Origin of Diagenetic Pyrite in the Quilon Limestone, Kerala, India

Abstract

ALTHOUGH microscopic pyrite from marine and non-marine argillaceous sediments of most geological ages has been extensively studied, its mode of origin has not been clearly understood. Berner¹ and Kalliokoski² attributed the origin to the reaction of hydrogen sulphide formed by sulphite reduction, with iron-bearing minerals in sediments; but these minerals were not discovered. I have recorded framboidal and other types of diagenetic pyrite in the thin bed of marine, fossiliferous, Quilon limestone³ of Burdigalian age⁴. Recent examination of the heavy minerals from limestone samples at Padappakara the type area has brought forward some new evidence, which clearly establishes that the fine-grained pyrite was produced by an alteration of detrital, iron-bearing mica, optically identified as biotite.