ABSTRACT

Neoproterozoic and Palaeozoic rocks of the Mérida Massif (SW Iberia) have been grouped into tectonostratigraphic units. Each unit is separated from the rest ones by either crustal-scale thrusts and/or extensional detachments. The lowermost unit (Magdalena Gneisses; lower plate) has continental crust affinity, and rest below a mafic-ultramafic ensemble, referred to as the Mérida Ophiolite (suture zone). The Serie Negra Group constitutes a unit with continental crust affinity (Upper Schist-Metagranitoid Unit; upper plate) located on top of the Mérida Ophiolite. A carbonate-rich succession (Carija Unit) occupies the uppermost structural position. Structural and previous isotopic data suggest that this suture zone was formed during the Cadomian Orogeny. Superimposed shortening during the late Palaeozoic formed upright to NE-verging folds and thrusts that affected this suture zone and juxtaposed it onto Ordovician strata during the Variscan Orogeny. The Mérida Ophiolite represents a new Cadomian suture zone exposure in the Gondwanan realm of the Iberian Massif, but its root zone is yet to be identified. This ophiolite shares a far-travelled nature with other Cadomian and Variscan suture zone exposures in Iberia, making the latter a piece of lithosphere built through inland transference of allochthonous terranes from peri-Gondwana onto mainland Gondwana during the Neoproterozoic-Cambrian and the Devonian-Carboniferous periods.

摘要

梅里达地块（伊比利亚西南部）的新元古代和古生代岩石被归类为构造地层单元。每个单元通过地壳尺度逆冲和/或伸展分离与其他单元分开。最下部的单元（马格达莱纳片麻岩；下板块）具有大陆地壳亲和力，位于镁铁质-超镁铁质系综之下，称为梅里达蛇绿岩（缝合带）。Serie Negra Group 构成一个位于梅里达蛇绿岩顶部的具有大陆地壳亲和力的单元（上片岩-变花岗岩单元；上板块）。一个富含碳酸盐的层序（Carija Unit）占据了最上部的构造位置。结构和以前的同位素数据表明，这个缝合带是在卡多姆造山运动期间形成的。在古生代晚期叠加的缩短形成了直立到 NE 边缘的褶皱和冲断层，影响了这个缝合带，并在华力斯坎造山运动期间将其并列到奥陶系地层上。梅里达蛇绿岩代表了伊比利亚地块冈瓦南地区新的卡多米亚缝合带暴露，但其根带尚未确定。这种蛇绿岩与伊比利亚的其他卡多米亚和瓦力斯坎缝合带暴露具有广泛的性质，使后者成为新元古代-寒武纪和泥盆纪-石炭纪期间，通过从冈瓦纳周边的异地地体向冈瓦纳大陆的内陆转移而形成的一块岩石圈期间。梅里达蛇绿岩代表了伊比利亚地块冈瓦南地区新的卡多米亚缝合带暴露，但其根带尚未确定。这种蛇绿岩与伊比利亚的其他卡多米亚和瓦力斯坎缝合带暴露具有广泛的性质，使后者成为新元古代-寒武纪和泥盆纪-石炭纪期间，通过从冈瓦纳周边的异地地体向冈瓦纳大陆的内陆转移而形成的一块岩石圈期间。梅里达蛇绿岩代表了伊比利亚地块冈瓦南地区新的卡多米亚缝合带暴露，但其根带尚未确定。这种蛇绿岩与伊比利亚的其他卡多米亚和瓦力斯坎缝合带暴露具有广泛的性质，使后者成为新元古代-寒武纪和泥盆纪-石炭纪期间，通过从冈瓦纳周边的异地地体向冈瓦纳大陆的内陆转移而形成的一块岩石圈期间。