Jutzeler, M and McPhie, J and Allen, SR, Facies architecture of a continental, below-wave-base volcaniclastic basin: the Ohanapecosh Formation, Ancestral Cascades arc (Washington, USA), Geological Society of America Bulletin, 126, (3-4) pp. 352-376. ISSN 0016-7606 (2014) [Refereed Article]
Copyright 2014 Geological Society of America
The abundance of angular pumice clasts, crystals and dense volcanic clasts, and the extreme thickness of several facies, suggest they were derived from magmatic volatile-driven explosive eruptions. The extremely thick beds are ungraded or weakly graded, and lack evidence of hot emplacement, suggesting deposition from subaqueous, water-supported, high-concentration volcaniclastic density currents. Some of the thickest beds contain coarse, rounded, dense clasts at their base and are interbedded with accretionary lapilli–bearing mudstone; these beds are interpreted to be deposits from subaqueous density currents fed by subaerial pyroclastic flows that crossed the shoreline. Shallow basaltic intrusions and mafic volcanic breccia composed of scoria lapilli indicate the presence of intra-basinal scoria cones that may have been partly subaerial.
The range in facies in the Ohanapecosh Formation is typical of below-wave-base, continental (lacustrine) basins that form in proximity to active volcanic arcs, and includes eruption-fed and resedimented facies. Extreme instantaneous aggradation rates are related directly to explosive eruptions, and sediment pathways reflect the locations of active volcanoes, in contrast to conventional sedimentation processes acting in non-volcanic environments.
|Item Type:||Refereed Article|
|Research Division:||Earth Sciences|
|Objective Division:||Expanding Knowledge|
|Objective Group:||Expanding knowledge|
|Objective Field:||Expanding knowledge in the earth sciences|
|UTAS Author:||Jutzeler, M (Dr Martin Jutzeler)|
|UTAS Author:||McPhie, J (Professor Jocelyn McPhie)|
|UTAS Author:||Allen, SR (Dr Sharon Allen)|
|Funding Support:||Australian Research Council (CE0561595)|
|Web of Science® Times Cited:||12|
|Deposited By:||Earth Sciences|
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