Marine Geology最新文献_第2页

Taphonomic signature of benthic foraminifera linked to methane release in the Barents Sea 与巴伦支海甲烷释放有关的底栖有孔虫的埋藏学特征

IF 2.2 3区地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY

Marine Geology

Pub Date : 2025-12-09 DOI: 10.1016/j.margeo.2025.107693

Gabriella M. Boretto , Mathia Sabino , Fiorenza Torricella , Gianmarco Ingrosso , Alessio Nogarotto , Giuliana Panieri , Jens Hefter , Gesine Mollenhauer , Leonardo Langone , Silvia Giuliani , Tommaso Tesi , Lucilla Capotondi

This study investigates methane seepage dynamics over the past several centuries in the southwestern Barents Sea through an integrated analysis of foraminiferal taphonomy, stable carbon isotopes, and the lipid biomarkers glycerol dialkyl glycerol tetraethers (GDGT) based molecular biomarkers. We examined the preservation state of nine calcareous benthic foraminiferal species from sediment core HH1141, grouping test alterations into five taphonomic categories. These preservation patterns correlate with geochemical indicators of methane emissions, such as depleted δ¹³C values of carbonate tests and organic matter and elevated Methane Index (MI), allowing the identification of three stratigraphic units reflecting distinct seepage regimes. Along with this gradient, electron microscopy and microprobe analyses reveal widespread diagenetic overgrowths and mineral replacements linked to anaerobic oxidation of methane. Furthermore, species-specific responses highlight that Elphidium clavatum, Stainforthia feylingi, Stainforthia loeblichi and Cassidulina reniforme are more susceptible to alteration, while Melonis barleeanus shows remarkable resistance. The observed temporal variability in methane seepage is interpreted as the result of multifactorial environmental drivers, including changes in subsurface dynamics and bottom-water conditions. This multidisciplinary approach demonstrates the utility of foraminiferal taphonomy as a sensitive proxy for methane-rich environments and cold seep evolution, especially in polar regions undergoing rapid climatic and oceanographic change.

本研究通过综合分析有孔虫色谱、稳定碳同位素和脂质生物标志物甘油二烷基甘油四醚（GDGT）为基础的分子生物标志物，研究了巴伦支海西南部过去几个世纪的甲烷渗流动力学。我们研究了9种钙质底栖有孔虫的保存状态，将测试变化分为5个分类类别。这些保存模式与甲烷排放的地球化学指标相关，如碳酸盐测试和有机质的δ13C值下降和甲烷指数（MI）升高，从而识别出反映不同渗流机制的三个地层单元。随着这种梯度，电子显微镜和显微探针分析揭示了广泛的成岩过度生长和与甲烷厌氧氧化有关的矿物替代。此外，物种特异性反应表明，clavatum Elphidium、feylingi Stainforthia loeblichi和Cassidulina reniforme对变异更敏感，而Melonis barleeanus表现出显著的抗性。观测到的甲烷渗流的时间变化被解释为多因素环境驱动因素的结果，包括地下动力学和底部水条件的变化。这种多学科方法证明了有孔虫埋藏学作为富甲烷环境和冷渗演化的敏感代理的效用，特别是在经历快速气候和海洋变化的极地地区。

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引用次数: 0

Anthropogenic disturbances drive stepwise geomorphic changes of shoal-channel systems in a tide-dominated estuary 人为干扰驱动潮汐控制的河口滩-水道系统的逐步地貌变化

IF 2.2 3区地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY

Marine Geology

Pub Date : 2025-12-08 DOI: 10.1016/j.margeo.2025.107694

Ping Zhang , Linxi Fu , Xiangyuan Li , Jianliang Lin , Huayang Cai , Zhijun Dai , Qingshu Yang

