K-Ar ages of Late Neogene monogenetic volcanoes in the east San-in district, Southwest Japan

DOI Web Site 9 Citations

Bibliographic Information

Other Title
  • 西南日本,山陰東部地域の後期新生代単成火山のK-Ar年代
  • 西南日本,山陰東部地域の後期新生代単成火山のK-Ar年代〔英文〕
  • セイナン ニホン サンイン トウブ チイキ ノ コウキ シンセイダイ タンセイ

Search this article

Abstract

About 30 volcanic rocks of late Neogene age from the east San-in district were collected for K-Ar age determination. Most of them are from basaltic monogenetic volcanoes, and remainders are voluminous calc-alkaline andesites. Degrees of dissection at scoria cones and geomorphology of lavas are consistent with their K-Ar ages. They are divided into two groups (Pliocene and Quaternary) based on K-Ar ages. Those of Pliocene age (Hamasaka, Todoroki and Oya Volcanoes) are located around the northwestern and southwestern border of an ellipsoidal area (50 km long and 35 km wide elongated in the direction N45° W) in the east part of the San-in region. Quaternary volcanic activity began at 1.6Ma at Genbudo and continued until the Holocene, with time gaps less than 0.1 ma between each monogenetic volcano, apart from two periods of repose, one at 1.3-1.5Ma and the other at 0.7-0.9Ma. Apart from these two periods, 1 to 4 monogenetic volcanoes per 0.1 ma formed in the Quaternary. Quaternary volcanic activity began mainly in the western and northeastern parts, and moved to the central and southeastern parts. In this district, the period of the most vigorous volcanic activity during the Quaternary was between 0.9and 1.3 Ma.

Journal

Citations (9)*help

See more

Keywords

Details 詳細情報について

Report a problem

Back to top