Processes governing serpentinite carbonation in fossil hydrothermal system

Carbonation of serpentinized follow up peridotite serpentinization at a minimum and develops at temperature ranging between 110 and 180 °C. Textures for Chenaillet ophicalcite breccia suggest for an hydrothermal and tectonic control of serpentinite carbonation.

Carbonation initiates in brittle domain with a discrete calcite vein networks characterized by a wide range of isotopic composition reflecting fluid cooling. Here, calcite recorded a specific “ultramafic” signature is. Then, the formation of metric monogenic breccia appears related to dramatic fluid decompression induce by cracking densification and fluid circulation toward surface. Hydrothermal system is maintained and breccia remains subject to colder veins development. Such veins act as major drain for fluid exfiltration toward surface.

We proposed a genetic model comparable to the one reported in the basement of long-lived hydrothermal assisted venting system.

GSA meeting and SGM poster presentations 2015.

Lafay et al., (2017) Lithos.