The shoal-channel system, a fundamental geomorphic feature in estuaries globally, plays a crucial role in ensuring navigational safety and sustaining estuarine-deltaic ecosystem services. However, in the Anthropocene, this system has undergone significant transformations, challenging its stability and functional integrity. To investigate these changes, we applied a Digital Elevation Model (DEM) and Morphological Shannon Entropy (MSE) to quantify the stepwise evolution of the shoal-channel system in the Shiziyang (SZY) Tidal Channel, a tide-dominated reach of the Pearl River Estuary (PRE). Our findings reveal that anthropogenic disturbances triggered a systematic eastward channel migration, progressive shoal expansion, and peak erosion of 2.37 × 10⁶ m³/yr during Period III (1989–2000), exceeding concurrent deposition by 50 %. These changes culminated in a systemic reconfiguration from a V-shaped to a W-shaped channel profile. Sequential dredging emerged as the principal driver, accounting for a 17 m incision and contributing up to 68.45 % of the total scouring in Period III. Additional factors, including port construction (which reduced channel width by 20.39 %), diminished sediment flux (causing a 27.65 % decrease in depositional bank extent), and intensified hydrodynamics (reflected by a tidal range increase of 4.56 mm/yr), acted synergistically to amplify the regime shift. By elucidating the key drivers and consequences of this geomorphic evolution, our study provides critical insights for the sustainable management of heavily engineered coastal systems in the Anthropocene.

浅滩-河道系统是全球河口的基本地貌特征，在确保航行安全和维持河口-三角洲生态系统服务方面发挥着至关重要的作用。然而，在人类世，这一系统发生了重大转变，挑战了其稳定性和功能完整性。为了研究这些变化，我们应用数字高程模型（DEM）和形态香农熵（MSE）量化了珠江口（PRE）潮汐控制河段狮子洋（SZY）潮汐通道的滩-道系统的逐步演变。研究结果表明，在第三时期（1989-2000年），人为干扰引发了系统的河道东移、浅滩渐进扩张和2.37 × 106 m3/yr的峰值侵蚀，超过同期沉积的50%。这些变化最终导致了从v形到w形通道剖面的系统重构。顺序疏浚成为主要驱动力，占17 m切口，占第三阶段总冲刷量的68.45%。其他因素，包括港口建设（使河道宽度减少20.39%）、泥沙通量减少（使沉积岸面积减少27.65%）和水动力增强（潮汐差增加4.56 mm/年），协同作用放大了制度转变。通过阐明这种地貌演变的关键驱动因素和后果，我们的研究为人类世重度工程海岸系统的可持续管理提供了重要见解。

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引用次数: 0

The updated distribution of clay minerals in the World Ocean 世界海洋粘土矿物的最新分布

IF 2.2 3区地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY

Marine Geology

Pub Date : 2025-12-08 DOI: 10.1016/j.margeo.2025.107695

Taylor R. Lee , Taylor Vander , Trilby Hill , Jeffrey Obelcz , Benjamin Phrampus , Jordan Graw

Clay mineral content in marine sediments is central to a wide variety of applications in the marine geosciences, including paleoclimate reconstruction and slope stability analyses. Most studies are not applicable to a global scale, focusing on single locations or regional areas. Additionally, dominant clay mineral data (kaolinite, illite, smectite, chlorite) are not curated for “big data” applications necessary to produce estimates on a global scale. Geospatial machine learning (GML) techniques have successfully produced global predictions of geological seafloor properties, such as sedimentation rate and total organic carbon. Here, we curate observed data of dominant clay mineral concentration for use in a GML algorithm to predict global surficial (< 1 m) seafloor estimates of relative clay mineral abundances. Our global seafloor clay mineral predictions are qualitatively similar to previous global estimates, but have more dynamic range and finer-scale spatial variation. Our results show that GML predictions are the best data-driven estimate (∼2-3× decrease in error) of clay mineral concentration where it has not been previously measured.

