A Characteristic Mineral Of The Greenschist Facies In Mafic Protoliths Is Chlorite Chlorite Has The Simplified Formula 1 (52.18 KiB) Viewed 19 times
A Characteristic Mineral Of The Greenschist Facies In Mafic Protoliths Is Chlorite Chlorite Has The Simplified Formula 2 (26.46 KiB) Viewed 19 times
A Characteristic Mineral Of The Greenschist Facies In Mafic Protoliths Is Chlorite Chlorite Has The Simplified Formula 3 (26.46 KiB) Viewed 19 times
A characteristic mineral of the greenschist facies in mafic protoliths is chlorite. Chlorite has the simplified formula (Mg)3A14SiO20(OH)16- (a) Calculate the wt% of H2O in chlorite and show your working (4 marks). (b) Oceanic lithosphere is often hydrated because ocean water can circulate through it along very deep fractures. Two relatively abundant, hydrous minerals that form in the ultramafic part of the lithosphere in this process are antigorite and chlorite. When the lithosphere is subducted into the mantle, eventually they both dehydrate as they encounter increasingly high temperatures and pressures, releasing H2O-rich fluids. The diagram below is based on high pressure experimental studies of the locations in PT space of the dehydration curves for antigorite and chlorite. For a cold subduction geotherm (indicated by the black arrow), estimate the pressure and temperature at which each of antigorite and chlorite would break down to produce a H2O-rich fluid (6 marks). 60 Peridotite + H,0 IND SO 150 chore Garnetales, 120 PRESSURE (GP) Ocho antine DEPTH 20 10 10 NO 00 200 NO TEMPERATURE (O)