Journal of Structural Geology最新文献_第2页

Reconstruction of denuded stratigraphic paleosurfaces of diverse folds based on structural element feature constraints 基于结构要素特征约束重建不同褶皱的剥蚀地层古地表

IF 2.6 2区地球科学

Journal of Structural Geology Pub Date : 2024-08-26 DOI: 10.1016/j.jsg.2024.105241

{"title":"Reconstruction of denuded stratigraphic paleosurfaces of diverse folds based on structural element feature constraints","authors":"","doi":"10.1016/j.jsg.2024.105241","DOIUrl":"10.1016/j.jsg.2024.105241","url":null,"abstract":"<div><p>Reconstructing the stratigraphic paleosurfaces of a fold is essential for deciphering the folding mechanism, simulating landscape evolution processes, and investigating mineral resource distribution. However, standard methods for reconstructing paleosurfaces in tectonic landforms, primarily applied on large-scale sedimentary basins and orogenic belts, heavily rely on extensive geological data and generally yield low-accuracy results. This limits their applicability to small to intermediate-scale geological structural areas. Therefore, this paper introduces a stratigraphic paleosurface reconstruction method tailored for small and intermediate-scale folds, leveraging structural element features to constrain this reconstruction, which is notably helpful when dealing with sparse geological and topographic data. This method involves several steps. Firstly, define the fold units for diverse landforms. Secondly, extract fold structural elements (FSEs) with diverse geological data. Next, fit the paleo-boundary of each stratum within the two-dimensional (2D) cross-section using elemental feature constraints. Finally, the Morphing technique is applied to interpolate multiple paleo-boundaries, which are then utilized in reconstructing the stratigraphic paleosurfaces through the Contour Reconstruction Algorithm (CRA). To validate the method, tests were conducted on three representative folds in China: the eastern Sichuan comb-like fold belt, the Dayueshan Anticline on Mount Lu, and the Wulongshan Dome near the Huangling Dome. Experimental results demonstrate that utilizing structural features as constraints enables automatic, accurate, and reliable stratigraphic paleosurface reconstruction. The reconstructed paleosurfaces facilitate the analysis of geometric characteristics and structural development mechanisms of folds within the study area. Furthermore, they can be readily incorporated into landscape evolution models (i.e., TTLEM) to simulate realistic topographic evolution and tectonic paleogeographic mapping or construct three-dimensional (3D) solid models.</p></div>","PeriodicalId":50035,"journal":{"name":"Journal of Structural Geology","volume":null,"pages":null},"PeriodicalIF":2.6,"publicationDate":"2024-08-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142098198","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Structural inheritance, morphotectonics and Holocene activity of the Cucalón-Pancrudo extensional fault (Iberian Chain, Spain) 库卡隆-潘克鲁多伸展断层（西班牙伊比利亚链）的结构传承、形态构造和全新世活动

IF 2.6 2区地球科学

Journal of Structural Geology Pub Date : 2024-08-22 DOI: 10.1016/j.jsg.2024.105234

