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Secondary welding of submarine pumice-lithic breccia at Mount Chalmers, Queensland, Australia


McPhie, J and Hunns, SR, Secondary welding of submarine pumice-lithic breccia at Mount Chalmers, Queensland, Australia, Bulletin of Volcanology, 57, (3) pp. 170-178. ISSN 0258-8900 (1995) [Refereed Article]

DOI: doi:10.1007/s004450050087


Very thick units of massive pumice and lithic clast-rich breccia in the Early Permian Berserker beds at Mount Chalmers, Queensland, are deposits from cold, water-supported, volcaniclastic mass flows emplaced in a below-wave base submarine setting. Adjacent to syn-volcanic andesitic and rhyolitic sills and dykes, the pumice-lithic breccia shows a well-developed eutaxitic texture. The eutaxitic foliation is parallel to intrusive contacts and extends as far as a few metres away from the contact. At these sites, pumice clasts are strongly flattened and tube vesicles within the pumice clasts are compacted and aligned parallel to the direction of flattening. Some lenticular pumice clasts contain small (≤2 mm), round, quartz-filled amygdales and spherulites. Further away from the sills and dykes, the pumice clasts have randomly oriented, delicate tube vesicle structure and are blocky or lensoid in shape. Round amygdales were generated by re-vesiculation of the glass and the spherulites indicate devitrification of the glass at relatively high temperatures. The eutaxitic texture is therefore attributed to re-heating and welding compaction of glassy pumice-lithic breccia close to contacts with intrusions. In cases involving sills, secondary welding along the contacts formed extensive, conformable, eutaxitic zones in the pumice-lithic breccia that could be mistaken for primary welding compaction in a hot, primary pyroclastic deposit. © 1995 Springer-Verlag.

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
UTAS Author:McPhie, J (Professor Jocelyn McPhie)
UTAS Author:Hunns, SR (Mr Steven Robert Hunns)
ID Code:9124
Year Published:1995
Web of Science® Times Cited:15
Deposited By:Earth Sciences
Deposited On:1995-08-01
Last Modified:2011-08-25

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