INHERITED ZIRCONS OF AN ANISIAN TUFFITE FROM THE SILICA NAPPE (NE HUNGARY): EVIDENCE FOR A HIDDEN CAMBRIAN BASEMENT IN THE TETHYS REALM - Carpathian Journal of Earth And Environmental Sciences

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Felicitász VELLEDITS¹, Péter KOVÁCS-PÁLFFY² & Wolfgang DÖRR³
¹ Limestone Bt., 2120 Dunakeszi Andrássy Gy. U. 6, Hungary, e-mail: fvelledits@freemail.hu
² Geological Institute of Hungary, 1143 Budapest, Stefánia u.14, e-mail: kovacs@mafi.hu
³ Institut für Geowissenschaften, Altenhöferallee 1D-60438 Frankfurt Germany, e-mail: w.doerr@em..uni-frankfurt.de

INHERITED ZIRCONS OF AN ANISIAN TUFFITE FROM THE SILICA NAPPE (NE HUNGARY): EVIDENCE FOR A HIDDEN CAMBRIAN BASEMENT IN THE TETHYS REALM

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Abstract: A tuffite of Illyrian age containing inherited zircons is present at the base of the Middle Triassic (Anisian) platform carbonate sequence in the Silica Nappe of NE Hungary. The original aim of the study was to date the zircons using the U-Pb Isotopic-Dilution-TIMS method, thereby making the age determination from fossils more precise by establishing the absolute age of the zircons. The upper intercept age of the zircons is 502-23/+26 Ma, which most probably refers to the age of the basement of the Silica Nappe and not the age of the reef because the zircons are inherited. The original basement of the Silica Nappe is today unknown, but the nearest volcanites of similar age are known from the Gelnica unit of the Gemericum in the Vlachovo Formation (Slovakia) which are mostly acid metavolcanics of Late Cambrian-Ordivician age.

Keyword: Middle Triassic, Aggtelek-Rudabánya Mts, U-Pb Isotopic-Dilution-TIMS method for single zircons, X-ray diffraction analyses.