{"title":"内部沙堤地震地层学为古屏障岛的保存提供了启示","authors":"","doi":"10.1016/j.margeo.2024.107359","DOIUrl":null,"url":null,"abstract":"<div><p>Barrier islands are rarely preserved on continental shelves following sea-level rise. Proxies like overwash deposits, tidal inlets, and wave ravinements identify the location of paleo-barrier islands through time. Barrier island remnants are potential sand resources for beach nourishment to combat shoreline erosion from increasing rates of sea-level rise. Additionally, understanding the conditions that lead to barrier island drowning can be used to advise coastal policy makers. This study aims to identify barrier island signatures and deposits to understand the coastal processes that maximize preservation of paleo-barrier island remnants. We employed high resolution chirp sub-bottom data coupled with legacy sediment cores collected over Heald and Sabine Banks, on the east Texas shelf, which have been identified as possible preserved barrier island associated facies. Heald Bank exhibits a predominantly homogenous, low-amplitude facies with few low-amplitude internal horizons overlying the transgressive ravinement, whereas Sabine Bank consists of high-amplitude, landward-dipping reflectors beneath this surface, likely indicative of preserved subaqueous overwash deposits. This stratigraphy suggests Sabine Bank includes barrier island associated facies, whereas Heald Bank is mostly a marine sand bank. The overwash unit of Sabine Bank displays landward-thinning and landward-dipping deposits with reflections increasing in amplitude and displaying lower slopes to the NW. We hypothesize that higher slopes to the SE indicate proximity to the former barrier island. The Sabine River paleo-valley is mostly filled with estuarine sediment, leaving only ∼4 m of antecedent accommodation in a limited area of the NE portion of the paleo-valley. The low shelf gradient, which increases accommodation, and initially high sediment supply that decreased during the drowning of Sabine Bank are the major factors controlling partial preservation of the subaqueous portion of the paleo-barrier island.</p></div>","PeriodicalId":18229,"journal":{"name":"Marine Geology","volume":null,"pages":null},"PeriodicalIF":2.6000,"publicationDate":"2024-07-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"Internal sand bank seismic stratigraphy provides insight into paleo-barrier island preservation\",\"authors\":\"\",\"doi\":\"10.1016/j.margeo.2024.107359\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<div><p>Barrier islands are rarely preserved on continental shelves following sea-level rise. Proxies like overwash deposits, tidal inlets, and wave ravinements identify the location of paleo-barrier islands through time. Barrier island remnants are potential sand resources for beach nourishment to combat shoreline erosion from increasing rates of sea-level rise. Additionally, understanding the conditions that lead to barrier island drowning can be used to advise coastal policy makers. This study aims to identify barrier island signatures and deposits to understand the coastal processes that maximize preservation of paleo-barrier island remnants. We employed high resolution chirp sub-bottom data coupled with legacy sediment cores collected over Heald and Sabine Banks, on the east Texas shelf, which have been identified as possible preserved barrier island associated facies. Heald Bank exhibits a predominantly homogenous, low-amplitude facies with few low-amplitude internal horizons overlying the transgressive ravinement, whereas Sabine Bank consists of high-amplitude, landward-dipping reflectors beneath this surface, likely indicative of preserved subaqueous overwash deposits. This stratigraphy suggests Sabine Bank includes barrier island associated facies, whereas Heald Bank is mostly a marine sand bank. The overwash unit of Sabine Bank displays landward-thinning and landward-dipping deposits with reflections increasing in amplitude and displaying lower slopes to the NW. We hypothesize that higher slopes to the SE indicate proximity to the former barrier island. The Sabine River paleo-valley is mostly filled with estuarine sediment, leaving only ∼4 m of antecedent accommodation in a limited area of the NE portion of the paleo-valley. The low shelf gradient, which increases accommodation, and initially high sediment supply that decreased during the drowning of Sabine Bank are the major factors controlling partial preservation of the subaqueous portion of the paleo-barrier island.</p></div>\",\"PeriodicalId\":18229,\"journal\":{\"name\":\"Marine Geology\",\"volume\":null,\"pages\":null},\"PeriodicalIF\":2.6000,\"publicationDate\":\"2024-07-08\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Marine Geology\",\"FirstCategoryId\":\"89\",\"ListUrlMain\":\"https://www.sciencedirect.com/science/article/pii/S0025322724001439\",\"RegionNum\":3,\"RegionCategory\":\"地球科学\",\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"Q2\",\"JCRName\":\"GEOSCIENCES, MULTIDISCIPLINARY\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Marine Geology","FirstCategoryId":"89","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S0025322724001439","RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"GEOSCIENCES, MULTIDISCIPLINARY","Score":null,"Total":0}