Plain language summary

Clay minerals in marine seafloor sediments are important to a variety of marine geology applications including reconstructing ancient climates and assessing slope instability hazards. Most of these studies publish sparse data that is limited to particular regions of the world. The inconsistent formatting of these data makes it difficult to utilize in a “big data” framework (e.g., machine learning applications). We harvest thousands of sparse clay mineral observations from a variety of different public sources including literature and repositories. We standardize these data in a manner compatible with machine learning efforts. We then utilize machine learning algorithms to estimate the global distribution of dominant clay minerals in shallow marine seafloor (< 1 m) sediments. Finally, we compare our predictions with previously published maps. Our predictions are descriptively similar, but statistically more accurate.

海洋沉积物中的粘土矿物含量在海洋地球科学中有着广泛的应用，包括古气候重建和边坡稳定性分析。大多数研究并不适用于全球范围，而是侧重于单个地点或区域。此外，主要的粘土矿物数据（高岭石、伊利石、蒙脱石、绿泥石）并没有为“大数据”应用进行整理，而产生全球范围内的估算是必要的。地理空间机器学习（GML）技术已经成功地产生了海底地质属性的全球预测，如沉积速率和总有机碳。在这里，我们整理了主要粘土矿物浓度的观测数据，用于GML算法来预测全球表面（< 1 m）海底相对粘土矿物丰度的估计。我们的全球海底粘土矿物预测在质量上与以前的全球估计相似，但具有更大的动态范围和更细尺度的空间变化。我们的研究结果表明，GML预测是以前没有测量过的粘土矿物浓度的最佳数据驱动估计（误差降低~ 2-3倍）。海洋海底沉积物中的粘土矿物对各种海洋地质应用非常重要，包括重建古代气候和评估边坡不稳定危险。大多数这些研究发表的稀疏数据仅限于世界上的特定地区。这些数据格式的不一致使得在“大数据”框架（例如，机器学习应用程序）中难以利用。我们从各种不同的公共资源（包括文献和存储库）中收获了数千个稀疏的粘土矿物观察结果。我们以一种与机器学习兼容的方式对这些数据进行标准化。然后，我们利用机器学习算法来估计浅海海底（< 1 m）沉积物中主要粘土矿物的全球分布。最后，我们将我们的预测与之前发表的地图进行比较。我们的预测在描述上是相似的，但在统计上更准确。

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引用次数: 0

Gran Roque Island partly submerged by a 2500-year-old tsunami, Los Roques Archipelago, Venezuela Leeward Antilles Islands 大罗克岛部分被2500年前的海啸淹没，委内瑞拉洛斯罗克群岛背风安的列斯群岛

IF 2.2 3区地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY

Marine Geology

Pub Date : 2025-12-08 DOI: 10.1016/j.margeo.2025.107696

Franck A. Audemard M. , Carlos E. Reinoza Gómez , Jesús Rafael Padilla Vásquez , Melody Philippon , Gabriela Quintana Sánchez , Valerie Clouard , Jean Roger , Sirel Colón Useche , Alejandra Fabiola Leal Guzmán , José Alejandro Méndez Dot , Jean-Frédéric Lebrun

Gran Roque Island (GRI), as the most northeastern salient of the Los Roques Archipelago, has been affected by several extreme-wave events (EWEs), as is recorded by several coastal boulder deposits (CBDs). The particular shape of its windward elevated coast and of its rather simple geology made of 2-end components: on one hand Mesozoic meta-igneous mafic rocks, and on the other Holocene sedimentary environments of typical active carbonate reef systems, allow differentiating a foreshore-lying CBD built by frequent storm and hurricanes from an inland CBD, which was deposited by a much larger and unusual EWE (tsunami). The former CBD is the source of the latter one. The source of this tsunami-transported CBD is unequivocal and forms and accumulates in the seashore of the Mal Viento Bay, the only opening of GRI to the North. This latter singularity also allows proposing that this 2500 yr cal BP tsunami must have generated in the northeastern Caribbean, because of the narrow opening to the North of this bay. A tsunamigenic earthquake about that time seems to have impacted, at least: a) Saint Thomas (Virgin Islands), b) lagoon Guichard in Saint Martin, c) 3 localities along the Atlantic coast of Martinique and d) Gran Roque Island (GRI). This pre-Current Era event now appears to have several run-ups at different localities. In the case of GRI, it has entrained blocks of diabase as heavy as 8.5–9 tons (volume of 3 m³) over a foreshore top of 2.2 m above msl, requiring a flow depth of 8.2 m. In a more realistic estimation, if the largest block is approximated to a 1-m-diameter, 3-m-long cylinder (volume of 2.35 m³ and ≈ 7 tons), a 6.5 m tsunami wave may have been sufficient to transport it inland by rolling/saltation.