{"title":"Structural inheritance, morphotectonics and Holocene activity of the Cucalón-Pancrudo extensional fault (Iberian Chain, Spain)","authors":"","doi":"10.1016/j.jsg.2024.105234","DOIUrl":"10.1016/j.jsg.2024.105234","url":null,"abstract":"<div><p>A large active extensional fault is characterized, which will contribute to improve seismic hazard assessment in an intraplate region of the Mediterranean domain whose seismic potential until today has been underestimated. The Cucalón-Pancrudo fault (CPF) is a NNW-SSE striking extensional fault that represents the negative (extensional) inversion of a previous, Late Variscan and Paleogene, transpressional fault. It is part of the Río Grío-Pancrudo fault zone, the largest active structure in the intraplate central-eastern Iberian Chain. This study focuses on characterizing the CPF structure, morphotectonics and paleoseismology. The fault offsets a well-known regional planation surface (lower level of the Fundamental Erosion Surface, FES3, 3.5 Ma), providing a basis for calculating the maximum fault throw (c. 280–300 m, including the contribution of a minor synthetic fault and a gentle accommodation monocline), and hence estimating the net slip (c. 305–325 m) and the long-term slip rate (0.09 mm/a). A trench dug in a Holocene fluvial terrace reveals an ensemble of listric, domino-style ruptures synthetic to the main fault. They were activated during at least two paleoseismic events (X, Z), 14.9 ± 1.4 ka and 6.9 ± 0.4 ka in age. An intermediate event (Y), dated to 11.0 ± 1.0 ka, as an uncertainty because the attribution of their ruptures to event Z cannot be ruled out. The total net slip accumulated during these events (1.15–1.25 m) provides an apparent short-term slip rate of 0.07–0.09 mm/a, very similar to the long-term slip rate. Nevertheless, it is very likely that the faults exposed in the surveyed trench do not represent a complete paleoseismic record. Therefore, the actual slip rate during Late Pleistocene-Holocene times could be significantly higher, approaching that reported for most of the recent extensional faults in the central Iberian Chain. The inclusion of CPF in the map of Active Faults of Iberia (QAFI database) will result in improving seismic hazard assessment in Spain.</p></div>","PeriodicalId":50035,"journal":{"name":"Journal of Structural Geology","volume":null,"pages":null},"PeriodicalIF":2.6,"publicationDate":"2024-08-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142058423","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Active strike-slip faulting, diapirism and seismic hazards. The case of the Kareh Bas fault and the associated Dandenjan salt extrusion in the zagros Mountains, SW Iran 活动走向滑动断层、断裂和地震灾害。伊朗西南部扎格罗斯山脉 Kareh Bas 断层及相关的 Dandenjan 盐挤压案例

IF 2.6 2区地球科学

Journal of Structural Geology Pub Date : 2024-08-22 DOI: 10.1016/j.jsg.2024.105239

{"title":"Active strike-slip faulting, diapirism and seismic hazards. The case of the Kareh Bas fault and the associated Dandenjan salt extrusion in the zagros Mountains, SW Iran","authors":"","doi":"10.1016/j.jsg.2024.105239","DOIUrl":"10.1016/j.jsg.2024.105239","url":null,"abstract":"<div><p>Strike-slip salt diapir systems have been scarcely investigated and have probably been underrecognized. The western Fars Arc of the Zagros Mountains hosts the most remarkable example of salt extrusions associated with seismogenic strike-slip faults within an oblique collisional setting. This study, mainly based on field mapping and observations carried out in the Kareh Bas fault system and the Dandenjan Diapir, explores several issues with practical implications related to these active fault-salt systems: (1) role of precursor diapirs on the initiation of shortening structures; (2) fault segmentation controlled by precursor diapirs, emergence of diapirs, and the development of pull-apart basins; (3) the relative timing of emergence of salt extrusions associated with a propagating strike-slip fault; (4) Quaternary deformation and paleoseismic evidence associated with the Kareh Bas fault; (5) the impact of the salt detachment depth on the seismogenic potential of the segmented Kareh Bas fault system; and (6) clustering of large potentially coseismic landslides in the vicinity of the Kareh Bas fault system.</p></div>","PeriodicalId":50035,"journal":{"name":"Journal of Structural Geology","volume":null,"pages":null},"PeriodicalIF":2.6,"publicationDate":"2024-08-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0191814124001913/pdfft?md5=de3df40fe2263d69dff115f967a99960&pid=1-s2.0-S0191814124001913-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142098199","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Petrofabric and Raman microspectroscopy study of the Mina Afortunada gneiss dome: Mapping its thermal gradient 对阿福图纳达矿脉片麻岩穹丘的岩石结构和拉曼微光谱研究：绘制热梯度图

IF 2.6 2区地球科学

Journal of Structural Geology Pub Date : 2024-08-20 DOI: 10.1016/j.jsg.2024.105236

