Marine Geology最新文献

{"title":"An abrupt change in long-term shoreline behaviour at Roches Beach, Tasmania: An early response to contemporary climate change-induced sea-level rise?","authors":"Chris Sharples,&nbsp;Christopher Watson","doi":"10.1016/j.margeo.2024.107475","DOIUrl":"10.1016/j.margeo.2024.107475","url":null,"abstract":"<div><div>This study analysed a 65-year air photo record for Roches Beach (Australia) which shows that after being mostly stable from at least 1946 until 1985, a major section of the shoreline abruptly switched to a net recession trend which persisted until 2011 when artificial sand replenishment began. Comparable changes have been identified on some other Tasmanian beaches but have only been rarely reported to date. At Roches Beach, consideration of potential causes has identified sea level rise (SLR) as the most plausible driver of the observed change, although increased wave height and vertical land movement (VLM) could also contribute. Climate change induced sea level rise is expected to eventually cause major recession of many shores, however most sandy beaches have not yet shown a clearly attributable response of this sort. We infer that the critical factor causing Roches Beach to undergo an early switch to shoreline recession in response to SLR is its mostly unidirectional littoral drift which transports sand into, through and out of its leaky embayment to a degree not seen in other beaches in the same coastal compartment of Frederick Henry Bay. This delivers a proportion of any eroded sand to the north end of the beach and beyond to a large sand sink at Seven Mile Beach. We deduce that the rising sea-level has increased the frequency and scale of upper beach erosion events, causing increasing net losses of eroded sand from the embayment until the formerly balanced sand budget changed to deficit. Storm records suggest that major erosion events abruptly tipped the beach into a recessional mode when its sand budget was close to deficit. Regional and local confounding processes that may prevent or overwhelm such responses to SLR are minor at this beach. These include swell wave directional variability and interannual sea level variability, both of which are minimal compared to many other Australian coasts. We contend that this allows sea level rise to be more persistently effective at changing the behaviour of Roches Beach than at many other sandy beaches where other causes of variability may be of sufficient magnitude as to mask or prevent persistent changes due to SLR. The factors identified as causing or allowing an early shoreline response to sea level rise will be widely applicable as indicators of other beaches likely to respond early to SLR. This underlines the importance of local studies to identify critical distinctions in susceptibility to SLR between what can be otherwise similar adjacent shores.</div></div>","PeriodicalId":18229,"journal":{"name":"Marine Geology","volume":"480 ","pages":"Article 107475"},"PeriodicalIF":2.6,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143093182","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}

{"title":"Widespread contamination of the Pacific upper mantle during the mid-Cretaceous","authors":"K. Durkin ,&nbsp;P.R. Castillo ,&nbsp;S.M. Straub ,&nbsp;S. Mallick ,&nbsp;A. Saal ,&nbsp;J.K. Muller","doi":"10.1016/j.margeo.2024.107460","DOIUrl":"10.1016/j.margeo.2024.107460","url":null,"abstract":"<div><div>This study presents new ¹⁷⁷Hf/¹⁷⁶Hf measurements on variably altered samples from the Early Cretaceous Pacific oceanic crust subducting into the Izu-Bonin trench. The new results are then combined with existing major and trace element and Nd<img>Pb isotopic data to provide further constraints on existing models for the evolution of the Mesozoic Pacific upper mantle. The samples, from an across flow line transect of the oceanic crust accreted along the Pacific-Izanagi ridge system, can be separated into a relatively older (140–127 Ma), mostly normal mid-ocean ridge basalt (N-MORB) group and a younger (&lt;127 Ma) group that includes many enriched (<em>E</em>-)MORBs. The Hf<img>Nd (±Pb) isotope and alteration-resistant incompatible trace element composition of the older N-MORBs is similar to those of the geochemically depleted Jurassic-Early Cretaceous MORBs and Shatsky-Hess Rise platform lavas. On the other hand, the younger <em>E</em>-MORBs are compositionally similar to those of coeval lavas from Ontong Java, Manihiki and Hikurangi plateaus, which were suggested to be previously con-joined as Ontong Java Nui super oceanic plateau, and Ojin Rise Seamounts, which were suggested to be the younger manifestation of the Shatsky-Hess Rise plume. We propose that the older Pacific-Izanagi N-MORBs originated from a depleted MORB mantle (DMM):FOZO (focal zone) mixed source whereas the younger <em>E</em>-MORBs originated from a DMM:FOZO:EMI (enriched mantle 1) ± high μ (HIMU) mixed source. Our results support the proposed widespread contamination of the Pacific upper mantle by geochemically enriched materials that formed the ancestral Ontong Java Nui plateau starting at ca. 125 Ma.</div></div>","PeriodicalId":18229,"journal":{"name":"Marine Geology","volume":"480 ","pages":"Article 107460"},"PeriodicalIF":2.6,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143093185","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}