大罗克岛（GRI）作为洛斯罗克群岛最东北的突出部分，受到了几次极端波事件（ewe）的影响，这是几个海岸巨石沉积（CBDs）的记录。其迎风隆起海岸的特殊形状和由两部分组成的相当简单的地质构造：一方面是中生代变质火成岩基性岩，另一方面是全新世典型的活跃碳酸盐礁系统沉积环境，这使得它能够区分出一个由频繁的风暴和飓风形成的滨前CBD和一个由更大、更不寻常的海啸形成的内陆CBD。前者是后者的根源。这个由海啸带来的CBD的来源是明确的，它形成并积聚在Mal Viento海湾的海滨，这是GRI唯一向北开放的地方。后一个奇点也允许提出这个2500年前的海啸一定是在加勒比海东北部产生的，因为这个海湾的北部有一个狭窄的开口。大约在那个时候发生的海啸性地震似乎至少影响了：A)圣托马斯（维尔京群岛），b)圣马丁岛的吉查德泻湖，c)马提尼克岛大西洋沿岸的3个地方和d)格兰罗克岛（GRI）。这个前现代时代的事件现在似乎在不同的地方有几个运行。在GRI的情况下，它携带重达8.5-9吨（体积为3立方米）的辉绿岩块在msl以上2.2米的前海岸顶部，需要8.2米的水流深度。在更现实的估计中，如果最大的块体近似为直径1米、长3米的圆柱体（体积为2.35立方米，≈7吨），则6.5米的海啸波可能足以通过滚动/跳跃将其运送到内陆。

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引用次数: 0

Morphodynamics of a composite barrier system, Westward Ho!, North Devon, UK 一个复合势垒系统的形态动力学，向西Ho！，北德文郡，英国

IF 2.2 3区地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY

Marine Geology

Pub Date : 2025-11-26 DOI: 10.1016/j.margeo.2025.107684

C.L. Rimmer, G. Masselink, M. Wiggins, L. Biermann

Understanding and predicting the morphodynamic evolution of gravel barrier systems is essential for coastal management, as these features provide natural protection for infrastructure and ecosystems. This study uses the composite gravel barrier system of Westward Ho!, south west England, characterised by a sandy intertidal region and a gravel high tide ridge, to quantify the morphological behaviour of this barrier system and link the dynamics to the external forcing, notably sea-level rise and waves. Since 1887, the barrier has retreated by 97 m, with an average retreat rate of 0.71 m yr⁻¹. Over the period 2007–2024, the system lost approximately 216,000 m³ of sediment, equivalent to 3.6 m³ m⁻¹ yr⁻¹. It is suggested that most of this material was transported to a beach-dune system north of the barrier, across an estuary. Over the past two decades, the retreat rate of the southern section has slowed to 0.18 m yr⁻¹, while the retreat rate of the northern section has increased to 2.39 m yr⁻¹. This suggests segmentation is occurring, with the southern end becoming swash-aligned and the northern end drift-aligned. Morphological changes did not strongly correlate with SLR or wave power (cross-shore or longshore). The low-tide shoreline appears near equilibrium with prevailing wave direction, but the gravel ridge is slightly misaligned, suggesting net northward sediment transport. Given current trends, the barrier is expected to continue retreating and losing sediment for several decades. However, a comprehensive understanding of the system's future behaviour requires development of a mixed-sediment morphodynamic model.

