Pub Date : 2025-11-01Epub Date: 2025-08-24DOI: 10.1016/j.margeo.2025.107641
C. Gouramanis , Y.T. Yan , Z. Yang , J.L. Soria , W. Yap , K. Jankaew , A.D. Switzer
Siliciclastic storm deposits have been described from coastlines around the world over the last six decades. Most of these storm deposits are formed from storms directly or obliquely making landfall, or tangentially bypassing nearby coastal systems. In these instances, coastal water piles up on the coast as the storm approaches the coastline before breaching or overtopping the beach barrier. Seldom have storm deposits been examined from coastlines on the lee of the storm. We describe the sedimentary and stratigraphical variation of a small storm fan from three short sediment cores from Ko Phra Thong, western Thailand. The fan was formed after a tropical depression crossed the Malay-Thai peninsula in May 2007, resulting in water piling up along the coast and breaching of the small berm on the western coastline of Ko Phra Thong. Sufficient accommodation space resulted in fine to medium quartz and heavy-mineral rich sands to be deposited upon the back beach sediments. The basal contact consists of a soil horizon above beach sands with an abundance of Casuarina equisetifolia needles. Horizontal laminations of heavy minerals characterise the lowest stratigraphic unit, conformably overlain by a massive unit which is in turn overlain by a unit with vertical and sub-horizontal root structures. At the landward extremity of the fan, faint landward dipping cross beds are observed, indicative of terminal foresets. As Ko Phra Thong preserves a well-established history of past tsunami sand washover deposits, the presence of a storm overwash fan along this coast complicates the inferred overwash event history. This complication is particularly pertinent when the palaeo-shoreline was closer to the swales where smaller, lower energy events, such as storms, can overtop the palaeo-berm and deposit sandy units. This most likely occurred between 2500 and 2000 years ago when thin, structureless sandy deposits were emplaced near the palaeo-shoreline.
{"title":"Storm sediment deposit from Ko Phra Thong, Thailand","authors":"C. Gouramanis , Y.T. Yan , Z. Yang , J.L. Soria , W. Yap , K. Jankaew , A.D. Switzer","doi":"10.1016/j.margeo.2025.107641","DOIUrl":"10.1016/j.margeo.2025.107641","url":null,"abstract":"<div><div>Siliciclastic storm deposits have been described from coastlines around the world over the last six decades. Most of these storm deposits are formed from storms directly or obliquely making landfall, or tangentially bypassing nearby coastal systems. In these instances, coastal water piles up on the coast as the storm approaches the coastline before breaching or overtopping the beach barrier. Seldom have storm deposits been examined from coastlines on the lee of the storm. We describe the sedimentary and stratigraphical variation of a small storm fan from three short sediment cores from Ko Phra Thong, western Thailand. The fan was formed after a tropical depression crossed the Malay-Thai peninsula in May 2007, resulting in water piling up along the coast and breaching of the small berm on the western coastline of Ko Phra Thong. Sufficient accommodation space resulted in fine to medium quartz and heavy-mineral rich sands to be deposited upon the back beach sediments. The basal contact consists of a soil horizon above beach sands with an abundance of <em>Casuarina equisetifolia</em> needles. Horizontal laminations of heavy minerals characterise the lowest stratigraphic unit, conformably overlain by a massive unit which is in turn overlain by a unit with vertical and sub-horizontal root structures. At the landward extremity of the fan, faint landward dipping cross beds are observed, indicative of terminal foresets. As Ko Phra Thong preserves a well-established history of past tsunami sand washover deposits, the presence of a storm overwash fan along this coast complicates the inferred overwash event history. This complication is particularly pertinent when the palaeo-shoreline was closer to the swales where smaller, lower energy events, such as storms, can overtop the palaeo-berm and deposit sandy units. This most likely occurred between 2500 and 2000 years ago when thin, structureless sandy deposits were emplaced near the palaeo-shoreline.</div></div>","PeriodicalId":18229,"journal":{"name":"Marine Geology","volume":"489 ","pages":"Article 107641"},"PeriodicalIF":2.2,"publicationDate":"2025-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144908855","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}
<div><div>Geological earthquake records are important for probabilistic seismic risk assessment. Such records can be obtained from studies of turbidites triggered by seismic activity in marine and lake basins. The Sea of Marmara (SoM), located on the North Anatolian Fault (NAF), serves as an important laboratory for subaqueous palaeoseismological research. This is because it has 2500 yrs. of historical earthquake records that can be correlated with radiometrically dated sedimentary earthquake records. Additionally, the relatively high sedimentation rate (∼3 mm/yr) in the deep subbasins allows the recognition of individual events. Following the destructive 1912 Mw 7.4 Şarköy–Mürefte and 1999 Mw 7.4 Izmit and Mw 7.2 Düzce earthquakes, the main submerged part of the NAF in the SoM represents a seismic gap, where the long–term earthquake history is of crucial importance for earthquake risk assessment.