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Evolution process of chemical weathering and sediment sources in the Makran Continental margin since the Younger Dryas 小干纪以来马克兰大陆边缘化学风化和沉积物来源的演变过程
IF 2.6 3区 地球科学
Marine Geology Pub Date : 2024-10-24 DOI: 10.1016/j.margeo.2024.107416
{"title":"Evolution process of chemical weathering and sediment sources in the Makran Continental margin since the Younger Dryas","authors":"","doi":"10.1016/j.margeo.2024.107416","DOIUrl":"10.1016/j.margeo.2024.107416","url":null,"abstract":"<div><div>The chemical weathering processes and sedimentary source evolution since the Younger Dryas (YD) in the low-latitude arid continental margin have been investigated. Two sediment cores, MK07G and MK09G, were retrieved from the Makran continental margin in the northern Arabian Sea and subjected to analyses of major and trace elements, along with AMS<sup>14</sup>C dating. The results show that since the YD, the weathered parent rocks of Makran sediments have remained relatively stable, predominantly consisting of felsic rocks, with some contributions from mafic rocks. The Makran sediments exhibit initial to moderate weathering, with no discernible effects from grain size sorting or disturbances from sediment recycling, indicating primary deposition. Significant contributions of terrigenous eolian dust from surrounding continents (e.g., the Indian subcontinent, Arabian Peninsula, and northeastern Africa) were identified, along with riverine inputs from the Dasht River and fine-grained components from the Late Pleistocene Indus delta sediment, as well as proximal basin sedimentation. The evolution of sediment sources in the study area is significantly influenced by the Indian Monsoon and westerly wind systems, with intensified monsoon phases and westerly conditions correlating with increased fluvial input. Furthermore, chemical weathering processes since the YD are closely linked to local precipitation patterns, where intensified rainfall enhances weathering intensity. Records from the Makran continental margin indicate a teleconnection between chemical weathering and sedimentary processes in the Arabian Sea and Bond events in the North Atlantic, highlighting the extensive influence of Northern Hemisphere climate fluctuations.</div></div>","PeriodicalId":18229,"journal":{"name":"Marine Geology","volume":null,"pages":null},"PeriodicalIF":2.6,"publicationDate":"2024-10-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142554541","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
How do morphological characteristics affect tidal asymmetry in the Radial Sand Ridges? 形态特征如何影响径向沙脊的潮汐不对称性?
IF 2.6 3区 地球科学
Marine Geology Pub Date : 2024-10-21 DOI: 10.1016/j.margeo.2024.107417
{"title":"How do morphological characteristics affect tidal asymmetry in the Radial Sand Ridges?","authors":"","doi":"10.1016/j.margeo.2024.107417","DOIUrl":"10.1016/j.margeo.2024.107417","url":null,"abstract":"<div><div>While it is widely recognized that the Radial Sand Ridges (RSR) in the South Yellow Sea are predominantly shaped by tidal forces, there remains a limited understanding of how this distinctive morphological configuration—characterized by an interlaced channel-ridge system—can subsequently influence local tidal dynamics. This study examines the effects of morphological features on tidal asymmetry, taking into account seabed slope, relative depths between ridges and channels, and channel convergence. Three principal indices—namely tidal-duration-asymmetry (TDA), peak-current-asymmetry (PCA), and slack-water-asymmetry (SWA)—are employed to quantify various dimensions of tidal asymmetry. The findings indicate that SWA serves as the most morphology-sensitive indicator, whereas TDA exhibits minimal sensitivity to morphological changes. Furthermore, seabed steepness emerges as a critical factor influencing tidal asymmetry within the RSR; steeper slopes enhance intrinsic energy conversion processes, thereby inducing tidal asymmetries. Additional analysis reveals that streamwise advection accounts for an average of 88 % of total advection scale while controlling for spatial heterogeneity. Specifically, the average integral sum of advection terms along submerged sand ridges is 2.53 times greater than that along the deepest section of the tidal channel line—a significant contributor to spatial variability in SWA. With a positive seabed slope, the apex of the RSR acts as a source for overtides which interact with incoming astronomical tides, consequently generating tidal asymmetries. Moreover, this study illustrates varying dependencies of tidal asymmetry on bottom stress across channels and ridges, contributing to spatial variability in arc direction among RSRs. Ultimately, this research elucidates complex interactions between tidal flow and morphological characteristics within RSRs and provides insights into tide evolution in analogous ebb-shoal systems.</div></div>","PeriodicalId":18229,"journal":{"name":"Marine Geology","volume":null,"pages":null},"PeriodicalIF":2.6,"publicationDate":"2024-10-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142560835","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
