続成過程における粘土鉱物の生成, 変化とその性質(自然条件下での粘土鉱物の生成とその性質)

概要

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IIlite/smectite mixed-layer minerals occur widely in diagenetic process of argillalaceous and acid pyroclastic sediments. The relative proportion of constituent layers and ordering in the mixed-layer structure are regarded as reflecting formation temperature (Fig.1). Chemical changes from random to regular interstratification are remarkable in tetrahedral Al and octahedral Al/(Al+Mg+Fe) ratio (Fig.2). Chlorite/saponite mixed-Iayer minerals are found in MgFe bearing sediments such as basic 〜 intermediate pyroclastics. The proportion of chlorite layers in the interstratification is discontinuous and is concentrated on ranges of less than 1O, 50,75 and morethan 90%. Randomly interlayering of chlorite/saponite occurs as replacement products of volcanic glass. An increase in chlorite layers with increasing burial depth is observed in the Miocene pyroclastic rocks of Yamagata-Yoshino (Fig.3). Whereas corrensite type minerals occurring as cementing materials of andesitic sandstone are found over the thick strata regardless of burial depth. Chemical changes of chlorite/ saponite mixed-layer with increasing burial depth are characterized by an increase of tetrahedral A1 and octahedral Fe (Fig.4).
日本粘土学会の論文
1985-09-10