</div><div>We have studied nine cores recovered along the most active northern strand of the NAF (i.e. the Main Marmara Fault: MMF), using high resolution digital X–ray radiography, μ–XRF core scanning, MSCL physical properties and grain–size analyses. The chronology was determined using accelerated mass spectrometry (AMS) radiocarbon and radionuclide methods. In the cores, coseismic turbidites commonly consist of a basal part with multiple sand–silt laminae above a sharp and often erosional base and an overlying graded mud part (homogenite). The basal parts exhibit high gamma density and MS, and are often enriched in one or more elements, such as Si, K, Fe, Ti, Zr, Ca and Sr, indicative of coarse siliciclastic and carbonate shell fragments.</div><div>Radionuclide- and radiocarbon-dated coseismic turbidites in different SoM subbasins extending back to more than 5000 yrs. indicate an average earthquake recurrence time between 220 and 300 yrs. along the different segments of the MMF. These results are compatible with the GPS velocities and geological slip rates. However, the intervals between two consecutive events vary widely between 50 and 695 yrs. for the different northern NAF segments.</div><div>Integration of our results with previous studies indicates that the M > 7 events recorded are the 1999, 1509, 1296 and 740 earthquakes on the İzmit Gulf segment; the 1894, 1509, 1343, 1090 and 740 earthquakes on the Prince Islands segment in the Çınarcık Basin; the 1894, 1766, 1509, 989, 869 or 862, 740 and 447 earthquakes on the Central High segment and in the Central Basin; and the 1912, 1766, 1344, 989 and 447 earthquakes on the western Marmara segment. The 1912 Şarköy–Mürefte earthquake record is absent in the Central Basin, which suggests that the earthquake rupture did not extend beyond the western end of the Western High. The distribution of the 2500 yr-long sedimentary earthquake records matched with the historical earthquakes along the MMF indicates the common occurrence of multiple-segment ruptures, and suggests that presently, the most earthquake
地质地震记录对概率地震危险性评估具有重要意义。这样的记录可以从海盆和湖盆地震活动引发的浊积岩研究中获得。马尔马拉海（SoM）位于北安那托利亚断层（NAF）上，是水下古地震学研究的重要实验室。这是因为它有2500年的历史。历史地震记录可以与放射性定年的沉积地震记录相关联。此外，深次盆地相对较高的沉积速率（~ 3 mm/yr）使个体事件的识别成为可能。继1912年Mw 7.4 Şarköy-Mürefte和1999年Mw 7.4 Izmit和Mw 7.2 d zce破坏性地震之后，SoM中NAF的主要淹没部分代表了一个地震间隙，其中长期地震历史对地震风险评估至关重要。我们研究了沿NAF最活跃的北线（即马尔马拉主断层：MMF）恢复的9个岩心，使用高分辨率数字x射线摄影，μ-XRF岩心扫描，MSCL物理性质和粒度分析。采用加速质谱法（AMS）放射性碳和放射性核素测定年表。在岩心中，同震浊积岩通常由在尖锐且常受侵蚀的基底上具有多个砂粉砂纹层的基底部分和上覆的分级泥质部分（均质岩）组成。基底部具有较高的伽马密度和质谱，通常富含Si、K、Fe、Ti、Zr、Ca和Sr等一种或多种元素，显示出粗糙的硅屑和碳酸盐壳碎片。不同SoM次盆地的放射性核素和放射性碳定年同震浊积岩可追溯到5000多年前。表明地震的平均复发时间在220年至300年之间。沿着MMF的不同部分。这些结果与GPS速度和地质滑动速率相吻合。然而，两个连续事件之间的间隔在50年到695年之间差别很大。不同的北部地区。将我们的研究结果与以往的研究结果相结合，表明并购与融资；记录的7次地震分别是1999年、1509年、1296年和740年İzmit海湾段的地震；1894年、1509年、1343年、1090年和740年发生在Çınarcık盆地普林斯群岛部分的地震；1894年、1766年、1509年、989年、869年或862年、740年和447年发生在中央高段和中央盆地的地震；以及1912年、1766年、1344年、1989年和447年发生在马尔马拉西部的地震。1912年Şarköy-Mürefte在中央盆地没有地震记录，这表明地震破裂并没有超出西部高地的西端。2500年的沉积地震记录与MMF沿线历史地震的分布相匹配，表明多段断裂现象普遍存在，表明MMF目前最易发生地震的部分是位于伊斯坦布尔西南的中央高段。
{"title":"Long–term sedimentary earthquake records along the northern branch the North Anatolian Fault in the Sea of Marmara (NW Türkiye)","authors":"M. Namık Çağatay , Demet Biltekin , Nurettin Yakupoğlu , Emin Güngör , Nurdan Güngör , Gülsen Uçarkuş , Pierre Henry , Alina Polonia , Luca Gasperini , Celine Grall , Dursun Acar , Umut Barış Ülgen , Christos Tsabaris , Asen Sabuncu","doi":"10.1016/j.margeo.2025.107630","DOIUrl":"10.1016/j.margeo.2025.107630","url":null,"abstract":"<div><div>Geological earthquake records are important for probabilistic seismic risk assessment. Such records can be obtained from studies of turbidites triggered by seismic activity in marine and lake basins. The Sea of Marmara (SoM), located on the North Anatolian Fault (NAF), serves as an important laboratory for subaqueous palaeoseismological research. This is because it has 2500 yrs. of historical earthquake records that can be correlated with radiometrically dated sedimentary earthquake records. Additionally, the relatively high sedimentation rate (∼3 mm/yr) in the deep subbasins allows the recognition of individual events. Following the destructive 1912 Mw 7.4 Şarköy–Mürefte and 1999 Mw 7.4 Izmit and Mw 7.2 Düzce earthquakes, the main submerged part of the NAF in the SoM represents a seismic gap, where the long–term earthquake history is of crucial importance for earthquake risk assessment.</div><div>We have studied nine cores recovered along the most active northern strand of the NAF (i.e. the Main Marmara Fault: MMF), using high resolution digital X–ray radiography, μ–XRF core scanning, MSCL physical properties and grain–size analyses. The chronology was determined using accelerated mass spectrometry (AMS) radiocarbon and radionuclide methods. In the cores, coseismic turbidites commonly consist of a basal part with multiple sand–silt laminae above a sharp and often erosional base and an overlying graded mud part (homogenite). The basal parts exhibit high gamma density and MS, and are often enriched in one or more elements, such as Si, K, Fe, Ti, Zr, Ca and Sr, indicative of coarse siliciclastic and carbonate shell fragments.</div><div>Radionuclide- and radiocarbon-dated coseismic turbidites in different SoM subbasins extending back to more than 5000 yrs. indicate an average earthquake recurrence time between 220 and 300 yrs. along the different segments of the MMF. These results are compatible with the GPS velocities and geological slip rates. However, the intervals between two consecutive events vary widely between 50 and 695 yrs. for the different northern NAF segments.