了解和预测砾石屏障系统的形态动力学演化对海岸管理至关重要，因为这些特征为基础设施和生态系统提供了自然保护。本研究采用西禾组复合砾石屏障体系。以沙质潮间带和砾石涨潮脊为特征的英格兰西南部，量化该屏障系统的形态行为，并将动力学与外部强迫联系起来，特别是海平面上升和海浪。自1887年以来，该屏障后退了97米，平均后退速度为0.71米/年。在2007-2024年期间，该系统损失了大约216000立方米的沉积物，相当于3.6立方米m−1年−1年。据推测，大部分这些物质被运输到屏障北部的海滩-沙丘系统，穿过河口。近20年来，南段退缩速度已减缓至0.18 m yr - 1，而北段退缩速度已增加至2.39 m yr - 1。这表明分割正在发生，南端变成斜向，北端变成漂向。形态变化与单反或波浪功率（跨岸或长岸）没有很强的相关性。低潮岸线与盛行波方向接近平衡，但砾石脊稍有错位，表明泥沙向北净输运。鉴于目前的趋势，预计在未来几十年里，这一屏障将继续后退并失去沉积物。然而，要全面了解该系统的未来行为，需要开发混合沉积物形态动力学模型。

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引用次数: 0

Decadal shoreline variability in urban beaches: Contributions from structural changes, storms, and nourishments to tipping points 城市海滩的年代际海岸线变化：结构变化、风暴和营养对临界点的贡献

IF 2.2 3区地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY

Marine Geology

Pub Date : 2025-11-25 DOI: 10.1016/j.margeo.2025.107683

J. Guillén, G. Simarro

The beaches of Barcelona are sediment-starved, heavily engineered, and subject to frequent human interventions. Over two decades of daily shoreline data obtained through video monitoring have yielded a comprehensive dataset, which is analysed to evaluate decadal shoreline dynamics, anthropogenic influences, and interactions with wave forcing across multiple urban beaches. Despite an overall erosive trend, shoreline retreat has been intermittently counteracted by periodic sand nourishments and the construction of coastal protection structures. A statistical definition of equilibrium shoreline position is introduced based on the frequency distribution of shoreline locations and potential drivers of abrupt shifts (“tipping points”) in shoreline behavior are identified. The analysis includes assessments of post-nourishment retreat rates and explores correlations between shoreline change and storm wave energy. While individual beach responses exhibit moderate correlation with wave energy, this relationship becomes more robust when data are aggregated over longer temporal windows or spatially across all beaches, highlighting the relevance of local controls. These findings provide a valuable first-order framework for anticipating shoreline behavior in urban beach settings and inform future coastal management strategies, although further refinement through advanced morphodynamic modeling is recommended to enhance predictive accuracy.

巴塞罗那的海滩缺乏沉积物，经过大量的工程设计，经常受到人类的干预。通过视频监测获得的20多年的每日海岸线数据产生了一个全面的数据集，分析该数据集以评估年代际海岸线动态，人为影响以及与多个城市海滩波浪强迫的相互作用。尽管总体上有侵蚀趋势，但海岸线的退缩已经被周期性的沙质滋养和海岸保护结构的建设间歇性地抵消了。基于岸线位置的频率分布，引入了平衡岸线位置的统计定义，并确定了岸线行为突变（“引爆点”）的潜在驱动因素。分析包括对营养后退缩率的评估，并探索海岸线变化与风暴波能量之间的相关性。虽然个别海滩的反应与波浪能量表现出适度的相关性，但当数据在较长的时间窗口或在所有海滩的空间上汇总时，这种关系变得更加强大，突出了局部控制的相关性。这些发现为预测城市海滩环境中的海岸线行为提供了一个有价值的一级框架，并为未来的海岸管理策略提供了信息，尽管建议通过先进的形态动力学建模进一步改进以提高预测准确性。

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引用次数: 0

Shoreline evolution in a low-lying coastal region under anthropogenic influence 人为影响下低洼沿海地区的海岸线演变

