Vörös A. szerk.: Fragmenta Mineralogica Et Palaentologica 13. 1987. (Budapest, 1987)

event (7. 1 kbar/517°C, ~20°C/km). This equilibrium was partially destroyed presumably due to the thermal effect of the granitic magmatism resulting in plagioclase blast formation and hornblende recrystallization in restricted parts of the rock. The changes of the Al-content of the hornblende-plagioclase pair in these areas suggest T-increase and P-decrease (4.9 kbar/524°C, 29°C/km). In another amphibolite occurrence (Álmosd area, sample Aim9. 1. , where no signs of late-kinematic magmatism are known) a retrograde hornblende II (actinolitic hornblende) + albite assemblage developed during the second event. The calculated P-T values (3. 1 kbar/ 480°C, ~43°C/km) indicate low-pressure (andalusitic) character. Relics of the first paragenesis (hornblende I + oligoclase-andesine) show that the second mineral equilibrium might have been approached in certain (more permeable ? ) parts of the rock mass only. In both (prograde and retrograde) cases higher gradient (29-43°C/km), low-pressure type metamorphism differing significantly from the Barrovian first event was evidenced. CaO FeO MgO ? • • • JÓ

M P m Fig. 6 Composition mapping of garnet porphyroclasts in blastomylonite sample No. Kaba-D4. 1/b Mainly in the Kaba-S region, and locally, in bores Kism-3 and Aim4. the retrograde recrystallization was preceded by cataclastic metamorphism (mylonite formation). The grade of the recrystallization following the cataclastic (shearing) deformation and crushing varied from the chlorite-zone ( < 400-450°C, bore Alm-4.) up to the garnet-zone ( ~480-500°C, bore Kaba-D-2, Plate 111:4) having reached generally the biotite-isograde (~400-450°C). Some textural features of blastomylonites with typical mineral associations of quartz, albite, biotite II, muscovite II j" garnet II are illustrated on Plates II: 3-4 and III: 1-2. With increasing T mica schist-like rocks were formed in which the recognition of the porphyroclasts (mylonite texture) turns to be more and more uncertain. Besides the morphological features (asymmetric position of the inclusion-rich core, irregular shape, see Plate 111:2-3) the porphyroclastic character can be proved by computer programmed, semi-quantitative composition mapping of large garnet grains. Some types of asymmetric composition zoning in lense-