Project Details
Projekt
Detecting Changes in Icelandic Volcanism Over the Past 500,000 Years in Marine Tephra
Applicant
Dr. Edward Marshall
Subject Area
Geology
Term
since 2024
Project identifier
Deutsche Forschungsgemeinschaft (DFG) - Project number 546775789
Recent studies have shown that climatic changes during glacial – interglacial cycles influence global volcanism. The rapid melting of ice sheets that occurs during deglaciation relieves confining pressure on magma systems in the lithosphere, resulting in excess decompression melting in the mantle and up to 100 times greater erupted volume. Due to its high latitude and near-continuous volcanic activity, Iceland is an exceptional location in which to study the changes in volcanic systems that occur throughout a glacial-interglacial cycle. However, although Iceland has experienced many glacial-interglacial cycles, the lavas of Iceland are rapidly buried by later lavas and are furthermore difficult to accurately date. Consequently, studies of climatic-volcanic interactions are limited to the relatively short ~14 kyr period following deglaciation, whereas glacial-interglacial cycles have a period of about 100 kyr. Poorly constrained chronology is also a major problem for the identification of long-term trends in Icelandic volcanism. Kitagawa et al. (2008) identified long term compositional and eruption rate trends in Neogene lava piles from 2 to 13 Ma, but because Icelandic Neogene lavas are compositionally distinct from modern rift lavas, it is not clear how relevant they are for understanding the history of the modern rift. A clearer test would be to study the composition and eruption rates of rift lavas extending back in time from the present, but this approach faces the same difficulties as climatic-volcanic interaction studies. Here, we overcome these issues by instead studying marine volcanic tephra deposits, located offshore of Iceland, that have been sampled in IODP sediment cores. We propose to undertake a detailed study of tephra over the past 500 kyr (the last 4 glacial – interglacial cycles), which will allow accurate dating of tephra, at very high (100 yr) resolution, using published O isotope data for these cores. Additional samples will be analysed to identify changes in Icelandic volcanism for the period 0.5 - 4 Ma, extending back to before the onset of Northern Hemisphere glaciation at 3.6 Ma. Major and trace element analyses will be used to determine changes in the average depth and degree of mantle melting and quantify the effect of deglaciation on subaerial volcanism at high latitudes. In collecting these data, we achieve two major goals: (1) we identify in detail the connection between volcanism and glaciation by studying four glacial cycles, and (2) we document geochemical changes within the modern rift, filling the gap in the Icelandic volcanic chronologic record.
DFG Programme
Infrastructure Priority Programmes
International Connection
Iceland, United Kingdom
Co-Investigators
Professor Dr. Karsten Matthias Haase; Privatdozent Dr. Marcel Regelous
Cooperation Partners
Professorin Dr. Esther Gudmundsdottir; Professor Dr. John Maclennan
