Marine Geology最新文献

Origin and evolution of giant comet marks along the North Atlantic Deep-Water flow on the Demerara plateau 德米拉高原上北大西洋深水流沿线巨大彗星标记的起源和演化

IF 2.2 3区地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY

Marine Geology

Pub Date : 2026-01-22 DOI: 10.1016/j.margeo.2026.107717

Paul Blin , Lies Loncke , Xavier Durrieu De Madron , Sébastien Zaragosi , Kelly Fauquembergue , Swanne Gontharet , Ivane Pairaud , Pauline Dupont , Sandrine Caquineau , Bruno Charriere , Raphael Lagarde , Christophe Basile , Scientific Team DIADEM

The Demerara Plateau, located in the equatorial Atlantic, is particularly well-suited for recording the activity of the Deep Western Boundary Current (DWBC), which transports North Atlantic Deep Water (NADW) southward into the Atlantic basin. This current, active between 1500 and 3500 m depth, constitutes the deep part of the global thermohaline circulation and plays a crucial role in climate regulation. The Demerara Plateau is remarkable for the abundance and wide distribution of comet mark-type sedimentary structures, which can reach several kilometres in length. These hydrodynamic bedforms, interpreted as erosional features associated with strong bottom currents, are currently used as proxies for deep currents velocities, with minimum formation thresholds estimated between 0.60 and 0.75 m/s according to the literature (Rebesco et al., 2014; Werner et al., 1980). The DIADEM (Dive At DEMerara) oceanographic cruise (Basile and Loncke, 2023) enabled detailed investigation of one such structure using a combination of complementary tools with the aim of better understanding their functioning and evolution with in-situ observation, physical records, and sampling. Those new data were also combined with formerly acquired high-resolution seismic data, allowing a new vision of these bedforms their formation, and their evolution over time.

The main findings are the following: (1) comet-marks localize on carbonate mass transported blocs outcropping on the seafloor; (2) Clearly show a polyphase evolution of the bedforms of comet mark presenting alternations of erosion and sedimentation phases. The bedforms therefore record long-term variations in bottom current activity with an alternation of intense hydrodynamic events (erosion) and quieter hydrodynamic periods (deposition) through time, reflecting a complex hydrodynamic history; (3) At present, comet-marks recorded a significant decrease in current velocity within the erosional zones located inside the comet tails associated with fined-grained sediments infill in this area, highlighting the need for cautious interpretation of such features as direct indicators of present-day current intensity; (4) Finally, a result that was not necessarily anticipated but documented by exploring those bedforms with the Nautile submersible, comet-marks host quite important benthic and epibenthic biodiversity with a wide variety of associated species.

德米拉高原位于赤道大西洋，特别适合记录深层西部边界流（DWBC）的活动，它将北大西洋深水（NADW）向南输送到大西洋盆地。该海流活跃于1500 ~ 3500 m深度，构成了全球热盐环流的深层部分，在气候调节中起着至关重要的作用。Demerara高原以彗星标记型沉积构造的丰富和广泛分布而闻名，其长度可达数公里。这些流体动力层状被解释为与强底流相关的侵蚀特征，目前被用作深流速度的代表，根据文献，最低地层阈值估计在0.60至0.75 m/s之间（Rebesco等人，2014；Werner等人，1980）。DIADEM （Dive At DEMerara）海洋巡航（Basile and lonke， 2023年）利用互补工具的组合对这样一个结构进行了详细的调查，目的是通过现场观察、物理记录和采样更好地了解它们的功能和演变。这些新数据还与以前获得的高分辨率地震数据相结合，从而对这些地层的形成及其随时间的演变有了新的认识。主要发现如下：(1)彗星标志定位于出露海底的碳酸盐块体搬运块体上；(2)清晰地显示了彗星标记的多阶段演化，呈现出侵蚀和沉积阶段的交替。因此，河床记录了海底水流活动的长期变化，随着时间的推移，剧烈的水动力事件（侵蚀）和较平静的水动力时期（沉积）交替发生，反映了复杂的水动力历史；(3)目前，彗星痕迹记录了该地区与细粒沉积物填充物有关的彗尾内部侵蚀带内水流速度的显著下降，突出表明需要谨慎解释这些特征作为当今水流强度的直接指标；(4)最后，用“鹦鹉螺号”潜水器对这些河床进行探索后发现，彗星标记拥有相当重要的底栖和底栖生物多样性，以及各种各样的相关物种，这一结果不一定是预料到的，但却是有文献记载的。

{"title":"Origin and evolution of giant comet marks along the North Atlantic Deep-Water flow on the Demerara plateau","authors":"Paul Blin , Lies Loncke , Xavier Durrieu De Madron , Sébastien Zaragosi , Kelly Fauquembergue , Swanne Gontharet , Ivane Pairaud , Pauline Dupont , Sandrine Caquineau , Bruno Charriere , Raphael Lagarde , Christophe Basile , Scientific Team DIADEM","doi":"10.1016/j.margeo.2026.107717","DOIUrl":"10.1016/j.margeo.2026.107717","url":null,"abstract":"<div><div>The Demerara Plateau, located in the equatorial Atlantic, is particularly well-suited for recording the activity of the Deep Western Boundary Current (DWBC), which transports North Atlantic Deep Water (NADW) southward into the Atlantic basin. This current, active between 1500 and 3500 m depth, constitutes the deep part of the global thermohaline circulation and plays a crucial role in climate regulation. The Demerara Plateau is remarkable for the abundance and wide distribution of comet mark-type sedimentary structures, which can reach several kilometres in length. These hydrodynamic bedforms, interpreted as erosional features associated with strong bottom currents, are currently used as proxies for deep currents velocities, with minimum formation thresholds estimated between 0.60 and 0.75 m/s according to the literature (<span><span>Rebesco et al., 2014</span></span>; <span><span>Werner et al., 1980</span></span>). The DIADEM (Dive At DEMerara) oceanographic cruise (<span><span>Basile and Loncke, 2023</span></span>) enabled detailed investigation of one such structure using a combination of complementary tools with the aim of better understanding their functioning and evolution with in-situ observation, physical records, and sampling. Those new data were also combined with formerly acquired high-resolution seismic data, allowing a new vision of these bedforms their formation, and their evolution over time.</div><div>The main findings are the following: (1) comet-marks localize on carbonate mass transported blocs outcropping on the seafloor; (2) Clearly show a polyphase evolution of the bedforms of comet mark presenting alternations of erosion and sedimentation phases. The bedforms therefore record long-term variations in bottom current activity with an alternation of intense hydrodynamic events (erosion) and quieter hydrodynamic periods (deposition) through time, reflecting a complex hydrodynamic history; (3) At present, comet-marks recorded a significant decrease in current velocity within the erosional zones located inside the comet tails associated with fined-grained sediments infill in this area, highlighting the need for cautious interpretation of such features as direct indicators of present-day current intensity; (4) Finally, a result that was not necessarily anticipated but documented by exploring those bedforms with the Nautile submersible, comet-marks host quite important benthic and epibenthic biodiversity with a wide variety of associated species.</div></div>","PeriodicalId":18229,"journal":{"name":"Marine Geology","volume":"493 ","pages":"Article 107717"},"PeriodicalIF":2.2,"publicationDate":"2026-01-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146078223","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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