{"title":"Petrofabric and Raman microspectroscopy study of the Mina Afortunada gneiss dome: Mapping its thermal gradient","authors":"","doi":"10.1016/j.jsg.2024.105236","DOIUrl":"10.1016/j.jsg.2024.105236","url":null,"abstract":"<div><p>Black quartzites and migmatitic orthogneisses from the Mina Afortunada dome have been analysed through quartz and graphite petrofabric analysis and Raman microspectrometry on graphitized carbonaceous material. The results permit us to recognize a deformation temperature increase from the dome envelope towards its core marking the transition from basal-<a> to rhomb-<a> quartz intracrystalline slip systems at maximum T of 475 °C, and from rhomb-<a> to prism-<a> at maximum T of 515 °C. The complementary petrofabric and Raman study on graphite discloses a change from basal to prismatic <a> slip systems at maximum T of ca. 470 °C, accompanied by a strengthening of its structural order.</p><p>The Raman study of large graphite grains revealed a non-random crystallinity organization in them, with domains of weaker lattice structural order (reflecting lower formation T) in core areas and higher crystallinity sectors (higher formation T) at the rims. This finding might reflect a shielding effect during prograde metamorphism, the rim material preventing grain core material from reorganization and increase in its crystallinity. This study shows also that graphite can be a good candidate for pressure-temperature-time path reconstruction in metamorphosed organic-rich rocks.</p></div>","PeriodicalId":50035,"journal":{"name":"Journal of Structural Geology","volume":null,"pages":null},"PeriodicalIF":2.6,"publicationDate":"2024-08-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0191814124001883/pdfft?md5=9cb27be52954334fb4ec506b2ea6546d&pid=1-s2.0-S0191814124001883-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142012420","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Slip and stress in block-in-matrix shear zones: 2. numerical modelling of a serpentine-filled dilational jog 块-基质剪切带中的滑动和应力： 2. 蛇纹石填充扩张斜面的数值模拟

IF 2.6 2区地球科学

Journal of Structural Geology Pub Date : 2024-08-19 DOI: 10.1016/j.jsg.2024.105238

{"title":"Slip and stress in block-in-matrix shear zones: 2. numerical modelling of a serpentine-filled dilational jog","authors":"","doi":"10.1016/j.jsg.2024.105238","DOIUrl":"10.1016/j.jsg.2024.105238","url":null,"abstract":"<div><p>We use 2-D numerical models to explore slip and stress dynamics in a fault-bound dilational jog, informed by a field example from the Dun Mountain Ophiolite in New Zealand. The jog is hosted in a metre-scale phacoid of massive serpentinite embedded in a “block-in-matrix” creeping serpentinite shear zone. The models show how periodic exceedance of the tensile strength of the contact between the sealed jog and host rock leads to episodic opening and deposition of a new crack-seal band, with a thickness limited by the release of stress around the tips of the stepover-bounding faults. Jog stress release in the model is lower than that predicted from linear elastic fracture mechanics because additional crack opening can occur slowly due to post-failure creep on the bounding faults. For 10 km overburden and constant high fluid pressure, we predict event stress release of ca. 16 MPa and total crack opening of ∼22 μm on either side of the jog, consistent with crack-seal band widths in the field example. Because our models show that total crack width reflects both initial cracking and subsequent creep, we suggest caution when using crack-seal band widths to directly infer stress release in similar shear zone settings.</p></div>","PeriodicalId":50035,"journal":{"name":"Journal of Structural Geology","volume":null,"pages":null},"PeriodicalIF":2.6,"publicationDate":"2024-08-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0191814124001901/pdfft?md5=0d8bf134b7884ed048fcb34498523863&pid=1-s2.0-S0191814124001901-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142098200","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Fracturing, comminution and grain-size-sensitive creep as a record of coseismic loading in the middle-crust: Insights from the Urtiga mylonitic pluton (NE Brazil) 断裂、粉碎和对晶粒尺寸敏感的蠕变是中间岩壳同震加载的记录：从 Urtiga mylonitic pluton（巴西东北部）获得的启示

