Marine Geology最新文献_第10页

The role of exposure on the vertical variation of mudflat sediment erodibility 暴露对泥滩沉积物可蚀性垂直变化的影响

IF 2.6 3区地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY

Marine Geology

Pub Date : 2025-09-01 Epub Date: 2025-05-14 DOI: 10.1016/j.margeo.2025.107579

Chuning Dong , Yongping Chen , Ian Townend , Yiming Wu , Zichao Guo , Qin Jiang , Giovanni Coco , Karin R. Bryan , Zeng Zhou

Variations in meteorological conditions are known to influence the erodibility of sediments on tidal flats. However, there is limited understanding of how evaporation during exposure affects the stability of mudflats. In this study, we conducted field tests spanning 5 days in January 2021 and 14 days in August 2022 in the intertidal zone along the Yancheng coast in Jiangsu Province, China. We selected critical shear stress for erosion (τ_cr) and shear strength (SS) as erosion parameters, and analyzed the variations in hydrodynamic and meteorological parameters, and vertical sediment properties. Our results indicate that bed exposure in summer significantly enhances sediment stability, an effect that extends below the surface layer and even to deeper layers. As exposure duration increases, the differences with depth become more pronounced, leading to increased variability in τ_cr. This vertical gradient increases with exposure duration and atmospheric evaporation intensity, with both the values of vertical τ_cr and SS in summer showing a nearly 2 times increase compared to that in winter. The primary controlling parameter for changes in sediment erodibility during summer exposure is water content, while in winter, the mean grain size (D50) and salinity are more significant. The causal relationship between summer and winter exposure and resistance to vertical erosion of mudflats, shown in this study, underscores the need to pay greater attention to the seasonal influence of atmospheric processes on the spatial heterogeneity of sediments that arises from tidal exposure.

众所周知，气象条件的变化会影响潮滩沉积物的可蚀性。然而，人们对暴露期间的蒸发如何影响泥滩稳定性的了解有限。在这项研究中，我们于2021年1月和2022年8月在中国江苏省盐城沿海的潮间带进行了为期5天和14天的现场试验。选取侵蚀临界剪应力τcr和抗剪强度SS作为侵蚀参数，分析了水动力、气象参数和垂直泥沙特性的变化规律。我们的研究结果表明，夏季的河床暴露显著提高了沉积物的稳定性，这种影响延伸到表层以下甚至更深的层。随着曝光时间的增加，随深度的差异变得更加明显，导致τcr的变异性增加。垂直梯度随暴露时间和大气蒸发强度的增大而增大，夏季垂直τcr和SS值均比冬季增大近2倍。夏季暴露时泥沙可蚀性变化的主要控制参数是含水量，冬季暴露时平均粒径（D50）和盐度变化更为显著。本研究表明，夏季和冬季暴露与泥滩抵抗垂直侵蚀之间的因果关系，强调需要更多地注意大气过程对潮汐暴露引起的沉积物空间异质性的季节性影响。

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引用次数: 0

Discovery of the world's largest cliff-top boulder: Initial insights and numerical simulation of its transport on a 30–40 m high cliff on Tongatapu (Tonga) 发现世界上最大的悬崖顶部巨石：在汤加30-40米高的悬崖上对其运输的初步见解和数值模拟

IF 2.6 3区地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY

Marine Geology

Pub Date : 2025-09-01 Epub Date: 2025-04-21 DOI: 10.1016/j.margeo.2025.107567

Martin Köhler , Annie Lau , Koki Nakata , Kazuhisa Goto , James Goff , Daniel Köhler , Mafoa Penisoni

This study provides the first scientific investigation of the Maka Lahi boulder, a large limestone cliff-top boulder, measuring 14 × 12 × 6.7 m and weighing approximately 1180 t, located 200 m inland at 39 m elevation on the southern coast of Tongatapu, Tonga. The boulder is one of the largest known wave-transported boulders worldwide. Fieldwork conducted in 2024 revealed its presence, geomorphic setting, and karstification features. Utilizing numerical modelling, we established that wave heights of approximately 50 m and periods of 90 s were required to transport the boulder from its cliff-edge origin, suggesting that its emplacement likely resulted from a landslide-triggered tsunami event. U/Th dating of flowstone on the surface is indicative of a minimum age of 6891 cal yr BP and contributes critical evidence of a significant early Holocene tsunami event in Tonga. Notably, this represents the earliest known Holocene tsunami in the Pacific, offering new insights into the long-term history of extreme wave events in the region. This research strengthens the understanding of megaclast transport mechanisms and their implications for coastal hazard assessments in tsunami-prone regions.

