustatic response to orbital-forcing and assumed to have an average duration of 405 Kyr corresponding to the long-eccentricity orbital cycle. The sequences are referred to as “stratons” and calibrated in the orbital time scale of Matthews and Al-Husseini (2010, abbreviated M&H-2010). An independent study by Huang et al. (2010) counted nearly 33 cycles of 405-Kyr in a deep-marine Aptian succession in the Piobicco core in central Italy. The Italian cycles and Arabian stratons can be correlated in GTS 2004 by the position and age of the oceanic anoxic event OAE1a (Selli Interval, ca. 124.5–123.1 Ma). Two lowermost Aptian stratons and at least nine upper Aptian ones show stratigraphic geometries that imply 40–50 m box-like drops in relative sea level. They provide evidence for the formation of an ice sheet, mainly in Antarctica, that held several 10s of meters sea-level equivalent. The ca. 5-Myr-long late Aptian drop started at Global SB Apt 5 (ca. 117.9 Ma), which correlates to a major eccentricity minimum predicted at 118.2 Ma in the M&H-2010 scale. Similar minima are predicted to recur every 14.58 Myr (36 × 405 Kyr), and to cause major glacio-eustatic drops and regional sequence boundaries (SB). The youngest SB 0 is predicted at 1.586 Ma, and SB 8 (118.2 = 1.586 + 8 × 14.58 Ma) is interpreted to have triggered the late Aptian glaciation. The M&H-2010 scale was tested against the high-resolution sea-level curve derived from benthic foraminiferal δ18O isotopes for the late Miocene to Holocene (9.25– 0.0 Ma, Miller et al., 2005, abbreviated Metal-2005). Antarctica’s glacio-eustatic signature is interpreted as high-frequency sea-level fluctuations with a period of 41 Kyr (obliquity) above -20 m relative to present-day sea level. The fluctuations ride up-and-down on longer-period sea-level cycles (transgression-regression) with amplitudes of 20–40 m. The cycles are bounded by prominent lowstands, have durations of 325–545 Kyr, and an average duration of 405 Kyr. Sequence Boundary SB 0 (predicted at 1.586 Ma) is interpreted at 1.54 Ma, and correlated to Calabrian Global sequence boundary Cala1 (1.54 Ma).","PeriodicalId":55118,"journal":{"name":"Geoarabia","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2013-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68185028","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2013-01-01DOI: 10.2113/geoarabia1801179
Q. Abeed, R. Littke, F. Strozyk, A. K. Uffmann
A 3-D basin model of the southern Mesopotamian Basin, southern Iraq, was built in order to quantify key aspects of the petroleum system. The model is based on detailed seismic interpretation and organic geochemical data, both for source rocks and oils. Bulk kinetic analysis for three source rock samples was used to quantify petroleum generation characteristics and to estimate the temperature and timing of petroleum generation. These analyses indicate that petroleum generation from the Yamama source rock (one of the main source rocks in the study area) starts at relatively low temperatures of 70–80°C, which is typical for Type II-S kerogen at low to moderate heating rates typical of sedimentary basins. Petroleum system analysis was achieved using the results from 1-D, 2-D, and 3-D basin modelling, the latter being the major focus of this study. The 1-D model reveals that the Upper Jurassic–Lower Cretaceous sediments are now within the oil window, whereas the formations that overlie the Yamama Formation are still immature in the entire study area. Present-day temperature reflects the maximum temperature of the sedimentary sequence, which indicates that no strong regional uplift affected the sedimentary rocks in the past. The 3-D model results indicate that oil generation in the Yamama source rock already commenced in the Cretaceous. At some locations of the basin this source rock reaches a present-day maximum temperature of 140–150°C. The most common migration pathways are in the vertical direction, i.e. direct migration upward from the source rock to the reservoir. This is partly related to the fact that the Lower Cretaceous reservoir horizons in southern Iraq directly overlay the source rock.
{"title":"The Upper Jurassic–Cretaceous petroleum system of southern Iraq: A 3-D basin modelling study","authors":"Q. Abeed, R. Littke, F. Strozyk, A. K. Uffmann","doi":"10.2113/geoarabia1801179","DOIUrl":"https://doi.org/10.2113/geoarabia1801179","url":null,"abstract":"\u0000 A 3-D basin model of the southern Mesopotamian Basin, southern Iraq, was built in order to quantify key aspects of the petroleum system. The model is based on detailed seismic interpretation and organic geochemical data, both for source rocks and oils. Bulk kinetic analysis for three source rock samples was used to quantify petroleum generation characteristics and to estimate the temperature and timing of petroleum generation. These analyses indicate that petroleum generation from the Yamama source rock (one of the main source rocks in the study area) starts at relatively low temperatures of 70–80°C, which is typical for Type II-S kerogen at low to moderate heating rates typical of sedimentary basins. Petroleum system analysis was achieved using the results from 1-D, 2-D, and 3-D basin modelling, the latter being the major focus of this study. The 1-D model reveals that the Upper Jurassic–Lower Cretaceous sediments are now within the oil window, whereas the formations that overlie the Yamama Formation are still immature in the entire study area. Present-day temperature reflects the maximum temperature of the sedimentary sequence, which indicates that no strong regional uplift affected the sedimentary rocks in the past. The 3-D model results indicate that oil generation in the Yamama source rock already commenced in the Cretaceous. At some locations of the basin this source rock reaches a present-day maximum temperature of 140–150°C. The most common migration pathways are in the vertical direction, i.e. direct migration upward from the source rock to the reservoir. This is partly related to the fact that the Lower Cretaceous reservoir horizons in southern Iraq directly overlay the source rock.","PeriodicalId":55118,"journal":{"name":"Geoarabia","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2013-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68185153","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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