IF 2.6 2区地球科学

Journal of Structural Geology Pub Date : 2024-08-15 DOI: 10.1016/j.jsg.2024.105237

{"title":"Fracturing, comminution and grain-size-sensitive creep as a record of coseismic loading in the middle-crust: Insights from the Urtiga mylonitic pluton (NE Brazil)","authors":"","doi":"10.1016/j.jsg.2024.105237","DOIUrl":"10.1016/j.jsg.2024.105237","url":null,"abstract":"<div><p>Evidence for mid-crustal seismic slip is scarce due to the limited capacity of downward propagation of rupture damage imposed by the confining pressure. Nevertheless, structures indicative of elevated stresses occur throughout the crustal profile. To further investigate this setting, we have studied the fabrics of the Urtiga pluton, emplaced at the south Patos shear zone (northeast Brazil), a major Neoproterozoic crustal boundary. K-feldspar and plagioclase porphyroclasts are fractured, with fine-grained K-feldspar + plagioclase mixtures filling cracks. The edges of the clasts are rimmed by fine feldspar grains that form a fine-grained matrix. Quartz ribbons are parallel to the mylonitic foliation and show microstructures and a fabric indicating deformation via dislocation creep. Chemical compositions of feldspars are typically similar between porphyroclasts, fractures and matrix, with plagioclase grains locally being more albitic within fractures. Crystallographic preferred orientations (CPO) in grains within fractures are host-controlled by the adjacent porphyroclast, while fine grains rimming the clasts show a weak CPO and are mostly strain-free. These characteristics suggest that grain size reduction in the Urtiga mylonitic pluton occurred through fracturing and subsequent grain-size-sensitive creep under mid-crustal conditions, which were possibly attained via downward propagation of seismic rupture from the overlying seismogenic zone during transient, seismic slip episodes, giving rise to spatially related pseudotachylytes at the boundaries of the southern Patos shear zone.</p></div>","PeriodicalId":50035,"journal":{"name":"Journal of Structural Geology","volume":null,"pages":null},"PeriodicalIF":2.6,"publicationDate":"2024-08-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142012454","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

3D study of dyke-induced asymmetric graben: The 1971 Mt. Etna (Italy) case by structural data and numerical modelling 堤坝诱发非对称地堑的三维研究：通过结构数据和数值建模研究 1971 年埃特纳火山（意大利）案例

IF 2.6 2区地球科学

Journal of Structural Geology Pub Date : 2024-08-15 DOI: 10.1016/j.jsg.2024.105231

{"title":"3D study of dyke-induced asymmetric graben: The 1971 Mt. Etna (Italy) case by structural data and numerical modelling","authors":"","doi":"10.1016/j.jsg.2024.105231","DOIUrl":"10.1016/j.jsg.2024.105231","url":null,"abstract":"<div><p>In this work, we have integrated field data and numerical models to characterise a unique dyke-induced graben system, exposed both in section and plan view, with an unexpected asymmetric fault geometry. This volcanotectonic feature is related to the 1971 eruption of Mt. Etna (southern Italy) and is located near the northern wall of the Valle del Bove, a huge depression carved into the eastern flank of the edifice. A new structural map and quantitative data were obtained from the analysis of aerial stereophotos collected before the onset of the 1971 eruption and after, high-resolution drone-derived models and field surveys carried out in the summer of 2022. In plan view, the graben is 2-km-long and its width ranges 27–143 m from the bottom to the upper part of the section view, with about 82 m of difference in elevation from top to bottom. Graben faults clearly show an asymmetric setting in terms of attitude, with one fault that dips 70° to the south, and the other one that dips 50° to the north. Vertical offset values are greater at higher elevations. We also ran a set of numerical models, aimed at investigating the distribution and orientation of stresses around the inferred dyke tip and in the host rock. The comparison between field data and numerical models suggests a key role of the inclined topography, as shown in section view, in determining the orientation of dyke-induced σ<sub>1</sub> and σ<sub>3</sub> in the host rock. This, in turn, controls the geometry of the graben faults, resulting in the observed asymmetric setting. Additionally, dyke-induced stress concentrations and vertical offset values support the hypothesis of a downward propagation of the graben faults, from the surface down to the dyke tip.</p></div>","PeriodicalId":50035,"journal":{"name":"Journal of Structural Geology","volume":null,"pages":null},"PeriodicalIF":2.6,"publicationDate":"2024-08-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0191814124001834/pdfft?md5=abef1e2ca03d9a66f2813e18816cc73a&pid=1-s2.0-S0191814124001834-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142049368","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Kinematic and dynamic fault slip analyses: Implications from the surface rupture of the 2023 Elbistan (Kahramanmaraş) (Mw7.6) earthquake, Türkiye 运动学和动态断层滑动分析：2023 年土耳其埃尔比斯坦（卡赫拉曼马拉什）（Mw7.6）地震地表断裂的影响