这项研究首次对Maka Lahi巨石进行了科学调查，这是一块巨大的石灰岩悬崖顶部巨石，尺寸为14 × 12 × 6.7米，重约1180吨，位于汤加汤加塔普南部海岸，海拔39米，内陆200米。这块巨石是世界上已知的最大的波浪搬运巨石之一。2024年的野外考察揭示了它的存在、地貌环境和岩溶特征。利用数值模拟，我们确定需要大约50米的波浪高度和90秒的周期才能将巨石从悬崖边缘的起源移动，这表明它的就位可能是由山体滑坡引发的海啸事件造成的。表面流石测年表明其最小年龄为6891 calyr BP，为汤加早全新世重大海啸事件提供了重要证据。值得注意的是，这代表了太平洋已知最早的全新世海啸，为该地区极端海浪事件的长期历史提供了新的见解。这项研究加强了对巨碎岩运输机制的理解及其对海啸易发地区沿海灾害评估的影响。

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引用次数: 0

Sources and transport-sedimentation processes of surficial detrital sediments in the southwest Arabian Sea: Insights from grain-size end-member component analysis 阿拉伯海西南部表层碎屑沉积物的来源和搬运-沉积过程：来自粒度端元组分分析的见解

IF 2.6 3区地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY

Marine Geology

Pub Date : 2025-09-01 Epub Date: 2025-05-11 DOI: 10.1016/j.margeo.2025.107578

Dongyi Li, Yonghang Xu, Jian Chen, Yunhai Li, Liang Wang

The Arabian Sea is an ideal region for exploring the sources and transport-sedimentation processes of surficial detrital sediments. Notably, grain-size end-member component (EMC) separation methods are powerful tools for this exploration. Through integration of this method with mineralogical and morphological characterization analyses, we identified four EMCs (EMC1-EMC4) suitable for the study area and elucidated the role of multiple forcings in controlling sources and transport-sedimentation processes. The findings revealed that variations in sources and diverse transport mechanisms govern the grain-size distribution patterns of surficial detrital sediments in the study area. The EMC1 ultrafine end-member is dominated by basalt weathering products from the Deccan Plateau and the west Indian Ocean, and is slightly influenced by aeolian dust from the interior of the Arabian Peninsula and northeast Africa. EMC2, EMC3, and EMC4 represent fine, coarse, and ultra-coarse fractions of aeolian dust primarily from different regions of the Arabian Peninsula, respectively. Monsoon circulation transports smectite-rich ultrafine sediments eastward across the Indian shelf, while Lower Circumpolar Deep Water (LCDW) carries them northward over long distances. Furthermore, the LCDW flows anticlockwise in the north Somali Basin, hindered by the Carlsberg Ridge, leading to the deposition of the ultrafine sediments it carries. Various wind systems interactions enable size-selective transport: fine EMCs traverse via mid-tropospheric pathways, whereas coarse EMCs are confined to the lower troposphere. The southwest monsoon facilitating the transport of fine EMC southward while impeding the transport-sedimentation of coarse EMCs.

阿拉伯海是研究表层碎屑沉积物来源和搬运-沉积过程的理想区域。值得注意的是，粒度端元组分（EMC）分离方法是这一探索的有力工具。通过将该方法与矿物学和形态学特征分析相结合，我们确定了适合研究区域的4种EMCs (EMC1-EMC4)，并阐明了多种强迫在控制物源和运输-沉积过程中的作用。研究结果表明，研究区表层碎屑沉积物的来源变化和不同的输运机制决定了其粒度分布格局。EMC1超细端元以来自德干高原和西印度洋的玄武岩风化产物为主，受阿拉伯半岛内部和非洲东北部风沙的影响较小。EMC2、EMC3和EMC4分别代表主要来自阿拉伯半岛不同地区的细粒、粗粒和超粗粒风沙组分。季风环流将富含蒙脱石的超细沉积物向东穿过印度陆架，而环极深水（LCDW）则将它们向北长距离输送。此外，LCDW在索马里盆地北部逆时针流动，受到嘉士伯山脊的阻碍，导致其携带的超细沉积物沉积。各种风系统的相互作用使大小选择性输送成为可能：细EMCs通过对流层中层路径穿越，而粗EMCs则局限于对流层下层。西南季风有利于细粒状电磁干扰南移，阻碍粗粒状电磁干扰南移沉降。

