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Northern Madagascar


Perhaps the most remarkable period of change on Earth is the time represented by the end of he Proterozoic eon and is transition into the Phanerozoic (~1000-545 Ma). This is a period when major tectonic, geochemical and biologic events occurred on a global scale. In an attempt to link these changes to a common cause, scientists have recently postulated that Earth experienced a radical shift in the distribution of continents-the breakup of a Proterozoic landmass (Rodina, ~1000 Ma) and its whole-scale reassembly into another 'supercontinent' called Gondwanaland - about 540 Ma ago.
During the field-season 2000 Professor Tucker together with his graduate student Robert Buchwaldt are going to work in wild and remote mountains of north Madagascar; a part of the island inhabited by chameleons and lemurs, and dotted with vanilla plantations, orchid farms and shrinking rain forests. In the last couple of years scientists from the Washington University, St. Louis have discovered a new geological suture in northernmost Madagascar that joins a previously unidentified volcanic arc terrane against Archean rocks of East Gondwana. These rocks within the suture zone are associated with middle to high grade metamorphism and plutonism. These metamorphic and igneous rocks contain within their mineralogy and mineral fabrics, a memory of pressure (P), temperature (T), fluid activity (C) and time (t) of crust forming and mountain building processes. A knowledge of these relationships of time with respect to P and T are crucial to our understanding of the magnitude and the rate of change of dynamic processes of the Earth's crust.