Characterization of 70k Toba Ash from Dahigaon, upland Deccan Traps, India

Abstract

The eruption of the Toba super volcano approximately 75,000 years ago on the Indonesian island of Sumatra left behind extensive ash deposits known as Toba ash, marking one of the largest volcanic events in recorded history. The eruption's impact extended far beyond Sumatra, with Toba ash deposits discovered across Southeast Asia and beyond, including regions as distant as the Bay of Bengal, the South China Sea, and the eastern Indian Ocean. This widespread distribution underscores the eruption's colossal scale and its profound consequences for the environment and human populations of the time. Toba ash is not confined to specific geological formations but has been found in diverse settings worldwide, from sedimentary records in Italy, Japan, and the Philippines to marine sediment cores in various oceanic regions. The eruption, characterized by a highly explosive Plinian phase, ejected immense volumes of ash, tephra, and pumice, blanketing vast swathes of central Sumatra and adjacent areas in South Asia. The presence of Toba ash in sedimentary archives globally attests to its significant impact on the Earth's climate and ecosystems. This research project focuses on the detailed study and characterization of Toba ash deposits located in Dahigaon and Bori within the Pune District of Maharashtra, India, as well as a potential new site in the Satara District. The investigation employs advanced petrological and scanning electron microscopy (SEM) techniques to analyze the physical and mineralogical properties of the ash. Additionally, mineralogical analysis of associated minerals will be conducted using advanced methods such as Raman spectroscopy, X-ray diffraction (XRD), and geochemical analysis through X-ray fluorescence (XRF) and laser ablation inductively coupled plasma mass spectrometry (LA ICP-MS). Through this interdisciplinary approach, the study aims to provide valuable insights into the characteristics and implications of Toba ash deposits in the Indian context and contribute to our understanding of past volcanic events and their global impacts.