GSA Connects 2021 in Portland, Oregon

Paper No. 167-8
Presentation Time: 3:35 PM


ABBOTT, Dallas, Lamont-Doherty Earth ObservatoryColumbia Univ, Rt 9W, PO Box 1000, Palisades, NY 10964-8000, SULTAN, Anzim, The City College of New York, New York, NY 10001 and ATADZHANOV, Malik, Kingsborough Community College

The Smithsonian Database of Holocene volcanoes lists 24 submarine volcanoes with unknown, rhyolitic or dacitic primary lavas located between 20°S and 45°N. Six have eruptive products of unknown composition despite historical reports of volcanic eruptions at these locations. Seventeen have lavas dominated by rhyolite or dacite but we found no quantitative chemical analyses in PETDB. We are focusing on large explosive eruptions so we exclude volcanoes dominated by andesitic or more basic compositions. These submarine volcanoes are important because EDS analyses and SEM imaging of volcanic glass from the GISP2 ice core dating to between 533 and 543 CE show four equatorial eruptions with associated marine diatoms. There is also a mid-latitude submarine volcano whose chemistry matches that of previously analyzed glasses deposited in the NEEM ice core in early 536 CE but whose identification is still tentative. All five temporally and chemically distinct glasses most likely originated from submarine eruptions. However, our analysis suggests that 70% of northern mId-latitude and equatorial submarine volcanoes lack quantitative, published chemical analyses of their glass. It is therefore not surprising that the source volcanoes for the equatorial submarine eruptions between 533 and 543 CE have not been identified. We calculated the distance between all LDEO cores and these seventeen poorly characterized volcanoes. We found numerous cores within 300 km of these volcanoes. After analyzing the best cores by sieving layers with high magnetic susceptibility, we found five ash different layers emanating from 5 of these volcanoes, one with a previously unknown composition. We are dating and quantitatively analyzing these ash layers. We seek the five submarine volcanic eruptions which contributed to the profound climate downturn between 536 and 543 CE.