The Early to Middle Miocene volcanism and development of a sedimentary basin in the Ou Backbone Range in Nishiwaga Town, Iwate Prefecture, Northeast Japan

DOI Web Site Web Site 4 Citations 40 References
  • Hosoi Jun
    Graduate School of Science and Engineering, Ibaraki University
  • Amano Kazuo
    Faculty of Science, Ibaraki University

Bibliographic Information

Other Title
  • 岩手県西和賀町周辺奥羽脊梁山脈における前期～中期中新世の火山活動と堆積盆発達史
  • イワテケン ニシワガマチ シュウヘン オウウ セキリョウ サンミャク ニ オケル ゼンキ~チュウキ チュウシンセイ ノ カザン カツドウ ト タイセキボン ハッタツシ

Search this article

Abstract

Since the late 19th century, research on the Green Tuff of Japan has focused on its stratigraphy, which was finally summarized around 1990. Recently, the stratigraphy of rocks of the Oga Peninsula, which is the type locality of the Green Tuff of Japan, was revised. We sought to unravel details of temporal changes in the volcanism and sedimentary environment at Nishiwaga Town, Iwate Prefecture in the Ou Backbone Range, Northeast Japan, based on facies analyses of volcanic and clastic rocks, which is a relatively recent method used to reconstruct paleo-sedimentary environments. We reconstructed the paleo-sedimentary basin architecture, sedimentary processes, and paleo-volcanism. Two types of non-explosive submarine volcanoes (Types A and B) and three types of explosive eruptions (Types 1, 2, and 3) were identified. From the field investigations and detailed facies analyses, five tectonic stages were identified in the Miocene, as follows. (1) A half-graben formed and Type A submarine volcanoes erupted in the basin at about 20 Ma. (2) The basin was filled with turbidites, debrites, and hemipelagic sediments from about 18 to 15 Ma. (3) Large tectonic subsidence and explosive volcanism (Types 1, 2 & 3) occurred at about 15 Ma. Seawater depth increased from several meters to over 1000 m. (4) The increase in seawater depth corresponded with a decrease in the intensity of volcanism, resulting in the formation of Type B submarine volcanoes at about 14 Ma. (5) The basin was then covered with hemipelagic sediments from about 14 Ma.

Journal

Citations (4)*help

See more

References(40)*help

See more

Keywords

Details 詳細情報について

Report a problem

Back to top