Mineralization of soft-bodied invertebrates in a Jurassic metalliferous deposit

The Jurassic marine biota of La Voulte-sur-Rhone, France, is characterized by three-dimensional preservation of soft-bodied animals and their internal organs. In contrast to other soft-bodied fossils, those from La Voulte are preserved in an unusual suite of minerals, dominated by apatite, calcite, gypsum, barite, and pyrite with accessory Cu, Pb, and Zn sulfides. These are thought to be sedimentary in origin, Fossilization occurred rapidly enough to be influenced by tissue composition and involved a diagenetic sequence: apatite --> calcite --> gypsum --> pyrite +/- chalcopyrite --> galena. The La Voulte fossils reveal the role of apatite as a ''template'' for calcification and pyritization in soft-tissue preservation.