</div><div>Integration of our results with previous studies indicates that the M > 7 events recorded are the 1999, 1509, 1296 and 740 earthquakes on the İzmit Gulf segment; the 1894, 1509, 1343, 1090 and 740 earthquakes on the Prince Islands segment in the Çınarcık Basin; the 1894, 1766, 1509, 989, 869 or 862, 740 and 447 earthquakes on the Central High segment and in the Central Basin; and the 1912, 1766, 1344, 989 and 447 earthquakes on the western Marmara segment. The 1912 Şarköy–Mürefte earthquake record is absent in the Central Basin, which suggests that the earthquake rupture did not extend beyond the western end of the Western High. The distribution of the 2500 yr-long sedimentary earthquake records matched with the historical earthquakes along the MMF indicates the common occurrence of multiple-segment ruptures, and suggests that presently, the most earthquake","PeriodicalId":18229,"journal":{"name":"Marine Geology","volume":"489 ","pages":"Article 107630"},"PeriodicalIF":2.2,"publicationDate":"2025-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144830905","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}
Pub Date : 2025-11-01Epub Date: 2025-08-09DOI: 10.1016/j.margeo.2025.107633
Deepak K. Agarwal , Parijat Roy , Esha Gadekar , John Kurian Palayil
The seawater precipitation, hydrothermal input (plume-derived or weathered sulfide), and weathering of nearby rock outcrops constrain the dominant end-member components in the mid-ocean ridge (MOR) sediments. We have conducted mineralogical, geochemical, and statistical studies of surface sediments from the eastern part of the ultra-slow spreading Southwest Indian Ridge (SWIR) 63°E–69°E. Further, we combined factor analysis and linear regression to demonstrate how relative enrichment/depletion of certain elements compared to the general regional sediment composition can constrain the local seafloor processes. Mineralogy and factor analysis of the carbonate-free geochemical data reveal that the sediments consist of three main end-members with respect to Al, Ti, Mg, Fe, Mn, K, Rb, Cu, Zn, V, Cr, Ni, and As; the end-members are mixed in different proportions in the sediments. The three endmember components, authigenic hydrothermal minerals – Fe-Mn-(oxyhydr)oxides, bernessite, and hematite; basaltic detritus – Labradorite and alteration products (montmorillonite, vermiculite, and illite); and ultramafic detritus – antigorite, account for 62.3 %, 21.8 %, and 10.2 % of the elemental variance, respectively. We also used Ti/Al vs Cr/Al and Ni/Al proxies to show that some samples consist of ultramafic and serpentinized detritus. The sediment sample C-GC-16(0-1 cm) at 67.260° E, 26.574° S, consists of relatively high conservative and redox-sensitive elements (U, Mo, V, As), alkali metals (K, Rb, Cs), and Cu, reflecting the presence of a hydrothermal source in the near vicinity. Moreover, linear relations reveal the relative scavenging of REEs from the seawater by Fe-Mn-(oxyhydr)oxides, which are recorded by Ce anomaly and REE fractionation values relative to Fe and Mn content.
{"title":"Geochemistry of surface sediments from ultra-slow spreading eastern SWIR 63°E–69°E: Inferences on hydrothermal signatures","authors":"Deepak K. Agarwal , Parijat Roy , Esha Gadekar , John Kurian Palayil","doi":"10.1016/j.margeo.2025.107633","DOIUrl":"10.1016/j.margeo.2025.107633","url":null,"abstract":"<div><div>The seawater precipitation, hydrothermal input (plume-derived or weathered sulfide), and weathering of nearby rock outcrops constrain the dominant end-member components in the mid-ocean ridge (MOR) sediments. We have conducted mineralogical, geochemical, and statistical studies of surface sediments from the eastern part of the ultra-slow spreading Southwest Indian Ridge (SWIR) 63°E–69°E. Further, we combined factor analysis and linear regression to demonstrate how relative enrichment/depletion of certain elements compared to the general regional sediment composition can constrain the local seafloor processes. Mineralogy and factor analysis of the carbonate-free geochemical data reveal that the sediments consist of three main end-members with respect to Al, Ti, Mg, Fe, Mn, K, Rb, Cu, Zn, V, Cr, Ni, and As; the end-members are mixed in different proportions in the sediments. The three endmember components, authigenic hydrothermal minerals – Fe-Mn-(oxyhydr)oxides, bernessite, and hematite; basaltic detritus – Labradorite and alteration products (montmorillonite, vermiculite, and illite); and ultramafic detritus – antigorite, account for 62.3 %, 21.8 %, and 10.2 % of the elemental variance, respectively. We also used Ti/Al vs Cr/Al and Ni/Al proxies to show that some samples consist of ultramafic and serpentinized detritus. The sediment sample C-GC-16(0-1 cm) at 67.260° E, 26.574° S, consists of relatively high conservative and redox-sensitive elements (U, Mo, V, As), alkali metals (K, Rb, Cs), and Cu, reflecting the presence of a hydrothermal source in the near vicinity. Moreover, linear relations reveal the relative scavenging of REEs from the seawater by Fe-Mn-(oxyhydr)oxides, which are recorded by Ce anomaly and REE fractionation values relative to Fe and Mn content.</div></div>","PeriodicalId":18229,"journal":{"name":"Marine Geology","volume":"489 ","pages":"Article 107633"},"PeriodicalIF":2.2,"publicationDate":"2025-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144841637","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}
