Jump to ContentJump to Main Navigation
Show Summary Details
More options …

American Mineralogist

Journal of Earth and Planetary Materials

Ed. by Baker, Don / Xu, Hongwu / Swainson, Ian


IMPACT FACTOR 2017: 2.645

CiteScore 2018: 2.55

SCImago Journal Rank (SJR) 2018: 1.355
Source Normalized Impact per Paper (SNIP) 2018: 1.103

Online
ISSN
1945-3027
See all formats and pricing
More options …
Volume 100, Issue 5-6

Issues

Hydrothermal chloritization processes from biotite in the Toki granite, Central Japan: Temporal variations of of the compositions of hydrothermal fluids associated with chloritization

Takashi Yuguchi
  • Corresponding author
  • Mizunami Underground Research Laboratory, Geoscientific Research Department, Sector of Decommissioning and Radioactive Waste Management, Japan Atomic Energy Agency, 1-64, Yamanouchi, Akiyo, Mizunami, Gifu 509-6132, Japan
  • Email
  • Other articles by this author:
  • De Gruyter OnlineGoogle Scholar
/ Eiji Sasao
  • Mizunami Underground Research Laboratory, Geoscientific Research Department, Sector of Decommissioning and Radioactive Waste Management, Japan Atomic Energy Agency, 1-64, Yamanouchi, Akiyo, Mizunami, Gifu 509-6132, Japan
  • Other articles by this author:
  • De Gruyter OnlineGoogle Scholar
/ Masayuki Ishibashi
  • Mizunami Underground Research Laboratory, Geoscientific Research Department, Sector of Decommissioning and Radioactive Waste Management, Japan Atomic Energy Agency, 1-64, Yamanouchi, Akiyo, Mizunami, Gifu 509-6132, Japan
  • Other articles by this author:
  • De Gruyter OnlineGoogle Scholar
/ Tadao Nishiyama
  • Department of Earth and Environmental Sciences, School of Science, Graduate School of Science and Technology, Kumamoto University, 2-39-1, Kurokami, Chuo-ku, Kumamoto 860-8555, Japan
  • Other articles by this author:
  • De Gruyter OnlineGoogle Scholar
Published Online: 2015-05-12 | DOI: https://doi.org/10.2138/am-2015-5126

Abstract

This paper describes the biotite chloritization process with a focus on mass transfer in the Toki granitic pluton, Central Japan, and also depicts the temporal variations in chemical characteristics of hydrothermal fluid associated with chloritization during the sub-solidus cooling of the pluton. Singular value decomposition (SVD) analysis results in chloritization reaction equations for eight mineral assemblages, leading to the quantitative assessment of mass transfer between the reactant and product minerals, and inflow and outflow of components through the hydrothermal fluid. The matrices for SVD analysis consist of arbitrary combinations of molar volume and closure component in the reactant and product minerals. The eight reactions represent the temporal variations of chemical characteristics of the hydrothermal fluid associated with chloritization: the progress of chloritization results in gradual increase of silicon, potassium, and chlorine and gradual decrease of calcium and sodium in the hydrothermal fluid with temperature decrease. The biotite chloritization involves two essential formation mechanisms: chlorite formation (CF) mechanism 1, small volume decrease from biotite to chlorite and large inflow of metallic ions such as Al3+, Fe2+, Mn2+, and Mg2+ from the hydrothermal fluid, and CF mechanism 2, large volume decrease and large outflow of the metallic ions into hydrothermal fluid. Chlorite produced with CF mechanism 1 dominates over that of CF mechanism 2, resulting in the gradual decrease of the metallic components in the hydrothermal fluid with chloritization progress. The chloritization reactions also give the temporal variations in physicochemical parameter of the hydrothermal fluid: a gradual decrease of pH and a gradual increase of redox potential in the hydrothermal fluid as chloritization proceeds. The combination of continuous reactions based on compositional variations in chlorite together with corresponding continuous AlIV variations gives an indication of the temporal variations in rates of decreasing and increasing concentration of chemical components in the hydrothermal fluid associated with chloritization. The biotite chloritization and resultant temporal variations of chemical and physicochemical characteristics in hydrothermal fluid act as a trigger for the successive dissolution-precipitation process of a granitic rock.

Keywords: Chloritization; fluorine-bearing biotite; hydrothermal fluid; tetrahedral aluminum in chlorite; singular value decomposition (SVD) analysis

About the article

Received: 2014-07-13

Accepted: 2014-10-29

Published Online: 2015-05-12

Published in Print: 2015-05-01


Citation Information: American Mineralogist, Volume 100, Issue 5-6, Pages 1134–1152, ISSN (Online) 1945-3027, ISSN (Print) 0003-004X, DOI: https://doi.org/10.2138/am-2015-5126.

Export Citation

© 2015 by Walter de Gruyter Berlin/Boston.

Comments (0)

Please log in or register to comment.
Log in