EGU24-20470, updated on 11 Mar 2024
EGU General Assembly 2024
© Author(s) 2024. This work is distributed under
the Creative Commons Attribution 4.0 License.

Storage and fate of volatiles in the shallow mantle: Insights from fluid mobile elements and light element (B, Li) isotopes in serpentinites

Ivan Savov1,2, Samuele Agostini2, CeesJan DeHoog3, William Osborne1, Andrew McCaig1, Detlef Rost4, Jeff Ryan5, Roy Price6, Dyonisis Foustoukos7, Haiyang Liu8, and International Ocean Discovery Program Expedition 399 Sci. Party9
Ivan Savov et al.
  • 1Univ. of Leeds, School of Earth and Environment, Leeds, UK (
  • 2IGG-CNR, Pisa, Italy
  • 3Univ. of Edinburgh, Edinburgh, UK
  • 4NMNH-Smithsonian, Washington DC, USA
  • 5Univ. South Florida, Tampa FL, USA
  • 6SUNY, Stony Brook, USA
  • 7Carnegie Institution, Washington DC, USA
  • 8Institute of Oceanology,CAS, Qingdao, China
  • 9Texas A&M University , College Station, TX, USA

We will present whole rock and mineral chemistry insights into the systematics of light elements (B, Li) and their isotopes during the serpentinization processes at both divergent and convergent plate margins. For the divergent plate case we have selected Site 1309D and some from the recently drilled (IODP Expedition 399, Atlantis Massif, Mid-Atlantic Ridge 30N) Site 1601C as the deepest in situ gabbo-peridotite drill cores ever recovered from the ocean floor. The downcore variation in fluid mobile elements and the vast Sr and light element isotope fractionations highlight the important role of seawater infiltration and seawater-crust interactions taking place at depth. However, it appears that the role of seawater is gradually diminishing with depth, where rather unaltered lithologies may still be involved in active metamorphic (hydration) reactions. For the convergent plate margin serpentinization we have selected to present the fascinating case of the Mariana serpentinite mud “volcanism” in the W. Pacific. Several key cores were recovered during ODP Legs 125 and 195, as well as during the IODP Expedition 366. The rocks and fluids at these forearc sites also show very large downcore elemental and isotope fractionations. In contrast to the oceanic intraplate sites, these are associated with fluids produced by metamorphic dehydration reactions occurring at blueschist and amphibolite facies conditions as a consequence of subduction of old and cold Pacific slabs. We will attempt to contrast the different tectonic settings and speculate on the importance of variously hydrated ocean crust as a volumetrically important carrier of volatiles from the surface to the deep mantle and back. Serpentinites may be important to kick-start subduction initiation.

How to cite: Savov, I., Agostini, S., DeHoog, C., Osborne, W., McCaig, A., Rost, D., Ryan, J., Price, R., Foustoukos, D., Liu, H., and Ocean Discovery Program Expedition 399 Sci. Party, I.: Storage and fate of volatiles in the shallow mantle: Insights from fluid mobile elements and light element (B, Li) isotopes in serpentinites, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20470,, 2024.