JpGU-AGU Joint Meeting 2017

Presentation information

[JJ] Poster

S (Solid Earth Sciences) » S-CG Complex & General

[S-CG73] [JJ] Petrology, Mineralogy and Resource Geology

Mon. May 22, 2017 5:15 PM - 6:30 PM Poster Hall (International Exhibition Hall HALL7)

[SCG73-P04] Unusual distribution of zeolite in Shirahama Formation, southern Boso Peninsular

*Shigenori Ogihara1 (1.Graduate School of Science, The University of Tokyo)

Keywords:zeolite, heulandite, analcime, nekoite, erionite

Zeolite group minerals with unusual occurrence were found from Late Pliocene Shirahama Formation, Cape Nozima and southern Shiramazu, Chikura town, most southern Boso peninsular. Each occurrence of zeolite was carried out the analysis of XRD, XRF, EPMA, carbonate carbon and oxygen isotope.

1. Analcime cemented mud chip (analcime nodule, 60cm x 40cm) in volcanoclastics under the Cape Nozima lighthouse: Mud chip found in volcanoclastic sediment was cemented fine grain analcime and/or calcite. Analcime was very fine grain and could not be observed under the microscope. Some calcite and analcime vein were found around the analcime nodule. Coarse grained analcime, 0.2 mm diameter, was observed in these veins.

2. Coexistane of heulandite and nekoite:Two pumice layers were found under and just above SH tuff, which is the important key bed of the Shirahama Formation. These pumice were altered in tabular heulandite and radiating nekoite. The occurrence of nekoite is first report in Japan. Nekoite was reported from skarun or altered limestone, not reported as diagenetic origin.