Marine Geology最新文献_第3页

Evaluating longshore sediment transport: A comparison between empirical formulas and XBeach 2DH numerical model

IF 2.6 3区地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY

Marine Geology

Pub Date : 2025-02-01 DOI: 10.1016/j.margeo.2024.107471

Samanta Buttò , Carla Lucia Faraci , Marta Corradino , Claudio Iuppa , Emanuele Colica , Fabrizio Pepe

Longshore sediment transport (LST) is a crucial process shaping coastal environments. As multiple site-specific factors (e.g. wave height, coastal topography) influence the LST, an accurate estimation of LST rate represents a scientific challenge.

This research evaluates the predictive capacity of three widely used empirical formulas (CERC, 1984; Kamphuis, 1991; Van Rijn, 2014) and the XBeach 2DH numerical model for estimating the LST rate by comparing the obtained results with field LST data.

We chose three coastal sites in Malta Island (Għadira Bay, GB) and northern Sicily (Cefalù, CF, and Campofelice di Roccella, CR) based on different sediment grain size, coastal type (open or embayed) and morpho-bathymetry.

For each site, we analysed wave parameters, grain size of the beach and seabed sediments, coastal morphology, and marine vegetation distribution. Furthermore, we used field measurements to calibrate the numerical model's sediment transport and morphological parameters.

The calibrated numerical model provides greater accuracy in LST rate estimation than the empirical formulas. The latter overestimates the LST rates by factors ranging from 435 to 7885, whereas the numerical model overestimates by factors of 1.8 and 1.9 at the CF site and GB, respectively, and underestimates by a factor of 0.5 at the CR site.

The good performance of the numerical model is due to its consideration of site-specific factors. The parameter values for the model calibration can be used successfully in embayed fine/coarse sandy beaches. Moreover, the numerical model, tested so far only for sandy beaches, also works well on gravelly beaches.

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引用次数: 0

Tectono-sedimentary processes shaping the West Sardinian margin and adjacent oceanic basin during the Plio-Quaternary (Western Mediterranean Sea)

IF 2.6 3区地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY

Marine Geology

Pub Date : 2025-02-01 DOI: 10.1016/j.margeo.2024.107450

Veronica Frisicchio , Anna Del Ben , Riccardo Geletti , Maria Cristina Caradonna , Michele Rebesco , Massimo Bellucci

A seismic analysis of the Plio-Quaternary stratigraphy of the West Sardinian continental margin and adjacent oceanic basin was conducted using single- and multi-channel seismic profiles. Two main chronostratigraphic boundaries have been used: i) the Ms horizon, marking the base of the Pliocene and corresponding to the top of the Messinian evaporites on the lower continental slope and deep basin, and the Messinian erosional truncation on the upper slope and shelf; and ii) the newly identified A₀ horizon, marking the base of the Quaternary (2.6 Ma). This study reveals key geological features affecting the Pliocene and Quaternary deposits: a) salt tectonic structures, b) normal faults, c) volcanic structures, d) pockmarks, e) canyon systems, and f) regressive clinoform system. These features are linked to tectono-sedimentary processes such as vertical movements, magmatic activity, halokinesis and sediment dynamics. Vertical movements are associated with the thermal subsidence of the Oligo-Miocene basin opening, water and sediment loading/unloading during and after the Messinian Salinity Crisis, and Pleistocene uplift onshore. These movements resulted in the tilting of the margin, which influenced normal faulting through reactivation of Oligo-Miocene faults, and the Plio-Quaternary depositional patterns. Several normal faults acted as conduits for lower Pliocene magmatic activity and gas migration, forming volcanoes and pockmarks on the continental shelf and upper slope. Salt tectonics in the lower slope and deep basin produced diapirs and rollover structures, significantly impacting the thickness and distribution of Pliocene and, to a lesser extent, Quaternary deposits. Canyons system formation seems to be controlled by the interplay of the Quaternary sea-level fluctuations with the margin's ongoing tilting. Similarly, the regressive clinoform system also results from these two factors, but is further influenced by erosion of uplifted Sardinian onshore areas.

