|
|
 |
|||||||||||||||||
|
|||||||||||||||||
 |
|||||||||||||||||
| JOURNAL HOME | HELP | CONTACT PUBLISHER | SUBSCRIBE | ARCHIVE | SEARCH | TABLE OF CONTENTS |
1 Department of Geology, Washington State University, Pullman, Washington 99164, USA
2 Department of Earth Sciences, Open University, Milton Keynes MK7 6AA, UK
Stratigraphic and chemical correlations of Tertiary volcanic units in eastern Oregon confirm that the Steens Basalt represents the earliest eruptions of the Columbia River flood-basalt province. Field correlations are supported by major and trace element analyses and confirmed by 40Ar/39Ar dates. Within the basalt of Malheur Gorge, situated between Steens Mountain and the southernmost extent of the previously mapped Columbia River Basalt Group, the lowest unit correlates with the Steens Basalt, and the conformably overlying middle and upper units correlate with the Imnaha and Grande Ronde Basalt Formations of the Columbia River Basalt Group. New dates indicate that Imnaha and Grande Ronde Basalt Formations on the Columbia Plateau (>90% of the Columbia River Basalt Group) erupted between 16.1 and 15.0 Ma. These were immediately preceded by the Steens Basalt, a plagioclase-phyric tholeiite that erupted above the calculated position of the Yellowstone hotspot at 16.6 Ma. In eastern Oregon, the flood-basalt tholeiites of Steens Mountain and Malheur Gorge form a voluminous but brief interlude (16.6–15.3 Ma) superimposed on the low-volume, calc-alkalic to mildly alkalic, volcanism associated with continuing Eocene to present east-west extension.
Key Words: calc-alkalic volcanism • Columbia River Basalt • extension • hotspot • Steens Basalt
This article has been cited by other articles:
|
|
 |
|
  V. E. Camp and B. B. Hanan A plume-triggered delamination origin for the Columbia River Basalt Group Geosphere, June 1, 2008; 4(3): 480 - 495. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
J. S. Oldow and E. S. Singleton Application of Terrestrial Laser Scanning in determining the pattern of late Pleistocene and Holocene fault displacement from the offset of pluvial lake shorelines in the Alvord extensional basin, northern Great Basin, USA Geosphere, June 1, 2008; 4(3): 536 - 563. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 D. W. Lerch, E. Miller, M. McWilliams, and J. Colgan Tectonic and magmatic evolution of the northwestern Basin and Range and its transition to unextended volcanic plateaus: Black Rock Range, Nevada GSA Bulletin, March 1, 2008; 120(3-4): 300 - 311. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 C. M. White The Graveyard Point Intrusion: an Example of Extreme Differentiation of Snake River Plain Basalt in a Shallow Crustal Pluton J. Petrology, February 1, 2007; 48(2): 303 - 325. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
I. S.E. Carmichael, R. A. Lange, C. M. Hall, and P. R. Renne Faulted and tilted Pliocene olivine-tholeiite lavas near Alturas, NE California, and their bearing on the uplift of the Warner Range GSA Bulletin, September 1, 2006; 118(9-10): 1196 - 1211. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
J. P. Colgan, T. A. Dumitru, M. McWilliams, and E. L. Miller Timing of Cenozoic volcanism and Basin and Range extension in northwestern Nevada: New constraints from the northern Pine Forest Range GSA Bulletin, January 1, 2006; 118(1-2): 126 - 139. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 R. S. Coe, G. M. Stock, J. J. Lyons, B. Beitler, and G. J. Bowen Yellowstone hotspot volcanism in California? A paleomagnetic test of the Lovejoy flood basalt hypothesis Geology, September 1, 2005; 33(9): 697 - 700. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
F. C. Ramos, J. A. Wolff, and D. L. Tollstrup Sr isotope disequilibrium in Columbia River flood basalts: Evidence for rapid shallow-level open-system processes Geology, June 1, 2005; 33(6): 457 - 460. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
Preeruption history of the Grande Ronde Formation lavas, Columbia River Basalt Group, American Northwest: Evidence from phenocrysts Geology, April 1, 2004; 32(4): 293 - 296.
|
|
|
|
|
|
A. K. Baksi Ages of the Steens and Columbia River flood basalts and their relationship to extension related calc-alkalic volcanism in eastern Oregon: Discussion GSA Bulletin, January 1, 2004; 116(1-2): 247 - 248. [Full Text] [PDF]
|
|
|
|
|
|
P. Hooper Reply GSA Bulletin, January 1, 2004; 116(1-2): 249 - 250. [Full Text] [PDF]
|
|
|
|
|
|
V. E. Camp, M. E. Ross, and W. E. Hanson Genesis of flood basalts and Basin and Range volcanic rocks from Steens Mountain to the Malheur River Gorge, Oregon GSA Bulletin, January 1, 2003; 115(1): 105 - 128. [Abstract] [Full Text] [PDF]
|
|
| JOURNAL HOME | HELP | CONTACT PUBLISHER | SUBSCRIBE | ARCHIVE | SEARCH | TABLE OF CONTENTS |