Pub Date : 2025-11-01Epub Date: 2025-08-11DOI: 10.1016/j.margeo.2025.107636
Jokotola Omidiji , Wayne Stephenson , Mark Dickson , Kevin Norton
Downwearing rates obtained from tectonically active coasts provide evidence of rapid rock breakdown following coseismic uplift. These measurements help solve puzzles about ‘missing' marine terraces and have implications for accurate reconstruction of past sea levels, earthquakes and rock coast evolution. However, very few detailed erosion datasets exist for uplifted shore platforms, making it uncertain if erosion records from one coast can be extrapolated to other regions with similar tectonic, geologic, or geomorphic characteristics. Here we present new downwearing rates from an inter-tidal mudstone shore platform at Kahutara Point, Māhia Peninsula, New Zealand that was uplifted likely by ∼3 m within the last 300 years. Downwearing rates were measured over 49 months/4.05 years using the Micro-Erosion Meter (MEM) and Structure-from-Motion photogrammetry: the mean annual downwearing rate was 1.08 mm yr−1, while the total erosion at individual MEM stations ranged from 0.44 to 14.37 mm (equivalent to mean downwearing rates of 0.11 to 3.54 mm yr−1). Orthophotographs of the eroded rock surfaces indicate the combined role of marine processes (waves and tides), sub-aerial weathering processes, salt weathering and biological activity in the erosion of the mudstone platform surface. The downwearing rates from Kahutara Point, Māhia Peninsula are statistically similar to previously published downwearing rates (1.23 mm yr−1) from mudstone platforms at Kaikōura Peninsula, New Zealand, that were obtained prior to the 2016 Kaikōura earthquake, but are significantly different from perturbed post-uplift downwearing rates (2.25 mm yr−1) obtained from the same MEM stations following coseismic uplift of ∼1 m. This work provides valuable data to support comparison of the development of shore platforms and marine terraces at Kaikōura and Māhia at different stages of their tectonic evolution.
从构造活跃的海岸得到的下降速率提供了同震隆起后岩石快速破碎的证据。这些测量有助于解决关于“失踪”的海洋梯田的难题，并对精确重建过去的海平面、地震和岩石海岸演变具有重要意义。然而，对于隆起的海岸平台，很少有详细的侵蚀数据集，因此不确定一个海岸的侵蚀记录是否可以外推到具有类似构造、地质或地貌特征的其他地区。在这里，我们展示了新西兰Māhia半岛Kahutara Point的潮间带泥岩海岸平台的新下降速率，该平台在过去300年中可能上升了约3米。使用微侵蚀仪（MEM）和动态结构摄影测量法测量了49个月/4.05年的侵蚀率：平均年侵蚀率为1.08毫米/年，而各个MEM站点的总侵蚀率为0.44至14.37毫米（相当于平均侵蚀率为0.11至3.54毫米/年）。侵蚀岩石表面的正射影片显示了海洋作用（波浪和潮汐）、空中风化作用、盐风化作用和生物活动在泥岩台地表面侵蚀中的综合作用。Māhia半岛Kahutara Point的下降速率与之前公布的2016年Kaikōura地震前在新西兰Kaikōura半岛泥岩平台上获得的下降速率（1.23 mm yr - 1）在统计上相似，但与同一MEM台站在同震隆起~ 1 m后获得的扰动后下降速率（2.25 mm yr - 1）有显著差异。这项工作为比较Kaikōura和Māhia不同构造演化阶段的海岸台地和海相台地的发育提供了有价值的资料。
{"title":"Micro-Erosion Meter derived downwearing rates on inter-tidal shore platforms at Māhia Peninsula, New Zealand: Implications for uplifted rock coasts","authors":"Jokotola Omidiji , Wayne Stephenson , Mark Dickson , Kevin Norton","doi":"10.1016/j.margeo.2025.107636","DOIUrl":"10.1016/j.margeo.2025.107636","url":null,"abstract":"<div><div>Downwearing rates obtained from tectonically active coasts provide evidence of rapid rock breakdown following coseismic uplift. These measurements help solve puzzles about ‘missing' marine terraces and have implications for accurate reconstruction of past sea levels, earthquakes and rock coast evolution. However, very few detailed erosion datasets exist for uplifted shore platforms, making it uncertain if erosion records from one coast can be extrapolated to other regions with similar tectonic, geologic, or geomorphic characteristics. Here we present new downwearing rates from an inter-tidal mudstone shore platform at Kahutara Point, Māhia Peninsula, New Zealand that was uplifted likely by ∼3 m within the last 300 years. Downwearing rates were measured over 49 months/4.05 years using the Micro-Erosion Meter (MEM) and Structure-from-Motion photogrammetry: the mean annual downwearing rate was 1.08 mm yr<sup>−1</sup>, while the total erosion at individual MEM stations ranged from 0.44 to 14.37 mm (equivalent to mean downwearing rates of 0.11 to 3.54 mm yr<sup>−1</sup>). Orthophotographs of the eroded rock surfaces indicate the combined role of marine processes (waves and tides), sub-aerial weathering processes, salt weathering and biological activity in the erosion of the mudstone platform surface. The downwearing rates from Kahutara Point, Māhia Peninsula are statistically similar to previously published downwearing rates (1.23 mm yr<sup>−1</sup>) from mudstone platforms at Kaikōura Peninsula, New Zealand, that were obtained prior to the 2016 Kaikōura earthquake, but are significantly different from perturbed post-uplift downwearing rates (2.25 mm yr<sup>−1</sup>) obtained from the same MEM stations following coseismic uplift of ∼1 m. This work provides valuable data to support comparison of the development of shore platforms and marine terraces at Kaikōura and Māhia at different stages of their tectonic evolution.</div></div>","PeriodicalId":18229,"journal":{"name":"Marine Geology","volume":"489 ","pages":"Article 107636"},"PeriodicalIF":2.2,"publicationDate":"2025-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144841638","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}
Pub Date : 2025-11-01Epub Date: 2025-08-24DOI: 10.1016/j.margeo.2025.107640
Freya Barr , Charlotte F.K. Uphues , Graziela Miot da Silva , Patrick A. Hesp