{"title":"Tectono-sedimentary processes shaping the West Sardinian margin and adjacent oceanic basin during the Plio-Quaternary (Western Mediterranean Sea)","authors":"Veronica Frisicchio , Anna Del Ben , Riccardo Geletti , Maria Cristina Caradonna , Michele Rebesco , Massimo Bellucci","doi":"10.1016/j.margeo.2024.107450","DOIUrl":"10.1016/j.margeo.2024.107450","url":null,"abstract":"<div><div>A seismic analysis of the Plio-Quaternary stratigraphy of the West Sardinian continental margin and adjacent oceanic basin was conducted using single- and multi-channel seismic profiles. Two main chronostratigraphic boundaries have been used: i) the Ms horizon, marking the base of the Pliocene and corresponding to the top of the Messinian evaporites on the lower continental slope and deep basin, and the Messinian erosional truncation on the upper slope and shelf; and ii) the newly identified A<sub>0</sub> horizon, marking the base of the Quaternary (2.6 Ma). This study reveals key geological features affecting the Pliocene and Quaternary deposits: a) salt tectonic structures, b) normal faults, c) volcanic structures, d) pockmarks, e) canyon systems, and f) regressive clinoform system. These features are linked to tectono-sedimentary processes such as vertical movements, magmatic activity, halokinesis and sediment dynamics. Vertical movements are associated with the thermal subsidence of the Oligo-Miocene basin opening, water and sediment loading/unloading during and after the Messinian Salinity Crisis, and Pleistocene uplift onshore. These movements resulted in the tilting of the margin, which influenced normal faulting through reactivation of Oligo-Miocene faults, and the Plio-Quaternary depositional patterns. Several normal faults acted as conduits for lower Pliocene magmatic activity and gas migration, forming volcanoes and pockmarks on the continental shelf and upper slope. Salt tectonics in the lower slope and deep basin produced diapirs and rollover structures, significantly impacting the thickness and distribution of Pliocene and, to a lesser extent, Quaternary deposits. Canyons system formation seems to be controlled by the interplay of the Quaternary sea-level fluctuations with the margin's ongoing tilting. Similarly, the regressive clinoform system also results from these two factors, but is further influenced by erosion of uplifted Sardinian onshore areas.</div></div>","PeriodicalId":18229,"journal":{"name":"Marine Geology","volume":"480 ","pages":"Article 107450"},"PeriodicalIF":2.6,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143097651","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Prediction of coastline evolution using remote sensing and deep learning approach; Case study of the Northwest of the Persian Gulf

IF 2.6 3区地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY

Marine Geology

Pub Date : 2025-02-01 DOI: 10.1016/j.margeo.2024.107472

Navid Bahrami, Seyed Mostafa Siadatmousavi

Considering the rapid population growth in coastal areas and the anthropogenic activities, it is important to have a forecast tool for monitoring and managing the coastal changes. In this manuscript the coastline dynamics are analyzed using remote sensing indices and deep learning approach. The studied area is approximately 212 km north of the Persian Gulf. This area is of great economic and political importance and includes several rivers, ports, estuaries, etc. The Landsat satellite images were collected from the USGS dataset over a period of 38 years. In the next step, two methods were used to detect the coastline. The first method was to use indices such as NDWI, and the second method was to combine the bands. To calculate the changes of the coastline and make predictions, several methods were employed including EPR, LRR, LMS, and SCE. The performance of these traditional methods were compared with the CNN method; especially in complex segments such as close to the mouth of the largest river in the study area. The results show that in the upper parts of the region, i.e. the area of Hendijan port, the situation of changes is relatively intense and on average it reaches ∼6 m/year of accretion. This amount reaches ∼1 m/year in the middle areas of the coast. In contrast, in the lower parts of the region, the coast is under erosion of ∼1 m/year. The predictions for the upper parts indicate an accretion of more than 80 m in the next 20 years, and the amount of erosion for the lower part is ∼13 m in this time period. Also, based on the results, CNN is able to predict the coastline dynamics successfully which is important because it can handle large amount of images and nonlinear interaction of coastline with physical phenomenon such as sea level rise and tidal effects.

