23 Undergraduate Student Research (Posters)

Tuesday, 10 March 2020
8:30 AM - 5:00 PM
Ballroom B

TIMING OF RIFTING IN THE CENTRAL WESTERN CARPATHIANS POST-VARISCAN OROGENY AND AGES OF SEDIMENTS OVERLYING MELIATA OCEAN OPHIOLITES (SLOVAKIA)

Paper number: 23-6
Program: Theme Sessions
Time: 8:30 AM – 5:00 PM

Authors

Abstract

Slovakia is located within the Central Western Carpathians (CWC), one of many connected curved mountain belts prominent throughout the Mediterranean area and Europe. Its geology is divided into tectonic domains considered “superunits,” termed the Gemeric, Veporic, and Tatric that correlate to the lower, middle, and upper Austoalpine nappes. The Gemeric has a debated history obscured by vegetation. For example, granite bodies exposed in the unit (termed apophyses) yield a wide range of zircon ages from 310±21 Ma to 87±4 Ma. This range of ages leads to problems in deciphering where the Gemeric unit was located in global plate reconstructions of eastern Europe and the western Carpathians specifically. This case study involves U-Pb dating of magmatic and detrital zircons from the Gemeric tectonic unit. This area records the Variscan orogeny that formed the CWC, rifting, and opening of the Meliata Ocean. This ocean was created due to the formation of a back-arc basin during closing/subduction of the Paleo-Tethys Ocean. We aim to constrain the timing of rifting and identify the provenance of Meliata Ocean radiolarian sediments collected from an obducted Meliata ophiolite suite (Dobsina, Slovakia). The relative age of the Variscan orogeny extends from the late Devonian to early Permian and was followed by rifting throughout the Mesozoic within the CWC. Eventually, the Meliata Ocean closed during the Cretaceous. Zircons from several S-type granites were collected throughout the Gemeric tectonic unit as part of an NSF-International Research Experiences for Students program. The grains were dated using Laser Ablation Inductively Coupled Plasma Mass Spectrometry and imaged using cathodoluminescence. Rim crystallization ages from the granites are 295.8±3.4 Ma (2σ, 238U-206Pb) to 213.1±4.4 Ma. The oldest age likely times the initiation of rifting after collision, whereas the youngest age demonstrates that magmatism stretched into the late Triassic. Ages from the detrital zircons are 346.4±4.5 Ma to 263.9±2.7 Ma, indicating that sediments overlying the Meliata Ocean ophiolite contain remnants of both the Variscan orogeny and Gemeric granites.

Geological Society of America Abstracts with Programs. Vol. 52, No. 1

doi: 10.1130/abs/2020SC-343818

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