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

9725347 Liou这个拟议的美日俄哈合作项目将继续对Kokchetav地块和Maksyutov杂岩中的克朗内超高压和高压变质岩进行野外、岩石学、稳定性、同位素、年代学和构造研究，其中已描述柯石英(微钻石)。主要目标是：(1)确定Kokchetav地块和Maksyutov杂岩中含金刚石片麻岩和大理岩、含柯石英榴辉岩和片麻岩以及其他超高压和高压岩石之间的区域分布和构造关系；(2)从榴辉岩、片麻岩、大理岩和片岩中识别和表征石榴石和锆石中的矿物包裹体，以建立超高压变质作用的条件和这种高压的影响；(3)圈定榴辉岩、白片岩、石榴石橄榄岩、蓝片岩、片麻岩和大理岩的共生矿物和P-T-T路径；(4)确定硅酸盐的~(18)O/~(16)O比值和金刚石、菱镁矿等碳酸盐的~(18)O/~(16)O，以评价地幔深部流体的作用；(5)确定原岩的结构和地球化学特征，以推断其板块构造环境；(6)通过U-Pb和~(40)Ar/~(39)Ar测年确定蓝片岩、榴辉岩和退变质作用的年龄；(7)将中亚的发现与中国东部的发现进行比较，以阐明已识别的变质岩、火成岩和构造特征之间的成因关系。

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.