Eruptive history of the Late Quaternary Ciomadul (Csomád) volcano, East Carpathians, part II: magma output rates

Abstract

This study, which builds on high-precision unspiked Cassignol-Gillot K-Ar age determinations, presents an advanced DEMbased volumetrical analysis to infer long-term magma output rates for the Late Quaternary Ciomadul (Csomád) dacitic lava dome complex (East Carpathians, Romania). The volcanic field of Ciomadul developed on the erosional surface of Lower Cretaceous flysch and~2 Ma old andesites and experienced an extended eruptive history from~850 to < 30 ka. Predominantly effusive activity took place during the first stage (~850 to~440 ka), producing volumetrically minor, isolated, peripheral domes. Subsequently, after a~250 ky repose interval, a voluminous central dome cluster developed in the second stage (~200 to < 30 ka). During the youngest phase of evolution (~60 to < 30 ka), highly explosive eruptions also occurred, resulting in the formation of two craters (Mohos and St. Ana). The calculated~8.00 ± 0.55 km 3 total volume of the lava domes, which includes the related volcaniclastic (1.57 km 3) as well as erosionally removed (0.18 km 3) material, is in line with dimensions of other medium-sized dacitic lava domes worldwide. This volume was extruded at an average long-term magma output rate of 9.76 km 3 / My (0.0098 km 3 /ky). However, most of the domes (7.53 ± 0.51 km 3) were formed in the 200 to < 30 ka period, implying a significantly increased magma output rate of 37.40 km 3 /My (0.0374 km 3 /ky), more than 30 times higher than in the first stage. Within these long-term trends, individual lava domes of Ciomadul (e.g. those with volumes between 0.02 and 0.40 km 3) would have been emplaced at much higher rates over a period of years to tens of years. The active periods, lasting up to hundreds of years, would have been followed by repose periods~30 times longer. The most recent eruption of Ciomadul has been dated here at 27.7 ± 1.4 ka. This age, which is in agreement with radiocarbon dates for the onset of lake sediment accumulation in St. Ana crater, dates fragmented lava blocks which are possibly related to a disrupted dome. This suggests that during the last, typically explosive, phase of Ciomadul, lava dome extrusion was still ongoing. In a global context, the analysis of the volumetric dynamism of Ciomadul's activity gives insights into the temporal variations in magma output; at lava domes, short-term (dayor week-scale) eruption rates smooth out in long-term (millenia-scale) output rates which are tens of times lower.

Volcanic Landforms and Landscapes of the East Carpathians (Romania) and Their Geoheritage Values

“…Karátson [37] and Karátson and Timár [28] have constrained a 30 m/Myr average erosion rate for the entire volcanic zone of CPR and for the Călimani-Gurghiu-Harghita (CGH) and Slansky-Tokaj volcanic segments, respectively. An average erosion rate of 31.5 m/Myr was accounted for the Ciomadul volcano from South Harghita [39]. The smallest average erosion rate-20 m/Myr-was recently established for the CGH as a whole, with 28 m/Myr for the Southern Harghita volcanic zone [40].…”

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

“…2) in eastern-central Europe. It formed over the last 1 Myr with its last eruptions at around 30 ka (Vinkler et al, 2007;Harangi et al, 2010Harangi et al, , 2015Szakács et al, 2015;Karátson et al, 2016Karátson et al, , 2019Molnár et al, 2018Molnár et al, , 2019Lahitte et al, 2019). It is a volcanic complex, where volcanism started with intermittent lava dome extrusion events (1000-300 ka; Molnár et al, 2018).…”

“…It is a volcanic complex, where volcanism started with intermittent lava dome extrusion events (1000-300 ka; Molnár et al, 2018). This was followed by development of the more voluminous Ciomadul volcanic complex (160-30 ka;Harangi et al, 2015;Karátson et al, 2016Karátson et al, , 2019Molnár et al, 2019), an amalgamation of several lava domes truncated by two deep explosion craters (Sft Ana and Mohos, respectively). Explosive eruptions characterized only the youngest eruptive epoch, which lasted from 57 to 30 ka (Harangi et al, 2015;Molnár et al, 2019).…”

A Würm glaciális második felének növénytakaró változásai a Kárpát-medence alföldi és hegyvidéki régióiban: refúgiumok és erdőtüzek

“…A kutatási eredmények KARÁTSON et al (2016KARÁTSON et al ( , 2017 munkái alapján 29600 év körülre teszik az utolsó, feltételezhetően erőteljes robbanással járó kitörés idejét, mely létrehozta a Szent Anna-tó kráterét (KARÁTSON et al 2016). A legújabb kormeghatározási módszerek eredményei alapján KARÁTSON et al (2019) az utolsó vulkanikus aktivitás idejét 27700 ± 1400 évben határozta meg.…”