Carbonate platform evolution in response to the Mid - Pleistocene climate transition on the North-West Shelf of Australia: Insights from forward stratigraphic modelling 澳大利亚西北陆架碳酸盐岩台地演化对中更新世气候转变的响应：来自正向地层模拟的启示

IF 2.2 3区地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY

Marine Geology

Pub Date : 2026-01-20 DOI: 10.1016/j.margeo.2026.107716

Carra Williams , Jody M. Webster , Tristan Salles , Victorien Paumard , Camille Grimaldi , Mostfa Lejri

This study presents the first forward stratigraphic model of Scott Reef - two isolated carbonate platforms on the Northwest Shelf (NWS) of Australia, spanning the Middle Pleistocene Transition (MPT; ca. 1.2–0.7 Ma). Scott Reef preserves a unique archive of reef growth sequences paced by millennial (10³-year) to orbital (10⁴–10⁵-year) scale sea-level variability under continuous high subsidence, providing valuable analogues for Quaternary reef dynamics and potential future reef responses to accelerated climatic change. We apply forward stratigraphic modelling (FSM) to reduce uncertainty in the existing chronostratigraphic models of Scott Reef, generate synthetic data to improve seismic interpretation, and to test how changing eustatic and environmental conditions during and after the MPT influenced carbonate production, facies distributions, and platform morphology. The model is calibrated using modern bathymetry, seismic sequence stratigraphy, sedimentary facies, coralgal assemblages, U/Th ages, and temporal changes in carbonate production and wave energy. The best fit simulations require increased carbonate production and wave energy after ca. 0.5 Ma, coupled with reduced carbonate production on the South Reef leeward margin. Model results indicate that the first high-amplitude lowstand of MIS 12 initiated prolonged subaerial exposure, karstification, and the development of a bucket-shaped platform morphology, coincident with increased monsoonal intensification after ca. 0.5 Ma. Subsequent reef expansion during the long-duration MIS 11 highstand produced an 80 m thick aggradational reef rim and is consistent with timings of reef growth elsewhere along the NWS, although there are differences to timing and style of reef response to the MPT globally. Synthetic stratigraphy indicates a transition from thin (10–30 m), low-relief progradational-aggradational sequences prior to 0.5 Ma, to thicker (20–50 m) aggradational sequences in the post-MPT 100-kyr world. Constant subsidence rates used in the model (0.29 mm/yr at South Scott Reef and 0.45 mm/yr at North Scott Reef) indicate that increasing sea-level amplitude and reduced periodicity associated with the MPT modulated sequence thickness, resulting in changes in platform morphology and facies patterns after ca. 0.5 Ma. Coupled with continuous high subsidence and increasing monsoonal intensity, these changes indicate that both environmental and eustatic processes were major controls on Scott Reef evolution. Our model has broader implications for understanding the MPT globally, including timing and stratigraphic expression of carbonate platform responses. Trial-and-error style FSM, when ground-truthed to multi-scale observational data, remains a powerful tool to test hypotheses about carbonate platform and coral reef response to rapid environmental changes.

本文首次建立了澳大利亚西北陆架（NWS）上的斯科特礁（Scott Reef）两个独立的碳酸盐岩台地的正向地层模型，该模型跨越中更新世过渡（MPT，约1.2-0.7 Ma）。斯科特礁保存了一个独特的珊瑚礁生长序列档案，记录了在持续高沉降下，以千年（103年）到轨道（104 - 105年）尺度的海平面变化，为第四纪珊瑚礁动态和未来可能的加速气候变化的珊瑚礁响应提供了有价值的类似物。我们应用正演地层模拟（FSM）来减少斯科特礁现有年代地层模型中的不确定性，生成合成数据以改进地震解释，并测试MPT期间和之后不断变化的海面和环境条件如何影响碳酸盐生产、相分布和台地形态。该模型使用现代测深、地震层序地层学、沉积相、珊瑚组合、U/Th年龄以及碳酸盐产量和波浪能的时间变化进行校准。最佳拟合模拟要求约0.5 Ma之后碳酸盐产量和波能增加，同时南礁背风边缘的碳酸盐产量减少。模型结果表明，MIS 12的第一次高振幅低气压开始了长时间的地面暴露，岩溶作用和桶状平台形态的发展，与季风强度在约0.5 Ma后增加相一致。在长时间的MIS 11高水位期间，随后的珊瑚礁扩张产生了80米厚的堆积礁缘，这与NWS其他地方的珊瑚礁生长时间一致，尽管在全球范围内，珊瑚礁对MPT的反应时间和风格存在差异。综合地层学表明，0.5 Ma之前的薄层（10-30 m）、低起伏递进堆积层序向mpt后100 kyr的厚层（20-50 m）堆积层序过渡。模型中使用的恒定沉降速率（南斯科特礁0.29 mm/yr，北斯科特礁0.45 mm/yr）表明，在约0.5 Ma之后，MPT调制层序厚度增加了海平面振幅，降低了周期性，导致台地形态和相模式发生了变化。再加上持续的高沉降和季风强度的增加，这些变化表明环境和上升过程是斯科特礁演化的主要控制因素。我们的模型对理解全球MPT具有更广泛的意义，包括碳酸盐台地响应的时间和地层表达。当对多尺度观测数据进行实地验证时，试错式FSM仍然是测试关于碳酸盐台地和珊瑚礁对快速环境变化反应的假设的有力工具。

