MICROFABRICS, COUNTER-CLOCKWISE P-T PATH AND MONAZITE DATING OF THE PRECAMBRIAN WADI EL MIYAH METAPELITES, EASTERN DESERT, EGYPT

The P-T path reconstruction from chiastolite -bearing garnet-mica schists suggest a new approach to the Pan-African structural and metamorphic evolution in the Wadi El Miyah, Central Eastern Desert, Egypt.

Microstructural data combined with field observations indicate that the studied rocks were subjected to three deformational phases D₁-D₃, each has its own impact on the development of planar and linear structures.

Geothermobarometry of the garnet-bearing assemblages indicate a counter-clockwise P-T path with a peak assemblage of garnet, chiatsolite± sillimanite and staurolite at 582 °C/5.8 kbars. Th-U-Pb dating of metamorphic monazite by electron microprobe (EMP) of El Miyah metapelites defines ages from 620 to 644 Ma, concordant with the emplacement of the syntectonic granitoids at the area. The recorded P-T path and the chronology of the studied rocks indicate that such LP/HT sequence is a typical example of regional contact metamorphism followed by crustal thickening