IF 2.6 2区地球科学

Journal of Structural Geology Pub Date : 2024-08-14 DOI: 10.1016/j.jsg.2024.105235

{"title":"Kinematic and dynamic fault slip analyses: Implications from the surface rupture of the 2023 Elbistan (Kahramanmaraş) (Mw7.6) earthquake, Türkiye","authors":"","doi":"10.1016/j.jsg.2024.105235","DOIUrl":"10.1016/j.jsg.2024.105235","url":null,"abstract":"<div><p>On 6 February 2023, the Elbistan (Kahramanmaraş) (Mw7.6) earthquake produced a strike-slip type coseismic surface rupture zone, involving the sinistral slip of the Doğanşehir Fault (DF) and Çardak Fault (ÇF). Fault slickenlines and seismic slickenlines were included in the inversion as part of the dynamic analysis. The inversion of fault slickenlines collected from nine outcrops along the surface rupture following the earthquake, many of which developed during the event and are referred to as coseismic slickenlines, reveals a strike-slip stress regime (σ2 = σv) characterized by a NE-SW (mean azimuth: N045°E) σ1 (maximum) axis. Relict slip planes adjacent to main slip surfaces were found to host slickenlines that appear much older than the most recent earthquake, referred to as paleoslip slickenlines. Inversion of the paleoslip slickenline collected from four outcrops reveals an extensional stress regime (σ1 = σv) characterized by a NE-SW σ3 (min) axis, consistent with previously published studies. To define a significant stress tensor concerning present-day faulting within the investigated area, the inversion method was applied to the seismic slickenlines of shallow earthquakes in the surface rupture area. The inversion of sixty selected nodal planes reveals a strike-slip stress regime (σ2 = σv) characterized by an NNE–SSW (N10°E) σ1 (max) axis. Besides, the moment tensor summation analysis using displacement vectors inferred from visible field markers offset during the earthquake was applied to the seismic slickenlines as part of the kinematic analysis. The shortening and extension results for the moment tensor summation are 044/36 and 307/11 indicating NE-SW compression. Results of the moment tensor summation (weighted by fault displacement) agree broadly with the inversion of seismic slickenlines results, indicating an NE orientation for shortening and an SE orientation for extension.</p></div>","PeriodicalId":50035,"journal":{"name":"Journal of Structural Geology","volume":null,"pages":null},"PeriodicalIF":2.6,"publicationDate":"2024-08-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142012452","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Refold structures of the Archaean Nyanzaga gold Project, Sukumaland Greenstone Belt, Tanzania: Precursors to the gold-bearing fault system 坦桑尼亚苏库马兰绿岩带太古宙尼扬扎加金项目的折叠结构：含金断层系统的前身

IF 2.6 2区地球科学

Journal of Structural Geology Pub Date : 2024-08-14 DOI: 10.1016/j.jsg.2024.105233

