Pyroclastic Density Currents and the Sedimentation of Ignimbrites
Pyoclastic density currents are awesome volcanic phenomena that can wreak destruction on a regional scale and can impact global climate. They deposit ignimbrites, which include vast impact lansdscape-modifying sheets with volumes exceeding 1000 km3.This book takes stock of our understanding of pyroclastic density currents and presents a new conceptual framework for investigating how ignimbrites are deposited. It integrates the results of field-based studies, laboratory experiments and numerical modelling, including work on clastic sedimentologym and industrial particle transport. Topics covered include the behaviour or particulate currents, mechanisms of clast support and segregation, interpreting ignimbrite lithofacies and architectures, and future research directions. The new approach focuses on processes and conditions within the lower flow-boundary zone of currents. Superb diagrams explain many new concepts, while the 95 photographs make an explanatiry atlas of deposit types. This is essential reading for workers investigating volcanic hazards, and for anyone wishing to interpret modern or ancient ignimbrites, as well as other catastrophically emplaced sediments.
“Given the depth of scholarship that they have brought to the subject, the power of their arguments, and the degree of synthesis with other fields, this would seemto qualify as a seminal work… I think that this will be the paper on the topic that others will have to contend with for many years to come.” Marcus Bursik, State University of New York
Overview, key implications and future research
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Published:January 01, 2002
Abstract
The vast extent of many ignimbrites shows that eruptions have occurred on almost unimaginable scales, well beyond any modern human experience. Evidence is emerging that plumes derived from large pyroclastic currents have impacted climate and biota on a global scale, whilst certain types of ignimbrites (e.g. extensive rheomorphic ignimbrites) indicate particularly awesome styles of eruption and emplacement that are regionally devastating and which we do not fully comprehend. Such unimaginable eruptions are bound to occur again. If we are to interpret such catastrophic events correctly, and possibly even anticipate the impact of future occurrences, it is essential that ignimbrite sheet architectures are studied further in order to understand the mechanisms, rates and durations of the fundamental processes. Of particular importance in risk mitigation will be the understanding of early stages of such devastating eruptions. The new approaches and descriptive schemes presented in this Memoir are intended to stimulate and facilitate such future work.