Pressure-temperature trajectory of the Sanbagawa metamorphism deduced from garnet zoning
Pressure-temperature trajectory of the Sanbagawa metamorphism deduced from garnet zoning
复制标题
从石榴石分带推导的三波川变质作用的压力-温度轨迹
DOI：
10.1016/0024-4937(86)90015-0
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发表时间：
1986
期刊：
影响因子：
3.5
通讯作者：
T. Higashino
中科院分区：
文献类型：
--
作者：
S. Banno;C. Sakai;T. Higashino
三八川泥质片岩中，小体积石榴石多为同时成核、生长，然后停止生长，与绿泥石、黑云母等共生矿物在进变质过程中保持近平衡。在三元MnFeMg体系中，分带石榴石的化学变化趋势按变质品位递增的顺序，有系统地由贫焦石向富焦石转变。三元（MnFeMg）模式体系表明，在前向变质过程中，高品位石榴石比低品位石榴石在较低的压力和较高的温度下开始生长。结果表明，高变质作用发生在三国中部三巴川变质地的石榴石-少长岩-黑云母带较低压力下。
Most garnets in a small volume of the pelitic Sanbagawa schists nucleated simultaneously, grew, and then ceased with their growth, maintaining near-equilibrium with coexisting minerals such as chlorite and biotite during the prograde metamorphism.Chemical trends of zoned garnets systematically shift from the pyrope-poor to pyrope-rich portions in a ternary MnFeMg system in order of ascending metamorphic grade.A ternary (MnFeMg) model system suggests that the higher-grade garnets started to grow at lower pressures and higher temperatures than the lower-grade ones during prograde metamorphism. It follows that high-grade metamorphism took place at lower pressures in the garnet to oligoclase-biotite zones of the Sanbagawa metamorphic terrain in central Shikoku.