{"title":"Carbonate platform evolution in response to the Mid - Pleistocene climate transition on the North-West Shelf of Australia: Insights from forward stratigraphic modelling","authors":"Carra Williams , Jody M. Webster , Tristan Salles , Victorien Paumard , Camille Grimaldi , Mostfa Lejri","doi":"10.1016/j.margeo.2026.107716","DOIUrl":"10.1016/j.margeo.2026.107716","url":null,"abstract":"<div><div>This study presents the first forward stratigraphic model of Scott Reef - two isolated carbonate platforms on the Northwest Shelf (NWS) of Australia, spanning the Middle Pleistocene Transition (MPT; ca. 1.2–0.7 Ma). Scott Reef preserves a unique archive of reef growth sequences paced by millennial (10<sup>3</sup>-year) to orbital (10<sup>4</sup>–10<sup>5</sup>-year) scale sea-level variability under continuous high subsidence, providing valuable analogues for Quaternary reef dynamics and potential future reef responses to accelerated climatic change. We apply forward stratigraphic modelling (FSM) to reduce uncertainty in the existing chronostratigraphic models of Scott Reef, generate synthetic data to improve seismic interpretation, and to test how changing eustatic and environmental conditions during and after the MPT influenced carbonate production, facies distributions, and platform morphology. The model is calibrated using modern bathymetry, seismic sequence stratigraphy, sedimentary facies, coralgal assemblages, U/Th ages, and temporal changes in carbonate production and wave energy. The best fit simulations require increased carbonate production and wave energy after ca. 0.5 Ma, coupled with reduced carbonate production on the South Reef leeward margin. Model results indicate that the first high-amplitude lowstand of MIS 12 initiated prolonged subaerial exposure, karstification, and the development of a bucket-shaped platform morphology, coincident with increased monsoonal intensification after ca. 0.5 Ma. Subsequent reef expansion during the long-duration MIS 11 highstand produced an 80 m thick aggradational reef rim and is consistent with timings of reef growth elsewhere along the NWS, although there are differences to timing and style of reef response to the MPT globally. Synthetic stratigraphy indicates a transition from thin (10–30 m), low-relief progradational-aggradational sequences prior to 0.5 Ma, to thicker (20–50 m) aggradational sequences in the post-MPT 100-kyr world. Constant subsidence rates used in the model (0.29 mm/yr at South Scott Reef and 0.45 mm/yr at North Scott Reef) indicate that increasing sea-level amplitude and reduced periodicity associated with the MPT modulated sequence thickness, resulting in changes in platform morphology and facies patterns after ca. 0.5 Ma. Coupled with continuous high subsidence and increasing monsoonal intensity, these changes indicate that both environmental and eustatic processes were major controls on Scott Reef evolution. Our model has broader implications for understanding the MPT globally, including timing and stratigraphic expression of carbonate platform responses. Trial-and-error style FSM, when ground-truthed to multi-scale observational data, remains a powerful tool to test hypotheses about carbonate platform and coral reef response to rapid environmental changes.</div></div>","PeriodicalId":18229,"journal":{"name":"Marine Geology","volume":"493 ","pages":"Article 107716"},"PeriodicalIF":2.2,"publicationDate":"2026-01-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146024222","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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

Combined flow-induced bed shear stress and sediment-biologic dynamics in a supratidal flat of the Bahía Blanca Estuary during a positive storm surge 正风暴潮期间Bahía布兰卡河口潮上滩地流致河床剪切应力和沉积生物动力学的联合研究

IF 2.2 3区地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY

Marine Geology

Pub Date : 2026-01-17 DOI: 10.1016/j.margeo.2026.107715

Camila Stempels Bautista , Lucía Maisano , Mauricio M. Perillo , Gerardo M.E. Perillo , Diana G. Cuadrado

This study examines bed shear stress generated by combined flows (

τ_{0}

) in a supratidal flat of the Bahía Blanca Estuary during a spring tide coinciding with a positive storm surge driven by an extratropical storm and evaluates the associated sedimentological and biological responses. Bed shear stress

τ_{0}

was quantified using high-frequency acoustic Doppler velocimeter (ADV) measurements and Reynolds stress estimates. They were analyzed together with cm-scale bedform observations and chlorophyll-a (Chl-a) and phaeopigment concentrations as proxies for photosynthetic microbial activity. Analyses of synoptic maps revealed an extratropical storm advancing SW–NE generating a positive storm surge of up to ∼1 m. During the event,

τ_{0}

frequently exceeded the critical bed shear stress of sterile sediments (

τ_{0 c}

), occurring persistently during ebb tide. During slack tide, sediment transport was observed to occur primarily under the influence of wind-induced waves. Despite the stabilizing effect of the biofilm, which increases

τ_{0 c}

, observed changes in surficial micro-geomorphology, together with

τ_{0}

estimates, indicate that combined flow forcing was sufficient to induce sediment transport during supratidal inundation. These physical disturbances were accompanied by an approximately 40% reduction in Chl-a concentrations during the storm period and a significant increase in phaeopigments. Therefore, the biofilm covering the supratidal flat sediments did not prevent erosion under the hydrodynamic forces generated during an extratropical storm event coupled with a spring tide. This event-based case study highlights the value of integrating hydrodynamic, sedimentological, and biological indicators in a supratidal setting, providing in situ evidence of the coupled response of supratidal flats to extreme hydrodynamic forcing.

本研究考察了Bahía布兰卡河口潮上滩地在春潮与由温带风暴驱动的正风暴潮同时发生时的联合流（τ0）所产生的河床剪切应力，并评估了相关的沉积学和生物学响应。利用高频声波多普勒测速仪（ADV）测量和雷诺应力估计对床层剪应力τ0进行了量化。将它们与厘米尺度的床形观测和叶绿素-a （Chl-a）和色素浓度（作为光合微生物活性的代表）一起进行分析。天气图分析显示，一场向西南-东北方向推进的温带风暴产生了高达1米的正风暴潮。在此期间，τ0频繁超过无菌沉积物临界床层剪应力（τ0c），在退潮期间持续发生。在退潮期间，泥沙输运主要发生在风致波的影响下。尽管生物膜的稳定作用增加了τ0c，但观测到的地表微地貌变化，以及τ0估算值表明，在潮上淹没期间，联合水流强迫足以诱导沉积物输运。这些物理扰动伴随着风暴期间Chl-a浓度降低约40%和色素显著增加。因此，覆盖在潮上平坦沉积物上的生物膜在一次温带风暴事件和一次大潮所产生的水动力作用下并不能阻止侵蚀。这个基于事件的案例研究强调了在潮上环境中整合水动力、沉积学和生物学指标的价值，为潮上滩涂对极端水动力强迫的耦合响应提供了原位证据。

{"title":"Combined flow-induced bed shear stress and sediment-biologic dynamics in a supratidal flat of the Bahía Blanca Estuary during a positive storm surge","authors":"Camila Stempels Bautista , Lucía Maisano , Mauricio M. Perillo , Gerardo M.E. Perillo , Diana G. Cuadrado","doi":"10.1016/j.margeo.2026.107715","DOIUrl":"10.1016/j.margeo.2026.107715","url":null,"abstract":"<div><div>This study examines bed shear stress generated by combined flows (<span><math><msub><mi>τ</mi><mn>0</mn></msub></math></span>) in a supratidal flat of the Bahía Blanca Estuary during a spring tide coinciding with a positive storm surge driven by an extratropical storm and evaluates the associated sedimentological and biological responses. Bed shear stress <span><math><msub><mi>τ</mi><mn>0</mn></msub></math></span> was quantified using high-frequency acoustic Doppler velocimeter (ADV) measurements and Reynolds stress estimates. They were analyzed together with cm-scale bedform observations and chlorophyll-<em>a</em> (Chl-<em>a</em>) and phaeopigment concentrations as proxies for photosynthetic microbial activity. Analyses of synoptic maps revealed an extratropical storm advancing SW–NE generating a positive storm surge of up to ∼1 m. During the event, <span><math><msub><mi>τ</mi><mn>0</mn></msub></math></span> frequently exceeded the critical bed shear stress of sterile sediments (<span><math><msub><mi>τ</mi><mrow><mn>0</mn><mi>c</mi></mrow></msub></math></span>), occurring persistently during ebb tide. During slack tide, sediment transport was observed to occur primarily under the influence of wind-induced waves. Despite the stabilizing effect of the biofilm, which increases <span><math><msub><mi>τ</mi><mrow><mn>0</mn><mi>c</mi></mrow></msub></math></span>, observed changes in surficial micro-geomorphology, together with <span><math><msub><mi>τ</mi><mn>0</mn></msub></math></span> estimates, indicate that combined flow forcing was sufficient to induce sediment transport during supratidal inundation. These physical disturbances were accompanied by an approximately 40% reduction in Chl-<em>a</em> concentrations during the storm period and a significant increase in phaeopigments. Therefore, the biofilm covering the supratidal flat sediments did not prevent erosion under the hydrodynamic forces generated during an extratropical storm event coupled with a spring tide. This event-based case study highlights the value of integrating hydrodynamic, sedimentological, and biological indicators in a supratidal setting, providing <em>in situ</em> evidence of the coupled response of supratidal flats to extreme hydrodynamic forcing.</div></div>","PeriodicalId":18229,"journal":{"name":"Marine Geology","volume":"493 ","pages":"Article 107715"},"PeriodicalIF":2.2,"publicationDate":"2026-01-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146023701","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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