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引用次数: 0

Controls of paleosedimentary environments and anthropogenic activities on coastal groundwater salinization: A case study of Laizhou Bay, China 古沉积环境和人类活动对沿海地下水盐渍化的控制作用——以莱州湾为例

IF 2.6 3区地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY

Marine Geology

Pub Date : 2025-09-01 Epub Date: 2025-05-28 DOI: 10.1016/j.margeo.2025.107594

Zhen Cui , Guangquan Chen , Xin Shan , Haitao Zhang , Qingjie Zhou , Tengfei Fu , Hongjun Yu , Xingyong Xu , Shenliang Chen

Groundwater salinization presents a substantial environmental challenge for coastal regions globally, particularly along the southern shore of Laizhou Bay. The processes contributing to groundwater salinization are intricate and involve interactions between natural factors and human activities. This study examines the mechanisms underlying groundwater salinization at varying depths in the southern Laizhou Bay area, with a particular emphasis on the effects of extensive groundwater extraction. Excessive groundwater extraction has intensified salinization by altering hydraulic gradients and promoting seawater intrusion. Utilizing sediment and pore water samples from two boreholes (SG100 and WF80) alongside shallow seismic data, we identified that sedimentary strata consisting of alternating marine and terrestrial deposits, formed during multiple transgressive events since the Late Pleistocene, are a significant source of salinity. Paleoenvironmental reconstructions based on grain size analysis, combined with Cl/Br ratios and stable isotope analysis, indicated that modern seawater intrusion is a primary driver of shallow groundwater salinization. In contrast, variations in deep groundwater salinity reflect differing paleoenvironmental recharge conditions. Ancient riverbed sediments exhibit high permeability, providing an efficient pathway for the transport of water and salts from upstream freshwater bodies. This process facilitates the dilution within the aquifer, leading to the formation of low-salinity groundwater. In contrast, the low permeability of floodplain sediments significantly restricts the renewal capacity of water bodies. As a result, the saline water layer maintains a high salinity state over extended periods due to the combined effects of evaporation and limited recharge. Notably, offshore freshwater was detected within ancient river channel deposits. These findings underscore the intricate interplay between sedimentary evolution and anthropogenic activities in influencing groundwater salinization, highlighting the necessity for scientifically informed, water-type-specific management strategies.

地下水盐渍化对全球沿海地区，特别是莱州湾南岸地区构成了严峻的环境挑战。导致地下水盐碱化的过程是复杂的，涉及自然因素和人类活动之间的相互作用。本研究探讨了莱州湾南部地区不同深度地下水盐渍化的机制，特别强调了地下水大量开采的影响。地下水的过度开采通过改变水力梯度和促进海水入侵而加剧了盐碱化。利用两个钻孔（SG100和WF80）的沉积物和孔隙水样本以及浅层地震数据，我们发现沉积地层由海相和陆相交替沉积组成，形成于晚更新世以来的多次海侵事件中，是盐度的重要来源。基于粒度分析的古环境重建，结合Cl/Br比值和稳定同位素分析，表明现代海水入侵是浅层地下水盐渍化的主要驱动因素。深层地下水盐度的变化反映了不同的古环境补给条件。古河床沉积物具有高渗透性，为上游淡水水体的水盐输送提供了有效途径。这一过程促进了含水层内部的稀释，从而形成低盐度地下水。而泛滥平原沉积物的低渗透性则严重限制了水体的更新能力。结果，由于蒸发和有限补给的综合作用，咸水层在较长时间内保持高盐度状态。值得注意的是，在古河道沉积物中发现了近海淡水。这些发现强调了影响地下水盐碱化的沉积演化和人为活动之间错综复杂的相互作用，强调了有必要制定有科学依据的、针对具体水类型的管理战略。

