The stability of antigorite in subduction zones revisited: The effect of F on antigorite stability and its breakdown reactions at high pressures and high temperatures, with implications for the geochemical cycles of halogens

Flemetakis, S; Tiraboschi, C; Rohrbach, A; Berndt, J; Klemme, S

Abstract

We present new experimental data on the effect of F on the stability of antigorite and its breakdown products at high pressures (2 – 6 GPa) and high temperatures (570 – 850°C). The experiments show that F does not affect the stability of antigorite, but addition of F to the system affects which minerals are formed when antigorite breaks down. In a F-free system and in a system with intermediate F contents (2 wt.% F), antigorite breaks down to olivine and orthopyroxene, but in a F-rich system (5 wt.% F), antigorite breaks down to other hydrous and F-bearing mineral assemblages which include chlorite, clinohumite and humite-group minerals (HGM). Since the latter mineral phases are stable at higher pressures and temperatures, and contain more F than antigorite, significant amounts of F and potentially other halogens can be retained in the subducting slab and transported deep into the mantle and possibly even into the Earth’s transition zone.

Projects the publication originates from

Promotionen, aus denen die Publikation resultiert