Abstract.
In moving pyroclastic systems, particles are sorted as a function of their sizes, densities and shapes. The analysis of the distribution of these characteristics in particle populations of pyroclastic deposits is a major tool in evaluating properties and regimes of parent transport systems. This paper reports a study of size-density relationships of component subpopulations from selected Quaternary pyroclastic deposits of the Latera Volcanic Complex (Vulsini, Italy), by means of integrated field and laboratory investigations, including grain-size and component analyses, density measurements and SEM crystal morphoscopy. Three kinds of particle size-density relationships characterize the studied deposits, as follows: (1) a significant correlation of decreasing sizes with increasing component densities exists for direct suspension sedimentation products, including Plinian fall and pyroclastic surge deposits; (2) a wide data dispersion with poor correlation normally occurs for the main zones of deposits from (high-concentration) pyroclastic flows; and (3) component subpopulations occur in a narrow size range irrespective of density in granular systems dominated by grain collisions, such as traction zones beneath (low-concentration) pyroclastic surges and sheared basal layers of pyroclastic flows. The regression coefficients of size-density relationships appear as a comparative measure of particle concentration in the parent systems, consistent with that inferred from the degree of sorting and abrasion of crystal subpopulations from sequential fragmentation/transport analysis of grain-size data, and quantitative morphoscopy. The crystal component becomes less sorted and more abraded as the fit to the size-density relationship decreases from Plinian fall to pyroclastic surge to pyroclastic flow, consistent with increasing particle concentration in the transporting current.
Similar content being viewed by others
Author information
Authors and Affiliations
Additional information
Electronic Publication
Rights and permissions
About this article
Cite this article
Taddeucci, J., Palladino, D.M. Particle size-density relationships in pyroclastic deposits: inferences for emplacement processes. Bull Volcanol 64, 273–284 (2002). https://doi.org/10.1007/s00445-002-0205-6
Received:
Accepted:
Issue Date:
DOI: https://doi.org/10.1007/s00445-002-0205-6