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引用次数: 0

The geomorphic evolution of the Tasmantid Seamount Chain 塔斯马tid海山链的地貌演化

IF 2.6 3区地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY

Marine Geology

Pub Date : 2025-08-01 Epub Date: 2025-04-18 DOI: 10.1016/j.margeo.2025.107560

Alysha M. Johnson , Mark E. Dickson , Sarah Hamylton , Colin D. Woodroffe

Oceanic volcanoes develop distinct post-eruptive morphologies depending on the geomorphic conditions they experience. Submerged, truncated, flat-topped volcanoes, known as guyots, result from marine erosion and subsidence, whereas on reefs or carbonate-capped volcanoes, carbonate accretion veneers the summit. New and existing bathymetric data are utilised to identify different geomorphic forms of oceanic volcanoes in the Tasmantid Seamount Chain, a hotspot chain off the east coast of Australia, dated from ∼6 Ma in the south to >50 Ma in the north. Profiles and slope calculations across long and short axes provide morphometric values on the basis of which four morphologic forms are identified: seamount, guyot, modern reef, and carbonate-capped guyot. Volcanoes which erupted on oceanic lithosphere are estimated to have subsided at an average rate of 46.5 mMyr⁻¹, faster than the subsidence rate of volcanoes that erupted on continental lithosphere (33.0 mMyr⁻¹). The guyots are estimated to have eroded at an average rate of 1.9 ± 0.5 kmMyr⁻¹. Substantial carbonate accretion has formed on the summits of eleven volcanoes, ranging in thickness from 1146 m in the north to 93 m in the south. The geomorphic evolution of the Tasmantid Seamount Chain, since the Oligocene, is synthesised into a conceptual model. This study finds that the post-eruptive morphology of each volcano in the chain is a product of the combined influence of the northward movement of the Australian Plate, erosion, subsidence, and carbonate accretion.

海洋火山根据其所经历的地貌条件，形成了不同的爆发后形态。淹没、截断、平顶的火山被称为 "盖奥特"（Guyots），是海洋侵蚀和沉降的结果，而在暗礁或碳酸盐盖火山上，碳酸盐的增生则是火山顶的表皮。利用新的和现有的测深数据，确定了澳大利亚东海岸外的热点链 Tasmantid 海山链中不同地貌形式的海洋火山，其年代从南部的 6 Ma 到北部的 50 Ma。长轴和短轴的剖面和坡度计算提供了形态测量值，在此基础上确定了四种形态：海山、盖奥特、现代礁和碳酸盐盖奥特。据估计，在海洋岩石圈上喷发的火山的平均沉降速度为 46.5 mMyr-1，快于在大陆岩石圈上喷发的火山的沉降速度（33.0 mMyr-1）。据估计，盖奥特的平均侵蚀速度为 1.9 ± 0.5 kmMyr-1。在 11 座火山的山顶上形成了大量的碳酸盐沉积，厚度从北部的 1146 米到南部的 93 米不等。自渐新世以来，Tasmantid 海山链的地貌演变被归纳为一个概念模型。该研究发现，海山链中每座火山的爆发后形态都是澳大利亚板块北移、侵蚀、沉降和碳酸盐增生共同影响的产物。

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引用次数: 0

Testing spatial interpolation methods for deep-time organic carbon burial in epicontinental seas by taking Sunda Shelf as an example 以巽他陆架为例，对陆表海深时间有机碳埋藏空间插值方法进行了验证