Natural and human made reef structures provide effective coastal protection by attenuating incident wave and current energy. Anticipated effects of climate change, such as sea level rise, threaten coastal zones and are predicted to reduce the protection provided to coastlines by reef structures. This study aims to investigate wave and current dynamics at a limestone reef site at Robe, South Australia, to improve our understanding of how limestone reefs act as protective reef structures in present-day and in changing climate conditions. Pressure sensors and acoustic doppler current profilers were deployed on a cross-reef transect to investigate rates of wave attenuation, shifts in spectral wave energy, and changes to current speed and direction. Field measurements indicate that the Town Beach reef acts as a tidally modulated low-pass filter, attenuating more wave energy at lower water levels compared to higher water levels. Despite attenuating less wave energy than other reported studies, the Town Beach reef effectively dissipates approximately 42 % of gravity wave energy, resulting in a domination of lower frequency, infragravity wave energy within the landward reef-protected lagoon. Current speeds landward of the reef are approximately one third lower than those observed seaward of the reef. Bidirectional flows (north-south and east-west, respectively) occur at higher water levels, changing to unidirectional flows (south and west, respectively) at lower water levels. Potential reasons for these observed dynamics are discussed, and future research is proposed to address key limitations, such as unknown ecological, geometric, and morphologic aspects of the reef.
{"title":"Observations of oscillatory and unidirectional flow dynamics over a limestone reef","authors":"Freya Barr , Charlotte F.K. Uphues , Graziela Miot da Silva , Patrick A. Hesp","doi":"10.1016/j.margeo.2025.107640","DOIUrl":"10.1016/j.margeo.2025.107640","url":null,"abstract":"<div><div>Natural and human made reef structures provide effective coastal protection by attenuating incident wave and current energy. Anticipated effects of climate change, such as sea level rise, threaten coastal zones and are predicted to reduce the protection provided to coastlines by reef structures. This study aims to investigate wave and current dynamics at a limestone reef site at Robe, South Australia, to improve our understanding of how limestone reefs act as protective reef structures in present-day and in changing climate conditions. Pressure sensors and acoustic doppler current profilers were deployed on a cross-reef transect to investigate rates of wave attenuation, shifts in spectral wave energy, and changes to current speed and direction. Field measurements indicate that the Town Beach reef acts as a tidally modulated low-pass filter, attenuating more wave energy at lower water levels compared to higher water levels. Despite attenuating less wave energy than other reported studies, the Town Beach reef effectively dissipates approximately 42 % of gravity wave energy, resulting in a domination of lower frequency, infragravity wave energy within the landward reef-protected lagoon. Current speeds landward of the reef are approximately one third lower than those observed seaward of the reef. Bidirectional flows (north-south and east-west, respectively) occur at higher water levels, changing to unidirectional flows (south and west, respectively) at lower water levels. Potential reasons for these observed dynamics are discussed, and future research is proposed to address key limitations, such as unknown ecological, geometric, and morphologic aspects of the reef.</div></div>","PeriodicalId":18229,"journal":{"name":"Marine Geology","volume":"489 ","pages":"Article 107640"},"PeriodicalIF":2.2,"publicationDate":"2025-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144912753","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}
Pub Date : 2025-11-01Epub Date: 2025-08-22DOI: 10.1016/j.margeo.2025.107639
Chang Ran , Shuqin Tao , Mengyuan Wang , Zhen Jiang , Xiang Ye , Aijun Wang
UK’37 and TEX86H palaeothermometers are widely applied to sea surface temperature (SST) reconstructions in global oceans. However, their applications in marginal seas often yields biased results due to regional environmental factors. This study investigated the applicability and controlling factors of these proxies in the subtropical, high-energy Taiwan Strait (TS). Utilizing a 35-year dataset (1982–2016) of AVHRR and MODIS-derived annual and seasonal average SST archives, we conducted regression analyses on UK’37 and TEX86H proxies of 58 surface sediment samples from the study area. Additionally, we employed Empirical Orthogonal Function (EOF) analysis to elucidate the physical processes influencing the index reliability. TEX86H-reconstructed SSTs exhibit a cold bias of −5.5–0.3 °C compared to observed SSTs, largely due to seasonal upwelling and terrestrial inputs. Conversely, UK’37-reconstructed SST in the muddy sediment zone of the northern TS shows a warm bias of 1.8–6.3 °C, relative to observed SST, attributable to lateral transport processes in the said environment. By accounting for terrestrial influences as the main non-temperature factor, we developed an improved regional calibration equation for TEX86H-SST in the TS. These results highlight the necessity of considering hydrodynamic effects when applying UK’37 index in such marginal seas. Through modern calibration using surface suspended particulate matter (SPM) and hydrodynamic correction, this study effectively mitigates lateral transport interference, providing a robust framework for palaeotemperature reconstruction in strong hydrodynamic strait-type marginal sea environments.