IF 2.2 3区地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY

Marine Geology

Pub Date : 2025-11-19 DOI: 10.1016/j.margeo.2025.107679

Matteo Meli , Enrica Vecchi , Claudia Romagnoli

This study aims to reconstruct and analyze shoreline evolution along the highly urbanized Emilia-Romagna coast (Italy) over the period 1984–2023 using satellite-derived shorelines. Landsat and Sentinel-2 imagery were processed with the CoastSat toolbox, and shoreline positions were corrected for tide and wave setup before deriving yearly averages from 2,200 transects. While the spatial resolution of yearly-averaged SDS is lower than that of conventional techniques, this approach enables, for the first time in this region, the reconstruction of shoreline dynamics as a continuous time series spanning interannual to multi-decadal scales. Results highlight substantial spatial and temporal variability across the shoreline, driven by the interplay of natural processes and anthropogenic interventions such as coastal defenses, repeated nourishments, and sediment extraction. Despite ongoing sea-level rise and subsidence, most of the coast exhibits stability or net advancement, largely maintained through human interventions. The resulting dataset provides one of the most temporally extensive records of shoreline variability for the Emilia-Romagna coast and represents a valid basis for future monitoring and coastal management.

本研究旨在利用卫星岸线重建和分析1984-2023年间高度城市化的艾米利亚-罗马涅海岸（意大利）的海岸线演变。使用海岸卫星工具箱处理Landsat和Sentinel-2图像，并根据潮汐和波浪设置对海岸线位置进行校正，然后从2200个样条中得出年平均值。虽然年平均SDS的空间分辨率低于常规技术，但该方法首次在该地区将海岸线动态重建为跨越年际至几十年尺度的连续时间序列。结果表明，在自然过程和人为干预（如海岸防御、重复营养和沉积物提取）的相互作用下，海岸线上存在大量的时空变化。尽管海平面持续上升和下沉，大多数海岸表现出稳定或净推进，主要是通过人类干预维持的。由此产生的数据集为艾米利亚-罗马涅海岸的海岸线变化提供了最广泛的时间记录之一，为未来的监测和海岸管理提供了有效的基础。

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引用次数: 0

Plio-pleistocene sediment grain size variability in the Western Bay of Bengal: Evidences of Indian Summer Monsoon intensification 孟加拉湾西部上新世-更新世沉积物粒度变化：印度夏季风增强的证据

IF 2.2 3区地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY

Marine Geology

Pub Date : 2025-11-19 DOI: 10.1016/j.margeo.2025.107682

Nitika Millicent Patrick, Nishant Vats , Ajoy K. Bhaumik, Satabdi Mohanty, Koustav Chattopadhyay

Grain size distribution patterns of the Bay of Bengal marine sediments have the potential to provide valuable insights into the long-term variability of the Indian Summer Monsoon (ISM). The study presents a Plio-Pleistocene marine sediment grain size record from the offshore Mahanadi Basin to decipher precipitation phases and reconstruct long-term ISM variability. We have analysed the grain size distribution of 150 marine sediment core samples recovered from the Hole NGHP-01-19A in the western Bay of Bengal, covering the Plio-Pleistocene interval. Through the application of end-member Modelling Analysis of grain size distribution, the study identifies key sediment transport modes and infers monsoon-influenced depositional changes. Three dominant end-members (EM1, EM2, and EM3) were identified, with the majority (∼ 96 %) of sediments falling within the silt-size range. The temporal distribution of EM3, sand (%), and mean grain size reveals the intensified monsoon precipitation phases between 5.3 Ma – 5.2 Ma, 4.6 Ma - 3.2 Ma, at 2.7 Ma, 1.4 Ma - 1.2 Ma and 0.8 Ma - Recent. These observations are validated using published monsoonal proxies [Runoff data (IODP U1445 and U1446), Uvigerina proboscidea abundance and δ¹⁸O of Planktic foraminifera (ODP 758)]. The spectral and continuous wavelet transformation of EM3 and sand (%) indicates a strong influence of orbital forcing during the entire Pliocene epoch on the ISM precipitation phases. These findings highlight the close connection between monsoonal variability, orbital forcing, and sediment delivery to the western Bay of Bengal.

