Paleofluid Fingerprint as an Independent Paleogeographic Correlation Tool: An Example from Pennsylvanian Sandstones and Neighboring Crystalline Rocks (Tisia Composite Terrane, S Hungary)

Abstract

In the basement areas of the southern Pannonian Basin, Central Europe (Tisia Composite Terrane, Hungary), Variscan blocks are essential components. The existing paleogeographic reconstructions, however, are often unclear and contradictory. This paper attempts to give a contribution for paleogeographic correlation of the Tisia using paleohydrological features (e.g., vein mineralization types, inclusion fluid composition and origin) of the Pennsylvanian continental succession and neighboring crystalline complexes. Vein-type mineralization in the studied samples dominantly forms blocky morphological types with inclusion-rich quartz and carbonate crystals. The evolution of hydrothermal mineralization and host rock alteration in the study area comprises three major stages. The first one is characterized by chloritization, epidotization, and sericitization of metamorphic rocks together with subsequent formation of Ca-Al-silicate and quartz-sulfide veins (clinopyroxene-dominant and epidote-dominant mineralization). The related fluid inclusion record consists of high-temperature and low-salinity aqueous inclusions, corresponding to a reduced retrograde-metamorphic fluid phase during the Late Westphalian (~310 Ma). The next mineralization stage can be related to a generally oxidized alkaline fluid phase with a cross-formational character (hematite-rich alkali feldspar-dominant and quartz-dolomite veins). High-salinity primary aqueous inclusions probably were originated from the Upper Permian playa fluids of the region. The parent fluid of the third event (ankerite-hosted inclusions) was derived from a more reductive and low-salinity environment and can represent a post-Variscan fluid system. Fluid evolution data presented in this paper support that the W Tisia (Mecsek–Villány area) belonged to the Central European Variscan belt close to the Bohemian Massif up to the Early Alpine orogenic phases. Its original position is presumably to the northeast from the Bohemian Massif at the Late Paleozoic, north to the Moravo-Silesian Zone. The presented paleofluid evolution refines previous models of the paleogeographic position of the Tisia and puts constraints on the evolution of the Variscan Europe.

Revealing the Mineralogical and Petrographic Signs of Fluid-Related Processes in the Kelebia Basement Area (Szeged Basin, S Hungary): A Case Study of Alpine Prograde Metamorphism in a Permo-Triassic Succession

“…The Szeged Basin is a subbasin on the southern margin of the Pannonian Basin in Hungary (Figure 1(a)). Within it, the pre-Cenozoic basement belongs structurally to the Tisza megaunit (Tisia Composite Terrane, as referred elsewhere [11,18]), which traditionally comprises four main nappe systems of Alpine origin formed in the Albian to Turonian (from bottom to top): Mecsek, Bihor, Codru, and Biharia [3,[14][15][16]19]. In the Hungarian part of the Tisza megaunit, the Mecsek, Bihor (Villány-Bihor), and Codru (Békés-Codru) Nappe Systems are only found [14][15][16][19][20][21].…”

“…For Lower Triassic siliciclastic sedimentary rock characterization, core samples from the exploration well Mórahalom-1 (well Móra-1, Móra field) were examined (Figure 2). The available core section #17 (Jakabhegy Sandstone Formation) from [3,[14][15][16]18]. Abbreviations: ALCAPA: Alpine-West Carpathian-Pannonian block; M: Mecsek Hills; S: Slavonian Mts; V: Villány Hills; HRV: Croatia; HUN: Hungary; ROU: Romania; and SRB: Serbia.…”

Structural Controls on Basin- and Crustal-Scale Fluid Flow and Resulting Mineral Reactions

“…Also focusing on the Pannonian Basin, Fintor and Varga [35] propose new paleogeographic reconstructions of Variscan basement blocks based on the fingerprints (veins and their fluid inclusions) of paleohydrological systems of the Tisia terrane. Their study of veins, dominated by quartz and carbonate minerals, and their host rock alterations, reveals three stages of fluid flow and mineral reactions.…”

“…Their study of veins, dominated by quartz and carbonate minerals, and their host rock alterations, reveals three stages of fluid flow and mineral reactions. By reconstructing the paleofluid flow evolution of the area, Fintor and Varga [35] conclude that the systems of the Hungarian part of the West Tisia area match the characteristic hydrothermal events of the Central European Variscan belt. They propose that this system belonged to the Bohemian Massif until the onset of the Alpine orogeny, and that its Late Paleozoic position was north of the Moravo-Silesian Zone.…”