{"title":"Provenance of sediments in the northern shelf of the South China Sea: Insights from Pb isotopes in detrital K-feldspar","authors":"Liangjie Wei ,&nbsp;Ce Wang ,&nbsp;Heqi Cui ,&nbsp;Junmin Jia ,&nbsp;Letian Zeng ,&nbsp;Ming Su","doi":"10.1016/j.margeo.2024.107448","DOIUrl":"10.1016/j.margeo.2024.107448","url":null,"abstract":"<div><div>The South China Sea is the largest collection area of fluvial sediments among the semi-closed marginal seas, offering a desirable geological window for studying the source-to-sink transport process of terrigenous sediments in global marginal seas. K-feldspar is a common rock-forming mineral that is likely representative of the source terranes and could offer a more unbiased constraint on the sediment routing system. Moreover, its susceptibility to weathering prevents it from undergoing more than one sedimentary cycling, thereby providing a better indication of the material's primary source. In this study, Pb isotopes in detrital K-feldspars were analyzed on the northern shelf of the South China Sea with the aims of tracking the provenance of sediments and understanding the sedimentary process in the continental margin. The results show that the compositions of ²⁰⁶Pb/²⁰⁴Pb isotopes in detrital K-feldspars are mainly concentrated in the range of 18.5 to 19.0, with a wide range of ²⁰⁷Pb/²⁰⁴Pb ratios from 15.1 to 16.7. Quantitative provenance results indicate that the detrital K-feldspar primarily originated from the Pearl River catchment (55 %) and southeastern Chinese mainland (37 %), with minor contributions from Taiwan Island (8 %). For the Pearl River system, the Xi River is the most important sediment contributor, while the Bei River also provides a large amount of sediments. In contrast to detrital zircons, conspicuous differences in provenance were discerned for the two distinct proxies. This discrepancy arises from variations in the density and volume of K-feldspar and zircon grains, leading to their distinct sedimentary patterns during transportation. The study emphasizes the limitations of relying solely on a single proxy and highlights the utility of Pb isotopes in detrital K-feldspar for understanding the sedimentary processes within the marginal source-to-sink systems.</div></div>","PeriodicalId":18229,"journal":{"name":"Marine Geology","volume":"480 ","pages":"Article 107448"},"PeriodicalIF":2.6,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143097645","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}

{"title":"Editorial: Celebrating six decades of marine geology","authors":"","doi":"10.1016/j.margeo.2024.107451","DOIUrl":"10.1016/j.margeo.2024.107451","url":null,"abstract":"","PeriodicalId":18229,"journal":{"name":"Marine Geology","volume":"480 ","pages":"Article 107451"},"PeriodicalIF":2.6,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143098304","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}