Effects of cobble extraction on two beaches in Northwestern Baja California 下加利福尼亚州西北部两个海滩的鹅卵石提取效果

IF 2.2 3区地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY

Marine Geology

Pub Date : 2026-01-16 DOI: 10.1016/j.margeo.2026.107714

Amaia Ruiz de Alegría-Arzaburu , Christian Zlolniski

Cobble extraction is a widespread socio-economic activity along the Pacific coast of Baja California, Mexico, with potential long-term impacts on coastal stability. This study evaluates the morphological response of two beaches exposed to prolonged cobble removal in locations where cobble extraction provides employment for local low-income communities. Morphological changes were analyzed using long-term satellite-derived shoreline data complemented by recent topographic surveys. The two studied beaches were San Jacinto, where cobbles overlie a rocky platform, and La Chorera, a former composite cobble-sand beach transformed into a predominantly sandy system following sustained cobble extraction. Their morphological evolution was compared with a nearby natural sandy beach, San Ramón. Results reveal contrasting responses: San Jacinto experienced chronic shoreline recession of nearly 0.5 m per year, while La Chorera exhibited long-term shoreline stability (+0.2 m/year) but recent supratidal erosion and duneface retreat. In contrast, the sandy beach of San Ramón showed an accretionary trend (+1.1 m/year) and dune stability. Beach volume changes between 2023 and 2025 indicate the most severe erosion at La Chorera (50 m³/m), followed by San Jacinto (32 m³/m) and minimal change at San Ramón (4 m³/m). These findings reveal that morphological responses to sustained cobble extraction are influenced by sediment composition. In any case, cobble removal compromises beach stability, increasing susceptibility to high-energy storms and threatening coastal ecosystems. In regions where extraction supports livelihoods for local low-income communities, it underscores the need for sustainable and equitable management practices.

鹅卵石开采是墨西哥下加利福尼亚州太平洋沿岸一项广泛的社会经济活动，对海岸稳定具有潜在的长期影响。本研究评估了两个海滩的形态反应暴露于长时间的鹅卵石清除，在鹅卵石提取为当地低收入社区提供就业的地方。利用长期卫星岸线数据，辅以最近的地形调查，分析了形态变化。被研究的两个海滩是圣哈辛托海滩，那里的鹅卵石覆盖在岩石平台上，而La Chorera海滩是一个以前的复合鹅卵石沙滩，经过持续的鹅卵石提取，变成了一个主要的沙质系统。它们的形态演变与附近的天然沙滩San Ramón进行了比较。结果显示了截然不同的反应：圣哈辛托经历了每年近0.5米的慢性海岸线衰退，而拉霍拉则表现出长期的海岸线稳定（+0.2米/年），但最近出现了潮上侵蚀和沙丘面退缩。而San Ramón沙滩则表现出+1.1 m/年的吸积趋势和沙丘稳定性。2023年至2025年间的海滩体积变化表明La Chorera的侵蚀最严重（50 m3/m），其次是San Jacinto (32 m3/m)， San Ramón变化最小（4 m3/m）。这些发现表明，持续鹅卵石提取的形态响应受到沉积物组成的影响。无论如何，清除鹅卵石会损害海滩的稳定性，增加对高能风暴的易感性，并威胁沿海生态系统。在开采支持当地低收入社区生计的地区，它强调需要可持续和公平的管理做法。

{"title":"Effects of cobble extraction on two beaches in Northwestern Baja California","authors":"Amaia Ruiz de Alegría-Arzaburu , Christian Zlolniski","doi":"10.1016/j.margeo.2026.107714","DOIUrl":"10.1016/j.margeo.2026.107714","url":null,"abstract":"<div><div>Cobble extraction is a widespread socio-economic activity along the Pacific coast of Baja California, Mexico, with potential long-term impacts on coastal stability. This study evaluates the morphological response of two beaches exposed to prolonged cobble removal in locations where cobble extraction provides employment for local low-income communities. Morphological changes were analyzed using long-term satellite-derived shoreline data complemented by recent topographic surveys. The two studied beaches were San Jacinto, where cobbles overlie a rocky platform, and La Chorera, a former composite cobble-sand beach transformed into a predominantly sandy system following sustained cobble extraction. Their morphological evolution was compared with a nearby natural sandy beach, San Ramón. Results reveal contrasting responses: San Jacinto experienced chronic shoreline recession of nearly 0.5 m per year, while La Chorera exhibited long-term shoreline stability (+0.2 m/year) but recent supratidal erosion and duneface retreat. In contrast, the sandy beach of San Ramón showed an accretionary trend (+1.1 m/year) and dune stability. Beach volume changes between 2023 and 2025 indicate the most severe erosion at La Chorera (50 m<sup>3</sup>/m), followed by San Jacinto (32 m<sup>3</sup>/m) and minimal change at San Ramón (4 m<sup>3</sup>/m). These findings reveal that morphological responses to sustained cobble extraction are influenced by sediment composition. In any case, cobble removal compromises beach stability, increasing susceptibility to high-energy storms and threatening coastal ecosystems. In regions where extraction supports livelihoods for local low-income communities, it underscores the need for sustainable and equitable management practices.</div></div>","PeriodicalId":18229,"journal":{"name":"Marine Geology","volume":"493 ","pages":"Article 107714"},"PeriodicalIF":2.2,"publicationDate":"2026-01-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146023702","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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

Extreme wave events inferred from large subaerial carbonate boulders on a rocky coast in Pasuquin, Ilocos Norte, Philippines 从菲律宾北伊洛科斯省帕苏昆的岩石海岸上的大型陆上碳酸盐岩巨石推断出的极端波浪事件

IF 2.2 3区地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY

Marine Geology

Pub Date : 2026-01-06 DOI: 10.1016/j.margeo.2026.107704

Edrian M. Tubalado , Noelynna T. Ramos , Lyndon P. Nawanao Jr. , Ace Matthew F. Cantillep , Alec Benjamin G. Ramirez , Jelian S. Reyes , Kathrine V. Maxwell , Shou-Yeh Gong , Tsai-Luen Yu , Chuan-Chou Shen

