Rare earth elements in seep carbonates as tracers of variable redox conditions at ancient hydrocarbon seeps

• DOI: 10.1111/j.1365-3121.2008.00855.x
• Publication Date: 2008-12-19T02:19:05Z
• Authors: Dong Feng; Duofu Chen; Jörn Peckmann
• Keywords: Petroleum seep; Devonian; Lithology; Rare-earth element; Cold seep

Abstract Marine hydrocarbon seeps are dynamic systems, which typically reflected in complex lithologies of limestones forming at these sites. In order to test if seep with their multiple generations carbonate phases reflect variable redox conditions, the rare earth element (REE) patterns from five ancient hydrocarbon‐seep localities, Hollard Mound (Middle Devonian), Iberg (Mississippian), Beauvoisin (Oxfordian), Canyon and Satsop River (Oligocene), Marmorito (Miocene) have been investigated. The total REE contents vary widely (0.3–43.7 p.p.m.). Early microcrystalline tend show higher than spatially associated later (microspar, sparite, blocky cement). shale‐normalized carbonates both negative positive Ce anomalies even for individual deposits, suggesting that conditions varied significantly. It is apparent addition anoxic oxic were common some environments. Intermittent oxygenation presumed resulted abrupt changes fluid flow.