IF 2.6 3区地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY

Marine Geology

Pub Date : 2025-08-01 Epub Date: 2025-04-25 DOI: 10.1016/j.margeo.2025.107566

Yida Yang , Pengfei Ma , Xiumian Hu , Yuan Gao , Chengshan Wang

Quantifying the burial of organic carbon (OC) in epicontinental seas is crucial for understanding its role in regulating global long-term carbon cycle and climate. Utilizing spatial interpolation methods, prior works have quantified OC burial globally or regionally based on limited, unevenly distributed measurements. However, there remains a notable lack of comparative studies and assessments regarding their applicability and uncertainty in deep-time research. Taking the middle Miocene Sunda Shelf OC burial estimation as an example, four popular spatial interpolation methods are assessed quantitatively and qualitatively, including Thiessen polygons, Inverse Distance Weighting (IDW), Ordinary Kriging (OK) and Random Forests (RF). Based on quantitative and qualitative evaluation, the data-driven RF method demonstrates superior performance due to fewer assumptions, effectively capturing nonlinear relationships and complex spatial patterns in heterogeneous, non-Gaussian deep-time data, and demonstrating strong generalizability and robustness. High-resolution RF-based reassessment reveals significant spatial-temporal heterogeneity of OC burial on the Sunda Shelf between the Miocene Climatic Optimum (MCO) and Middle Miocene Climate Transition (MMCT). Although the overall OC burial and sediment accumulation rates (SAR) increase during the MMCT, notable spatial discrepancies emerge, with OC burial rates elevated near basin margins but decreased in distal regions. These variations primarily reflect the combined influences of eustatic sea-level fall and enhanced terrigenous input, highlighting the complex interplay of factors modulating OC burial efficiency. Machine learning methods such as RF prove highly effective in handling deep-time spatial data, but their application should be adapted to specific objectives, geological conditions, and data characteristics.

陆表海洋有机碳埋藏量的量化对于理解其在全球长期碳循环和气候调节中的作用至关重要。利用空间插值方法，以前的工作是基于有限的、不均匀分布的测量来量化全球或区域的碳埋藏。然而，对于它们在深度时间研究中的适用性和不确定性，目前还缺乏比较研究和评估。以中新世中巽他陆架OC埋藏估算为例，定量和定性地评价了四种常用的空间插值方法：Thiessen多边形、逆距离加权（IDW）、普通克里格（OK）和随机森林（RF）。基于定量和定性评价，数据驱动射频方法由于较少的假设，能够有效捕获异构非高斯深度时间数据中的非线性关系和复杂空间模式，并且具有较强的泛化性和鲁棒性。基于高分辨率rf的重新评估揭示了中新世气候最佳期（MCO）和中中新世气候过渡期（MMCT）之间巽他陆架OC埋藏的时空异质性。在MMCT期间，尽管总体的OC埋藏率和沉积物堆积率（SAR）增加，但存在显著的空间差异，盆地边缘附近的OC埋藏率升高，而远端区域的OC埋藏率降低。这些变化主要反映了海平面上升和陆源输入增强的综合影响，突出了调节OC埋藏效率的因素的复杂相互作用。像RF这样的机器学习方法在处理深时空间数据方面被证明是非常有效的，但它们的应用应该适应特定的目标、地质条件和数据特征。

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引用次数: 0

Morphology and Holocene activity of a high-latitude Canyon – Channel system: The proximal Lofoten Basin channel system (Norwegian Sea) 高纬度峡谷-水道系统的形态与全新世活动：挪威海罗弗敦盆地近端水道系统

IF 2.6 3区地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY

Marine Geology

Pub Date : 2025-08-01 Epub Date: 2025-04-30 DOI: 10.1016/j.margeo.2025.107574

Hilde B. Amundsen , Jan Sverre Laberg, Daniel H. Wiberg , Tom Arne Rydningen, Amando P.E. Lasabuda , Stine Bjordal-Olsen, Matthias Forwick

Canyon – channel systems have the potential to be biological and marine litter “hotspots”, and they can act as important carbon sinks. However, knowledge about the modern (Holocene) activity of many of these systems remains poor. This includes the high-latitude Andøya Canyon - Lofoten Basin Channel located in the Norwegian Sea (∼69^oN). This study focuses on the proximal Lofoten Basin Channel and associated deposits (the Andøya Canyon is previously reported). The Lofoten Basin Channel includes two channel branches representing the canyon continuation beyond the foot of the continental slope, terminating in an area resembling a braidplain including braided channels, bars, as well as MTDs. Sediment cores included sandy turbidites. Based on their age and Ca/Fe ratios, we infer that the youngest sandy turbidites were deposited during the same event, suggesting that the event covered an area of c. 120 km × 20 km. Assuming an average thickness of ∼10 cm, this result in a volume of ∼0,24 km³ of terrigenous sand deposited in the basin over an area of ∼2400 km² sometime during the period from 3.7 to 2.4 kyrs BP. This equals a sand thickness of 4.8 m in the c. 50 km long and 1 km wide thalweg part of the Andøya Canyon, here considered to be the source area. The sand could derive from failure of sandy accumulations within the canyon and/or from sand piracy. Another aspect of this Holocene turbidite event is that it represented a substantial export of inorganic carbon into the deep sea which in this way got buried, representing a carbon sink removing carbon from the carbon cycle (a carbon draw-down effect). These results shows that the canyon is a potential source and route for sediments that may cover ∼2400 km² of the sea floor, large deep-sea areas that also represent carbon sinks so far not well accounted for.