{"title":"Refold structures of the Archaean Nyanzaga gold Project, Sukumaland Greenstone Belt, Tanzania: Precursors to the gold-bearing fault system","authors":"","doi":"10.1016/j.jsg.2024.105233","DOIUrl":"10.1016/j.jsg.2024.105233","url":null,"abstract":"<div><p>This study presents a complete investigation into the structural-hydrothermal evolution of the Nyanzaga and Kilimani gold deposits within the Neoarchean Sukumaland Greenstone Belt, Tanzania Craton. The first compressional stage, D<sub>1a</sub>, creates upright E-W folds in response to N-S-oriented shortening. The second stage, D<sub>1b</sub>, refolds the previously formed structures during ongoing compression/transpression under N-S-oriented shortening. Due to the brittle nature of late deformation, during D<sub>1c</sub>, a set of faults emerges, with the NW-SE ones exhibit dextral shearing and control the formation of normal N-S vertical faults.</p><p>A protracted hydrothermal history is recorded, beginning with a disseminated silicate minerals- and pyrite-rich, gold-barren stage associated with the D<sub>1a</sub> and D<sub>1b</sub> deformations, followed by the development of a gold-endowed vein system during progressive D<sub>1b</sub> and D<sub>1c</sub> stages. Gold was mainly concentrated within vertical NW-SE (Kilimani) and N-S (Nyanzaga) faults. Our findings challenge traditional polyphase deformation models presented in the other gold deposits of the area, by proposing a progressive and continuous deformation-hydrothermal history. In addition, we highlight the influence of refold structures on fault geometry, which is crucial in concentrating gold mineralization under continuous N-S compression and transpression.</p></div>","PeriodicalId":50035,"journal":{"name":"Journal of Structural Geology","volume":null,"pages":null},"PeriodicalIF":2.6,"publicationDate":"2024-08-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142011585","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Frictional strength of siliciclastic sediment mixtures in fault stability assessment 断层稳定性评估中硅质泥沙混合物的摩擦强度

IF 2.6 2区地球科学

Journal of Structural Geology Pub Date : 2024-08-10 DOI: 10.1016/j.jsg.2024.105232

{"title":"Frictional strength of siliciclastic sediment mixtures in fault stability assessment","authors":"","doi":"10.1016/j.jsg.2024.105232","DOIUrl":"10.1016/j.jsg.2024.105232","url":null,"abstract":"<div><p>Frictional strength of fault zones is a key parameter for evaluation of fault stability and reactivation. We measure friction using the direct shear test (DST) for (i) sand-clay mixes mimicking fault gouges, and (ii) strength of fault zone interfaces. The sand-clay mixing ratio is linked to the established Shale Gouge Ratio (SGR) used in fault seal analysis, suggesting an approach for linking the measured frictional properties to the established subsurface fault characterization methods and risk assessment. We use powdered caprock material from the Draupne Formation mixed with sand to prepare the fault gouge and discuss application of results for fault zones on the Horda Platform, Norwegian North Sea.</p><p>Shearing of fault gouge show a systematic decrease in residual friction coefficient with increasing clay content from 0.6 (φ = 31°) in pure sand (SGR 0%) to 0.4 (φ = 22°) for clay rich mixtures (SGR 100%). Interface testing mimicking fault gouge on sand surface is less systematic and shows residual friction coefficients ranging from 0.53 to 0.6 (φ = 28–31°) for SGR 0–50%. Detailed interpretation of the shear testing results shows changes in drainage properties, volumetric changes during shearing and shear responses to normal stresses indicating threshold values for sand versus clay dominated material behaviour. However, the results are non-conclusive on the question if a linear variation of friction with clay content or a threshold between sand dominated versus clay dominated friction provides the best approach for linking friction to fault clay content.</p></div>","PeriodicalId":50035,"journal":{"name":"Journal of Structural Geology","volume":null,"pages":null},"PeriodicalIF":2.6,"publicationDate":"2024-08-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141992655","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0