Measuring and adjusting the weathering and hydraulic sorting effects for rigorous provenance analysis of sedimentary rocks: A case study from the Jurassic Ashikita Group, south-west Japan

Tohru Ohta*

*この研究の対応する著者

研究成果: Article査読

31 被引用数 (Scopus)

抄録

The present study examines the provenance of the Jurassic Ashikita Group distributed in south-west Japan, which is composed of the Idenohana, Kyodomari and Sakamoto Formations. Two geochemical diagrams for provenance analysis were utilized, which incorporate full consideration of compositional modifications resulting from weathering (MFW diagram) and hydraulic sorting processes (SiO2/Al2 O3-Na2O/K2O diagram). The MFW diagram delineates weathering trends of sedimentary rocks and allows estimation of the original source rock composition by tracing the weathering trends backwards to an unweathered domain. Weathering trends of the Idenohana and Kyodomari Formations extend backward to the domain of intermediate and felsic igneous rocks. In contrast, sediments of the Sakamoto Formation do not fit into a linear weathering trend, indicating that the source rock cannot be approximated to igneous rocks. On the SiO2/Al2O3-Na2O/K2 O diagram, sediments are organized into compositional trends, in which the range reflects compositional variations induced by the hydraulic sorting effect. On this diagram, sediments derived from the igneous and recycled sedimentary provenances can be distinguished by reading the inclination of the trend. By utilizing this principle, source rocks of the Idenohana and Kyodomari Formations are interpreted as igneous rocks and those of the Sakamoto Formation are interpreted as recycled sedimentary rocks. Therefore, these diagrams concurrently estimate the source rock composition through quantifying and adjusting the weathering and sorting effects, and reveal a systematic transition in the provenance of the Ashikita Group. The Idenohana and Kyodomari Formations were supplied chiefly from an igneous provenance, which shifted from intermediate to felsic compositions in stratigraphic order. Whereas, sediments of the Sakamoto Formation were sourced primarily from a recycled sedimentary provenance.

本文言語English
ページ(範囲)1687-1701
ページ数15
ジャーナルSedimentology
55
6
DOI
出版ステータスPublished - 2008 12月 1

ASJC Scopus subject areas

  • 地質学
  • 層序学

フィンガープリント

「Measuring and adjusting the weathering and hydraulic sorting effects for rigorous provenance analysis of sedimentary rocks: A case study from the Jurassic Ashikita Group, south-west Japan」の研究トピックを掘り下げます。これらがまとまってユニークなフィンガープリントを構成します。

引用スタイル