峡谷-水道系统有可能成为生物和海洋垃圾的“热点”，它们可以作为重要的碳汇。然而，关于这些系统的现代（全新世）活动的知识仍然很贫乏。这包括位于挪威海（~ 69oN）的高纬度Andøya峡谷-罗弗敦盆地海峡。本研究的重点是罗浮敦盆地近端水道及其伴生矿床（先前报道了Andøya峡谷）。罗浮敦盆地海峡包括两个分支，代表了大陆斜坡脚下以外的峡谷延伸，终止于一个类似辫状平原的区域，包括辫状海峡、沙洲和mtd。沉积物岩心包括砂质浊积岩。根据它们的年龄和Ca/Fe比值，我们推断最年轻的砂质浊积岩是在同一事件中沉积的，表明该事件覆盖面积约为120 km × 20 km。假设平均厚度为~ 10 cm，这导致在3.7至2.4 kyrs BP的某个时间内，在盆地约2400 km2的面积上沉积了约0.24 km3的陆源砂。这相当于在50公里长、1公里宽的Andøya峡谷中部的4.8米厚的沙子，这里被认为是源区。这些沙子可能来自于峡谷内的沙质堆积的破坏和/或沙的掠夺。全新世浊积岩事件的另一个方面是，它代表了大量无机碳出口到深海，这些无机碳以这种方式被埋藏，代表了碳汇从碳循环中去除碳（碳下降效应）。这些结果表明，峡谷是沉积物的潜在来源和路径，可能覆盖约2400平方公里的海底，大型深海区域也代表碳汇，迄今尚未得到很好的解释。

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引用次数: 0

A coral microatoll record of sea-level rise, interseismic deformation, and El Niño in La Union, Philippines since 1906 CE 自公元1906年以来，菲律宾La Union的海平面上升，地震间变形和El Niño的珊瑚微环礁记录

IF 2.6 3区地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY

Marine Geology

Pub Date : 2025-08-01 Epub Date: 2025-04-19 DOI: 10.1016/j.margeo.2025.107565

Gina M. Sarkawi , Aron J. Meltzner , Dongju Peng , Joanne T.Y. Lim , Xinnan Li , Rohan Gautam , Anandh Gopal , Andrew Mitchell , Loraine Faye Sarmiento , Jennifer Weil-Accardo , Kathrine V. Maxwell , Junki Komori , Noelynna T. Ramos

Relative sea level (RSL) along western Luzon is influenced by climate change, tectonic deformation, and the El Niño–Southern Oscillation. Long, high-resolution records of past changes in sea level and land level are crucial to distinguish these contributions for forecasting future RSL or identifying tectonic hazards. Coral microatolls are invaluable proxies for reconstructing RSL, but their interpretation relies on understanding how short- and long-term changes are recorded in the coral skeleton. We analyzed growth bands from 1906 to 2018 CE of a Porites microatoll from Balaoan, La Union, Philippines, using X-rays of vertical cross sections. The microatoll's surface morphology, annual banding, and growth history reveal RSL rise during its lifetime punctuated by 17 diedowns. Coral diedowns generally coincide with low water near the site, often resulting from El Niño events. Excluding eroded sections, 10 of the 11 strongest El Niños since 1918 produced a diedown. Similarly, excluding a diedown caused by the coral tilting, 10 of the 12 preserved diedowns exceeding 3 mm in amplitude occurred during strong El Niños. Between 1948 and 2018 CE, RSL rose at 1.3 ± 1.8 mm/yr (2σ). Comparing sea-level rates from satellite altimetry and RSL from the coral, we estimate vertical land motion at −0.1 ± 12.1 mm/yr between 1995 and 2018 CE. The indicative meaning at Balaoan, defined as the relationship between local water levels and the highest level of growth of a coral microatoll before its most recent diedown, is estimated at 31.5 ± 10.0 cm (2σ) above lowest astronomical tide.