Double tombolo formation by regressive barrier widening and landside submergence: The case of Orbetello, Italy 退行性屏障加宽和陆坡淹没形成的双墓道:意大利奥贝泰罗的案例
IF 2.6 3区 地球科学
Marine Geology Pub Date : 2024-10-18 DOI: 10.1016/j.margeo.2024.107415
{"title":"Double tombolo formation by regressive barrier widening and landside submergence: The case of Orbetello, Italy","authors":"","doi":"10.1016/j.margeo.2024.107415","DOIUrl":"10.1016/j.margeo.2024.107415","url":null,"abstract":"<div><div>The double tombolo of Orbetello, in Italy, has formed during the Holocene around an ancient central tombolo. Earlier models consider that its sand barriers formed as sand spits that stretched from the mainland to a coastal island before enlarging seawards. This evolution, however, remains speculative. In order to test these models, we conducted the first study of a double tombolo that combines coring of its sand barriers and comprehensive imaging of its internal structure using sub-bottom acoustic surveys offshore and in the back-barrier. Sediment ages were constrained by <sup>14</sup>C, luminescence, and U/Th dating. Acoustic images below the lagoon show that the barriers are in fact broad regressive strandplains that initiated on the flanks of the preexisting central isthmus when sea level was −7 ± 1 m lower than today. The strandplains then rose upwards and outwards, tracking sea level rise over the past 7 kyr. The oldest and lowest parts of the strandplains were flooded into the shallow intervening lagoon. The central isthmus is composed of regressive sand barriers accreted around a MIS 5.5 core during subsequent stages MIS 5.3 and MIS 5.1. The emplacement of the isthmus interrupted longshore drift between the mainland and the coastal island, converting the flanks of the initial tombolo into terminal sinks in which sand accretion accelerated, spurring early and rapid regression during the Holocene. A review of the environmental parameters conducive to double tombolo formation suggests that double tombolos may represent a frequent, albeit short-lived stage during the enlargement of single tombolos.</div></div>","PeriodicalId":18229,"journal":{"name":"Marine Geology","volume":null,"pages":null},"PeriodicalIF":2.6,"publicationDate":"2024-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142529851","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
Formation of vertical columnar seismic structures and seafloor depressions by groundwater discharge in the drowned Miami Terrace platform and overlying deep-water carbonates, southeastern Florida 佛罗里达州东南部淹没的迈阿密台地平台和上覆深水碳酸盐岩中地下水排放形成的垂直柱状地震结构和海底洼地
IF 2.6 3区 地球科学
Marine Geology Pub Date : 2024-10-18 DOI: 10.1016/j.margeo.2024.107413
{"title":"Formation of vertical columnar seismic structures and seafloor depressions by groundwater discharge in the drowned Miami Terrace platform and overlying deep-water carbonates, southeastern Florida","authors":"","doi":"10.1016/j.margeo.2024.107413","DOIUrl":"10.1016/j.margeo.2024.107413","url":null,"abstract":"&lt;div&gt;&lt;div&gt;The presence of vertical cross-formational fluid migration passageways within sedimentary basins can profoundly impact aquifer and reservoir fluid-flow and their identification is fundamental to informing management of subsurface fluid resources (groundwater, oil, gas). In an onshore and offshore southeastern part of Florida, 2D/3D seismic-reflection and bathymetry data document ∼153 vertical columnar structures composed of reflection disruptions up to 790 m in the height and averaging 360 m in diameter, and ∼219 subcircular to circular seafloor depressions up to 1334 m wide. Our study focuses on these features found within the offshore shallow-marine carbonate Miami Terrace platform, which drowned approximately at the end of the middle Miocene, and within overlying Plio-Quaternary deep-water carbonate slope and drift deposits. Most columnar structures are rooted in stratiform aquifers of the Miami