Development of framboidal pyrite during diagenesis, low-grade regional metamorphism, and hydrothermal alteration

Abstract

Distribution patterns, microstructural relationships, and compositional variations for framboidal pyrite in the Paleozoic sedimentary host rocks to gold deposits on the northern Carlin trend, Nevada, and at Fosterville in central Victoria, collectively demonstrate that it is not all of synsedimentary-early diagenetic origin. Framboidal pyrite also nucleated in hydrothermal veins formed at several kilometers depth and along dissolution surfaces (stylolites and crenulation cleavages) formed during metamorphism at up to anchizonal grade (i.e., prehnitepumpellyite facies). There are no obvious differences in either the size range or internal morphology of framboids formed in these various settin..