吕宋岛西部相对海平面（RSL）受气候变化、构造变形和El Niño-Southern涛动的影响。长期、高分辨率的过去海平面和陆地水平变化记录对于预测未来的RSL或识别构造危险至关重要。珊瑚微环礁是重建RSL的宝贵替代品，但它们的解释依赖于对珊瑚骨架中记录的短期和长期变化的理解。我们使用垂直截面的x射线分析了菲律宾La Union Balaoan的Porites微环礁1906年至2018年的生长带。微环礁的表面形态、年带状带和生长历史显示，RSL在其一生中呈上升趋势，其间有17次衰减。珊瑚凋零通常与该地点附近的低潮同时发生，通常是由El Niño事件造成的。除去被侵蚀的部分，自1918年以来11次最强的厄尔尼诺Niños中有10次出现了减弱。同样，排除珊瑚倾斜引起的衰减，12个保存下来的振幅超过3毫米的衰减中有10个发生在强厄尔尼诺Niños期间。1948年至2018年，RSL以1.3±1.8 mm/年（2σ）的速度上升。通过比较卫星测高数据的海平面速率和珊瑚的RSL，我们估计1995年至2018年期间陆地垂直运动为−0.1±12.1毫米/年。巴罗安的指示意义是指当地水位与珊瑚微环礁最近一次消亡前的最高生长水平之间的关系，估计在最低天文潮以上31.5±10.0 cm （2σ）。

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引用次数: 0

Hydrodynamic processes and extreme events recognized from the sedimentary records at ancient Port Shuomen in the Oujiang River mouth, Southeast China 从中国东南部瓯江口古硕门港沉积记录中认识水动力过程和极端事件

IF 2.6 3区地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY

Marine Geology

Pub Date : 2025-08-01 Epub Date: 2025-04-13 DOI: 10.1016/j.margeo.2025.107562

Xin Wei , Yanhua Liang , Tuanhui Liu , Zhihang Ma , Xiaolin Ma , Shiyu Ji , Fangyou Lin , Hao Xu , Zhanghua Wang (王张华)

Identifying extreme events from geological records is fundamental to Paleotempestology. Archaeological excavations at the ancient Port Shuomen on the Southeast Chinese coast have provided high-resolution stratigraphic data for recognizing deposits associated with extreme events. This study examined three profiles from the Port and surficial sediments from modern colluvial and estuarine environments in the lower Oujiang River basin. Analyses including chronology, sedimentology, alkaline earth metal geochemistry, and ancient environmental DNA (eDNA) were performed on the sedimentary records to identify hydrodynamic processes and extreme events during the Song Dynasty (960–1279 CE). Comparisons of alkaline earth metal compositions between the profiles and surficial sediments suggest a reduction in salinity at the Port Shuomen, driven by increased freshwater discharge during the mid- to late-Northern Song Dynasty. High eDNA concentrations and consistent frequency distributions of fragment lengths further suggest rapid channel siltation during a single typhoon season. Following this typhoon season, the Port evolved into tide-dominated regime and experienced five periods of flooding, three of which were characterized by intensified salinity intrusion as evidenced by elevated Sr content. In particular, a mud unit (U10) exhibits the highest Sr content and is interpreted as a depositional record of extreme typhoon events that occurred in the 1160s CE. Furthermore, this study demonstrates that in estuarine environments, the preservation of eDNA is more impacted by sedimentary processes than grain size.