Coastal boulder deposits serve as sedimentary markers of extreme wave events (EWEs), with their morphological analysis offering valuable insights into the nature of these events. In the coastal regions of Pasuquin, Ilocos Norte, and other parts of northwest Luzon Island in the Philippines, extensive fields of large carbonate boulders are often found on Holocene emergent reefs. We studied 198 carbonate boulders at two boulder field sites in Pasuquin (Davila and Dilavo). The emergent fringing reef, at an elevation of between −0.21 below to 1.5 m above mean sea level across the platform (corrected from the Currimao tide station), is characterized by spur-and-groove morphology with solution pans/pools, and occasional fossil microatolls. Boulders had varying orientations and were mostly flat blocks in shape, with the largest measured boulder weighing up to 31.49 t. Based on their overall shape, composition, and observed tilting/overturning, these boulders are inferred to have been sourced from the underlying reef platform. Spatial statistics, bivariate statistics, and frequency distribution of carbonate boulders in Dilavo (south boulder field) show clustering with multimodal weight distribution and include more boulders weighing over 9 t compared to Davila (north boulder field). Framework corals comprising the boulders reveal ²³⁰Th ages between 1262.6 ± 4.8 and 2815.9 ± 6.7 YBP (relative to 1950 CE), which may indicate the timing of initial displacement and deposition due to an extreme overwash event. Meanwhile, fossil corals within the emergent reef have ages between 444.9 ± 1.8 and 677.9 ± 2.2 YBP, possibly indicating a younger uplift event after boulder displacement and subsequent emplacement. This new information on the spatial distribution and morphology of large carbonate boulders in northern Luzon provides additional insights into the characteristics of past EWEs and may be useful in understanding and preparing for future coastal hazards in the region.

海岸巨石沉积物是极端波浪事件（ewe）的沉积标志，其形态分析为这些事件的性质提供了有价值的见解。在菲律宾的Pasuquin， Ilocos north的沿海地区和吕宋岛西北部的其他地区，在全新世涌现的珊瑚礁上经常发现大面积的大型碳酸盐巨石。我们在Pasuquin的两个巨石场（Davila和Dilavo）研究了198个碳酸盐岩巨石。突出边缘礁位于平均海平面以下- 0.21 ~ 1.5 m之间（由Currimao潮汐站校正），以刺槽形态为特征，有溶液盘/池，偶有微环礁化石。巨石的方向各异，形状大多为扁平块，测量到的最大巨石重达31.49吨。根据它们的整体形状、成分和观察到的倾斜/倾覆，推断这些巨石来自下面的礁台地。Dilavo（南部boulder田）碳酸盐岩抱石的空间统计、二元统计和频率分布均显示出多模态重量分布的聚类性，并且与Davila（北部boulder田）相比，Dilavo（南部boulder田）碳酸盐岩抱石的重量大于9 t。构成巨石的框架珊瑚显示230年代在1262.6±4.8至2815.9±6.7 YBP之间（相对于1950 CE），这可能表明由于极端冲过事件导致的初始位移和沉积时间。同时，涌现礁内的化石珊瑚年龄在444.9±1.8 ~ 677.9±2.2 YBP之间，可能表明在巨石位移和侵位之后发生了更年轻的隆升事件。这一关于吕宋岛北部大型碳酸盐巨石空间分布和形态的新信息为了解过去ewe的特征提供了额外的见解，可能有助于了解该地区未来的沿海灾害并为其做好准备。

{"title":"Extreme wave events inferred from large subaerial carbonate boulders on a rocky coast in Pasuquin, Ilocos Norte, Philippines","authors":"Edrian M. Tubalado , Noelynna T. Ramos , Lyndon P. Nawanao Jr. , Ace Matthew F. Cantillep , Alec Benjamin G. Ramirez , Jelian S. Reyes , Kathrine V. Maxwell , Shou-Yeh Gong , Tsai-Luen Yu , Chuan-Chou Shen","doi":"10.1016/j.margeo.2026.107704","DOIUrl":"10.1016/j.margeo.2026.107704","url":null,"abstract":"<div><div>Coastal boulder deposits serve as sedimentary markers of extreme wave events (EWEs), with their morphological analysis offering valuable insights into the nature of these events. In the coastal regions of Pasuquin, Ilocos Norte, and other parts of northwest Luzon Island in the Philippines, extensive fields of large carbonate boulders are often found on Holocene emergent reefs. We studied 198 carbonate boulders at two boulder field sites in Pasuquin (Davila and Dilavo). The emergent fringing reef, at an elevation of between −0.21 below to 1.5 m above mean sea level across the platform (corrected from the Currimao tide station), is characterized by spur-and-groove morphology with solution pans/pools, and occasional fossil microatolls. Boulders had varying orientations and were mostly flat blocks in shape, with the largest measured boulder weighing up to 31.49 t. Based on their overall shape, composition, and observed tilting/overturning, these boulders are inferred to have been sourced from the underlying reef platform. Spatial statistics, bivariate statistics, and frequency distribution of carbonate boulders in Dilavo (south boulder field) show clustering with multimodal weight distribution and include more boulders weighing over 9 t compared to Davila (north boulder field). Framework corals comprising the boulders reveal <sup>230</sup>Th ages between 1262.6 ± 4.8 and 2815.9 ± 6.7 YBP (relative to 1950 CE), which may indicate the timing of initial displacement and deposition due to an extreme overwash event. Meanwhile, fossil corals within the emergent reef have ages between 444.9 ± 1.8 and 677.9 ± 2.2 YBP, possibly indicating a younger uplift event after boulder displacement and subsequent emplacement. This new information on the spatial distribution and morphology of large carbonate boulders in northern Luzon provides additional insights into the characteristics of past EWEs and may be useful in understanding and preparing for future coastal hazards in the region.</div></div>","PeriodicalId":18229,"journal":{"name":"Marine Geology","volume":"493 ","pages":"Article 107704"},"PeriodicalIF":2.2,"publicationDate":"2026-01-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145979524","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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

A new and more accurate overfill ratio for beach nourishments and its comparison with James' RA 一个新的和更准确的海滩营养的溢填比及其与詹姆斯的RA的比较

IF 2.2 3区地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY

Marine Geology

Pub Date : 2026-01-06 DOI: 10.1016/j.margeo.2026.107705

Antonio Contreras-de-Villar , Enzo Pranzini , Giorgio Anfuso , Juan J. Muñoz-Perez

Pranzini et al. (2018) designed a method, for borrowed sediment selection in beach nourishment projects, that solved the problems inherent to James' abacus (1975). However, it suffered in turn from the lack of an overfill ratio. A new and more accurate methodology is presented here to calculate the mentioned ratio. To demonstrate the implications of the new proposed method, the overfill ratios calculated are compared with those obtained using the method of James (R_A) for nine beaches and nourished sands with different granulometries. The comparison showed that the method of James (1975) predicted a much larger fraction of the borrow sediment to be unstable, thus requiring higher nourishment volumes to achieve a certain beach width and implying increased economic costs.

