Ultrahigh-pressure subfacies of Eclogite facies

Index Minerals

Coesite

Required Geological Setting

Accretionary complexes + High-P metamorphic rocks

Occurrence

Metamorphic rocks formed by regional metamorphism in the following condition: 600-700 degree and more than 2.5 GPa (deeper than 100 km depth). A metamorphic facies formed in collision zones. Ultrahigh-pressure subfacies metamorphic rocks are continent-continent collision zones such as Dabieshan-Sulu metamorphic zone (China) and Kokchetav metamorphic zone (Kazakhstan).

Change of mineral assemblages

• [ Extinct ] Quartz
• [ Appear ] Coesite

Mineral Assemblages

• [ Felsic Rocks ] Coesite, Phengite, Jadeite/Omphacite, Pyrope
• [ Mafic Rocks ] Omphacite, Pyrope, (Kyanite, Hornblende, Zoisite)
• [ Ultramafic Rocks ]
• [ Mudstone ] Phengite, Pyrope, Kyanite, Coesite, (Talc, Jadeite)
• [ Laterite ] Phengite, Pyrope, Kyanite, Chloritoid, Coesite
• [ Bedded Mn ]
• [ Carbonate Rocks ] Aragonite, Dolomite, Diopside