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Peperite: a review of magma-sediment mingling

Citation

Skilling, LP and White, JDL and McPhie, J, Peperite: a review of magma-sediment mingling, Journal of volcanology and geothermal research, 114, (1-2) pp. 1-17. ISSN 0377-0273 (2002) [Refereed Article]

DOI: doi:10.1016/S0377-0273(01)00278-5

Abstract

The study of peperite is important for understanding magma-water interaction and explosive hydrovolcanic hazards. This paper reviews the processes and products of peperite genesis. Peperite is common in arc-related and other volcano-sedimentary sequences, where it can be voluminous and dispersed widely from the parent intrusions. It also occurs in phreatomagmatic vent-filling deposits and along contacts between sediments and intrusions, lavas and hot volcaniclastic deposits in many environments. Peperite can often be described on the basis of juvenile clast morphology as blocky or fluidal, but other shapes occur and mixtures of different clast shapes are also found. Magma is dominantly fragmented by quenching, hydromagmatic explosions, magma-sediment density contrasts, and mechanical stress as a consequence of inflation or movement of magma or lava. Magma fragmentation by fluid-fluid shearing and surface tension effects is probably also important in fluidal peperite. Fluidisation of host sediment, hydromagmatic explosions, forceful intrusion of magma and sediment liquefaction and shear liquification are probably the most important mechanisms by which juvenile clasts and host sediment are mingled and dispersed. Factors which could influence fragmentation and mingling processes include magma, host sediment and peperite rheologies, magma injection velocity, volatile content of magma, total volumes of magma and sediment involved, total volume of pore-water heated, presence or absence of shock waves, confining pressure and the nature of local and regional stress fields. Sediment rheology may be affected by dewatering, compaction, cementation, vesiculation, fracturing, fragmentation, fluidisation, liquefaction, shear liquification and melting during magma intrusion and peperite formation. The presence of peperite intraclasts within peperite and single juvenile clasts with both sub-planar and fluidal margins imply that peperite formation can be a multi-stage process that varies both spatially and temporally. Mingling of juvenile clast populations, formed under different thermal and mechanical conditions, complicates the interpretation of magma fragmentation and mingling mechanisms. © 2002 Elsevier Science B.V. All rights reserved.

Item Details

Item Type:Refereed Article
Research Division:Earth Sciences
Research Group:Geology
Research Field:Volcanology
Objective Division:Expanding Knowledge
Objective Group:Expanding Knowledge
Objective Field:Expanding Knowledge in the Earth Sciences
Author:McPhie, J (Professor Jocelyn McPhie)
ID Code:46311
Year Published:2002
Web of Science® Times Cited:157
Deposited By:Centre for Ore Deposit Research - CODES CoE
Deposited On:2007-08-01
Last Modified:2007-08-31
Downloads:0

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