{"title":"Prediction of coastline evolution using remote sensing and deep learning approach; Case study of the Northwest of the Persian Gulf","authors":"Navid Bahrami, Seyed Mostafa Siadatmousavi","doi":"10.1016/j.margeo.2024.107472","DOIUrl":"10.1016/j.margeo.2024.107472","url":null,"abstract":"<div><div>Considering the rapid population growth in coastal areas and the anthropogenic activities, it is important to have a forecast tool for monitoring and managing the coastal changes. In this manuscript the coastline dynamics are analyzed using remote sensing indices and deep learning approach. The studied area is approximately 212 km north of the Persian Gulf. This area is of great economic and political importance and includes several rivers, ports, estuaries, etc. The Landsat satellite images were collected from the USGS dataset over a period of 38 years. In the next step, two methods were used to detect the coastline. The first method was to use indices such as NDWI, and the second method was to combine the bands. To calculate the changes of the coastline and make predictions, several methods were employed including EPR, LRR, LMS, and SCE. The performance of these traditional methods were compared with the CNN method; especially in complex segments such as close to the mouth of the largest river in the study area. The results show that in the upper parts of the region, i.e. the area of Hendijan port, the situation of changes is relatively intense and on average it reaches ∼6 m/year of accretion. This amount reaches ∼1 m/year in the middle areas of the coast. In contrast, in the lower parts of the region, the coast is under erosion of ∼1 m/year. The predictions for the upper parts indicate an accretion of more than 80 m in the next 20 years, and the amount of erosion for the lower part is ∼13 m in this time period. Also, based on the results, CNN is able to predict the coastline dynamics successfully which is important because it can handle large amount of images and nonlinear interaction of coastline with physical phenomenon such as sea level rise and tidal effects.</div></div>","PeriodicalId":18229,"journal":{"name":"Marine Geology","volume":"480 ","pages":"Article 107472"},"PeriodicalIF":2.6,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143093186","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Shallow seismic stratigraphy of the southwestern Algarve shelf (Portugal) and characteristics of offshore tsunami deposits

IF 2.6 3区地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY

Marine Geology

Pub Date : 2025-02-01 DOI: 10.1016/j.margeo.2024.107463

Lisa Feist , Pedro J.M. Costa , Juan I. Santisteban , Stijn Albers , Piero Bellanova , Ivana Bosnic , Marc De Batist , João F. Duarte , Aurora Rodrigues , Klaus Reicherter

Understanding the sedimentary dynamics of continental shelves is crucial for decoding past high-energy events like tsunamis. Based on data from HSV FISÁLIA cruise of the Portuguese Navy, this study investigates the geomorphological features of the southwestern Algarve shelf and the seismo-stratigraphic characteristics of sedimentary units attributed to two tsunamis that occurred in 1755 CE (Lisbon earthquake) and ca. 3600 cal yr BP. Using high-resolution geoacoustic profiling in combination with sedimentological analyses and radiocarbon dating from prior studies, this study is the first to identify an Infralittoral Prograding Wedge on the shallow southwestern Algarve shelf. Furthermore, remnants of an older transgressive prograding wedge-shaped sediment body have been detected on the mid to outer shelf off Portimão. A crucial finding of this study is a high-amplitude reflector which has been associated with the ca. 3600 cal yr BP tsunami deposit. This reflector is particularly strong based on the corresponding deposit's stark compositional contrast with the surrounding sediment. In its distribution, this reflector is restricted to the base of the Infralittoral Prograding Wedge indicating this wedge as the most likely sediment source for the ca. 3600 cal yr BP deposit. On the other hand, the 1755 CE Lisbon tsunami deposit has no clear geophysical signature on the southwestern Algarve shelf due to its vestigial thicknesses and scarce compositional contrast with the surrounding sediment. This divergence raises significant questions about the different triggering mechanisms and transport processes that define both offshore tsunami deposits. Our findings highlight the significance of local bathymetric conditions, sediment sources, as well as triggering mechanisms and transport pathways in shaping offshore tsunami deposits.