UK ' 37和TEX86H古温度计被广泛应用于全球海洋的海表温度重建。然而，由于区域环境因素，它们在边缘海域的应用往往产生有偏差的结果。研究了这些指标在副热带高能台湾海峡的适用性及其控制因素。利用35年（1982-2016）AVHRR和modis衍生的年平均和季节平均海温数据，对研究区58个表层沉积物样本的UK ' 37和TEX86H代理进行了回归分析。此外，我们采用经验正交函数（EOF）分析来阐明影响指标信度的物理过程。与观测到的海温相比，tex86h重建的海温表现出−5.5-0.3°C的冷偏，这主要是由于季节性上升流和陆地输入。相反，UK’37重建的北TS泥质沉积带海温相对于观测海温偏暖1.8 ~ 6.3°C，这是由于该环境的侧向输运过程所致。通过考虑陆地影响作为主要的非温度因素，我们建立了改进的TS中TEX86H-SST区域定标方程，这些结果突出了在边缘海应用UK ' 37指数时考虑水动力效应的必要性。通过海面悬浮颗粒物（SPM）的现代定标和水动力校正，有效减轻了横向输运干扰，为强水动力海峡型边缘海环境的古温度重建提供了强有力的框架。
{"title":"Application potential of UK′37 and TEX86H palaeothermometers in high-energy strait-type marginal seas: a case study in the Taiwan Strait","authors":"Chang Ran , Shuqin Tao , Mengyuan Wang , Zhen Jiang , Xiang Ye , Aijun Wang","doi":"10.1016/j.margeo.2025.107639","DOIUrl":"10.1016/j.margeo.2025.107639","url":null,"abstract":"<div><div>U<sup>K’</sup><sub>37</sub> and TEX<sub>86</sub><sup>H</sup> palaeothermometers are widely applied to sea surface temperature (SST) reconstructions in global oceans. However, their applications in marginal seas often yields biased results due to regional environmental factors. This study investigated the applicability and controlling factors of these proxies in the subtropical, high-energy Taiwan Strait (TS). Utilizing a 35-year dataset (1982–2016) of AVHRR and MODIS-derived annual and seasonal average SST archives, we conducted regression analyses on U<sup>K’</sup><sub>37</sub> and TEX<sub>86</sub><sup>H</sup> proxies of 58 surface sediment samples from the study area. Additionally, we employed Empirical Orthogonal Function (EOF) analysis to elucidate the physical processes influencing the index reliability. TEX<sub>86</sub><sup>H</sup>-reconstructed SSTs exhibit a cold bias of −5.5–0.3 °C compared to observed SSTs, largely due to seasonal upwelling and terrestrial inputs. Conversely, U<sup>K’</sup><sub>37</sub>-reconstructed SST in the muddy sediment zone of the northern TS shows a warm bias of 1.8–6.3 °C, relative to observed SST, attributable to lateral transport processes in the said environment. By accounting for terrestrial influences as the main non-temperature factor, we developed an improved regional calibration equation for TEX<sub>86</sub><sup>H</sup>-SST in the TS. These results highlight the necessity of considering hydrodynamic effects when applying U<sup>K’</sup><sub>37</sub> index in such marginal seas. Through modern calibration using surface suspended particulate matter (SPM) and hydrodynamic correction, this study effectively mitigates lateral transport interference, providing a robust framework for palaeotemperature reconstruction in strong hydrodynamic strait-type marginal sea environments.</div></div>","PeriodicalId":18229,"journal":{"name":"Marine Geology","volume":"489 ","pages":"Article 107639"},"PeriodicalIF":2.2,"publicationDate":"2025-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144931797","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}
Pub Date : 2025-10-01Epub Date: 2025-06-24DOI: 10.1016/j.margeo.2025.107608
Riccardo Arosio , David Amblas
Submarine canyons are deep, large-scale incisions found on most of the world's continental margins. In Antarctica, canyons are widespread features driving mesoscale oceanographic processes with significant implications for global climate and circulation, connecting shallow to deep sedimentary processes and positively influencing biodiversity and ecosystem functioning. The understanding of their oceanographic, climatic, geological and ecological significance is limited by the detail, accuracy and extent of canyon inventory. This study aims to create the best possible catalogue of Antarctic submarine canyons and gullies taking advantage of the new International Bathymetric Chart of the Southern Ocean (IBSCO) v.2. Semi-automatic hydrological techniques were adopted to delineate the drainage network, and to extract attributes such as the stream order, stream gradient and sinuosity. We identified 332 drainage networks with 3291 stream segments, nearly 5 times the number of canyons identified in previous studies, and calculated 15 morphometric parameters for each segment. We observe significant differences across Antarctic margins. East Antarctica shows the most complex and largest drainage networks, while the Antarctic Peninsula has the greatest number of networks, although with the lowest stream orders and shortest lengths. Western Antarctica has less complexity and shorter network lengths compared to East Antarctica. These differences may reflect the contrasting glacial histories of the two regions, with the earlier onset of the East Antarctic Ice Sheet leading to older and more developed canyon systems.
