Abstract
The Pacific coast of the Shimokita Peninsula, Northeast Japan, is occupied by one of the larger dune complexes in Japan. This coastal aeolian dune complex developed during the Holocene in a monsoon-influenced temperate climatic belt. The stratigraphic and sedimentological characteristics of outcrops, exposures and cores indicate that four generation of aeolian dunes are presented. These dunes developed during eustatic regression following the post-glacial sea-level highstand. Seaward shoreline movement, combined with strong winds from the Pacific Ocean, enhanced aeolian grain transport on the beach, resulting in the onset of dune growth and the consequent shrinkage of the coastal forest. Northeast Japan is located in a transitional zone affected largely by monsoonal circulation from Siberia and Southeast Asia. Thus, the regional climate is responsible for atmospheric changes on a hemispheric scale. Intensified monsoons contributed to flooding produced by rains and snow-melt. Steep increases in annual precipitation at 7200–6300, 4700–3600, 3050–2500, 1850–1100, and 550–200 calendar years before present (cal. yr. BP) increased the amount of surface erosion, causing a large volume of sediment discharge toward the coast. Shimokita has experienced frequent earthquakes and tsunamis, which have reduced dune landform relief by sediment displacement.
Highlights
The growth of coastal dunes has generally been ascribed to marine transgression-regression, wind strength, and sand supply [1,2,3,4,5]
Owing to the lack of meaningful geological information in the lower part of the core, which was composed of homogenous sand with no mud seams or fossils, this study focused on the upper half (450–0 cm drilling depths) for sedimentological, mineralogical, paleontological, and limnological data after measuring wet and dry densities
Quartz and feldspathic minerals account for 75% or more of all grains, and the remainder consists of heavy minerals, including orthopyroxene, clinopyroxene, magnetite, amphiboles, olivine, and biotite
Summary
The growth of coastal dunes has generally been ascribed to marine transgression-regression, wind strength, and sand supply [1,2,3,4,5]. An abundant sand supply from the surf zone may increase the potential of dune development [2,4,15]. The role of water table responses to sea level changes is an important factor that influences coastal dune systems [16]. Www.jma.go.jp/), the changes in climate between NE Japan and China, together with the global atmospheric events,obtained suggest results from the Wetland core may be applied to the reconstruction of the paleo-climate in that the paleoclimatic reconstruction and zoning has hemispheric application. The last cool/dry climate stage influence afforestation (forest growth and expansion) around theago Www.jma.go.jp/), the changes in climate between NE Japan and China, together with the global atmospheric events,obtained suggest results from the Wetland core may be applied to the reconstruction of the paleo-climate in that the paleoclimatic reconstruction and zoning has hemispheric application. the Shimokita
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