[SCG73-P04] Unusual distribution of zeolite in Shirahama Formation, southern Boso Peninsular
Keywords:zeolite, heulandite, analcime, nekoite, erionite
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.