Pranzini等人（2018）设计了一种方法，用于海滩营养项目中借来的沉积物选择，解决了James' abacus（1975）固有的问题。然而，它反过来又因缺乏溢满率而受到影响。本文提出了一种新的更精确的方法来计算上述比率。为了证明新建议方法的影响，我们将计算的过填率与使用James （RA）方法获得的过填率进行了比较，其中包括9个不同粒度的海滩和营养砂。通过比较可知，James（1975）的方法预测的借来泥沙不稳定的比例要大得多，因此需要更高的营养体积才能达到一定的滩宽，这意味着经济成本的增加。

引用次数: 0

Integrating the Bruun rule with sediment compatibility analysis for shoreline change evaluation under water level fall 结合Bruun规则和泥沙相容性分析的水位下降下岸线变化评价

IF 2.2 3区地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY

Marine Geology

Pub Date : 2026-01-05 DOI: 10.1016/j.margeo.2025.107701

Hesamodin Enayatighadikolaei , Takayuki Suzuki , Martin Mäll , Mohsen Soltanpour

Shoreline progradation in enclosed basins such as the Caspian Sea—driven by climate-induced hydrological change—poses unique challenges for coastal prediction, as most existing models were developed for water-level rise and open-coast dynamics. The original Bruun rule assumes a closed sediment budget and therefore tends to overpredict shoreline advance under falling water levels, overlooking the offshore loss of finer sediment fractions. To address this gap, the study introduces a new index, the Compatibility Index (CI), and integrates it into the Bruun rule, comparing six CI methods across six sandy and two sandy–gravel monitoring stations. While the Bruun rule was originally designed for sandy beaches, its applicability was extended here to mixed sand–gravel profiles. A practical decision framework—combining acceptable CI ranges from three prioritized methods and local bed slope—identifies an optimal CI (CI_O) for each station. Shoreline change from 2013 to 2022 was tracked using cross-shore profiles and high-resolution satellite imagery. Incorporating the CI_O into the Bruun rule reduced root mean square error from 61.3 m to 21.4 m, mean absolute error from 49.0 m to 16.6 m, and mean bias error from 49.0 m to 14.6 m, improving prediction accuracy by 73.2%. The resulting model delivers robust, site-specific shoreline forecasts and provides a practical tool for coastal managers planning setback zones or adaptation strategies in enclosed-basin environments, while offering a transferable framework for similar settings worldwide.

里海等封闭盆地的海岸线进退是由气候引起的水文变化驱动的，这给沿海预测带来了独特的挑战，因为大多数现有模型都是针对水位上升和开放海岸动态而开发的。最初的布鲁恩规则假设了一个封闭的泥沙收支，因此倾向于过度预测水位下降下的海岸线推进，忽略了近海较细泥沙组分的损失。为了解决这一差距，该研究引入了一个新的指标，即相容性指数（CI），并将其整合到Bruun规则中，比较了六个砂质监测站和两个砂质砾石监测站的六种CI方法。虽然布鲁恩规则最初是为沙滩设计的，但它的适用性在这里扩展到混合砂砾剖面。一个实用的决策框架——结合可接受的CI范围，从三种优先方法和局部床坡度——确定每个站点的最佳CI （CIO）。研究人员利用跨海岸剖面和高分辨率卫星图像追踪了2013年至2022年的海岸线变化。将CIO纳入Bruun规则后，均方根误差从61.3 m降至21.4 m，平均绝对误差从49.0 m降至16.6 m，平均偏置误差从49.0 m降至14.6 m，预测精度提高73.2%。由此产生的模型提供了可靠的、特定地点的海岸线预测，并为沿海管理者在封闭盆地环境中规划挫折带或适应战略提供了实用工具，同时为全球类似环境提供了可转移的框架。

{"title":"Integrating the Bruun rule with sediment compatibility analysis for shoreline change evaluation under water level fall","authors":"Hesamodin Enayatighadikolaei , Takayuki Suzuki , Martin Mäll , Mohsen Soltanpour","doi":"10.1016/j.margeo.2025.107701","DOIUrl":"10.1016/j.margeo.2025.107701","url":null,"abstract":"<div><div>Shoreline progradation in enclosed basins such as the Caspian Sea—driven by climate-induced hydrological change—poses unique challenges for coastal prediction, as most existing models were developed for water-level rise and open-coast dynamics. The original Bruun rule assumes a closed sediment budget and therefore tends to overpredict shoreline advance under falling water levels, overlooking the offshore loss of finer sediment fractions. To address this gap, the study introduces a new index, the Compatibility Index (CI), and integrates it into the Bruun rule, comparing six CI methods across six sandy and two sandy–gravel monitoring stations. While the Bruun rule was originally designed for sandy beaches, its applicability was extended here to mixed sand–gravel profiles. A practical decision framework—combining acceptable CI ranges from three prioritized methods and local bed slope—identifies an optimal CI (CI<sub>O</sub>) for each station. Shoreline change from 2013 to 2022 was tracked using cross-shore profiles and high-resolution satellite imagery. Incorporating the CI<sub>O</sub> into the Bruun rule reduced root mean square error from 61.3 m to 21.4 m, mean absolute error from 49.0 m to 16.6 m, and mean bias error from 49.0 m to 14.6 m, improving prediction accuracy by 73.2%. The resulting model delivers robust, site-specific shoreline forecasts and provides a practical tool for coastal managers planning setback zones or adaptation strategies in enclosed-basin environments, while offering a transferable framework for similar settings worldwide.</div></div>","PeriodicalId":18229,"journal":{"name":"Marine Geology","volume":"493 ","pages":"Article 107701"},"PeriodicalIF":2.2,"publicationDate":"2026-01-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145928349","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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

Sedimentation behavior of deep-sea mining plumes in a marine ionic environment: Insights from the west Philippine Basin 海洋离子环境下深海采矿柱的沉积行为：来自西菲律宾盆地的见解

IF 2.2 3区地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY

Marine Geology

Pub Date : 2026-01-02 DOI: 10.1016/j.margeo.2025.107703

Ning Ma , Xian Zhang , Zhengqi Wu , Xuguang Chen , Xingzheng Gao , Fengpeng Zhang

Benthic plumes generated by deep-sea polymetallic nodule mining pose significant threats to the marine ecological environment and represent one of the primary challenges hindering the commercialization of deep-sea mining. This study investigates the sedimentation behavior of deep-sea sediment plumes in the West Philippine Basin to assess the potential environmental impacts of mining activities. The results reveal that the presence of marine inorganic salts markedly enhances the sedimentation efficiency of suspended sediment particles, and the settling rate in seawater was approximately two to three times higher than that in pure water, highlighting the strong promotion effect of inorganic ions—especially divalent cations such as Ca²⁺ and Mg²⁺—on particle aggregation and sedimentation efficiency. A characteristic thickness parameter introduced through numerical simulations quantitatively describes interparticle electrostatic interactions and provides a predictive tool for plume-settling behavior under different salinity and concentration conditions. By linking plume sedimentation kinetics with marine physicochemical processes, this study enhances understanding of how electrochemical properties of particles influence plume motion and dispersion in deep-sea environments.

