Please use this identifier to cite or link to this item: http://hdl.handle.net/1959.14/26641
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- Title
- Magma composition and viscosity as controls on peperite texture : an example from Passamaquoddy Bay, southeastern Canada
- Related
- Journal of volcanology and geothermal research, Vol. 114, Issue 1-2, p.63-80
- DOI
- 10.1016/S0377-0273(01)00288-8
- Publisher
- Elsevier
- Date
- 2002
- Author/Creator
- Dadd, K. A
- Author/Creator
- Van Wagoner, N. A
- Description
- Silurian mafic lava flows and rhyolite sills in the Passamaquoddy Bay area, southeastern Canada, interacted with wet sediment to produce peperitic breccia. The pahoehoe-type mafic flows flowed over and bulldozed into wet, unconsolidated silt and sand to produce both blocky and fluidal peperite at their lower contacts. Soft-sediment deformation structures in the siltstone adjacent to the flows, irregularly shaped vesicles in the siltstone, and siltstone-filled vesicles in the mafic lava all indicate the sediment was wet at the time of flow emplacement. Sills of rhyolite emplaced into the same sedimentary sequence also interacted with the wet sediment and produced peperite at both the upper and lower contacts. Evidence for the rhyolitic previous termmagmanext term interacting with wet sediment includes sediment-filled vesicles in rhyolite, quartz-filled vesicles in siltstone and angular, non-vesicular shards of rhyolite in clastic dykes. Peperite formed by this process is exclusively blocky. The rhyolitic previous termmagmanext term in the Passamaquoddy Bay sequence and other examples of high-previous termviscosity magmanext term producing only blocky peperite suggest that in contrast to low-previous termviscosity magmas,next term which produce a combination of blocky and fluidal peperite, only blocky peperite will form associated with highly viscous rhyolite previous termmagma.next term The sediment that interacted with both the mafic and rhyolitic lavas is of similar texture indicating that, in this case, sediment texture did not control peperite type. The change from fluidal to blocky peperite texture may also be controlled in part by the previous termmagmanext term temperature and/or confining pressure, and the generation and maintenance of a steam film at the previous termmagma/next termwet sediment interface.
- Description
- 18 page(s)
- Subject Keyword
- peperites
- Subject Keyword
- peperitic breccia
- Subject Keyword
- magma viscosity
- Subject Keyword
- bimodal volcanism
- Subject Keyword
- Silurian
- Subject Keyword
- northern Appalachians
- Resource Type
- journal article
- Organisation
- Macquarie University. Dept. of Earth and Planetary Sciences
- Identifier
- http://hdl.handle.net/1959.14/26641
- Identifier
- ISSN:0377-0273
- Identifier
- mq-rm-2002014650
- Language
- eng
- Reviewed
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