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Imnaha Basalt

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Series: GSA Special Papers
Published: 01 January 1989
DOI: 10.1130/SPE239-p105
... The K-Ar data for various sections of the Columbia River basalt (Imnaha, Picture Gorge, and Grande Ronde Basalt formations) have been reevaluated, utilizing the atmospheric argon contents of the rocks to identify the least altered samples. These ages, together with the results of paleomagnetic...
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Isopach map) of the <b>Imnaha</b> <b>Basalt</b>, the basal section of the CRBG. A thick s...
Published: 01 July 2020
Figure 4. Isopach map) of the Imnaha Basalt, the basal section of the CRBG. A thick section of the Imnaha Basalt is oriented subparallel to the modern Hells Canyon: this increased thickness requires the presence of a Miocene proto-Hells Canyon. The modern Hells Canyon is coincident with the proto
Series: GSA Special Papers
Published: 01 August 2013
DOI: 10.1130/2013.2497(11)
... We present a reappraisal of Columbia River basalt petrogenesis based on an internally consistent X-ray fluorescence and inductively coupled plasma–mass spectrometry data set for major and trace elements plus new and existing isotopic analyses of the Imnaha, Steens, Picture Gorge, and Grande...
Journal Article
Journal: GSA Bulletin
Published: 01 February 1976
GSA Bulletin (1976) 87 (2): 215–225.
...GREGORY S. HOLDEN; PETER R. HOOPER Abstract Field characteristics, petrography, and major-element analyses are given for 17 of the 19 flows of the Columbia River Group present in a canyon in the southeast corner of the Columbia Plateau. The 17 flows are divided into 4 flows of Imnaha Basalt...
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TABLE 1. ISOTOPE ANALYSES OF STEENS AND <b>IMNAHA</b> <b>BASALTS</b>*
Published: 01 June 2008
TABLE 1. ISOTOPE ANALYSES OF STEENS AND IMNAHA BASALTS*
Journal Article
Published: 01 July 2020
Rocky Mountain Geology (2020) 55 (1): 27–54.
...Figure 4. Isopach map) of the Imnaha Basalt, the basal section of the CRBG. A thick section of the Imnaha Basalt is oriented subparallel to the modern Hells Canyon: this increased thickness requires the presence of a Miocene proto-Hells Canyon. The modern Hells Canyon is coincident with the proto...
FIGURES | View All (9)
Series: GSA Special Papers
Published: 01 August 2013
DOI: 10.1130/2013.2497(09)
.../ 86 Sr ratios of <0.7040. In contrast, Imnaha, Grande Ronde, Wanapum, and Saddle Mountains basalts likely assimilated crust with more radiogenic Sr (>0.7040) including a cratonic component, perhaps as a result of residence in magma chambers partly located east of the 87 Sr/ 86 Sr = 0.7060 line...
Series: GSA Special Papers
Published: 01 August 2013
DOI: 10.1130/2013.2497(03)
... with the plagioclase ages. Various forms of the geomagnetic polarity time scale for mid-Miocene time are examined, along with the ages of lavas and their magnetic polarity. The main sections of the Columbia River Basalt Group (Imnaha through Wanapum Basalt) were formed in ~0.5 m.y. between 16.3 and 15.8 Ma. Steens...
Journal Article
Journal: GSA Bulletin
Published: 01 May 1976
GSA Bulletin (1976) 87 (5): 777–792.
... ratios (0.7035 to 0.7039) and a major- and trace-element composition consistent with an origin from the upper mantle. The Picture Gorge Basalt is clearly distinguished from the Imnaha basalt in northeast Oregon and from the widespread, mainly younger Yakima Basalt. The Yakima Basalt, including lava flows...
Journal Article
Journal: Geology
Published: 31 January 2020
Geology (2020) 48 (4): 348–352.
... with the strongest arc-like (but depleted) geochemical signal of PGB among CRBG units indicates that the shallowest metasomatized backarc-like mantle was tapped first and concurrently, with later units (Steens and Imnaha Basalts) showing increased influence of a plume-like source. * E-mails: ecahoon@pdx.edu...
