Science Links Japan | Relationship between Gypsum Formation due to Chemical Weathering and Mineral Composition of Original Rocks. A Case Study of the Onnagawa Sedimentary Rocks in Oga Peninsula, Akita Prefecture, Japan.

Relationship between Gypsum Formation due to Chemical Weathering and Mineral Composition of Original Rocks. A Case Study of the Onnagawa Sedimentary Rocks in Oga Peninsula, Akita Prefecture, Japan.

Accession number;02A0689277

Title;Relationship between Gypsum Formation due to Chemical Weathering and Mineral Composition of Original Rocks. A Case Study of the Onnagawa Sedimentary Rocks in Oga Peninsula, Akita Prefecture, Japan.

Author; SHIKAZONO NAOTATSU (Keio Univ., Faculty of Sci. and Technol., JPN) KIMURA SHIN'ICHI (Mitsubishi Mater. Corp.) IWAI SHUHEI (Keio Univ., Faculty of Sci. and Technol., JPN)

Journal Title;Journal of the Japan Society of Engineering Geology

Journal Code:G0269B

ISSN:0286-7737

VOL.43;NO.3;PAGE.134-142(2002)

Figure&Table&Reference;FIG.5, TBL.1, REF.30

Pub. Country;Japan

Language;Japanese

Abstract;Mineralogical studies on two types of Miocene sedimentary rocks (shale and siliceous shale) in the Oga Peninsula, northern part of Japan indicate that (1) weathered shale contains gypsum, while weathered siliceous shale does not, and (2) carbonates are abundant in unweathered shale, but they are poor and feldspar is abundant in unweathered siliceous shale. The calculations on the change in groundwater chemistry due to the dissolution of calcite and feldspar indicates that gypsum is formed by the calcite dissolution but it is difficult to be formed by the feldspar dissolution. The mineralogical studies and the dissolution calculations suggest that the mineralogical composition of original sedimentary rocks is important factor controlling gypsum formation, together with pyrite abundance in the original rocks and humidity. (author abst.)

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