{"title":"Shallow seismic stratigraphy of the southwestern Algarve shelf (Portugal) and characteristics of offshore tsunami deposits","authors":"Lisa Feist , Pedro J.M. Costa , Juan I. Santisteban , Stijn Albers , Piero Bellanova , Ivana Bosnic , Marc De Batist , João F. Duarte , Aurora Rodrigues , Klaus Reicherter","doi":"10.1016/j.margeo.2024.107463","DOIUrl":"10.1016/j.margeo.2024.107463","url":null,"abstract":"<div><div>Understanding the sedimentary dynamics of continental shelves is crucial for decoding past high-energy events like tsunamis. Based on data from HSV FISÁLIA cruise of the Portuguese Navy, this study investigates the geomorphological features of the southwestern Algarve shelf and the seismo-stratigraphic characteristics of sedimentary units attributed to two tsunamis that occurred in 1755 CE (Lisbon earthquake) and ca. 3600 cal yr BP. Using high-resolution geoacoustic profiling in combination with sedimentological analyses and radiocarbon dating from prior studies, this study is the first to identify an Infralittoral Prograding Wedge on the shallow southwestern Algarve shelf. Furthermore, remnants of an older transgressive prograding wedge-shaped sediment body have been detected on the mid to outer shelf off Portimão. A crucial finding of this study is a high-amplitude reflector which has been associated with the ca. 3600 cal yr BP tsunami deposit. This reflector is particularly strong based on the corresponding deposit's stark compositional contrast with the surrounding sediment. In its distribution, this reflector is restricted to the base of the Infralittoral Prograding Wedge indicating this wedge as the most likely sediment source for the ca. 3600 cal yr BP deposit. On the other hand, the 1755 CE Lisbon tsunami deposit has no clear geophysical signature on the southwestern Algarve shelf due to its vestigial thicknesses and scarce compositional contrast with the surrounding sediment. This divergence raises significant questions about the different triggering mechanisms and transport processes that define both offshore tsunami deposits. Our findings highlight the significance of local bathymetric conditions, sediment sources, as well as triggering mechanisms and transport pathways in shaping offshore tsunami deposits.</div></div>","PeriodicalId":18229,"journal":{"name":"Marine Geology","volume":"480 ","pages":"Article 107463"},"PeriodicalIF":2.6,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143097652","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Sedimentation of tidal sand ridges off the Liuguhe River mouth in the Liaodong Bay, Bohai Sea

IF 2.6 3区地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY

Marine Geology

Pub Date : 2025-02-01 DOI: 10.1016/j.margeo.2024.107473

Libo Wang , Jun Li , Jingtao Zhao , Fenglong Bai , Bangqi Hu , Yanguang Dou , Weiyu Song , Liang Zou

The Liuguhe River mouth sand ridges in the Liaodong Bay, Bohai Sea, provide a good example for further understanding the sedimentation of small-scale tidal sand ridges. However, little is known about their morphological and sedimentary characteristics. This paper presents a comprehensive study of these sand ridges using survey data from sub-bottom profiling, side-scan sonar mapping, and acoustic doppler current profiling, along with piston core analyses of grain-size and heavy minerals. The sand ridges span widths of 1–2.5 km and heights of 4–16 m, with diminishing heights toward the sea. Their cross-sections are asymmetrical, featuring gentler and steeper slope angles of less than 1.5° and up to 4.5°, respectively. Sand waves are widely superimposed on the sand ridges, exhibiting wavelengths of 0.7–62.3 m and heights of 0.11–3.12 m. The ridge sediment consists of well sorted medium sand, while the trough sediment consists of very poorly sorted silty sand, indicating that the ridges are coarser and better sorted than the troughs. The tidal deposits are characterized by high levels of magnetite and hematite. Provenance discrimination based on heavy mineral assemblages indicates that the sediment is mainly derived from the Liuguhe River. The sand ridges have been formed since the middle Holocene and are still active at present. The tidal currents are rectilinear. Near-bed currents exceeding the critical velocity of sediment motion account for 20 % of a tidal cycle, implying that the tidal currents are capable of maintaining the development of bedforms. The longitudinal axes of the sand ridges exhibit anticlockwise rotation relative to the direction of the maximum tidal current, with an angle of up to 30°. The steeper slopes of the sand waves on both flanks of the sand ridges point to ridge crestlines, implying a tendency for sand streams to converge on the ridge crestlines. The sand ridges and adjacent troughs consist entirely of modern tidal deposits in the shoreward area, while the troughs are incised in the underlying strata with a thin layer of modern tidal deposits covering on the surface in the seaward area. Seaward decrease in sediment supplies may explain the seaward changes in ridge structures and heights.