引用次数: 0
摘要
海平面上升后,大陆架上很少保留屏障岛。冲刷沉积物、潮汐入海口和波浪冲积物等代用资料可以确定古屏障岛的位置。壁垒岛遗迹是潜在的海沙资源,可用于滋养海滩,以应对海平面上升导致的海岸线侵蚀。此外,了解导致屏障岛溺水的条件还可以为沿海决策者提供建议。这项研究旨在识别屏障岛的特征和沉积物,以了解最大限度地保存古屏障岛遗迹的沿岸过程。我们采用了高分辨率啁啾底层数据,以及在得克萨斯州东部大陆架 Heald Bank 和 Sabine Banks 采集的遗留沉积物岩芯,这些沉积物被确定为可能保存下来的屏障岛相关岩层。希尔德浅滩主要呈现出同质、低振幅的地层,很少有低振幅的内部地层覆盖在横向沟壑上,而萨宾湾浅滩则由高振幅、向陆地倾斜的反射体组成,很可能是保留下来的水下冲刷沉积物。这种地层学表明,萨宾河岸包括与屏障岛相关的地层,而希尔德河岸则主要是海洋沙岸。Sabine Bank 的冲刷单元显示了向陆地稀疏和向陆地倾斜的沉积物,反射振幅增大,并向西北方向显示了较低的斜坡。我们推测,向东南方倾斜的坡度较高,表明靠近前屏障岛。萨宾河古河谷大部分被河口沉积物填满,只在古河谷东北部的有限区域内留下了 4 米左右的前生容积。陆架坡度低,增加了容积,最初沉积物供应量大,但在萨宾河岸淹没过程中沉积物供应量减少,这些都是控制古屏障岛水下部分部分保存的主要因素。
Internal sand bank seismic stratigraphy provides insight into paleo-barrier island preservation
Barrier islands are rarely preserved on continental shelves following sea-level rise. Proxies like overwash deposits, tidal inlets, and wave ravinements identify the location of paleo-barrier islands through time. Barrier island remnants are potential sand resources for beach nourishment to combat shoreline erosion from increasing rates of sea-level rise. Additionally, understanding the conditions that lead to barrier island drowning can be used to advise coastal policy makers. This study aims to identify barrier island signatures and deposits to understand the coastal processes that maximize preservation of paleo-barrier island remnants. We employed high resolution chirp sub-bottom data coupled with legacy sediment cores collected over Heald and Sabine Banks, on the east Texas shelf, which have been identified as possible preserved barrier island associated facies. Heald Bank exhibits a predominantly homogenous, low-amplitude facies with few low-amplitude internal horizons overlying the transgressive ravinement, whereas Sabine Bank consists of high-amplitude, landward-dipping reflectors beneath this surface, likely indicative of preserved subaqueous overwash deposits. This stratigraphy suggests Sabine Bank includes barrier island associated facies, whereas Heald Bank is mostly a marine sand bank. The overwash unit of Sabine Bank displays landward-thinning and landward-dipping deposits with reflections increasing in amplitude and displaying lower slopes to the NW. We hypothesize that higher slopes to the SE indicate proximity to the former barrier island. The Sabine River paleo-valley is mostly filled with estuarine sediment, leaving only ∼4 m of antecedent accommodation in a limited area of the NE portion of the paleo-valley. The low shelf gradient, which increases accommodation, and initially high sediment supply that decreased during the drowning of Sabine Bank are the major factors controlling partial preservation of the subaqueous portion of the paleo-barrier island.
期刊介绍:
Marine Geology is the premier international journal on marine geological processes in the broadest sense. We seek papers that are comprehensive, interdisciplinary and synthetic that will be lasting contributions to the field. Although most papers are based on regional studies, they must demonstrate new findings of international significance. We accept papers on subjects as diverse as seafloor hydrothermal systems, beach dynamics, early diagenesis, microbiological studies in sediments, palaeoclimate studies and geophysical studies of the seabed. We encourage papers that address emerging new fields, for example the influence of anthropogenic processes on coastal/marine geology and coastal/marine geoarchaeology. We insist that the papers are concerned with the marine realm and that they deal with geology: with rocks, sediments, and physical and chemical processes affecting them. Papers should address scientific hypotheses: highly descriptive data compilations or papers that deal only with marine management and risk assessment should be submitted to other journals. Papers on laboratory or modelling studies must demonstrate direct relevance to marine processes or deposits. The primary criteria for acceptance of papers is that the science is of high quality, novel, significant, and of broad international interest.