We report the metamorphic press
ure
x2013;temperat
ure (P
x2013;T) history of mafic gran
ulites from two localities in so
uthern India, one from Kanja Malai in the northern margin and the other from Per
und
urai in the central domain of the Palghat
x2013;Ca
uvery S
ut
ure Zone (PCSZ). The PCSZ is described in recent models as the trace of the s
ut
ure along which cr
ustal blocks were amalgamated within the Gondwana s
upercontinent d
uring Late Neoproterozoic
x2013;Cambrian. The mafic gran
ulite from Kanja Malai yields P
x2013;T conditions of 750
x2013;800 °C and 8
x2013;12 kbar reflecting the partially retrograded conditions following a peak high-press
ure (HP) metamorphic event. The common Grt + Cpx + Qtz assemblage in these rocks and lack of decompression text
ure s
uggest that peak metamorphism was probably b
uffered by Grt + Cpx + Opx + Pl + Qtz assemblage, following which the rocks were exh
umed thro
ugh a grad
ual P
x2013;T decrease. The mafic gran
ulite from Per
und
urai (Grt + Cpx + Pl) contains Opx + Pl symplectite commonly occ
urring between garnet and clinopyroxene, s
uggesting the progress of reaction: Grt + Cpx + Qtz → Opx + Pl, with the Grt + Cpx + Qtz representing the peak metamorphic assemblage. The reaction microstr
uct
ures and calc
ulated P
x2013;T conditions s
uggest that the mafic gran
ulites from Per
und
urai
underwent peak HP metamorphism at P > 12 kbar and T = 800
x2013;900 °C and s
ubseq
uent isothermal decompression along a clockwise P
x2013;T path, in contrast to the P
x2013;T path inferred for Kanja Malai. The contrasting P
x2013;T paths obtained from the two localities s
uggest that whereas Per
und
urai is a part of the metamorphic orogen developed within the PCSZ d
uring Gondwana assembly, the high-press
ure gran
ulites of Kanja Malai belong to a different orogenic regime.
In order to evaluate this aspect further, we analyzed zircons in a charnockite and garnet-bearing quartzo-feldspathic gneiss associated with the HP granulites from Kanja Malai which yielded mean up>207up>Pb/up>206up>Pb magmatic protolith emplacement ages of 2536.1 ± 1.4 Ma and 2532.4 ± 3.7 Ma, and peak metamorphic ages of 2477.6 ± 1.8 Ma and 2483.9 ± 2.5 Ma, respectively. These results closely compare with the available magmatic (2530x2013;2540 Ma) and metamorphic (2470x2013;2480 Ma) ages reported from charnockites in the Salem Block at the southern fringe of the Archean Dharwar craton, immediately north of the PCSZ. The Neoarchean/Paleoproterozoic ages obtained from Kanja Malai correlate with the tectonic history at the margin of the Archean craton. Although no age data are available for the Perundurai mafic granulite, the close correspondence of their Px2013;T data and exhumation path with those reported for Late Neoproterozoicx2013;Cambrian HPx2013;UHT metamorphism within the PCSZ suggest that these rocks form part of the Gondwana-forming orogen.