大别山菖蒲—碧溪岭地区高压—超高压榴辉岩相变质岩和有关岩石的岩石类型及其原岩性质  

Lithology and Protolith of HP-UHP Eclogite Facies Metamorphic Rocks and Relevant Rocks of the Changpu-Bixiling Area, Dabie Mountains

作　　者：程裕淇[1] 庄育勋[2] 高天山[3] 简平[1] 

机构地区：[1]中国地质科学院地质研究所,北京100037 [2]中国地质调查局,北京100029 [3]安徽省地质调查院,合肥23000

出　　处：《地质学报》2002年第1期1-13,T001,共14页Acta Geologica Sinica

基　　金：原地质矿产部重大基础项目"大别造山带高压一超高压变质岩石与区域变质作用研究"(编号9501102-2)的部分成果。

摘　　要：安徽岳西菖蒲—碧溪岭地区出露两条北北西向的高压—超高压变质岩带:西带由土桥冲至菖蒲水电站,该带由层状硬玉石英岩类、大理岩及少量的石英深色榴辉岩以及浅色榴辉岩等组成;东带由小南山岭至碧溪岭,主要由层状的浅色榴辉岩系列和层状深色榴辉岩系列岩石组成。该区发育的层状浅色榴辉岩和层状的深色榴辉岩两种榴辉岩在岩石组合、矿物组合、矿物成分等方面有明显差别。浅色榴辉岩一般由硬玉质绿辉石(Jd 65～45)、+镁铝以及钙铝端元成分(Pyr+Gro,60±)的石榴子石+蓝晶石±多硅白云母±石英及次生的角闪石、绿帘石组成。其中夹有硬玉质绿辉石石英岩、富蓝晶石岩石、石榴子石岩和硬玉石榴白云片岩等岩石薄层。深色榴辉岩由绿辉石(Jd20～50)±富铁铝端元的石榴子石(Alm 50～60)+金红石±石英及次生的角闪石等组成。石英深色榴辉岩由绿辉石(Jd 40～45)+镁铝端元的石榴子石(Pyr 10～30)+石英+金红石及次生的角闪石、长石组成。深色榴辉岩与石榴橄榄岩分布上紧密相随。浅色榴辉岩的原岩为基性凝灰质沉积岩,相伴随的硬玉石英岩、硬玉岩、白云片岩的原岩大致分别为粉砂岩、长石砂岩、泥质粉砂岩;深色榴辉岩为基性凝灰质熔岩。大理岩的原岩为灰岩。同时,本文的研究表明,在相同的变质作用条件下。Two NNW-trending HP-UHP belts are found in the Changpu-Bixiling area, Yuexi County, Anhui Province, The western belt from Tuqiaochong to the Changpu Hydropower Station consists mainly of banded jadeite quartzite and marble with minor quartz-bearing dark eclogite and light-coloured eclogite, and the eastern one from Xiaolanshanling to Bixiling, banded light-coloured eclogite series and dark-coloured eclogite series. The two eclogite series in the area are different in their rock associations, mineral assemblages and mineral com-positions. The light-coloured eclogite is interbanded with jadeitic omphacite quartzite, kyanite-rich rock, gar-netite and jadeite-garnet-white mica schist. The light-coloured eclogite contains jadeitic omphacite (Jd 65~45) + garnet (Pyr + Gro,60 ± ) + kyanite ± phengite ± quartz, with secondary amphibole and epidotite; whereas the dark-coloured eclogite is composed of omphacite (Jd 20~50) + almandine-rich garnet(Alm 50~ 60)+ rutile ±quartz, with secondary amphibole, and the quartz dark-coloured eclogite, omphacite(Jd 40-45) + pyrope-rich garnet(Pyrl0-30)+ quartz + rutile, with secondary amphibole and feldspar. In the field, the dark-coloured eclogite is closely associated with garnet peridotite. The protolith of the light-coloured eclogite is basic tuffaceous sediments, and those of the associated jadeite quartzite, jadeitite and white mica schist are silt-stone, feldspar sandstone and muddy siltstone respectively. The protolith of the dark-coloured eclogite is basic tuffaceous lava. The protolith of marble is limestone. Besides, the chemical compositions of garnet and om-phacite in eclogite facies rocks evidently depend on their protoliths under the same metamorphic conditions.

关 键 词：榴辉岩相岩石 岩石类型 原岩性质 大别山 超高压变质岩 石榴子石 绿辉石 变质作用 

分 类 号：P588.3[天文地球—岩石学]