Terrace platform and associated with faults or fault intersections produced by Eocene and circa late Miocene tectonics. The columns commonly terminate within the platform or as subcircular depressions along an amalgamated karstic and drowning unconformity at the platform top. The columns typically stretch upwards from a zone of deep karst cavity collapse through the Miami Terrace platform with upward decreasing sag on internal reflections. Following drowning and Plio-Quaternary partial burial of the Miami Terrace platform by deep-water deposits, the subcircular depressions and faults along the platform top were points of origin for a second phase of column growth upward into the deep-water deposits. The continuation of deep platform cavity collapse and column evolution produced pockmarks along paleo-seafloors within the deep-water deposits and at the present-day sea floor. The Plio-Quaternary pockmarks formed at water depths too deep to suggest an origin related to meteoric karst above or near sea level, but rather their formation is suggested to be related to cyclic sea level falls that drove increased groundwater head and density gradients, and seafloor discharge of offshore freshened groundwater sourced from the underlying platform. Plausibly, mixing of freshened groundwater and seawater at the seafloor discharge sites drove dissolution of the host deep-water deposits, which together with erosion by groundwater venting and current scouring formed the pockmarks.&lt;/div&gt;&lt;div&gt;Seaward of the Plio-Quaternary seafloor pockmarks, at the late-middle Miocene upper slope of the Miami Terrace platform and along the regional karst/drowning unconformity is a slope-parallel band of ∼189 densely distributed subcircular seafloor depressions with diameters up to 1334 m at water depths up to ∼660 m. It is plausible that along the upper slope, faults and fractures produced by gravity-driven slope instability and possibly tectonics formed a dense network of fluid passageways that promoted upward artesian freshened groundwater flow to sites of discharge where mi","PeriodicalId":18229,"journal":{"name":"Marine Geology","volume":null,"pages":null},"PeriodicalIF":2.6,"publicationDate":"2024-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142586087","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
Morphosedimentary evolution of the Belgica Mound Drift: Controls on contourite depositional system development in association with cold-water coral mounds 贝尔吉卡丘陵漂移的形态沉积演化:与冷水珊瑚丘相关的等高线沉积系统发展的控制因素
IF 2.6 3区 地球科学
Marine Geology Pub Date : 2024-10-13 DOI: 10.1016/j.margeo.2024.107410
{"title":"Morphosedimentary evolution of the Belgica Mound Drift: Controls on contourite depositional system development in association with cold-water coral mounds","authors":"","doi":"10.1016/j.margeo.2024.107410","DOIUrl":"10.1016/j.margeo.2024.107410","url":null,"abstract":"<div><div>Small-scale contourite drift is an important component of continental margins that can record information about complex oceanographic processes. The Belgica Mound Drift is one example of a small-scale contourite drift. It is formed under the influence of cold-water coral (CWC) mounds and represents one of the most distal contouritic expressions influenced by the Mediterranean Outflow Water (MOW) in the NE Atlantic Ocean. Three distinct evolutionary stages have been identified from new high-resolution pseudo-3D reflection seismic data, each associated with a significant change in paleoceanography, affecting both bottom-current intensity and sediment input. The pre-drift stage (Pliocene–Early Pleistocene) corresponds to the regional RD1 erosive event, which was caused by the reintroduction of the MOW in the Porcupine Seabight, creating a distinct paleotopography that will influence all ensuing sedimentary processes. The second stage (Early Pleistocene–Middle Pleistocene) is the contourite drift inception in two distinct centres of growth, strongly steered by topographic obstacles such as the CWC mounds. During the third and final stage (Middle Pleistocene–present day), the contourite drift is developed under a more stable but less dynamic environment, characterised by more continuous and mounded aggradational stratification. The final stage of the contourite drift is related to the Middle Pleistocene Transition, with a spatially variable reduction in the MOW-related bottom currents and sediment input. The spatial and temporal evolution of this drift shows that its present-day morphology is controlled by the location of initial growth. Evolving moat morphology indicates that the intensity of the bottom currents generally increases during the drift evolution.</div><div>This research presents a crucial paradigm for advancing our knowledge of elucidating the complexities of smaller-sized contourite systems in diverse oceanic environments.</div></div>","PeriodicalId":18229,"journal":{"name":"Marine Geology","volume":null,"pages":null},"PeriodicalIF":2.6,"publicationDate":"2024-10-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142529920","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
