In the Sivrihisar Massif, central Turkey, blueschist facies metabasalt, quartzite, and marble are spectacularly exposed. The blueschist rocks contain pods of eclogite, including lawsonite eclogite, which is very rarely observed at the Earth's surface, although it is not rare in subduction zones. That is, formation of lawsonite eclogite is not unusual, but preservation and exposure of it at the Earth's surface is -- there are only about a dozen known localities in the world. The Sivrihisar locality is exceptional for its large area, excellent exposures, and pristine (unaltered) mineral assemblages. It is also among the highest pressure lawsonite eclogites known: P ~ 22-26 kbar, T ~ 500 C.

Because the locality is so well exposed and contains abundant eclogites -- a couple of hundred pods ranging from a few cm to a few meters in length-- we can use these rocks to characterize and understand metamorphic and deformation processes in subduction zones. Also present in the field area are lawsonite blueschists, epidote blueschists, lawsonite + epidote blueschists, and epidote eclogites. Each one represents a different pressure-temperature path through a subduction zone, so we can reconstruct conditions and processes at different structural levels in the subduction zone.

This work is supported by NSF grant EAR-0711263 to Whitney and Teyssier.

Publications

Davis, P.B., and Whitney, D.L. (in press) Petrogenesis and structural petrology of high-pressure metabasalt pods, Sivrihisar, Turkey. Contributions to Mineralogy and Petrology.

Davis, P.B., and Whitney, D.L. (2006) Petrogenesis of lawsonite and epidote eclogite and blueschist, Sivrihisar Massif, Turkey. Journal of Metamorphic Geology, 24, 823-849.

Whitney, D.L., and Davis, P.B. (2006) Why is lawsonite eclogite so rare? Metamorphism and preservation of lawsonite eclogite, Sivrihisar, Turkey. Geology, 34, 473-476.

Also: University of Minnesota Ph.D. thesis, P.B. Davis (2008)

See also webpages on metamorphic geology research in Turkey

Below: An example of a lawsonite eclogite from Sivrihisar: lawsonite (white), garnet (pink-red), omphacite (green), glaucophane (dark blue-black, lower left); scale = 2 cm diameter.