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Journal Article
Journal: Geosphere
Published: 01 June 2008
Geosphere (2008) 4 (3): 480–495.
...TABLE 1. ISOTOPE ANALYSES OF STEENS AND IMNAHA BASALTS* ...
FIGURES | View All (10)
Journal Article
Journal: Geosphere
Published: 26 September 2018
Geosphere (2018) 14 (6): 2505–2532.
...-rock and mineral compositions, which we use to evaluate how the balance of magma differentiation processes change in time. Temporal petrochemical variations in the Steens Basalt are analogous to the transition from Imnaha Basalt to Grande Ronde Basalt units of the Columbia River Flood Basalt and have...
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Series: GSA Special Papers
Published: 01 August 2013
DOI: 10.1130/2013.2497(02)
... that compose the lava stratigraphy. Combining robust Ar-Ar data with field constraints and paleomagnetic information leads to the following recommendations for the age of emplacement of the constituent formations: Steens Basalt, ca. 16.9 to ca. 16.6 Ma; Imnaha Basalt, ca. 16.7 to ca. 16 Ma; Grande Ronde Basalt...
Series: GSA Special Papers
Published: 01 August 2013
DOI: 10.1130/2013.2497(05)
... in the interior and an abbreviated and variable stratigraphy along the margins. The areal extent of many flows suggests that the Chief Joseph dike swarm greatly expanded after Imnaha Basalt time, and now many dikes are buried beneath younger flows in the eastern part of the province. The Grande Ronde Basalt has...
Journal Article
Journal: GSA Bulletin
Published: 01 January 2004
GSA Bulletin (2004) 116 (1-2): 249–250.
... Mountain and Malheur Gorge is petrographically unusual in that it contains significantly more and larger phenocrysts than the overlying Imnaha Basalt. The reversed-to-normal magnetic break recorded by Taubeneck at the base of the Imnaha Basalt along the southern margin of the Wallowa Mountains ( Carlson...
Series: GSA Special Papers
Published: 01 January 1989
DOI: 10.1130/SPE239-p321
... percent; K 2 O, 6 percent; and TiO 2 , 0.7 percent. The modal abundance by volume varies from a trace in the Picture Gorge Basalt and 1 percent in some Imnaha Basalt flows to 10 percent in the Grande Ronde Basalt and as much as 24 percent in the Wanapum Basalt. If segregated and accumulated, this glass...
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Geochemistry of our Picture Gorge <b>Basalt</b> (PGB, northwestern United States) ...
Published: 31 January 2020
Figure 2. Geochemistry of our Picture Gorge Basalt (PGB, northwestern United States) study samples compared to the Steens Basalt data from Moore et al. (2018) (*) and all main-phase Columbia River Basalt Group (CRBG) units from Wolff and Ramos (2013) (**). For the Imnaha Basalt, only
Journal Article
Journal: GSA Bulletin
Published: 01 January 2004
GSA Bulletin (2004) 116 (1-2): 247–248.
...Ajoy K. Baksi References Baksi , A.K. , 1989 , Reevaluation of the timing and duration of extrusion of the Imnaha, Picture Gorge and Grande Ronde Basalts, Columbia River basalt group ,: in Reidel , S.P. , and Hooper , P.R. , eds., Volcanism and tectonism in the Columbia...
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Figure 5. Stratigraphy and map distribution of main Columbia River <b>Basalt</b> G...
Published: 01 June 2008
as depicted in the cross-sectional diagrams of Figure 7 . Paleo-magnetic units R0–N2 correspond with sequential reverse and normal paleomagnetic intervals during the main-phase eruptions. The terms lower Steens and upper Steens Basalts are defined in Hooper et al. (2002) and Camp et al. (2003) . Imnaha
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Primitive mantle normalization plots of Grande Ronde <b>Basalt</b> ( n  = 40) and ...
Published: 20 December 2018
Figure 13. Primitive mantle normalization plots of Grande Ronde Basalt ( n = 40) and Imnaha Basalt ( n = 52) (data of Wolff et al., 2008 ) and samples of Hunter Creek Basalt, Birch Creek formation lavas, and an upper Pole Creek formation lava.