{"title":"Sedimentation of tidal sand ridges off the Liuguhe River mouth in the Liaodong Bay, Bohai Sea","authors":"Libo Wang , Jun Li , Jingtao Zhao , Fenglong Bai , Bangqi Hu , Yanguang Dou , Weiyu Song , Liang Zou","doi":"10.1016/j.margeo.2024.107473","DOIUrl":"10.1016/j.margeo.2024.107473","url":null,"abstract":"<div><div>The Liuguhe River mouth sand ridges in the Liaodong Bay, Bohai Sea, provide a good example for further understanding the sedimentation of small-scale tidal sand ridges. However, little is known about their morphological and sedimentary characteristics. This paper presents a comprehensive study of these sand ridges using survey data from sub-bottom profiling, side-scan sonar mapping, and acoustic doppler current profiling, along with piston core analyses of grain-size and heavy minerals. The sand ridges span widths of 1–2.5 km and heights of 4–16 m, with diminishing heights toward the sea. Their cross-sections are asymmetrical, featuring gentler and steeper slope angles of less than 1.5° and up to 4.5°, respectively. Sand waves are widely superimposed on the sand ridges, exhibiting wavelengths of 0.7–62.3 m and heights of 0.11–3.12 m. The ridge sediment consists of well sorted medium sand, while the trough sediment consists of very poorly sorted silty sand, indicating that the ridges are coarser and better sorted than the troughs. The tidal deposits are characterized by high levels of magnetite and hematite. Provenance discrimination based on heavy mineral assemblages indicates that the sediment is mainly derived from the Liuguhe River. The sand ridges have been formed since the middle Holocene and are still active at present. The tidal currents are rectilinear. Near-bed currents exceeding the critical velocity of sediment motion account for 20 % of a tidal cycle, implying that the tidal currents are capable of maintaining the development of bedforms. The longitudinal axes of the sand ridges exhibit anticlockwise rotation relative to the direction of the maximum tidal current, with an angle of up to 30°. The steeper slopes of the sand waves on both flanks of the sand ridges point to ridge crestlines, implying a tendency for sand streams to converge on the ridge crestlines. The sand ridges and adjacent troughs consist entirely of modern tidal deposits in the shoreward area, while the troughs are incised in the underlying strata with a thin layer of modern tidal deposits covering on the surface in the seaward area. Seaward decrease in sediment supplies may explain the seaward changes in ridge structures and heights.</div></div>","PeriodicalId":18229,"journal":{"name":"Marine Geology","volume":"480 ","pages":"Article 107473"},"PeriodicalIF":2.6,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143093139","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Characterizing Holocene environmental transitions using magnetic properties of sediments from the continental shelf of the northern South China Sea

IF 2.6 3区地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY

Marine Geology

Pub Date : 2025-02-01 DOI: 10.1016/j.margeo.2024.107464

Yi Wu , Guanqiang Cai , Shun Li , Shixun Wang , Shuqing Fu , Yulin Han , Shichen Tao

Understanding past climate changes during the Holocene epoch, as recorded in continental shelf sediments, is crucial for reconstructing past climate patterns, sea-level fluctuations, and the influence of human activities. To explore Holocene environmental transitions in the northern South China Sea, we analyzed the sedimentary magnetic properties of the continental shelf east of Hainan Island. Our measurements revealed two significant transitions in magnetic mineral composition and grain size: around 7.6 ka and near 2 ka. The early transition around 7.6 ka is attributed to eustatic sea-level changes that altered coastal erosion, fluvial input, and sediment transportation due to the region's shallow shelf dynamics. Conversely, the recent transition near 2 ka is primarily due to the strengthened Atlantic Meridional Overturning Circulation, which influenced the East Asian monsoon regime. This later period coincides with intensified anthropogenic agricultural activities over the last ca. 2 kyr, highlighting interactions between natural and early human intervention. Between these transitions, from ca. 7.6 ka to ca. 2 ka, the magnetic proxy data suggest relatively stable environmental conditions resembling an event similar to a Holocene climatic optimum. This interval is characterized by consistent sedimentary magnetic properties, indicating a period of climatic stability under the monsoonal climate regime.