{"title":"The geomorphometry of Antarctic submarine canyons","authors":"Riccardo Arosio , David Amblas","doi":"10.1016/j.margeo.2025.107608","DOIUrl":"10.1016/j.margeo.2025.107608","url":null,"abstract":"<div><div>Submarine canyons are deep, large-scale incisions found on most of the world's continental margins. In Antarctica, canyons are widespread features driving mesoscale oceanographic processes with significant implications for global climate and circulation, connecting shallow to deep sedimentary processes and positively influencing biodiversity and ecosystem functioning. The understanding of their oceanographic, climatic, geological and ecological significance is limited by the detail, accuracy and extent of canyon inventory. This study aims to create the best possible catalogue of Antarctic submarine canyons and gullies taking advantage of the new International Bathymetric Chart of the Southern Ocean (IBSCO) v.2. Semi-automatic hydrological techniques were adopted to delineate the drainage network, and to extract attributes such as the stream order, stream gradient and sinuosity. We identified 332 drainage networks with 3291 stream segments, nearly 5 times the number of canyons identified in previous studies, and calculated 15 morphometric parameters for each segment. We observe significant differences across Antarctic margins. East Antarctica shows the most complex and largest drainage networks, while the Antarctic Peninsula has the greatest number of networks, although with the lowest stream orders and shortest lengths. Western Antarctica has less complexity and shorter network lengths compared to East Antarctica. These differences may reflect the contrasting glacial histories of the two regions, with the earlier onset of the East Antarctic Ice Sheet leading to older and more developed canyon systems.</div></div>","PeriodicalId":18229,"journal":{"name":"Marine Geology","volume":"488 ","pages":"Article 107608"},"PeriodicalIF":2.6,"publicationDate":"2025-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144490025","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}
Pub Date : 2025-10-01Epub Date: 2025-06-24DOI: 10.1016/j.margeo.2025.107607
Raphaël Paris , Franck Lavigne , Christine Hatté , Juan Francisco Betancort , Jean-Pierre Flandrois , Arnauld Vinçon-Laugier , Eve Poulallion , Simon Falvard , Bachtiar W. Mutaqin , Christophe Lécuyer
14C dating of tsunami deposits in arid environments is often challenging, especially when there is no organic material available. The marine bioclasts found in the tsunami deposits thus become the main dating possibility. Apart from the reservoir effect, the main source of uncertainty is the age difference between the shells and the tsunami that transported them. Taking as an example a tsunami deposit on the island of La Graciosa (Canary Islands), we demonstrate that the marine shells (Patella) come from different sources, with 14C ages ranging from >45 kBP to 200 BP, the main source being an ancient marine terrace probably of MIS5e age. In addition, we propose a landslide source for this tsunami, the scar of which can be observed on the Famara cliff to the northeast of Lanzarote, just opposite the tsunami deposit outcrops at La Graciosa. In addition to the methodological aspects of shell dating, this study also serves as a reminder that local tsunamis generated by coastal cliff collapses are not a hazard to be neglected.
{"title":"14C dating of tsunami deposits in arid environments: How challenging can it be? The example of La Graciosa, Canary Islands","authors":"Raphaël Paris , Franck Lavigne , Christine Hatté , Juan Francisco Betancort , Jean-Pierre Flandrois , Arnauld Vinçon-Laugier , Eve Poulallion , Simon Falvard , Bachtiar W. Mutaqin , Christophe Lécuyer","doi":"10.1016/j.margeo.2025.107607","DOIUrl":"10.1016/j.margeo.2025.107607","url":null,"abstract":"<div><div><sup>14</sup>C dating of tsunami deposits in arid environments is often challenging, especially when there is no organic material available. The marine bioclasts found in the tsunami deposits thus become the main dating possibility. Apart from the reservoir effect, the main source of uncertainty is the age difference between the shells and the tsunami that transported them. Taking as an example a tsunami deposit on the island of La Graciosa (Canary Islands), we demonstrate that the marine shells (<em>Patella</em>) come from different sources, with <sup>14</sup>C ages ranging from >45 kBP to 200 BP, the main source being an ancient marine terrace probably of MIS5e age. In addition, we propose a landslide source for this tsunami, the scar of which can be observed on the Famara cliff to the northeast of Lanzarote, just opposite the tsunami deposit outcrops at La Graciosa. In addition to the methodological aspects of shell dating, this study also serves as a reminder that local tsunamis generated by coastal cliff collapses are not a hazard to be neglected.</div></div>","PeriodicalId":18229,"journal":{"name":"Marine Geology","volume":"488 ","pages":"Article 107607"},"PeriodicalIF":2.6,"publicationDate":"2025-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144490026","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}
Pub Date : 2025-10-01Epub Date: 2025-07-03DOI: 10.1016/j.margeo.2025.107615
Wenjian Li , Guan-hong Lee , Jongwi Chang , Ojudoo Darius Ajama , Zhenyan Wang
In natural aquatic systems, flocculation affects sediment transport by altering particle size and settling velocity. However, the asymmetry in floc size over tidal cycles and its influence on sediment transport, especially in turbid coastal regions affected by human activities, remains understudied. This study uses comprehensive observations from ADV, HR-ADCP, Signature ADCP, LISST, and CTD within a man-made tidal channel located on the west coast of the Korean Peninsula to elucidate the size-dependent sediment transport process. Our findings reveal a tidal asymmetry in bottom shear velocity and particle size distribution (PSD). During ebb tide, the bottom shear velocity was higher, but suspended sediment concentration (SSC), Total Volume Concentration (TVC), and mean size () were lower compared to flood tide. This suggests that advection transport, in addition to resuspension, is a significant source of particles during flood tide. These particles increased SSC, TVC, and landward sediment flux, while low shear velocity facilitated flocculation, resulting in higher . Consequently, a higher proportion of microflocs and macroflocs occurred, leading to a higher settling flux from flood tide to high slack water. In contrast, weaker advection transport and low SSC during ebb tide led to lower seaward sediment flux, with stronger shear velocity and lower concentration resulting in weak flocculation and lower . During ebb tide, flocculi (10–20 μm diameter) exceeded microflocs and macroflocs, causing a lesser settling flux. This tidal asymmetry in floc size explains the trapping of larger particles during flood tide and high water levels, ultimately leading to net landward sediment flux in the channel over tidal cycles.
