The Morphological Characteristics of Authigenic Pyrite Formed in Marine Sediments

Pyrites are widely distributed in marine sediments, the morphology of which is applied as a proxy to infer redox conditions bottom water, and identify diagenetic stages hydrocarbon leakage activities. In this review, methods used for morphological study pyrite summarized. The textural size characteristics euhedral aggregates, formation evolution mechanism discussed their significance reconstructing geochemical environment. includes shape observation, estimation, surface feature analysis. Scanning electron microscope optical main observation; transmission scanning tunneling applicable observe nanoscale structures crystal growth on surface, X-ray computed tomography capable measuring distribution at scale micrometer. Under sedimentary condition, single appears cube, octahedron, dodecahedron, intermediates, ranges from several nanometers more than 100 µm. controlled by temperature, pH, chemical composition interstitial etc., might have been experienced later reformation processes. aggregates occur framboid, rod-like, fossil-infilling, characterized comparatively large microns millimeters. It found that certain textures correspond with different mechanisms environments. Particularly, under special geological conditions, instance, methane and/or decomposition gas hydrate, anomaly enriched massive framboid cluster, rod-like mean diameter (>20 µm) standard deviation (>10 µm). These typical features can be employed ascertain position paleo sulfate transition zone (SMTZ).