Fossil Chemosynthetic Communities Related to Vents or Seeps in Sedimentary Basins: The Pseudobioherms of Southeastern France Compared to Other World Examples

TLDR

Pseudobioherms are fossil calcareous bodies that resemble bioherms but are not organism‑built, and Jurassic examples in southeastern France were among the first to be linked to deep‑sea seeps via synsedimentary faults that channel fluids to the seafloor. These pseudobioherms form through sedimentary carbonate precipitation, host mainly infaunal non‑building bivalves, and indicate that chemosynthetic communities may have existed near seeps, with early diagenetic carbonate deposition.

Abstract

The term pseudobioherm is used for fossiliferous calcareous bodies with a bioherm-like shape but neither built by organisms, nor bulging at the sediment/water interface. Jurassic pseudobioherms of southeastern France are among the first fossiliferous carbonate bodies whose relation to deep-sea seeps was recognized. They are built by carbonate precipitation in the sediment and they contain mainly infaunal non-building animals (chiefly bivalves). They are related to active synsedimentary faults that allowed the migration of fluids to the sea floor. Chemosynthetic life could occur in the vicinity of seeps, and early diagenetic carbonate precipitated