{"title":"Floc size asymmetry modulated by tidal dynamics drives net landward sediment transport in a man-made tidal channel","authors":"Wenjian Li , Guan-hong Lee , Jongwi Chang , Ojudoo Darius Ajama , Zhenyan Wang","doi":"10.1016/j.margeo.2025.107615","DOIUrl":"10.1016/j.margeo.2025.107615","url":null,"abstract":"<div><div>In natural aquatic systems, flocculation affects sediment transport by altering particle size and settling velocity. However, the asymmetry in floc size over tidal cycles and its influence on sediment transport, especially in turbid coastal regions affected by human activities, remains understudied. This study uses comprehensive observations from ADV, HR-ADCP, Signature ADCP, LISST, and CTD within a man-made tidal channel located on the west coast of the Korean Peninsula to elucidate the size-dependent sediment transport process. Our findings reveal a tidal asymmetry in bottom shear velocity and particle size distribution (PSD). During ebb tide, the bottom shear velocity was higher, but suspended sediment concentration (SSC), Total Volume Concentration (TVC), and mean size (<span><math><msub><mi>M</mi><mi>z</mi></msub></math></span>) were lower compared to flood tide. This suggests that advection transport, in addition to resuspension, is a significant source of particles during flood tide. These particles increased SSC, TVC, and landward sediment flux, while low shear velocity facilitated flocculation, resulting in higher <span><math><msub><mi>M</mi><mi>z</mi></msub></math></span>. Consequently, a higher proportion of microflocs and macroflocs occurred, leading to a higher settling flux from flood tide to high slack water. In contrast, weaker advection transport and low SSC during ebb tide led to lower seaward sediment flux, with stronger shear velocity and lower concentration resulting in weak flocculation and lower <span><math><msub><mi>M</mi><mi>z</mi></msub></math></span>. During ebb tide, flocculi (10–20 μm diameter) exceeded microflocs and macroflocs, causing a lesser settling flux. This tidal asymmetry in floc size explains the trapping of larger particles during flood tide and high water levels, ultimately leading to net landward sediment flux in the channel over tidal cycles.</div></div>","PeriodicalId":18229,"journal":{"name":"Marine Geology","volume":"488 ","pages":"Article 107615"},"PeriodicalIF":2.6,"publicationDate":"2025-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144580594","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}
Pub Date : 2025-10-01Epub Date: 2025-06-03DOI: 10.1016/j.margeo.2025.107595
B. Najjarifarizhendi, G. Uenzelmann-Neben, J. Gruetzner
The Falkland/Malvinas Trough (F/MT) bounds the southern extremity of the Falkland/Malvinas Plateau. This Cenozoic bathymetric depression developed as the orogenic foreland basin of the North Scotia Ridge. The sedimentary infill of the F/MT carries a history of development in a transpressional setting along the South American-Scotian Plate boundary, in association with the evolution of the Drake Passage-Scotia Sea zone. Since the F/MT is located on the pathway of the Antarctic Circumpolar Current, the current-controlled depositional and erosional features within its sedimentary infill provide valuable information on the palaeoceanographic modifications in the southwestern South Atlantic. Via a set of 2D high-resolution seismic reflection data, the structural and morphological features of these strata are investigated and discussed with respect to the tectonic evolution of the Drake Passage-Scotia Sea zone. Evidence of fold structures and normal faulting during Oligocene to mid-Miocene times in the study area argue for a transpressional regime linked with the development of the Drake Passage-Scotia Sea zone. The current-related depositional and erosional processes in the F/MT started between Oligocene to early Miocene times. With the full opening of the Drake Passage, the evolution of the Scotia Sea and the demise of the Ancestral South Sandwich Arc by the mid-Miocene, an oceanographic setting analogous to the present would have established. Evidences suggests that since then, with the enhancement of the abyssal circulation subsequent to the perennial Antarctic glaciation, a precursor of the Weddell Sea Deep Water has been circulating the F/MT, shaping a confined sediment drift deposit.
{"title":"Falkland/Malvinas Trough: Indications for Cenozoic tectonic and oceanographic evolution in the southwestern South Atlantic","authors":"B. Najjarifarizhendi, G. Uenzelmann-Neben, J. Gruetzner","doi":"10.1016/j.margeo.2025.107595","DOIUrl":"10.1016/j.margeo.2025.107595","url":null,"abstract":"<div><div>The Falkland/Malvinas Trough (F/MT) bounds the southern extremity of the Falkland/Malvinas Plateau. This Cenozoic bathymetric depression developed as the orogenic foreland basin of the North Scotia Ridge. The sedimentary infill of the F/MT carries a history of development in a transpressional setting along the South American-Scotian Plate boundary, in association with the evolution of the Drake Passage-Scotia Sea zone. Since the F/MT is located on the pathway of the Antarctic Circumpolar Current, the current-controlled depositional and erosional features within its sedimentary infill provide valuable information on the palaeoceanographic modifications in the southwestern South Atlantic. Via a set of 2D high-resolution seismic reflection data, the structural and morphological features of these strata are investigated and discussed with respect to the tectonic evolution of the Drake Passage-Scotia Sea zone. Evidence of fold structures and normal faulting during Oligocene to mid-Miocene times in the study area argue for a transpressional regime linked with the development of the Drake Passage-Scotia Sea zone. The current-related depositional and erosional processes in the F/MT started between Oligocene to early Miocene times. With the full opening of the Drake Passage, the evolution of the Scotia Sea and the demise of the Ancestral South Sandwich Arc by the mid-Miocene, an oceanographic setting analogous to the present would have established. Evidences suggests that since then, with the enhancement of the abyssal circulation subsequent to the perennial Antarctic glaciation, a precursor of the Weddell Sea Deep Water has been circulating the F/MT, shaping a confined sediment drift deposit.</div></div>","PeriodicalId":18229,"journal":{"name":"Marine Geology","volume":"488 ","pages":"Article 107595"},"PeriodicalIF":2.6,"publicationDate":"2025-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144280056","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}
扫码关注我们
求助内容：
应助结果提醒方式：
京公网安备 11010802042870号