Dear Mr. Serna,

You are going to investigate metabasic rocks; I suppose amphibolites, garnet-amphibolites, and ecologite-amphibolites. As you mentioned Ti contents I recommend having a look at different minerals. Commonly, these metamorphic rocks also contain small amounts of rutile and quartz and offer a tool to constrain the physical-chemical regime of formation. I would like to refer to Zr content in rutile (T (°C) = 127.8 x ln (Zr ppm) – 10 (Zack et al., 2004). Another geothermometer based on the Zr content in rutile was elaborated by Watson et al. (2006) (T (°C) = 4470/(7.36 – log10[Zr ppm]) – 273). The Ti-in-quartz geothermometer of Wark and Watson (2006) provides a tool to determine the quartz crystallization temperature based on the temperature dependence of the Ti4+−Si4+ substitution in quartz.

I wish you much success

H.G.Dill

Helz (1973) proposed

that the Ti (apfu) content from magmatic as well as

subsolidus hornblendes can be used as a thermometer if the

oxygen fugacity was near the quartz-fayalite-magnetite

(QFM) buffer and calcic amphiboles are associated with

Ti-rich minerals such as ilmenite, rutile and titanite.

See the review of geothermometers in the attached article.

Dear Serna,

In my opinion, you should try the phase equilibria modeling to constrain the metamorphic history of the metabasites rocks.

Hi Santiago! What type of amphiboles do you have> Did you happen to find a good geobarometer for these rocks? I have metabasites that have been hard to model in phase equilibria diagrams, Im interested in knowing what approach to take!