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11.
Three-dimensional seismic data and wireline logs from the western Niger Delta were analyzed to reveal the sedimentary and tectonic history of a major deltaic growth-fault depocenter comprising a kilometer-scale rollover anticline. The seismic units of the rollover show a non-uniform thickness distribution with their respective maximum near the main bounding growth-fault on the landward side of the system. This wedge-shaped sediment-storage architecture ultimately reflects the non-uniform creation of accommodation space in the study area that was controlled by 1) the differential compaction of the hanging-wall and footwall strata, 2) the lateral variation of fault-induced tectonic subsidence above the listric master fault, and possibly 3) local subsidence related to the subsurface movement of mobile shale reacting to loading and buoyancy. A sequential three-dimensional decompaction of the interpreted deltaic rollover units allowed to reconstruct and measure the compaction development of the rollover succession through time, documenting that sediment compaction contributed per depositional interval to between 25 and 35% of the generation of depositional space subsequently filled by deltaic sediments. The incremental decompaction of sedimentary units was further used to quantify the cumulative amount of accommodation space at and around the studied rollover that was created by fault movement, shale withdrawal, regional tectonic subsidence, isostasy and changes in sea level. If data on the regional subsidence and eustasy are available, the contribution of these basinwide controls to the generation of depositional space can be subtracted from the cumulative accommodation balance, which ultimately quantifies the amount of space for sediments to accumulate created by fault movement or shale withdrawal. This observation is important in that it implies that background knowledge on subsidence, stratigraphic age and sea-level changes allows to reconstruct and quantify fault movement in syn-tectonic deltaic growth successions, and this solely based on hanging-wall isopach trends independent of footwall information. 相似文献
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习水桑木场铅锌成矿带位于黔中隆起与四川盆地过渡部位桑木场背斜核部,通过对成矿带代表性矿床的地质特征和矿床成因等的研究,总结成矿带内铅锌矿床的成矿规律,并分析其成矿潜力,认为本区具有十分有利的成矿地质条件和利于赋矿的地层、构造空间,找矿潜力大,宜开展系统的地质工作,以实现地质找矿突破。 相似文献
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Upper Hauterivian deposits in the Kurilovo area, Kamenica 1 section, NE of Niš, are described based of abundant and diverse orbitolinids. So far, the interval was assigned to the Barremian–Aptian on the geological map. Such a new age assignment results from the first detailed study carried out on the orbitolinid fauna contained in the Lower Cretaceous (upper Hauterivian) shallow-water limestones of eastern Serbia. The upper Hauterivian is documented on the basis of two key stratigraphic markers, specifically Valserina primitiva and Paleodictyoconus beckerae.In addition to these late Hauterivian index fossils, the studied section bears orbitolinids having a larger stratigraphic distribution: Cribellopsis neoelongata, Cribellopsis thieuloyi?, Montseciella glanensis, Orbitolinopsis debelmasi, Orbitolinopsis cf. debelmasi, Orbitolinopsis sp., Paleodictyoconus cuvillieri, Paleodictyoconus cf. cuvillieri, Paleodictyoconus cf. beckerae, Paleodictyoconus cf. actinostoma, Paleodictyoconus sp., Paracoskinolina? jourdanensis, Paracoskinolina cf. hispanica, Urgonina alpillensis, Valserina sp. The microfossil assemblage includes other foraminifers such as Charentia cuvillieri, Mayncina bulgarica, Nautiloculina cretacea, Pfenderina globosa, Pseudocyclammina cf. lituus, Pseudolituonella gavonensis, Ammobaculites sp., Bolivinopsis sp., abundant trocholinids, various miliolids, other foraminifers and sparse algae which will be presented separately. 相似文献
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鄂西黄陵背斜地区虽已发现众多矿点,但是矿床规模较小,找矿潜力不明。由于区内植被茂盛、覆盖严重,致使地质异常信息被削弱或掩盖,对进一步找矿工作造成了严重干扰。本次研究使用成分数据分析和能谱-面积(S-A)分形模型识别与金矿化相关的异常,结果表明:(1)等距对数比(ILR)变换后的主成分分析结果相比对数(Log)变换更能够反应元素的共生组合规律,第一主成分(PC1)元素组合为Au-Cu-Ag,且Au元素占有最大的载荷,与金矿密切相关,PC1元素组合异常的分布模式与矿点的分布更加吻合;(2) S-A方法抑制了黄陵背斜区域水系沉积物的背景模式,增强了异常模式;(3)根据地质特征和以往勘查工作情况,圈定了三处找矿远景区,为该地区金矿下一步勘查工作提供了重要依据。 相似文献
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通过褶皱、断裂、节理、线理等构造形迹的系统观测对铜官山S状背斜的形成过程和机制进行了综合构造解析,发现该背斜经过了3次构造变形,2次构造叠加复合.早期NE向褶皱的S状弯曲是由于前期EW向断裂限制的结果;晚期S状弯曲是由于新华夏构造应力场导致轴近水平的麻花状旋扭的结果;还通过物理模拟和数字模拟验证了限制型及麻花型S状构造形成机制.值得注意的是,通过铜官山S状背斜的综合构造解析可以扩大到整体下扬子台褶带的构造演化力学解析.从而证明根据局部地区的构造综合解析才是认识区域大地构造运动方式、方向及其变化最直接、最可靠的证据. 相似文献
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