Retrograded eclogite from the Staré Město Belt, NE margin of the Bohemian Massif
Strongly retrograded eclogite was found at the NE edge of the Staré Město Belt most probably representing a suture zone, in the eastern rim the Orlice-Klodsko Unit. While primary garnet is preserved, (Alm 51-59, Grs 17-31, Pyr 13-17, Sps 1.3-2.1), clinopyroxene I is completely replaced by clinopyroxene II (Jd 18) - plagioclase I (An 10-14) symplectite. Continuing retrogression led to growth of hornblende + plagioclase II (An 17-42) at the expense of symplectite. Amphibolite sampled nearby displays a prograde zoning of garnet in the range of amphibolite facies, (Alm 56-62, Grs 24-30, Pyr 5-10 Sps 0.4-10); the assemblage includes hornblende, plagioclase (An 12-31), quartz and biotite. Thermobarometry indicates that local equilibrium of rocks of different previous P-T histories has been attained at conditions of high amphibolite facies at 650-725-C and 8-11 Kb. The highest pressure record of 11.5-12.5 Kb at 600-680-C, indicating conditions transitional between eclogite and amphibolite facies, yielded the sample of retrograded eclogite with preserved symplectite. The partial P-T path of retrograded eclogite shows a moderate uplift between 40-30 km and a re-equilibration at depth of about 30 km.
SNIP (Scopus, 2017): 1.120
IF (ISI, 2017): 1.415
5 YEAR IF (ISI, 2017): 1.738
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