孟加拉湾海洋沉积物的粒度分布模式有可能为印度夏季风（ISM）的长期变化提供有价值的见解。本文利用Mahanadi盆地上新世-更新世海相沉积粒度记录，对降水阶段进行了解析，重建了ISM的长期变化。本文分析了孟加拉湾西部NGHP-01-19A孔150个海相沉积物岩心样品的粒度分布，样品覆盖了上新世-更新世区间。通过对粒度分布的端元模拟分析，确定了关键的输沙模式，推断了受季风影响的沉积变化。确定了三个主要的端元（EM1， EM2和EM3），大多数（~ 96%）的沉积物落在粉砂粒度范围内。EM3、沙粒（%）和平均粒径的时间分布揭示了5.3 Ma ~ 5.2 Ma、4.6 Ma ~ 3.2 Ma、2.7 Ma、1.4 Ma ~ 1.2 Ma和0.8 Ma ~近期的季风降水增强阶段。这些观测结果通过已公布的季风代用物[径流数据（IODP U1445和U1446）、长形假水蛭丰度和浮游有孔虫的δ18O (ODP 758)]得到了验证。EM3和沙（%）的光谱和连续小波变换表明，整个上新世的轨道强迫对ISM降水阶段有很强的影响。这些发现强调了季风变率、轨道强迫和向孟加拉湾西部输送沉积物之间的密切联系。

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引用次数: 0

Hydro-sedimentary processes of mangrove wetland over a meso-macrotidal estuary 中潮河口红树林湿地的水沉积过程

IF 2.2 3区地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY

Marine Geology

Pub Date : 2025-11-18 DOI: 10.1016/j.margeo.2025.107681

Wenjun Zeng , Zhijun Dai , Jiejun Luo , Yi Chen , Xiaowen Xie , Riming Wang

Mangrove wetlands play a vital role in reducing water flow and wave energy, facilitating sediment capture and accumulation, thereby stabilizing coastlines and protecting coastal zones. Nevertheless, few studies have comprehensively investigated the hydrodynamic and sedimentary processes from bare flat zone to the forest interior of mangrove wetlands. Therefore, this study collected comprehensive field data, including hydrological, sediment, and elevation measurements between 2020 and 2022, aiming to diagnosing the attenuation of hydrodynamic and sediment processes in an undisturbed mangrove wetland of the Nanliu River Estuary. Results showed both current velocity and wave height declined markedly landward, accompanied by spatial fluctuations. Specifically, mean flood velocity, mean ebb velocity, and mean significant wave height decreased by over 70 %, 40 %, and 50 %, respectively. Correspondingly, surface sediments showed a general fining trend landward, with localized variations reflecting spatial heterogeneity of hydrodynamic forces. Meanwhile, surface elevation in bare flat zone increased sharply landward at an average slope of 1.6 ‰, while vegetated zone displayed a much gentler profile, averaging around 0.3 m. Vegetated zone was in relatively stable state, typically undergoing weak erosion or strong accretion, whereas bare flat zone experienced pronounced erosion or minor deposition. Dense, mature mangroves could effectively dissipate wave energy and slowing tidal currents, reducing flood velocity, ebb velocity, and wave height by 0.42 %/m, 0.25 %/m, and 0.45 %/m, respectively. Typhoons not only triggered substantial erosion but also reshaped sediment characteristics, with their impacts modulated by water depth controlled by tidal cycle variations.

