Eustatic, Climatic and Tectonic Controls on the Evolution of a Middle to Late Holocene Coastal Dune System in Shimokita, Northeast Japan

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.

Keywords

• aeolian dune
• climate fluctuation
• eustatic change
• Japan
• Holocene