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Miocene silicic volcanism in southwestern Idaho: Geochronology, geochemistry, and evolution of the central Snake River Plain

Bulletin of Volcanology

By:
, , , , and
DOI: 10.1007/s00445-007-0141-6

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Abstract

New 40Ar-39Ar geochronology, bulk rock geochemical data, and physical characteristics for representative stratigraphic sections of rhyolite ignimbrites and lavas from the west-central Snake River Plain (SRP) are combined to develop a coherent stratigraphic framework for Miocene silicic magmatism in this part of the Yellowstone 'hotspot track'. The magmatic record differs from that in areas to the west and east with regard to its unusually large extrusive volume, broad lateral scale, and extended duration. We infer that the magmatic systems developed in response to large-scale and repeated injections of basaltic magma into the crust, resulting in significant reconstitution of large volumes of the crust, wide distribution of crustal melt zones, and complex feeder systems for individual eruptive events. Some eruptive episodes or 'events' appear to be contemporaneous with major normal faulting, and perhaps catastrophic crustal foundering, that may have triggered concurrent evacuations of separate silicic magma reservoirs. This behavior and cumulative time-composition relations are difficult to relate to simple caldera-style single-source feeder systems and imply complex temporal-spatial development of the silicic magma systems. Inferred volumes and timing of mafic magma inputs, as the driving energy source, require a significant component of lithospheric extension on NNW-trending Basin and Range style faults (i.e., roughly parallel to the SW-NE orientation of the eastern SRP). This is needed to accommodate basaltic inputs at crustal levels, and is likely to play a role in generation of those magmas. Anomalously high magma production in the SRP compared to that in adjacent areas (e.g., northern Basin and Range Province) may require additional sub-lithospheric processes. ?? Springer-Verlag 2007.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Miocene silicic volcanism in southwestern Idaho: Geochronology, geochemistry, and evolution of the central Snake River Plain
Series title:
Bulletin of Volcanology
DOI:
10.1007/s00445-007-0141-6
Volume
70
Issue:
3
Year Published:
2008
Language:
English
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
Bulletin of Volcanology
First page:
315
Last page:
342
Number of Pages:
28