Paleoenvironmental Variability during the Holocene in the Area of Izumo Plain-Lake Shinji Based on the Results of Sedimentary Cores

DOI Web Site 5 Citations 55 References

Bibliographic Information

Other Title
  • 出雲平野―宍道湖地域における完新世の古環境変動―ボーリングコア解析による検討―
  • イズモ ヘイヤ シンジコ チイキ ニ オケル カンシン セイ ノ コ カンキョウ ヘンドウ ボーリングコア カイセキ ニ ヨル ケントウ
  • Based on the Results of Sedimentary Cores
  • ―ボーリングコア解析による検討―

Search this article

Abstract

Three sediment cores were recovered from the areas of Izumo Plain and Lake Shinji, Shimane Prefecture, western Japan. These cores were examined for lithological features, sedimentation rate by multi measurements of AMS radiocarbon dating and total organic carbon (TOC), total nitrogen (TN), and total sulfur (TS) contents using CNS analysis, in order to clarify the temporal and spatial changes in the sedimentary environment in this area during the Holocene. The environmental changes in the areas indicated by these data are as follows. An inner bay environment began at least 9,300 cal BP due to a rise in sea level and lasted until ca. 7,000 cal BP. At ca. 7,000 cal BP, the sedimentary environment changed to a closed brackish lake or lagoon with the formation of sand-bars, as suggested by temporary stopping or weakening of the Jomon transgression. During 6,000 to 4,000 cal BP, one large occupied lagoon was divided into two parts at the central area owing to the development of an alluvial fan of the Hii River from the southward direction. After that, on the east side, a stable closed brackish lake environment indicated a very low sedimentation rate (average 0.68 mm/yr), and high TOC and TS contents began to form and lasted until the geomorphological event of an eastward course change of the Hii River in A.D. 1635 or 1639. On the west side, a drastic environmental change from brackish to fresh lake condition at 4,000 cal BP occurred ; this might have been caused by two phenomena : a flood to the lagoon originating from volcanic activities of Mt. Sanbe at the same time, and a global climate cooling phase. After 2,000 to 3,000 cal BP, the lagoon on the west side returned to a brackish lake condition, and after that it was rapidly buried by delta deposits of the Hii River until 1,000 cal BP.

Journal

Citations (5)*help

See more

References(55)*help

See more

Related Projects

See more

Keywords

Details 詳細情報について

Report a problem

Back to top