中文摘要：

在藏东南错那县西南约20km的麻玛沟中发现了呈透镜体产出于石榴石矽线石片麻岩中的石榴辉石岩，其矿物组合为石榴石＋透辉石＋石英＋铁角闪石＋磁铁矿，并含有锆石、磷灰石等副矿物。石榴石呈他形产出，以铁铝榴石和钙铝榴石端员组分为主，贫镁铝榴石组分，并具成分环带：核部相对富铁铝榴石分子，贫镁铝榴石分子，而边部则相反。透辉石同样富铁、贫镁，Fe^2＋／（Fe^2＋Mg）比值一般大于0．6。铁角闪石呈熔蚀状被透辉石和石榴石所包裹，或产出于自形的透辉石颗粒之间，以贫钛为特征。该岩石的全岩成分以SiO2（59％～61％）、Fe2O3（全铁）（18％～19％）、CaO（12％～13％）和Al2O3（5．3％～5．4％）为主。运用石榴石一单斜辉石温压计估算出该岩石石榴石与透辉石的平衡温压条件分别为650～700℃、0．8～1．0GPa。这些特征表明该石榴辉石岩很可能系富铁的斜长角闪岩存中地斋尺度发生所形成的残余。本文研究提供了一个角闪岩相石榴辉石岩的实例。

英文摘要：

Garnet clinopyroxenites were found in Mama valley of Cona area, southeastern Tibet. They are enclosed as lenses in the garnet sillimanite gneisses of the Greater Himalayan Crystallines and consist of Fe-rich anhedral garnet, diopside with high Fe^2＋/（Fe^2＋ ＋ Mg） ratio, quartz, Ti-poor ferrohomblende and magnetite, together with such accessory minerals as zircon and apatite. The garnet grains somewhat exhibit zoning patterns formed in the prograde metamorphism. Whole-rock compositions of the garnet clinopyroxenites are charactenzea by high SiO2（59%--61%）, Fe2O3（18%--19%, total iron）, CaO （12%--13%）and A1203（5.3%--5.4%）. Solid-Dhase thermobarometrv reveals recrystallization of the garnet and diopside at temperature of 650-700℃ and pressure of 0.8- 1.0 GPa. Texture, mineral paragenesis and compositions, therefore, indicate probable derivation of the garnet clinopyroxenites from dehydration-driven partial melting of Fe-rich amphibolites in the middle crustal levels. Thus an example of amphibolite facies garnet clinopyroxenites is presented in this study.