Fingerprinting the Late Pleistocene tephras of Ciomadul volcano, eastern–central Europe

Szabolcs Harangi,Kata Molnár,Theodoros Ntaflos,Mihály Molnár,Réka Lukács,Balázs Kiss,Paul R D Mason,Ágnes Novothny,István Dunkl,Axel K Schmitt,Ioan Seghedi

doi:10.1002/jqs.3177

Abstract

ABSTRACTLate Pleistocene tephras derived by large explosive volcanic eruptions are widespread in the Mediterranean and surrounding areas. They are important isochronous markers in stratigraphic sections and therefore it is important to constrain their sources. We report here tephrochronology results using multiple criteria to characterize the volcanic products of the Late Pleistocene Ciomadul volcano in eastern–central Europe. This dacitic volcano had an explosive eruption stage between 57 and 30 ka. The specific petrological character (ash texture, occurrence of plagioclase and amphibole phenocrysts and their compositions), the high‐K calc‐alkaline major element composition and particularly the distinct trace element characteristics provide a strong fingerprint of the Ciomadul volcano. This can be used for correlating tephra and cryptotephra occurrences within this timeframe. Remarkably, during this period several volcanic eruptions produced tephras with similar glass major element composition. However, they differ from Ciomadul tephras by glass trace element abundances, ratios of strongly incompatible trace elements and their mineral cargo that serve as discrimination tools. We used (U‐Th)/He zircon dates combined with U‐Th in situ rim dates along with luminescence and radiocarbon dating to constrain the age of the explosive eruptions of Ciomadul that yielded distal tephra layers but lack of identified proximal deposits.

Highlights

Tephra layers in terrestrial sediments are often used as key horizons in Quaternary sections because they provide isochronous markers and are a fundamental tool for correlating distant occurrences and yielding absolute age constraints (Lowe, 2011)
The U‐Th dates of the outermost ~4‐μm margin of zircon crystals have a particular relevance, because they provide an upper limit for the eruption age, i.e. the eruption must post‐date the youngest crystallization age
In this study we demonstrate that multiple criteria involving precise geochronological data, petrological and geochemical fingerprinting of volcanic products can be effectively used to characterize the distinctive features of a volcano and/or a volcanic eruption and correlate distal tephras with their source volcanoes. (U‐Th)/He zircon geochronology combined with U‐Th in situ rim dating is a powerful tool to determine the eruption ages of Late Pleistocene tephras

Summary

Introduction

Tephra layers in terrestrial sediments are often used as key horizons in Quaternary sections because they provide isochronous markers and are a fundamental tool for correlating distant occurrences and yielding absolute age constraints (Lowe, 2011). These are important in various fields, such as palaeoclimatic, palaeoenvironmental and archaeological research. There has been significant progress in the documentation of tephra and cryptotephra layers, correlation with proximal equivalents is not always straightforward and the source volcanoes often remain elusive.

Results

Discussion

Conclusion