Chromian spinels from the Magura Unit (Western Carpathians, Eastern Slovakia) – their petrogenetic and palaeogeographic implications

• DOI: 10.7306/gq.1292
• Publication Date: 2016-07-28T05:22:24Z
• Authors: Katarína BÓNOVÁ; Ján SPIŠIAK; Ján BÓNA; Martin KOVÁČIK
• Keywords: Forearc; Ultramafic rock; Siliciclastic

Detrital chromian spinels in sedimentary rocks provide much information concerning the tectonics of their parental ultrabasic rocks. Chromian occurring Eocene to Oligocene deposits from Magura Nappe were examined some constraints on history Basin. The is a part Flysch Belt belonging External Western Carpathians. separated by narrow zone associated with Pieniny Klippen and divided into three principal tectono-lithofacies units (from S N): Krynica, Bystrica Rača units. Cr-spinel common accessory mineral (2.3–5.9 vol% heavy spectra) siliciclastic Krynica In terms texture chemical composition, two types Cr-spinels recognized: unaltered altered. Unaltered found contain silicate inclusions such as chromio-pargasite, enstatite, diopside, pargasite, plagioclase olivine (forsterite). show wide variations compositional parameters Cr# (0.3–0.7), Mg# TiO2 (<0.03–1.9 wt.%) Fe 2+ /Fe 3+ (2.5–13) whereas differences between are insignificant. These suggest peridotitic volcanic origin spinels, respectively. ophiolite source consisting harzburgitic mantle peridotites was developed mainly supra-subduction setting; indicate an mid-ocean ridge basalts, back-arc basin basalts sporadically ocean-island basalts. Concerning geochemical features, we propose that during Early Oligocene, ophiolitic detritus eastern Basin may have been derived area located Fore-Marmarosh Suture Zone (Eastern Carpathians) considered equivalent Black Ceahlau Some successions resedimented older Late Cretaceous-Paleocene formations Unit, which reworked material Belt.