FORMATIVE PROCESSES AND EXHUMATION TECTONICS OF HIGH-TEMPERATURE METAMORPHIC BELTS IN ISLAND ARCS

1)日高变质带研究：通过对日高带麻粒岩相变质岩英云闪长质岩浆部分熔融和生成条件及过程的分析，揭示了岛弧地壳深部的热结构及岩浆对变质作用的影响。结合研究结果，提出地壳深熔作用的起始深度制约着地壳中地壳规模滑脱作用的形成深度。2）辽辽变质带研究：通过对辽变质带主要变质区的原始岩性、构造和构造变质史的研究，明确了以下几个方面的问题; 1）原始岩性包括硅质碎屑岩序列、泥砂岩胶结层、破碎层、混杂岩等。2)变形阶段划分为D_1（压扁，具S_1叶理）、D_2（局部剪切，具叶内褶皱和剪切面S_2，并伴有俯冲变质）、D_3（局部剪切，具S_1叶理）、D_4（局部剪切，具S_1叶理）、D_5（局部剪切，具S_2叶理）、D_6（局部剪切，具S_2叶理）、D_7（局部剪切，具S_3叶理）、D_8（局部剪切，具S_3叶理）、D_9（局部剪切，具S_2叶理）、D_9（局部剪切，具S_3叶理 关于我们 通过对热结构和加热过程的分析和数值模拟，证实了同变质花岗质侵入岩的热源作用。CHIME独居石年龄测定结果表明，变质年龄为100 Ma，花岗质侵入体从95 Ma延续到80 Ma。侵入时代不存在自西向东的缩短趋势，而K-Ar年龄的缩短趋势则意味着自西向东的不断折返。3）东后片麻岩区的研究：发现含辉绿-富辉的过铝质岩石呈块状产出，包夹在蛇纹岩中。Nd-Sm和SHRIMP锆石年龄表明，该变质带形成于250 Ma，并经历了Ryoke期的多变质热作用。4）对该带高温变质带的烃源岩进行了研究，明确了沉积岩的性质和源区;早元古代至晚元古代的碎屑岩被包括在Ryoke带的副片麻岩中，就像在组成侏罗纪增生杂岩的沉积岩中一样。少

1) Study of the Hidaka metamorphic belt : Thermal structure and effects of magma to metamorphism in the deep island arc crust was revealed based on the analyzes of conditions and processes of partial melting and generation of tonalitic magma of granulite facies metamophic rocks in the Hidaka belt. Related to the results, it is proposed that the depth of initiation of crustal anatexis constraints the depth of crustal scale decollement formed in the crust.2) Study of the Ryoke metamorphic belt : The following aspects were made clear according to the studies of original lithology, structures and tectono-metamorphic histories in major metamorphic fields of the Ryoke belt ; 1) the original lithology involves chert-clastic sequence, coherent strata of shale and sandstone, broken formation, and melange. 2) deformational stages are defined as D1 (flattening with S1 foliation), D2 (local shearing with intrafolial folds and shear planes S2 accompnied with prograde metamorphism), D3 (local sheari … More ng with retrograde metamorphism) and D4 (shortening with upright folds and crenulation cleavages).The thermal structure and heating process were analyzed and numerically sumilated to confirm that syn-metamorphic granitic intrusives playd as a heat source. CHIME monazite age determinations have been advanced and showed that the metamorphic age is 100Ma, and granitic intrusions were continued from 95Ma to 80Ma. There is no younging trend of intrusive age from west to east of the Ryoke belt, while the younging trend of K-Ar ages so far advocated implies a continuous exhumation taking place from west to east.3) Study of the Higo gneiss region : Saphilline-corundum bering peraluminous rocks were found to occur as blocks included in serpentinite. The Nd-Sm and SHRIMP zircon ages indicate that the metamorphic rocks were formed at 250Ma, and suffered polymetamorphic thermal effect during the Ryoke period.4) Studies on source rocks of high temperature metamorphic rocks in these belts have been advanced to make clear the nature of sedimentary rocks and their source regions ; Early to late Proterozoic clastics are included in paragneisses in the Ryoke belt as in the sedimentary rocks consisting Jurassic accretionary complex. Less