Australia: The Land Where Time Began

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Antarctica Volcanic Eruption the Largest in the Holocene – Timing and Widespread effects

According to Antoniades et al. the volcanic eruption that led to the collapse of the Deception Island volcano, Antarctica, was on a comparable scale to some of the largest eruptions that have occurred on Earth over the last several thousand years. The age of this eruption has not been determined, in spite of its magnitude and potential for far-reaching environmental effects. In this paper Antoniades et al. presents the results of their analysis of nearby lake sediments in which they identified a singular event that resulted from the collapse of the Deception Island caldera which occurred 3,980 ± 125 calibrated years BP. The tephra that was erupted record the distinct geochemical composition of the ejecta from the eruption that formed the caldera, and the sediments of the lake immediately overlying of the collapsed tephra recorded an extreme seismic episode. The newly constrained caldera collapse is now the largest volcanic eruption in Antarctica during the Holocene. Evidence revealed in the marine and lacustrine sediments by examination of palaeorecords for contemporaneous seismicity around the Antarctic Peninsula; synchronous glaciochemical volcanic signatures also record the eruption in ice cores that are spread around Antarctica, which reached more than 4,600 km from the source. It is suggested by the widespread footprint that this eruption would have had significant climatic and ecological effects across a vast area of the south polar region.

Pervasive climatic, ecological and economic effects can result from large volcanic eruptions (Robock, 2000). Crop failure, starvation, disease and civil unrest and has been linked to the rise and fall of civilisations, can result from climate cooling that is caused by volcanic aerosols (Oppenheimer, 2015; Büntgen, 2016). High latitude volcanic eruptions may also have environmental consequences that are wide-ranging and trigger pronounced cooling at hemispheric scales (Sigl, 2015; Pausata et al., 2015; Oman et al., 2005), though there are often major climate impacts associated with topical volcanoes. Understanding of environmental and climate impacts of many polar volcanic events, however, is limited by a lack of precision in regards to the age of past eruptions as well as the uncertainty of the provenance of many tephra layers in ice and sediment cores (Sigl et al., 2016; Smellie, 1999).

The largest active volcano in the Antarctic Peninsula region is Deception Island; with a basal diameter of 30 km it is on the scale of the volcanoes that have produced the largest eruptions on Earth in the past several thousand years (Smellie, 2001; Martί, Geyer & Aguirre-Diaz, 2013; Kandlbauer & Sparks, 2014; Smellie et al., 2002). Located in the South Shetland Islands (SSI), it is in a region that is volcanically active where there are 9 active volcanoes that are known in the SSI and several more adjacent to the Northern Antarctica Peninsula (Smellie et al., 1999). According to Antoniades et al. the potential for eruptions of Deception Island to affect climates around Antarctica and beyond was demonstrated by the identification of its tephra layers in marine and lacustrine sediments that are located up to ~1,300 km from the volcano (Smellie et al., 1999; Olivia-Urcia et al., 2015; Björck, Sandgren & Zale, 1991; Liu et al., 2016; Moreton & Smellie, 1998) as well as Antarctica Peninsula ice cores and East Antarctica, and including the South Pole (Smellie et al., 1999; Narcisi et al., 2005; Mulvaney et al., 2012).

Since the 19th century Deception Island has erupted more than 20 times, which includes 3 eruptions between 1967 and 1970 and seismic crises in 1992, 1999 and 2015 (Martί, Geyer & Aguirre-Diaz, 2013; Bartolini et al., 2014; Almendros et al., 2018). These recent eruptions have been of relatively modest magnitude, but the event that formed the caldera that is yet to be firmly dated ejected a dense-rock equivalent (DRE) of 30-60 km3 of magma, which is equivalent to the catastrophic eruption of Tambora in 1815 that resulted in global cooling and the “the year without summer” (Robock, 2000; Oppenheimer, 2015; Martί, Geyer & Aguirre-Diaz, 2013; Kandlbauer & Sparks, 2014; Smellie et al., 2002). It has never been firmly established what the age of this major Deception Island eruption is. The event has been placed by estimates between the Late Pleistocene and 3,370 BP, the most widely repeated age has been 10,000 year (Smellie et al., 2002; Olivia-Urcia et al., 2015; Moreton, 1999; Roberts et al., 2017). Rapid volcano-tectonic subsidence along the tectonically-influenced faults that were pre-existing resulted in a modern caldera that was 8-10 km in diameter that is of similar dimensions to those of Santorini and Krakatau (Smellie et al., 2002 & references therein). Caldera collapses that are on this scale are often associated with intense seismic swarms that include multiple high magnitude earthquakes (Hildreth & Fierstein, 2012), and it is implied by the large volume of magma that is erupted what the likelihood of significant, widespread climate impacts of are.

Byers Peninsula, which is on Livingston Island ~40 km northwest of Deception Island, is ideally located to record the history of the Deception Island volcano eruptions due to the proximity and the presence of many lakes. In this study Antoniades et al. examined sediments from lakes on Byers Peninsula where there are detailed long-term environmental records of Deception Island volcanic activity in the form of tephra deposits. Direct compositional comparisons between tephras from the Byers Peninsula and those of Deception Island to provide age constraints that significantly improved age constraints for the eruption that formed a caldera. In this paper data is presented from 4 lakes on Byers Peninsula, Escondido, Cerro Negro, Chester and Limnopolar, in which there are 3 major tephra horizons which are referred to as T1, T2 and T3 and whose composition indicated that a Deception Provenance, were correlated based on geochemistry and physical properties (Liu et al., 2016). This integration of cumulative evidence that had been derived from geochemical, petrological and palaeolimnological studies provides significant new insights into the chronology and physical processes that occurred during the collapse of the Deception Island caldera.

Sources & Further reading

Antoniades, D., et al. (2018). "The timing and widespread effects of the largest Holocene volcanic eruption in Antarctica." Scientific Reports 8(1): 17279.

 

Author: M. H. Monroe
Email:  admin@austhrutime.com
Last Updated 03/12/2018
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                                                                                           Author: M.H.Monroe  Email: admin@austhrutime.com     Sources & Further reading