Flow conditions of the Quaternary Deep-water Current reconstructed by sediment waves in the northeastern South China Sea 南海东北部沉积物波浪重建的第四纪深水洋流流动状况
IF 2.6 3区 地球科学
Marine Geology Pub Date : 2024-10-13 DOI: 10.1016/j.margeo.2024.107414
{"title":"Flow conditions of the Quaternary Deep-water Current reconstructed by sediment waves in the northeastern South China Sea","authors":"","doi":"10.1016/j.margeo.2024.107414","DOIUrl":"10.1016/j.margeo.2024.107414","url":null,"abstract":"<div><div>The South China Sea (SCS) plays a key role in maintaining the circulation in the Pacific and Indian oceans. After entering the northeast South China Sea from the Luzon Strait, the Pacific Deep Water transforms into the Deep-water Current (DWC) and flows westward. The upwelling of the DWC in the SCS could outflow into both the Indian and Pacific oceans. However, when and how this modern circulation was established in the SCS remains unclear. By using seismic reflection data tied to the Ocean Drilling Program wells in the northeastern SCS margin, we have discovered fields of previously unreported sediment waves, of which the onset dates back to ∼2.6 Ma. The sediment wave heights increased from 2.0 to 7.5 m, in association with spatial extent from 630 km<sup>2</sup> to 800 km<sup>2</sup> between ∼2.6 Ma and ∼ 0.7 Ma. After that, the wave heights and spatial extent reduced to ∼5.5 m and 700 km<sup>2</sup>, respectively. Considering the location, morphological features and water depth, we propose that these sediment waves were formed by the DWC. The morphological changes of the sediment waves are linked to energy increase and decrease of the DWC within ∼2.6–0.7 Ma and ∼ 0.7–0 Ma, respectively. We interpret the intensification as caused by the narrowing and uplifting of the Luzon Strait that is the sole deep-water gateway of the SCS, and speculate that the post-0.7 Ma weakening was probably related to the reduced Kuroshio Current intrusion due to the middle Pleistocene climate transition. This study proposes a novel model for the evolution of the Quaternary DWC hydrodynamics, fostering our understanding of the paleo-oceanographic links between the SCS and the Pacific Ocean.</div></div>","PeriodicalId":18229,"journal":{"name":"Marine Geology","volume":null,"pages":null},"PeriodicalIF":2.6,"publicationDate":"2024-10-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142529852","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
Size-frequency distribution of submarine mass movements on the palomares continental slope (W Mediterranean) 帕洛马雷斯大陆坡(地中海西部)海底大规模运动的规模-频率分布
IF 2.6 3区 地球科学
Marine Geology Pub Date : 2024-10-09 DOI: 10.1016/j.margeo.2024.107411
{"title":"Size-frequency distribution of submarine mass movements on the palomares continental slope (W Mediterranean)","authors":"","doi":"10.1016/j.margeo.2024.107411","DOIUrl":"10.1016/j.margeo.2024.107411","url":null,"abstract":"<div><div>In this work, over 3620 km<sup>2</sup> from the Palomares continental slope, which is located in the W. Mediterranean Sea, was analysed to quantify the impact of recent mass movements on this margin. A total of 936 landslides were identified, mapped and characterised by defining several morphometric variables that outline the accumulated impact of landslides equivalent to 918 km<sup>2</sup> and 10.34 km<sup>3</sup> of eroded sediment on the continental slope. The smallest event area was 0.0014 km<sup>2</sup>, whereas the largest event area was 32.48 km<sup>2</sup>. Smaller scars with a higher headwall gradient tend to dominate when the environment is steeper, and major mass movements are located on open slopes and structural highs. However, the slight or null correlations between variables indicate that a wide range of sizes may occur on any slope gradient and at any depth.</div><div>The Palomares continental slope is intensively affected by mass movements. Compared with other passive margins (e.g., the U.S. Atlantic continental margin), landslides mobilised a limited amount of sediment, although it is comparable to other Mediterranean areas where small- to moderate-sized events are characteristic.