深海多金属结核开采产生的底栖生物羽流对海洋生态环境构成严重威胁，是阻碍深海采矿商业化的主要挑战之一。本研究研究了西菲律宾盆地深海沉积物羽流的沉积行为，以评估采矿活动对环境的潜在影响。结果表明，海洋无机盐的存在显著提高了悬浮泥沙颗粒的沉降效率，其在海水中的沉降速率约为纯水中的2 ~ 3倍，凸显了无机离子尤其是Ca2+、Mg2+等二价阳离子对悬浮泥沙颗粒聚集和沉降效率的强烈促进作用。通过数值模拟引入的特征厚度参数定量描述了颗粒间静电相互作用，为不同盐度和浓度条件下的羽流沉降行为提供了预测工具。通过将羽流沉积动力学与海洋物理化学过程联系起来，本研究增强了对深海环境中颗粒电化学性质如何影响羽流运动和扩散的认识。

{"title":"Sedimentation behavior of deep-sea mining plumes in a marine ionic environment: Insights from the west Philippine Basin","authors":"Ning Ma , Xian Zhang , Zhengqi Wu , Xuguang Chen , Xingzheng Gao , Fengpeng Zhang","doi":"10.1016/j.margeo.2025.107703","DOIUrl":"10.1016/j.margeo.2025.107703","url":null,"abstract":"<div><div>Benthic plumes generated by deep-sea polymetallic nodule mining pose significant threats to the marine ecological environment and represent one of the primary challenges hindering the commercialization of deep-sea mining. This study investigates the sedimentation behavior of deep-sea sediment plumes in the West Philippine Basin to assess the potential environmental impacts of mining activities. The results reveal that the presence of marine inorganic salts markedly enhances the sedimentation efficiency of suspended sediment particles, and the settling rate in seawater was approximately two to three times higher than that in pure water, highlighting the strong promotion effect of inorganic ions—especially divalent cations such as Ca<sup>2+</sup> and Mg<sup>2+</sup>—on particle aggregation and sedimentation efficiency. A characteristic thickness parameter introduced through numerical simulations quantitatively describes interparticle electrostatic interactions and provides a predictive tool for plume-settling behavior under different salinity and concentration conditions. By linking plume sedimentation kinetics with marine physicochemical processes, this study enhances understanding of how electrochemical properties of particles influence plume motion and dispersion in deep-sea environments.</div></div>","PeriodicalId":18229,"journal":{"name":"Marine Geology","volume":"493 ","pages":"Article 107703"},"PeriodicalIF":2.2,"publicationDate":"2026-01-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145895937","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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

Control of sediment supply and fault-controlled topography on the evolution of undulating bedforms in the Eastern Shenhu Slope, northern South China Sea 南海北部神狐坡东部坡面起伏地貌演化中的沉积物供给控制与断层地形控制

IF 2.2 3区地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY

Marine Geology

Pub Date : 2025-12-26 DOI: 10.1016/j.margeo.2025.107702

Kunwen Luo , Ming Su , Shan Liu , Zhi Lin Ng , Zhixuan Lin , Ce Wang , Hui Chen , Haiteng Zhuo

Depositional and erosional bedforms are prevalent in submarine environments worldwide, and have the potential to preserve critical records of continental margin evolution, ocean circulation, climate variability, and paleo-geohazards. However, the origin and evolution of such bedforms remain debated. This study employs high-resolution three-dimensional seismic reflection data to investigate the origin, evolution, and controlling factors of undulating bedforms on the eastern Shenhu slope, northern South China Sea. Morphometric analyses of these bedforms, as well as morphometric-based calculating of turbidity currents velocity, distinguish them as turbidity current-generated bedforms. Initiated since Marine Isotope Stage (MIS) 38 (horizon SB3) until the present, bedforms on the Shenhu slope are divided into two stages: (1) from MIS 38 to MIS 20 (horizons SB3–SB4), where erosional crescentic scours and elongated troughs, are formed under vigorous turbidity currents; (2) from MIS 12 to the present (horizon SB5–seafloor), where depositional bedforms, sediment waves, with near-linear crests, formed under relatively weaker current. Their evolution was governed by the interplay of the progradation of the paleo-Pearl River shelf-edge delta and the development of a horsetail normal fault system in the upper slope, with an increase in sediment supply since 1.6 Ma and a decrease in fault activity between 2.58 Ma until 474 ka (MIS 12). Fault-controlled conduits enhanced current velocity and erosion until MIS 20, which transitioned into unconfined flows and depositional waves as faults were progressively buried. These findings highlight the pivotal roles of sediment supply and seafloor topography in shaping deep-water sedimentary systems, offering insights into the sedimentary dynamics on continental margins.

沉积和侵蚀床型在全球海底环境中普遍存在，并有可能保存大陆边缘演化、海洋环流、气候变化和古地质灾害的重要记录。然而，这种床型的起源和演化仍有争议。利用高分辨率三维地震反射资料，探讨了南海北部神狐坡东部起伏地貌的成因、演化及其控制因素。对这些床型的形态计量学分析，以及基于形态计量学的浊流流速计算，将它们区分为浊流产生的床型。神虎斜坡自38期（SB3层）开始至今，形成了两个阶段：1)38期至20期（SB3 - sb4层），形成了强浊流作用下的侵蚀新月形冲刷槽和细长槽；(2)从MIS 12到现在（sb5 -海床层），在相对较弱的洋流作用下形成了沉积层，沉积波具有近线性波峰。它们的演化受古珠江陆架边缘三角洲的进积和上坡马尾正断层系统发育的相互作用支配，1.6 Ma以来泥沙供应增加，2.58 Ma至474 ka之间断层活动减少（MIS 12）。断层控制的管道增强了流速和侵蚀，直到MIS 20，随着断层逐渐被掩埋，它转变为无约束流和沉积波。这些发现强调了沉积物供应和海底地形在形成深水沉积体系中的关键作用，为大陆边缘的沉积动力学提供了见解。

