Collaborative Research: Petrotectonic Study of Ultrahigh-Pressure Rocks From the Kokchetav Massif, Northern Kazakhstan, and the Maksyutov Complex...

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9725347 Liou This proposed U.S.-Japan-Russia-Kazakhstan cooperative project will continue field, petrologic, stable, isotopic, geochronologic, and tectonic investigations of intracratonal ultrahigh-pressure and high-pressure metamorphic rocks in the Kokchetav Massif and the Maksyutov Complex, where coesite ( microdiamonds have been described. Primary objectives are to: (1) determine the regional distribution and structural relationships among diamond-bearing gneiss and marble, coesite-bearing eclogite and gneiss, and other UHP and HP rocks in the Kokchetav Massif and the Maksyutov Complex; (2) identify and characterize the mineral inclusions in garnet and zircon from eclogite, gneiss, marble, and schist to establish conditions of UHP metamorphism and the effect of such elevated pressures; (3) delineate mineral parageneses and P-T-t paths for eclogite, whiteschist, garnet peridotite, blueschist, gneiss and marble; (4) characterize 18O/16O ratios of silicates and carbon isotopes of diamond, magnesite, and other carbonates in order to evaluate the role of fluids at mantle depths; (5) determine the structural and geochemical characteristics of protoliths in order to infer their plate tectonic settings; (6) establish the ages of blueschist, eclogite, and retrograde metamorphism through U-Pb and 40Ar/39Ar dating; and (7) compare findings from central Asia with those from eastern China in order to elucidate the genetic relationships among recognized metamorphic, igneous, and tectonic features.