</div><div>The cumulative size distribution can be defined by a power-law function that describes events larger than 0.7 km<sup>2</sup> with an exponent of α = 1.269. These results are consistent with those of other published inventories, including onshore cases. This result allows us to assume that the scale-invariant properties of the events are mapped. Scale-invariant properties can be explained by different models; self-organised criticality (SOC) is probably the most assumed by the scientific community, although alternative models may be nominated. Each model has important implications in terms of the landslide distribution and long-term landslide history of any slope. Alternative scenarios, such as submarine slopes, with more precise landslide inventories may contribute to new hazard assessment models that consider scaling exponents derived from size–frequency distributions.</div></div>","PeriodicalId":18229,"journal":{"name":"Marine Geology","volume":null,"pages":null},"PeriodicalIF":2.6,"publicationDate":"2024-10-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142442096","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
Mid to late Holocene Indian monsoon variability, aridification and civilization changes in the Deccan Plateau, India 印度德干高原全新世中期至晚期的印度季风变异、干旱化和文明变迁
IF 2.6 3区 地球科学
Marine Geology Pub Date : 2024-10-09 DOI: 10.1016/j.margeo.2024.107412
{"title":"Mid to late Holocene Indian monsoon variability, aridification and civilization changes in the Deccan Plateau, India","authors":"","doi":"10.1016/j.margeo.2024.107412","DOIUrl":"10.1016/j.margeo.2024.107412","url":null,"abstract":"<div><div>Climate change has been a key driver throughout human history and has frequently been associated with the rise and fall of civilizations. Holocene settlement changes or population displacements were almost always preceded by changes in climate. A high-resolution sedimentary record from the western Bay of Bengal offers insights to centennial-scale mid- to late-Holocene Indian summer monsoon (ISM) variability and its role in the decline of chalcolithic human settlements on India's Deccan Plateau. Increased erosion in the Indian peninsula during the mid- to late-Holocene, due to aridification and agricultural expansion, is evidenced by higher sedimentation, more magnetic mineral content, coarser magnetic grain size, and increased sand content. The results from mineral magnetic and textural analyses reveal centennial-scale abrupt weak ISM during the Bond events in the core monsoon zone of India. The Deccan Chalcolithic civilizations flourished between ∼4.0–3.0 ka BP owing to the favorable climatic conditions, but most of the settlements were deserted after ∼3.0 ka BP. We argue that the abrupt weakening of ISM during Bond event 2 (∼3.1–2.8 ka BP) caused this collapse of Deccan Chalcolithic. The results from this study together with the published records of number of settlements and summed radiocarbon dates suggest a climate-culture link in the Deccan Plateau. The weak ISM periods in this study are coherent with the records of total solar irradiance and the percentage of hematite-stained grains from the North Atlantic and suggest solar control on these abrupt climatic events.</div></div>","PeriodicalId":18229,"journal":{"name":"Marine Geology","volume":null,"pages":null},"PeriodicalIF":2.6,"publicationDate":"2024-10-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142442097","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
Geomorphic processes within the La Gomera-Tenerife Channel (Canary Islands): Decoding the interaction of bottom currents with seabed topography 拉戈梅拉-特内里费海峡(加那利群岛)的地貌过程:解码底流与海底地形的相互作用
IF 2.6 3区 地球科学
Marine Geology Pub Date : 2024-10-05 DOI: 10.1016/j.margeo.2024.107406
{"title":"Geomorphic processes within the La Gomera-Tenerife Channel (Canary Islands): Decoding the interaction of bottom currents with seabed topography","authors":"","doi":"10.1016/j.margeo.2024.107406","DOIUrl":"10.1016/j.margeo.2024.107406","url":null,"abstract":"<div><div>The La Gomera-Tenerife Channel is a narrow passage between La Gomera and Tenerife Islands, i.e., two volcanic edifices of the Canary Archipelago (Atlantic Ocean). A geophysical study was conducted to identify the main geomorphic processes affecting the seabed and their interplay. In particular, submetric resolution bathymetric and side scan sonar backscatter data were collected in the southern sector of the