Constraining the timing and areal distribution of geofluid activities in the crust using high-grade metamorphic rocks

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The brine activity during the early stage of exhumation of the high-grade metamorphic rocks formed at the continental collision zone (ca. 600 Ma, 800oC, 0.8GPa) is detected from the Sør Rondane Mountains (SRM), East Antarctica. The brine activity can be traced somewhat linearly for about 200 km long, and this is the first report of such a large scale brine activity. In the Lützow-Holm Complex (LHC), East Antarctica (850oC, 1.2GPa), brine activity was detected to have accompanied by the partial melting as suggested by the presence of nanogranite inclusions in garnet. On the other hand, brine activity was not detected from the Nepal Himalayas and instead, boron-bearing fluid activity was detected. This difference can be the result of the difference in the depth level of the continental collision zones presently exposed in the SRM or LHC and in Himalayas.