北大别罗田榴辉岩的减压出溶结构与超高压变质作用

Breakdown textures the eclogites from the and ultrahigh-pressure metamorphism of Luotian Dome in the North Dabie Complex

岩石学研究表明北大别罗田榴辉岩经过了榴辉岩相、麻粒岩相和角闪岩相变质作用，表现出多种减压出溶结构。特征性的减压出溶结构有单斜辉石和石榴石中分别发育石英＋角闪石＋斜长石等与金红石＋单斜辉石＋角闪石等针状矿物出溶体，以及锆石中含有柯石英残晶。这些进一步证明北大别南部（罗田一带）同北部（如黄尾河、百丈岩等地）榴辉岩一样经过了〉5～7GPa的超高压变质作用。

Metamorphic petrology of eclogites was carried out at Luotian in southwestern part of the North Dabie Complex（NDC） , central China. The results suggested that the eclogites experienced eclogite-, granulite- and amphibolite-facies metamorphism, and displayed multistage breakdown textures. The most striking features of breakdown textures were presence of exsolution of different phases in pyroxene and garnet from the studied eclogites. In particular, we documented the exsolution of rutile ＋ clinopyroxene ＋ amphibole ＋ apatite being discovered in the sodic garnet and quartz ＋ amphibole ＋ sodic plagioclase in the clinopyroxene respectively, and rare coesite relics being discovered in the zircon. All these implied that the eclogites around Luotian area from southern part of the NDC should be similar to those from northern part of the NDC（e. g. Huangweihe and Baizhangyan）and suffered Triassic UHP metamorphism with a possible pressure of 〉 5 -7 GPa.