{"title":"Control of sediment supply and fault-controlled topography on the evolution of undulating bedforms in the Eastern Shenhu Slope, northern South China Sea","authors":"Kunwen Luo , Ming Su , Shan Liu , Zhi Lin Ng , Zhixuan Lin , Ce Wang , Hui Chen , Haiteng Zhuo","doi":"10.1016/j.margeo.2025.107702","DOIUrl":"10.1016/j.margeo.2025.107702","url":null,"abstract":"<div><div>Depositional and erosional bedforms are prevalent in submarine environments worldwide, and have the potential to preserve critical records of continental margin evolution, ocean circulation, climate variability, and paleo-geohazards. However, the origin and evolution of such bedforms remain debated. This study employs high-resolution three-dimensional seismic reflection data to investigate the origin, evolution, and controlling factors of undulating bedforms on the eastern Shenhu slope, northern South China Sea. Morphometric analyses of these bedforms, as well as morphometric-based calculating of turbidity currents velocity, distinguish them as turbidity current-generated bedforms. Initiated since Marine Isotope Stage (MIS) 38 (horizon SB3) until the present, bedforms on the Shenhu slope are divided into two stages: (1) from MIS 38 to MIS 20 (horizons SB3–SB4), where erosional crescentic scours and elongated troughs, are formed under vigorous turbidity currents; (2) from MIS 12 to the present (horizon SB5–seafloor), where depositional bedforms, sediment waves, with near-linear crests, formed under relatively weaker current. Their evolution was governed by the interplay of the progradation of the paleo-Pearl River shelf-edge delta and the development of a horsetail normal fault system in the upper slope, with an increase in sediment supply since 1.6 <em>Ma</em> and a decrease in fault activity between 2.58 <em>Ma</em> until 474 ka (MIS 12). Fault-controlled conduits enhanced current velocity and erosion until MIS 20, which transitioned into unconfined flows and depositional waves as faults were progressively buried. These findings highlight the pivotal roles of sediment supply and seafloor topography in shaping deep-water sedimentary systems, offering insights into the sedimentary dynamics on continental margins.</div></div>","PeriodicalId":18229,"journal":{"name":"Marine Geology","volume":"492 ","pages":"Article 107702"},"PeriodicalIF":2.2,"publicationDate":"2025-12-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145880212","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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

Sea-level and basement structural controls on Late Quaternary sedimentation in a tropical wave-dominated delta: Evidence from subsurface cores in Kaveri Delta, India 海平面和基底构造对热带波主导型三角洲晚第四纪沉积的控制：来自印度Kaveri三角洲地下岩心的证据

IF 2.2 3区地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY

Marine Geology

Pub Date : 2025-12-24 DOI: 10.1016/j.margeo.2025.107700

Kartika Goswami , Linto Alappat , Manoj K. Jaiswal , Sivakumar Krishnan , Anbarasu Kumaresan , Senthil Kumar Sadasivam , Xianjiao Ou

The Kaveri (Cauvery) River delta on the southeast coast of India is among the largest sedimentary archives of peninsular India, preserving a complex record of sea-level fluctuations, fluvial dynamics, and tectonic controls in a tropical wave-dominated setting. This study presents results from four 25 m-deep sediment cores, analysed for chronology using quartz optically stimulated luminescence (OSL) dating, along with sedimentological characterisation and micropalaeontological (foraminiferal) analysis. Chronological data reveal four marine transgressions during MIS 5.5 (∼122 ka), MIS 5.1 (∼72 ka), MIS 3 (∼41 ka), and MIS 1 (9-6 ka). Corresponding foraminiferal assemblages confirm episodic marine influence well into the deltaic interior. Stratigraphic contrasts between inland and coastal cores indicate that the structural high along the Vedaranyam Ridge influenced accommodation space and sediment trapping within the adjoining Nagapattinam depression. Our findings emphasise that Late Quaternary delta development was governed by both allogenic (climate, sea level) and autogenic (sediment load, channel dynamics) processes. Notably, while Holocene sea-level records are relatively well documented, reliable evidence for Pleistocene highstands from the east coast of India remains sparse and discontinuous. By providing one of the few continuous stratigraphic and chronological records of multiple late Pleistocene highstands from the east coast of India, this study offers new insights into long-term deltaic response to external forcing in low-latitude coastal systems.

位于印度东南海岸的Kaveri （Cauvery）河三角洲是印度半岛最大的沉积档案之一，在热带波浪主导的环境中保存了海平面波动、河流动力学和构造控制的复杂记录。这项研究展示了四个25米深的沉积物岩心的结果，使用石英光学刺激发光（OSL）测年法分析了年代学，以及沉积学特征和微古生物学（有孔虫）分析。时间数据显示在MIS 5.5 （~ 122 ka）、MIS 5.1 （~ 72 ka）、MIS 3 （~ 41 ka）和MIS 1 （9-6 ka）期间发生了4次海侵。相应的有孔虫组合证实了海相对三角洲内部的影响。内陆岩心与沿海岩心的地层对比表明，沿Vedaranyam脊的构造高压影响了相邻Nagapattinam凹陷内的可容纳空间和沉积圈闭。我们的研究结果强调，晚第四纪三角洲的发育是由异体（气候、海平面）和自生（泥沙负荷、河道动力学）过程共同控制的。值得注意的是，虽然全新世的海平面记录相对较好，但来自印度东海岸的更新世高地的可靠证据仍然稀少且不连续。通过提供印度东海岸多个晚更新世高地的为数不多的连续地层和年代学记录之一，本研究为低纬度沿海系统中三角洲对外部强迫的长期响应提供了新的见解。

{"title":"Sea-level and basement structural controls on Late Quaternary sedimentation in a tropical wave-dominated delta: Evidence from subsurface cores in Kaveri Delta, India","authors":"Kartika Goswami , Linto Alappat , Manoj K. Jaiswal , Sivakumar Krishnan , Anbarasu Kumaresan , Senthil Kumar Sadasivam , Xianjiao Ou","doi":"10.1016/j.margeo.2025.107700","DOIUrl":"10.1016/j.margeo.2025.107700","url":null,"abstract":"<div><div>The Kaveri (Cauvery) River delta on the southeast coast of India is among the largest sedimentary archives of peninsular India, preserving a complex record of sea-level fluctuations, fluvial dynamics, and tectonic controls in a tropical wave-dominated setting. This study presents results from four 25 m-deep sediment cores, analysed for chronology using quartz optically stimulated luminescence (OSL) dating, along with sedimentological characterisation and micropalaeontological (foraminiferal) analysis. Chronological data reveal four marine transgressions during MIS 5.5 (∼122 ka), MIS 5.1 (∼72 ka), MIS 3 (∼41 ka), and MIS 1 (9-6 ka). Corresponding foraminiferal assemblages confirm episodic marine influence well into the deltaic interior. Stratigraphic contrasts between inland and coastal cores indicate that the structural high along the Vedaranyam Ridge influenced accommodation space and sediment trapping within the adjoining Nagapattinam depression. Our findings emphasise that Late Quaternary delta development was governed by both allogenic (climate, sea level) and autogenic (sediment load, channel dynamics) processes. Notably, while Holocene sea-level records are relatively well documented, reliable evidence for Pleistocene highstands from the east coast of India remains sparse and discontinuous. By providing one of the few continuous stratigraphic and chronological records of multiple late Pleistocene highstands from the east coast of India, this study offers new insights into long-term deltaic response to external forcing in low-latitude coastal systems.</div></div>","PeriodicalId":18229,"journal":{"name":"Marine Geology","volume":"492 ","pages":"Article 107700"},"PeriodicalIF":2.2,"publicationDate":"2025-12-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145880211","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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