The ‘Roxolany Tephra’ (Ukraine) − new evidence for an origin from Ciomadul volcano, East Carpathians

Abstract

We present major element glass data and correlations of the 'Roxolany Tephra' -a so far geochemically unconstrained volcanic ash layer previously described in last glacial (MIS2) loess deposits of the Roxolany loess-palaeosol complex in the SW Ukraine. This exceptionally well preserved, 2-3 cm thick tephra layer is characterised by a rhyolitic glass composition that is comparable to that of proximal tephra units from Ciomadul volcano in the East Carpathians, central Romania. The chemistry particularly matches that of the final LSPA pyroclastic fall unit of St. Ana crater that is radiocarbon dated in the proximal Mohoş coring site (MOH-2) at 29.6±0.62 cal ka BP. The age of the tephra correlative is in agreement with the newest radiocarbon and IR-OSL age constraints from overlying palaeosols and tephraembedding loess of the Roxolany sequence, respectively, which place the tephra between ca. 33 and 24 cal ka BP, and thus confirm the long-debated chronostratigraphy of this important 2 environmental archive. The occurrence of a distal Ciomadul tephra ca. 350 km east of its source indicates a great potential of further tephra and cryptotephra findings from this volcanic complex in the south-eastern Mediterranean and Black Sea region.

Periodic input of dust over the Eastern Carpathians during the Holocene linked with Saharan desertification and human impact

“…The Mohos crater is related to volcanic activity from the Ciomadul volcano, which last erupted roughly 29.6 cal kyr BP in the neighbouring younger crater currently occupied by the Lake Sfânta Ana (Harangi et al, 2010;Karátson et al, 2016;Magyari et al, 2014;Wulf et al, 2016). The surrounding geology is dominated by andesites and dacites, occasionally capped by pyroclastic deposits and a thick soil cover.…”

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

“…Karátson et al () argued that glass major element data could be used effectively to distinguish at least three successive eruption episodes (EPPA–MPA–LSPA) of Ciomadul. This concept was used to correlate Roxolany tephra in south‐western Ukraine with the youngest eruptions (LSPA) of Ciomadul (Wulf et al , ). However, most of the LSPA glasses show a Tuşnad affinity (Fig.…”

“…). Tephras from Roxolany (Wulf et al , ) and from Black Sea drill cores (Cullen et al , ) also have similar glass compositions. Using various bivariate major element plots, the Pantellerian Green tuff can be readily distinguished based on its high FeO content, which differs from other tephras.…”

“…the late Pleistocene Ciomadul volcano (Harangi et al , ; Szakács et al , ; Karátson et al , ; Molnár et al , , ). Tephra beds in the Black Sea drilling cores (Cullen et al , ), in loess deposits of Ukraine (Wulf et al , ) and in Middle Palaeolithic caves (Veres et al , ) have been recently suggested as derived from large explosive eruption events of Ciomadul volcano. However, to confirm this and to elucidate the regional impact of the Ciomadul eruptions, a better characterization of the Ciomadul tephras is necessary through geochronological, petrological and geochemical fingerprinting to constrain the accurate age and the nature of the volcanic products.…”

“…Volcanoes in and around the Mediterranean region that produced large explosive eruptions resulting in deposition of far‐reaching distal tephra for the last 100 kyr (references are in Supporting Material_1). Roxolany (Wulf et al , ) and drill sites in the southern Black Sea (Cullen et al , ) are shown where distal tephra of Ciomadul origin was assumed. For Ciomadul only the latest, dominantly explosive volcanic epoch is shown (Harangi et al , ; Molnár et al , ).…”