Paleocene methane seep and wood-fall marine environments from Spitsbergen, Svalbard

A recently discovered Paleocene seep locality from Fossildalen on Spitsbergen, Svalbard, is described. This is one of a very few seep communities of the latest Cretaceous–earliest Palaeogene age, and the best preserved Paleocene seep community known so far. The seep carbonates and associated fossils have been first identified in museum collections, and subsequently sampled in the field. The carbonates are exclusively ex-situ and come from the offshore siltstones of the Basilika Formation. Isotopically light composition (δ13C values approaching -50‰ V-PDB), and characteristic petrographic textures of the carbonates combined with the isotopically light archaeal lipid are consistent with the formation at fossil hydrocarbon seep. The invertebrate fauna associated with the carbonates is of moderate diversity (16 species) and has a shallow water affinity. It contains a species of the thyasirid genus Conchocele, common in other seeps of that age. The finding sheds new light onto the history of seepage on Svalbard, and onto the evolution and ecology of seep faunas during the latest Cretaceous–earliest Palaeogene time interval.