岡山大学 地球科学研究報告
Published by Okayama University Earth Science Reports Editorial Committee

Provenance of Early Cretaceous Hayama Formation, Okayama Prefecture, Inner Zone of Southwest Japan: constraints from modal mineralogy and mineral chemistry of derived detrital grains

アシード ダニエル Department of Earth Science, University of Ghana
鈴木 茂之 岡山大学
柴田 次夫 岡山大学
抄録
Petrographic and phase chemistry studies of detrital grains were carried out on sandstones from the Lower Cretaceous Hayama Formation, Inner Zone of Southwest Japan, to determine their provenance and the tectonic setting during the early Cretaceous. The results of the modal mineralogy suggest that the Hayama Formation has magmatic arc provenance and that deposition of the sediments took place in the back-arc areas with detritus mostly derived from the magmatic arc and rifted continental margins. The chemical compositions of chromian spinel, chlorite and sphene indicate that significant proportions of the detrital grains were derived from mafic and/or ultramafic sources. The source areas are the mafic and ophiolitic rocks in the Sangun-Renge and Akiyoshi terranes and the felsic volcanic rocks probably from either the Akiyoshi terrane or a source not presently exposed in southwest Japan. However, minor amounts of the detritus were derived from the basement rocks; i.e., carbonates and siliciclastic rocks of the Akiyoshi terrane and the metamorphosed mafic rocks of the Chizu terrane.
キーワード
modal analysis
sandstone
mineral chemistry
provenance
Hayama Formation
ISSN
1340-7414
NCID
AN10506284
NAID