{"title":"Characterizing Holocene environmental transitions using magnetic properties of sediments from the continental shelf of the northern South China Sea","authors":"Yi Wu , Guanqiang Cai , Shun Li , Shixun Wang , Shuqing Fu , Yulin Han , Shichen Tao","doi":"10.1016/j.margeo.2024.107464","DOIUrl":"10.1016/j.margeo.2024.107464","url":null,"abstract":"<div><div>Understanding past climate changes during the Holocene epoch, as recorded in continental shelf sediments, is crucial for reconstructing past climate patterns, sea-level fluctuations, and the influence of human activities. To explore Holocene environmental transitions in the northern South China Sea, we analyzed the sedimentary magnetic properties of the continental shelf east of Hainan Island. Our measurements revealed two significant transitions in magnetic mineral composition and grain size: around 7.6 ka and near 2 ka. The early transition around 7.6 ka is attributed to eustatic sea-level changes that altered coastal erosion, fluvial input, and sediment transportation due to the region's shallow shelf dynamics. Conversely, the recent transition near 2 ka is primarily due to the strengthened Atlantic Meridional Overturning Circulation, which influenced the East Asian monsoon regime. This later period coincides with intensified anthropogenic agricultural activities over the last ca. 2 kyr, highlighting interactions between natural and early human intervention. Between these transitions, from ca. 7.6 ka to ca. 2 ka, the magnetic proxy data suggest relatively stable environmental conditions resembling an event similar to a Holocene climatic optimum. This interval is characterized by consistent sedimentary magnetic properties, indicating a period of climatic stability under the monsoonal climate regime.</div></div>","PeriodicalId":18229,"journal":{"name":"Marine Geology","volume":"480 ","pages":"Article 107464"},"PeriodicalIF":2.6,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143093184","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Event beds in Andaman beach sediments – records of 2004 Tsunami

IF 2.6 3区地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY

Marine Geology

Pub Date : 2025-02-01 DOI: 10.1016/j.margeo.2024.107470

Debaleena Majumdar, H.N. Bhattacharya

The coastal zones of the Andaman Islands in the Bay of Bengal experienced the severe impact of an earthquake-generated tsunami on 26 December 2004. This study, conducted in 2023 investigates the sedimentary attributes of tsunami deposits found in trench and pit sections across three beaches: Bada Balu, Collinpur, and Mayabunder. The identified tsunami deposits include matrix-supported gravelly sand, massive sand, matrix-supported gravelly organic mud, normally graded to massive sand, and large bouldery gravel facies types. Bipartite flows, characterized by lower debris flows and upper turbidity currents generated after flow separation are responsible for the formation of gravelly mud or gravelly sand and sand couplets. Massive sand drapes over erosional surfaces are attributed to the waning phases of sand-laden tsunami run-up, while large bouldery gravel spreads, featuring rounded boulders, represent traction carpet deposits sourced from emerged coral reefs. The extreme variation in sediment composition and texture reveals that the strength of the tsunami waves and their propagation directions varied significantly across different coastal zones, largely influenced by coastal morphology. The distinct sedimentary structures of the studied 2004 earthquake-generated tsunami will serve as a valuable tool for interpreting tsunami deposits in the ancient record. Furthermore, the diagnostic criteria established in this study can be applied to distinguish between tsunami and cyclonic storm deposits.

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引用次数: 0

Morphology and evolution of a modern mixed (turbidite-contourite) depositional system associated with deeply-incised submarine canyons in the Patagonian Continental Margin

IF 2.6 3区地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY

Marine Geology

Pub Date : 2025-02-01 DOI: 10.1016/j.margeo.2025.107476

José I. Isola , Fermín I. Palma , Sebastían Y. Principi , Graziella Bozzano , Ornella Silvestri , Juan P. Ormazabal , Alejandro A. Tassone

This study integrates a novel multi-beam bathymetry and high-resolution sub-bottom seismic database with previous works, to investigate a Late Quaternary Mixed (turbidite-contourite) Depositional System (MDS) related to a major submarine canyon system located on the Patagonian Continental Margin (PCM) between water depths of 1500 and 4000 m.

The studied MDS exhibits unique and unusual features, including the along-slope deviation of three submarine canyons, large-mounded drifts (>100 ms TWT) forming downstream of canyons, and small patchy drifts (a few tens ms TWT) accumulating in canyon-free slope areas. The genesis of these features is explained by a temporal substitution from contourite to mixed settings and different styles of interaction between along-slope and across-slope processes.

The along-slope deviation of the canyons is associated with the temporal substitution of contourite processes dominated period to the establishment of a MDS, marked by increased down-slope activity inferred to have occurred after the Mid-Pleistocene Transition (MPT). The fossil mounded morphologies developed during the dominant contourite period (pre MPT) acted as barriers to the subsequent submarine canyons formed during the increased down-slope activity period (post MPT), causing them to deviate by 90° along the slope.

