P-T-t path of the lower crust in The Hercynian fold belt of southern Calabria
P-T-t path of the lower crust in The Hercynian fold belt of southern Calabria
复制标题
卡拉布里亚南部海西褶皱带下地壳的P-T-t路径
DOI：
--
复制
发表时间：
1989
期刊：
影响因子：
--
通讯作者：
V. Schenk
中科院分区：
文献类型：
--
作者：
V. Schenk
南卡拉布里亚（意大利）是世界上少数几个暴露出大陆地壳倾斜部分的地方之一（Schenk 1980、1981、1984）。超过约 50 公里（图 1），人们可以追踪到一系列岩石序列，从麻粒岩相和上角闪岩相岩石（即下地壳岩石）到花岗岩，一直到角闪岩绿片岩相和未变质沉积岩。在海西造山运动期间，岩石发生变质并部分隆起，但最终向上倾斜到地表发生在亚平宁造山旋回期间。本文研究的是卡拉布里亚南部地壳部分的前下部，厚度约为 7-8 公里。通过岩石学和地质年代学方法重建了两条独立的 P-T-t 路径：一条路径用于前下地壳下部较热的部分，另一条路径用于上部较冷的部分。岩性 卡拉布里亚下地壳部分由两个不同的岩性单元组成（图 1）。下部单元（麻粒岩-黄铁矿单元）由变基性岩和少量长英质麻粒岩以及一些明显地壳起源的变泥质岩和偏碳酸盐岩透镜体组成。上部单元（变钙岩单元）位于南部，主要由混合岩铝质片麻岩组成，夹有变基性岩和偏碳酸盐岩。在这个单元中，可以追踪超过 10 公里的单一、标记清晰的碳酸盐岩和 Grt-Sil 片麻岩层位，表明地层保存完好。变泥质岩单元上方是闪长质片麻岩单元，具有变基性岩和变泥质岩透镜体。峰值变质作用 下地壳内的变质梯度 在长英质中
Southern Calabria (Italy) is one of the few places in the world where a tilted section through the continental crust is exposed (Schenk 1980, 1981,1984). Over about 50 km (Fig. 1), one can trace a rock sequence ranging from granulite- and upper amphibolite-facies rocks (i.e. lower crustal rocks) through granitoids, up to amphibolite-greenschist facies and unmetamorphosed sedimentary rocks. The rocks were metamorphosed and partially uplifted during the Hercynian orogeny but the final tilting up to the surface occurred during the Apenninic orogenic cycle. The present paper deals with the former lower part of the southern Calabrian crustal section, which is about 7–8 km thick. Two separate P-T-t paths have been reconstructed by petrological and geochronological methods: one path for the lower and hotter part of the former lower crust, and another for the upper, colder part. Lithology The Calabrian lower crustal section is built up of two distinct lithological units (Fig. 1). The lower unit (granulite-pyriclasite unit) comprises metabasic rocks with minor felsic granulites and some lenses of metapelitic and metacarbonate rocks of clearly epicrustal origin. The upper unit (metapelite unit) lies to the south and consists mainly of migmatitic aluminous paragneisses with intercalations of metabasic and metacarbonate rocks. In this unit, single, well-marked, horizons of carbonatic rocks and Grt-Sil gneisses can be traced over more than 10 km, suggesting a well-preserved stratigraphy. Above the metapelite unit is a dioritic gneiss unit with lenses of metabasic and metapelitic rocks. Peak metamorphism Metamorphic gradient within the lower crust In the felsic