An introduction to the stratigraphy, structural geology, and hydrogeology of the Columbia River Flood-Basalt Province: A primer for the GSA Columbia River Basalt Group field trips

2009 ◽  
pp. 599-643 ◽  
Author(s):  
Terry L. Tolan ◽  
Barton S. Martin ◽  
Stephen P. Reidel ◽  
James L. Anderson ◽  
Kevin A. Lindsey ◽  
...  
Keyword(s):  
Structural Geology ◽  
Columbia River ◽  
Flood Basalt ◽  
Field Trips ◽  
Columbia River Basalt ◽  
River Flood ◽  
Columbia River Basalt Group

scholarly journals Reshuffling the Columbia River Basalt chronology—Picture Gorge Basalt, the earliest- and longest-erupting formation

Geology ◽  
2020 ◽  
Vol 48 (4) ◽  
pp. 348-352 ◽  
Author(s):  
Emily B. Cahoon ◽  
Martin J. Streck ◽  
Anthony A.P. Koppers ◽  
Daniel P. Miggins
Keyword(s):  
National Park ◽  
Columbia River ◽  
Flood Basalt ◽  
Temporal Context ◽  
Broad Area ◽  
Subsequent Evolution ◽  
Continental Flood Basalt ◽  
Columbia River Basalt ◽  
Geochemical Significance ◽  
Columbia River Basalt Group

Abstract The Columbia River Basalt Group (CRBG) is the world’s youngest continental flood basalt province, presumably sourced from the deep-seated plume that currently resides underneath Yellowstone National Park in the northwestern United States. The earliest-erupted basalts from this province aid in understanding and modeling plume impingement and the subsequent evolution of basaltic volcanism. We explore the Picture Gorge Basalt (PGB) formation of the CRBG, and discuss the location and geochemical significance in a temporal context of early CRBG magmatism. We report new ARGUS-VI multicollector 40Ar/39Ar incremental heating ages from known PGB localities and additional outcrops that we can geochemically classify as PGB. These 40Ar/39Ar ages range between 17.23 ± 0.04 Ma and 16.06 ± 0.14 Ma, indicating that PGB erupted earlier and for longer than other CRBG main-phase units. These ages illustrate that volcanism initiated over a broad area in the center of the province, and the geochemistry of these early lavas reflects a mantle source that is distinct both spatially and temporally. Combining ages 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.

scholarly journals Annually resolved sediments in the classic Clarkia lacustrine deposits (Idaho, USA) during the middle Miocene Climate Optimum

Geology ◽  
2021 ◽  
Author(s):  
Daianne Höfig ◽  
Yi Ge Zhang ◽  
Liviu Giosan ◽  
Qin Leng ◽  
Jiaqi Liang ◽  
...  
Keyword(s):  
Middle Miocene ◽  
Drainage System ◽  
Columbia River ◽  
Flood Basalt ◽  
Elemental Ratios ◽  
Plant Fossil ◽  
Columbia River Basalt ◽  
Mineral Assemblages ◽  
Northern Idaho ◽  
Columbia River Basalt Group

The world-renowned Miocene Clarkia paleolake in northern Idaho (USA) is closely associated with Columbia River Basalt Group volcanism. The flood basalt dammed a local drainage system to form the paleolake, which preserved a plant fossil Lagerstätte in its deposits. However, the precise age and temporal duration of the lake remain unsettled. We present the first unequivocal U-Pb zircon ages from interbedded volcanic ashes at the P-33 type location, constraining the deposition to 15.78 ± 0.039 Ma. Using micro–X-ray fluorescence and petrographic and spectral analyses, we establish the annual characteristics of laminations throughout the stratigraphic profile using the distribution of elemental ratios, mineral assemblages, and grain-size structures, as well as organic and fossil contents. Consequently, the ~7.5-m-thick varved deposit at the type location P-33 represents ~840 yr of deposition, coincident with the end of the main phase of Columbia River Basalt Group eruptions during the Miocene Climate Optimum. The timing and temporal resolution of the deposit offer a unique opportunity to study climate change in unprecedented detail during global warming associated with carbon-cycle perturbations.

scholarly journals Igneous Rock Associations 27. Chalcophile and Platinum Group Elements in the Columbia River Basalt Group: A Model for Flood Basalt Lavas

2020 ◽  
Vol 47 (4) ◽  
pp. 187-214
Author(s):  
Stephen P. Reidel ◽  
D. Brent Barnett
Keyword(s):  
Pacific Northwest ◽  
Columbia River ◽  
Flood Basalt ◽  
Platinum Group Elements ◽  
Large Igneous Province ◽  
Chalcophile Elements ◽  
Columbia River Basalt ◽  
The Pacific ◽  
Platinum Group ◽  
Columbia River Basalt Group

The Columbia River Basalt Group is the youngest and best preserved continental Large Igneous Province on Earth. The 210,000 km3 of basaltic lavas were erupted between 16.6 and 5 Ma in the Pacific Northwest, USA. The peak of the eruptions occurred over a 700,000-year period when nearly 99% of the basalts consisting of the Steens, Imnaha, Picture Gorge, Grande Ronde and Wanapum Basalts were emplaced. In this study we examined the Platinum Group Elements (PGEs) Pt and Pd, and the chalcophile elements Cu and Zn in the Columbia River Basalt Group. The presence of Pt, Pd and Cu in the compositionally primitive Lower Steens, Imnaha and Picture Gorge Basalts suggests that the Columbia River Basalt Group magma was a fertile source for these elements. The PGEs are contained mainly in sulphides in the earliest formations based on their correlation with immiscible sulphides, sulphide minerals and chalcophile elements. Grande Ronde, Wanapum and Saddle Mountains Basalts are depleted in PGEs and chalcophile elements compared to earlier formations. Sulphur was saturated in many flows and much of it probably came from assimilation of cratonic rock from a thinned lithosphere. We propose a model where the presence or absence of PGEs and chalcophile elements results primarily from the interaction between an advancing plume head and the crust/lithosphere that it encountered. The early lavas erupted from a plume that had little interaction with the crust/lithosphere and were fertile. However, as the plume head advanced northward, it assimilated crustal/lithospheric material and PGE and chalcophile elements were depleted from the magma. What little PGE and chalcophile elements remained in the compositionally evolved and depleted Grande Ronde Basalt flows mainly were controlled by substitution in basalt minerals and not available for inclusion in sulphides.  

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