After the MPT, spatial intercalation and interactions between along and across slope processes produced patchy and mounded drifts. The patchy drifts are associated with unconfined settings and are interpreted as the outcome of turbidites redistributed by bottom currents. Synchronous interactions between along-slope and across-slope processes appear to have played a crucial role in the formation of large, mounded drifts near submarine canyons.

This study highlights the temporal and spatial complexity of MDSs and provides new insights into their development within submarine canyon systems. Additionally, this work addresses the role that the stratification of deep-water masses could have played in the distribution of sediments along the PCM during the Late Quaternary.

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引用次数: 0

Tsunami boulder transport in coastal environments: insights from physical experiments and dimensional analysis

IF 2.6 3区地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY

Marine Geology

Pub Date : 2025-02-01 DOI: 10.1016/j.margeo.2024.107474

Storm Roberts , Alison Raby , Sarah J. Boulton , William Allsop , Alessandro Antonini , Ivo van Balen , David McGovern , Keith Adams , Ian Chandler , Jonas Cels , Irene Manzella

Coastal boulder deposits hold the potential to aid in the reconstruction of past extreme wave events. However, commonly used hydrodynamic equations for calculating wave heights from transported boulders can be inaccurate. New and alternative methods need to be explored in an interdisciplinary way to ensure a more complete picture of the phenomenon of boulder transport is achieved. Through the use of a physical experiment, this study aims to investigate the influence of different tsunami wave types, wave parameters and boulder shapes on boulder transport distance. The experimental results also allow for a novel application of dimensional analysis to enable comparisons with other experiments as well as a field case study. In the experiment an elongate irregularly shaped boulder showed transport distances up to 1 m farther than a cuboid shaped boulder under the influence of the same waves. The irregularly shaped boulder had a predominant transport mode of rolling, whereas the cuboid shaped boulder predominantly underwent sliding transport. Tsunami wave type also influenced boulder transport distances, with N-waves frequently showing greater transport than E-waves of a comparable wave steepness. Key offshore wave and boulder parameters were then compared through dimensional analysis using Buckingham's Pi Theorem, enabling comparisons to other datasets to be made. Data from another published experimental study and a field study in Settai, Japan, showed reasonable agreement, particularly for the shorter period field data. These findings emphasize the importance of incorporating boulder shape, wave type, and dimensional analysis into future studies, providing a foundation for more accurate reconstructions of past tsunami events.

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引用次数: 0

Delayed response of the coastal sedimentary record to the southward shift of the Huanghe (Yellow River) course during AD1128–1855

IF 2.6 3区地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY

Marine Geology

Pub Date : 2025-02-01 DOI: 10.1016/j.margeo.2024.107439

Chengfeng Xue , Yang Yang , Xibin Han , Ya Ping Wang , Yining Chen , Xiaoming Xia , Jianjun Jia

The sediment source-to-sink process is an important topic in marine sedimentology. However, how sedimentary signals evolve along source-to-sink path remains less clear. This study focuses on the southward shift of the Huanghe River course between AD 1128 and 1855, and the manifestation and variation of sedimentary signals in a natural diffusion system were investigated through sedimentological analysis of three spatially adjacent regions, the abandoned Huanghe Delta, the central coast of Jiangsu, and the Changjiang Delta. Laboratory analyses including Optically Stimulated Luminescence (OSL), geochemical element analysis, and grain size analysis, were conducted. The results show that sedimentary signals manifest in various forms, primarily manifested in two ways: grain size refinement and sedimentation rate acceleration. The fining of grain size is most pronounced in the abandoned Huanghe delta, followed by the central coast of Jiangsu, and is least pronounced in the Changjiang subaqueous delta. The response of the coastal system to the event was delayed by approximately 0–100, 100–300, and 300–500 years for the abandoned Huanghe Delta, the central coast of Jiangsu, and the Changjiang River Delta, respectively. These findings indicate that sediment transport processes exhibit sedimentary signal attenuation and response lag. This study not only highlights the variation along the source-sink path of coastal sedimentary signals but also illuminates the sedimentary record of drastic changes in sediment flux, which will help study the source-to-sink process given the variable changes in sedimentary fluxes.

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引用次数: 0