从地质记录中识别极端事件是古气象学的基础。中国东南沿海的朔门古港考古发掘为识别与极端事件相关的沉积物提供了高分辨率的地层数据。本研究考察了朔门港的三个剖面以及瓯江流域下游现代冲积和河口环境的表层沉积物。对沉积记录进行了年代学、沉积学、碱土金属地球化学和古环境 DNA（eDNA）等分析，以确定宋代（公元 960-1279 年）的水动力过程和极端事件。对剖面和表层沉积物的碱土金属成分进行比较后发现，北宋中后期淡水排放量的增加推动了朔门港盐度的降低。高浓度的 eDNA 和一致的片段长度频率分布进一步表明，在一个台风季节，河道淤积迅速。在台风季节之后，港口演变为以潮汐为主的水系，并经历了五次洪水泛滥，其中三次洪水泛滥的特点是盐分入侵加剧，锶含量升高就是证明。其中，一个泥质单元（U10）的锶含量最高，被解释为公元 1160 年代极端台风事件的沉积记录。此外，这项研究还证明，在河口环境中，eDNA 的保存受沉积过程的影响比受粒度的影响更大。

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引用次数: 0

Evidence for mixing of migrated hydrocarbons and indigenous organic matter in the Paleocene deepest core in IODP Expedition 378 Hole U1553D, Campbell Plateau, New Zealand 新西兰坎贝尔高原378孔U1553D古新世最深处运移烃与原生有机质混合的证据

IF 2.6 3区地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY

Marine Geology

Pub Date : 2025-08-01 Epub Date: 2025-05-07 DOI: 10.1016/j.margeo.2025.107576

Simon C. George , Lian Jiang , Blanca Ausín , Eleni Anagnostou , Ann G. Dunlea , Laurel B. Childress , Ursula Röhl , Deborah J. Thomas

International Ocean Discovery Program (IODP) Expedition 378 recovered a continuous, > 580 m thick Paleogene sedimentary sequence at Site U1553 on the Campbell Plateau, south of the South Island of New Zealand. Oil stain samples are rarely recovered during scientific ocean drilling, but one was recovered from the deepest Paleocene core in Hole U1553D (579.94 m CSF-A), associated with high amounts of methane and wet gases detected by on-board instrumentation, that led to drilling any deeper being prevented. This oil stain was analysed by gas chromatography–mass spectrometry and gas chromatography–triple quadrupole mass spectrometry, and compared with the indigenous Paleocene organic matter.

The n-alkane distribution of the oil stain sample is bimodal, suggesting mixing of a thermogenic migrated oil with a signal from the indigenous Paleocene sediments. This is confirmed by the ≥C₂₇ hopanoid and steroid biomarkers in the oil stain sample which are very similar to the immature Unit Vb early Paleocene sediments, including the presence of neohop-13(18)-enes, ββ hopanes, and βαα steranes. The C₁₀–C₂₀ aromatic compound distributions are in the molecular weight range where there is a mixed signal. The migrated thermogenic oil and gas were derived from a marine source rock containing a significant contribution from terrigenous and probably coniferous organic matter, deposited in a dysoxic depositional environment. Vertical migration of thermogenic oil and gas penetrated the early Paleocene sediments, but did not reach into the Eocene section due a significant permeability barrier associated with a middle–late Paleocene unconformity. Deeper drilling and geophysical investigation are required to understand the putative Cretaceous or older strata in this region.

国际海洋发现计划（IODP）的378号探险队发现了一个连续的，>；新西兰南岛南部坎贝尔高原U1553遗址上580米厚的古近系沉积层。在科学海洋钻探过程中很少回收油渍样本，但在U1553D孔（579.94 m CSF-A）最深的古新世岩心中回收了一个油渍样本，与船上仪器检测到的大量甲烷和湿气有关，导致钻探更深的钻探被阻止。采用气相色谱-质谱联用、气相色谱-三重四极杆质谱联用对油样进行了分析，并与当地古新世有机质进行了对比。油渍样品的正构烷烃分布呈双峰型，表明热源运移油与古新世原生沉积物的信号混合。油斑样品中的≥C27类藿烷和甾类生物标志物与早古新世未成熟的Vb单元沉积物非常相似，包括新藿烷-13(18)-烯、ββ藿烷和βαα甾烷的存在，证实了这一点。C10-C20芳香族化合物分布在分子量范围内，存在混合信号。运移的热生油气来自海相烃源岩，其中陆源有机质占很大比重，可能有针叶有机质，沉积于欠氧沉积环境。热生油气垂直运移穿透了早古新世沉积层，但由于中晚古新世不整合相关的显著渗透率障碍，未进入始新世剖面。需要进行更深入的钻探和地球物理调查，以了解该地区假定的白垩纪或更古老的地层。

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引用次数: 0