红树林湿地在减少水流和波浪能，促进沉积物的捕获和积累，从而稳定海岸线和保护海岸带方面发挥着至关重要的作用。然而，很少有研究对红树林湿地从光秃秃的平坦带到森林内部的水动力和沉积过程进行全面的研究。因此，本研究收集了2020 - 2022年的水文、泥沙和高程测量等野外综合数据，旨在诊断南流河口未受干扰的红树林湿地水动力和泥沙过程的衰减。结果表明，流速和波高向陆地方向均明显下降，并伴有空间波动。平均涨潮速度、平均退潮速度和平均有效波高分别下降了70%、40%和50%以上。与此相对应的是，表层沉积物总体呈向陆地细化的趋势，其局部变化反映了水动力的空间异质性。与此同时，光秃秃的平坦带地表高程向陆地方向急剧上升，平均坡度为1.6‰，而植被带地表高程平缓，平均坡度在0.3 m左右。植被带处于相对稳定的状态，典型的是弱侵蚀或强淤积，而光秃秃的平坦带则是明显的侵蚀或轻微的沉积。茂密、成熟的红树林可以有效地耗散波浪能量，减缓潮流，使洪水速度、退潮速度和波高分别降低0.42% /m、0.25% /m和0.45% /m。台风不仅引发了大量的侵蚀，而且重塑了沉积物的特征，其影响受潮汐周期变化控制的水深调节。

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引用次数: 0

A submarine mud volcano eruption triggered a 100 m thick mass flow 海底泥火山爆发引发了100米厚的物质流

IF 2.2 3区地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY

Marine Geology

Pub Date : 2025-11-05 DOI: 10.1016/j.margeo.2025.107680

Muhedeen A. Lawal, Ann E. Cook, Derek E. Sawyer

Offshore mud volcanoes can be sites of energetic eruptions and flank collapse. Using three dimensional seismic data from the Gulf of Mexico, we reveal an extensive mass flow (>1.1 × 10⁹ m³) that is linked to one of the region's largest and active mud volcanoes, the Kohl mud volcano. Our analysis reveals a collapsed southeastern crater flank that is ∼1300 m wide and marked by collapse scarps at Kohl. The resulting mass flow is characterized by basin-verging (∼16°) toe thrusts, widens downslope, and ends abruptly at a moat on the seafloor. Unlike typical thin, less cohesive mud volcano flows, this deposit is ∼100 m thick, extends ∼6000 m downslope, and originates from the failed southeastern flank. The deposit is bound by kilometer-scale faults that connect the collapse scarp upslope at the mud volcano crater, and exhibits localized erosion below its debris tongue, typical of mass transport deposits. Erosive and compressional behaviors define the terminal phase of the mass flow emplacement and likely reflect an energetic emplacement event. We argue that an energetic eruption and subsequent crater rim and flank collapse provides the most plausible explanation for our observations, highlighting the feedback between submarine mud volcanism and mass wasting. This study represents an important step forward for understanding how submarine mud volcanism influences the formation of thick and erosive mass flows and the processes that govern the emplacement of such flows on seafloors globally.

近海泥火山可能是剧烈喷发和侧翼塌陷的场所。利用来自墨西哥湾的三维地震数据，我们揭示了一个广泛的质量流（>1.1 × 109 m3），它与该地区最大和活跃的泥火山之一科尔泥火山有关。我们的分析揭示了一个塌陷的东南火山口侧面，大约1300米宽，在科尔以塌陷的悬崖为标志。由此产生的质量流的特征是盆地边缘（~ 16°）脚趾推力，下坡变宽，并在海底护城河处突然结束。不同于典型的薄的、粘性较低的泥火山流，该沉积物厚约100米，下坡延伸约6000米，起源于断裂的东南侧翼。该矿床被连接泥火山火山口上坡的崩塌陡坡的千米级断层所束缚，并在其碎屑舌下表现出局部侵蚀，这是典型的块体搬运矿床。侵蚀和挤压行为定义了质量流侵位的结束阶段，可能反映了一次高能侵位事件。我们认为，一次高能喷发和随后的火山口边缘和侧面塌陷为我们的观察提供了最合理的解释，突出了海底泥火山活动和大量消耗之间的反馈。这项研究是了解海底泥火山作用如何影响厚的侵蚀物质流的形成以及控制这些物质流在全球海底就位的过程的重要一步。

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