Title:
 Distribution and geochronology of Oregon Plateau (U.S.A.) flood basaltvolcanism; the Steens Basalt revisited 
Reference Number:
 2056 
ISSN:
 0377-0273
Publication Year:
 2007
GeoREF Number:
 2007-123678 (View Original Data File)
Authors:
 Brueseke, Matthew E; Heizler, Matthew T; Hart, William K; Mertzman,Stanley A
Descriptors:
 absolute age; Ar/Ar; basalts; Cenozoic; Columbia River Basalt Group;dates; flood basalts; Harney County Oregon; igneous rocks; MalheurGorge; Miocene; Neogene; Oregon; Oregon Plateau; Steens Basalt; SteensMountain; Tertiary; United States; volcanic rocks; volcanology;Yellowstone Hot Spot
Source:
 Journal of Volcanology and Geothermal Research, vol. 161, no. 3,pp.187-214, 15 Mar 2007
Abstract:
 The timing and petrogenesis of mid-Miocene flood basalt volcanism inthe northwest United States has been extensively addressed, yet thechemical characteristics and temporal details of the Steens Basalt,exposed on the Oregon Plateau, are poorly defined. Steens Basaltvolcanism has generally been accepted to have occurred atapproximately 16.6 Ma, coeval and/or just prior to the onset ofColumbia River Basalt Group volcanism to the north. New major andtrace element analyses and nine (super 40) Ar/ (super 39) Ar agesranging from 15.51+ or -0.28 to 16.58+ or -0.18 Ma were obtained onOregon Plateau flood basalt lava flows from stratigraphic sections inclose proximity to Steens Mountain. Additionally, new (super 40) Ar/(super 39) Ar ages were obtained on the uppermost and thirty-firstlava flow down from the top of the approximately 1 km section ofSteens Basalt exposed at Steens Mountain and yield eruption ages of16.59+ or -0.10 and 16.55+ or -0.10 Ma, respectively. Field relation!
Notes:
 Based on Publisher-supplied data
Copyright:
 GeoRef, Copyright 2007, American Geological Institute. Referenceincludes data from CAPCAS, Elsevier Scientific Publishers, Amsterdam,Netherlands

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