THE OPHIOLITIC MELANGE IN THE GJILAN REGION (KOSOVE) IS THE SUPRA-OPHIOLITIC SEDIMENTARY MELANGE OR INFRA-OPHIOLITIC TECTONIC MELANGE?

Autor: Fejza, Islam, Meshi, Avni, Muceku, Bardhyl, Tmava, Ahmet, Utu, Andrea, Avdullahi, Sabri, Meha, Murat
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Zdroj: Proceedings of the International Multidisciplinary Scientific GeoConference SGEM; 2011, Vol. 1, p297-304, 8p
Abstrakt: Dinarido-Albanido-Hellenic folded alpine belt is interpreted as a result of Mesozoic - Cenozoic convergence and continental collision of a series of micro-blocks localized between the Eurasian and African plates. The ophiolites of the Balkan Peninsula are particularly formed in the ocean basins which were divided by micro-continents during the Mesozoic period and they are products of the Mesozoic - Cenozoic obduction. The Vardar Ophiolites from the region of Gjilan are covered by a chaotic sequence, well stratified, including the ophiolitic melange. In the region of Gjilan, the Ophiolitic constituens are the upper part of the stratified gabbros, isotropic gabbros and a dolerite dike-complex. The geochemical analysis (unpublished data) of the dolerite dike -- complex confirm a normal composition MORB - type rocks. After mapping (1: 25000) the region of Gjilan [1], we have concluded that the ophiolitic melange is placed on gabbros, on the parallel dike-complex and on the granites that are mainly intruded in parallel dolerite-dikes. This melange consists of a marl -- clay matrix and interbedded sandstones. The blocks are mostly represented by basalt from a few meters to a few tens of meters in size. There are also limestone blocks, meta-sandstones etc. This succession is followed by pelagic sediments represented by breccias limestones, marls and typical radiolarites of turbidites. In the micrite to pelmicrite breccias limestones the presence of Crescientiella morronensis confirm the Upper Jurassic age. The limestones with siliceous intercalations show benthic small foraminifera assemblages characteristics of the Upper Jurassic age. In the top of this sedimentary melange (the sediments show the characteristics of a true flysche where the thickness of limestone layers is around 100m). The age is Upper Jurassic. The entire sequence is closed by a massive limestone with clayly-marly intercalations. The structural relations of the sedimentary melange with the ophiolites situated below and the litostratigraphic evidence of this sedimentary melange of Gjilan region suggest their sedimentary origin and not their tectonic origin [2]. The structural and kinematic data concerning the metamorphic rock of the Dardania zone show the evidence of a transport of the ocean slab towards the northeast. [ABSTRACT FROM AUTHOR]
Databáze: Complementary Index