Channel, down to 1200 m water depth. Their integrated analysis revealed a complex seabed morphology and a variety of morpho-sedimentary features, resulting from three main geomorphic processes: submarine volcanic activity, mass wasting (e.g., turbidity currents, small landslides and exotic blocks emplaced by a massive landslide event), and bottom currents activity. Bottom currents strongly reshaped the seabed into bedforms, confined drifts, and moats. Although the flanks of volcanic islands are typically dominated by mass wasting and volcanic features, our results indicate that bottom current activity can be predominant in confined settings and around topographic features due to modification of flow patterns and enhancement of current flows.</div><div>This study is the first to document volcanic, mass wasting and bottom current features within the La Gomera-Tenerife Channel. Furthermore, it provides insights on: i) morpho-sedimentary reconstructions of narrow passages between volcanic islands; ii) interplay among different geomorphic processes; iii) oceanographic reconstructions. The variety of geomorphic processes shaping the La Gomera-Tenerife Channel makes this area significant for high-resolution studies. Moreover, it provides new insights on poorly known processes, such as: the interaction of bottom currents with complex topography and bottom current morpho-dynamic in curved moats.</div></div>","PeriodicalId":18229,"journal":{"name":"Marine Geology","volume":null,"pages":null},"PeriodicalIF":2.6,"publicationDate":"2024-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142529853","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
Discerning sediment provenance in the Outer Banks (USA) through detrital zircon geochronology 通过碎屑锆石地质年代学辨别外滩(美国)的沉积物出处
IF 2.6 3区 地球科学
Marine Geology Pub Date : 2024-10-05 DOI: 10.1016/j.margeo.2024.107409
{"title":"Discerning sediment provenance in the Outer Banks (USA) through detrital zircon geochronology","authors":"","doi":"10.1016/j.margeo.2024.107409","DOIUrl":"10.1016/j.margeo.2024.107409","url":null,"abstract":"<div><div>Detrital zircon data from modern barrier island and estuarine environments in the Outer Banks (Atlantic Coast, USA) were statistically compared to sands from nearby rivers to assist in determining source-to-sink pathways. Fluvial samples, collected from near the Fall Line contact between the Appalachian Orogen and sediments of the coastal plain, all have age unique distributions, making them ideal for tracing provenance. Three samples from the Atlantic foreshore showed high similarities to one another, as well as to three samples from the estuarine (back-barrier) Pamlico and Albemarle Sounds. Mixture modeling with multiple data reduction methods and three different statistical tests for similarity consistently indicated that the nearby Potomac River was the primary source for all Atlantic foreshore and estuarine zircons, followed by minor contributions from the James River in some models. The models indicate little or no sediment contribution from the Susquehanna, Roanoke, Tar, Neuse, Cape Fear, and Peedee Rivers. Both Atlantic foreshore and estuarine sands are therefore interpreted to have initially originated from Appalachian bedrock to the north of their present-day location, and subsequently to have been transported southward through the Chesapeake Bay watershed before deposition in Virginia and North Carolina. Prior to barrier island formation in the last several thousand years, differing geomorphology of the Chesapeake Bay facilitated southward movement of sediments from its constituent rivers via longshore drift, where they were deposited in coastal settings on the mainland. The modern barrier islands, formed during the most recent post-glacial transgression, may be reworked from these deposits, but may also include a contribution from sediments that were derived more recently from relict deposits on the shelf. Oceanographic and sedimentological evidence suggests that movement of sand-sized grains from southern rivers across the back-barrier sounds is unlikely. These findings can assist with coastal resilience planning and resource management in a region under severe threat from climate change and rising sea levels.</div></div>","PeriodicalId":18229,"journal":{"name":"Marine Geology","volume":null,"pages":null},"PeriodicalIF":2.6,"publicationDate":"2024-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142423067","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
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