{"title":"A newly discovered submarine mud volcano in the southeastern continental shelf of Korea: Its evolution through mud volcanism, cold-water coral growth and bottom-current erosion","authors":"Joohyeon Kim ,&nbsp;Young Jae Shinn ,&nbsp;Yuri Kim ,&nbsp;Eun Min Yeo ,&nbsp;Bong Jun Kim ,&nbsp;Jinsoon Park ,&nbsp;Jeong Hyeon Moon","doi":"10.1016/j.margeo.2025.107493","DOIUrl":"10.1016/j.margeo.2025.107493","url":null,"abstract":"<div><div>This study reports the first discovery of a mud volcano off southeastern Korea, based on multi-beam bathymetry, chirp seismic profiles, and sediment core analysis. The dimensions of the mound are comparable to mud volcanoes and mud cones previously identified on the Mediterranean Ridge and Gulf of Cádiz. A deep-rooted diapiric structure and lobate flow-like seafloor at the flanks also support that the mound formed by mud volcanism and mudflows. The mound crest is covered by dead cold-water corals, appearing as cone-shaped mound or rugged seafloor. The radiocarbon ages of coral fragments suggest that the mud volcano formed earlier than 7.1 ka; however, the timing and duration of coral habitation on the mound remain unknown. Currently, the morphology of the mound has been influenced by a strong bottom current, leading to the formation of a moat and drift system around the mound. The discovered mound is thus interpreted as a composite mud volcano that originated from mud volcanism and evolved via cold-water coral colonization and bottom-current erosion.</div></div>","PeriodicalId":18229,"journal":{"name":"Marine Geology","volume":"481 ","pages":"Article 107493"},"PeriodicalIF":2.6,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143376542","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}

{"title":"Evaluating longshore sediment transport: A comparison between empirical formulas and XBeach 2DH numerical model","authors":"Samanta Buttò ,&nbsp;Carla Lucia Faraci ,&nbsp;Marta Corradino ,&nbsp;Claudio Iuppa ,&nbsp;Emanuele Colica ,&nbsp;Fabrizio Pepe","doi":"10.1016/j.margeo.2024.107471","DOIUrl":"10.1016/j.margeo.2024.107471","url":null,"abstract":"<div><div>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.</div><div>This research evaluates the predictive capacity of three widely used empirical formulas (<span><span>CERC, 1984</span></span>; <span><span>Kamphuis, 1991</span></span>; <span><span>Van Rijn, 2014</span></span>) and the XBeach 2DH numerical model for estimating the LST rate by comparing the obtained results with field LST data.</div><div>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.</div><div>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.</div><div>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.</div><div>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.</div></div>","PeriodicalId":18229,"journal":{"name":"Marine Geology","volume":"480 ","pages":"Article 107471"},"PeriodicalIF":2.6,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143093181","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}

{"title":"Tectono-sedimentary processes shaping the West Sardinian margin and adjacent oceanic basin during the Plio-Quaternary (Western Mediterranean Sea)","authors":"Veronica Frisicchio ,&nbsp;Anna Del Ben ,&nbsp;Riccardo Geletti ,&nbsp;Maria Cristina Caradonna ,&nbsp;Michele Rebesco ,&nbsp;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 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.</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}

{"title":"Prediction of coastline evolution using remote sensing and deep learning approach; Case study of the Northwest of the Persian Gulf","authors":"Navid Bahrami,&nbsp;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}

{"title":"Shallow seismic stratigraphy of the southwestern Algarve shelf (Portugal) and characteristics of offshore tsunami deposits","authors":"Lisa Feist ,&nbsp;Pedro J.M. Costa ,&nbsp;Juan I. Santisteban ,&nbsp;Stijn Albers ,&nbsp;Piero Bellanova ,&nbsp;Ivana Bosnic ,&nbsp;Marc De Batist ,&nbsp;João F. Duarte ,&nbsp;Aurora Rodrigues ,&nbsp;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}

{"title":"Sedimentation of tidal sand ridges off the Liuguhe River mouth in the Liaodong Bay, Bohai Sea","authors":"Libo Wang ,&nbsp;Jun Li ,&nbsp;Jingtao Zhao ,&nbsp;Fenglong Bai ,&nbsp;Bangqi Hu ,&nbsp;Yanguang Dou ,&nbsp;Weiyu Song ,&nbsp;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}