Spinifex‐like textured metaperidotites from the Higo Metamorphic Rocks (HMR), west‐central Kyushu, Japan, may be formed by high‐pressure dehydration of antigorite, and may indicate deep subduction of serpentinite reaching a pressure–temperature condition of 1.6 GPa and 740–750 °C. Three rock types have been identified based on mineral assemblage and rock texture: Type I (L) consisting of medium‐grained (1–5 cm long) olivine + enstatite + chromite ±tremolite with secondary talc and anthophyllite that occurs in low‐grade metamorphic rocks of the biotite zone, Type I (H) of coarse‐grained (up to 10 cm long) olivine + enstatite (with clinoenstatite lamella) + chromite ±tremolite with secondary talc that occurs in high‐grade metamorphic rocks of the garnet‐cordierite zone, and Type II composed of Al‐spinel + chlorite + olivine + apatite + ilmenite with minor sodic gedrite in the garnet‐cordierite zone together with Type I (H). Olivines in all rock types are mostly serpentinized during exhumation. The chromite‐olivine thermometer gives 560–690 °C for Type I (L) rocks, and the spinel‐olivine thermometer gives 610–740 °C for Type II rocks. The peak metamorphic pressure will be higher than 1.6 GPa based on the location of the experimentally determined invariant point (P = 1.6 GPa and T = 670 °C) of antigorite + forsterite + enstatite + talc + H₂O. This estimate is consistent with the occurrence of chlorite in Type II rocks, which is stable up to 890 °C at 2.0 GPa. The spinifex‐like textured metaperidotites occur as small bodies in the low P/T type gneisses, implying tectonic juxtaposition of them probably during exhumation of the HMR. Recent findings of medium pressure (0.9–1.2 GPa) granulites and gneisses from the HMR may indicate that the HMR has a deep root into the wedge mantle from which the spinifex‐like textured metaperidotites have derived.

中文翻译：

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来自日本Higo变质岩的Spinifex样质变质橄榄岩，可能是反蛇纹石蛇纹岩的高压脱水产物

来自日本九州中西部肥后变质岩（HMR）的Spinifex样质变质橄榄岩，可能是由蛇纹石的高压脱水作用形成的，可能表明蛇纹岩的深层俯冲作用达到了压力温度为1.6 GPa和740的条件–750°C。根据矿物组成和岩石质地，已鉴定出三种岩石类型：I（L）型，由中等粒度（1-5 cm长）的橄榄石+顽辉石+亚铬酸盐±透闪石和次滑石和直闪石组成，发生在低品位变质中黑云母带的岩石，粗晶（长至10 cm）的I型（H）橄榄石+顽辉石（含斜长石片晶）+亚铬酸盐±次闪石，其次生滑石发生在石榴石-堇青石的高级变质岩中区，II型由Al-尖晶石+亚氯酸盐+橄榄石+磷灰石+钛铁矿组成，在石榴石-堇青石带中有少量钠铁钠盐，以及I型（H）。各种岩石类型的橄榄石在尸体挖掘过程中大多是蛇纹石化的。对于I型（L）岩石，铬铁矿-橄榄石温度计可提供560-690°C的温度；对于II型岩石，尖晶石-橄榄石温度计可提供610-740°C的温度。根据实验确定的不变点的位置，峰值变质压力将高于1.6 GPa。P =为1.6GPa和Ť = 670°+叶蛇纹石镁橄榄石+顽火辉石+滑石+ H的C）₂ O.这估计是用亚的在II型岩石的发生，这是稳定高达890℃，在为2.0GPa一致。在低P / T型片麻岩中，棘形的纹理化的橄榄岩橄榄石以小物体的形式出现，这意味着它们的构造并列可能是在HMR挖掘过程中。HMR中压（0.9-1.2 GPa）中的花岗石和片麻岩的最新发现可能表明，HMR在楔形地幔中具有深厚的根源，而该楔形地幔中衍生出了如刺针状的质变橄榄岩。