The Steens Basalt: Earliest lavas of the Columbia River Basalt Group

Camp, Victor E.; Ross, Martin E.; Duncan, Robert A.; Jarboe, N. A.; Coe, Robert S.; Hanan, B. B.; Johnson, Jenda A.

doi:10.1130/2013.2497(04)

Cited by 41 publications

(83 citation statements)

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“…3). An overlying unit Ts ~75 m thick is predominantly aphyric basalt flows and is stratigraphically equivalent to unit Taf (andesitic flows) of Minor et al (1989b), which is basalt according to the analyses of Camp et al (2013). Detailed petrographic and geochemical studies demonstrate that both Tsb and Ts of this study (Starkel, 2014;Starkel et al, 2014) and Ts and Taf of Minor et al (1989b) at Catlow Peak are Steens Basalt.…”

Section: Steens Basalt (Tsb Ts) Around the Mcdermitt Caldera Mafic mentioning

confidence: 55%

“…Precaldera rocks are predominantly Steens Basalt (Tsb, Tb) and intermediate composition lavas (Tpi), which are extensively exposed around the northern half of the caldera and regionally ( Fig. 4B; Greene, 1972Greene, , 1976Brueseke et al, 2007;Bondre and Hart, 2008;Jarboe et al, 2010;Camp et al, 2013), along with numerous interbedded local to distal silicic lavas and tuffs. Erupted rocks generally became more silicic through time, although rhyolite lavas are locally interbedded with Steens Basalt low in the stratigraphic section.…”

Section: Steens Basalt (Tsb Tb) and Precaldera Intermediate Lavas (Tpi)mentioning

confidence: 99%

“…Camp et al (2013) reviewed the controversy over what constitutes the Steens Basalt, stratigraphic unit versus geochemical rock type (e.g., Brueseke et al, 2007), and formally proposed stratigraphic limits to the unit. Based on 2 measured sections 13 km northwest and 15 km north of the northern margin of the McDermitt caldera, Camp et al (2013) Table 2). …”

Section: Steens Basalt (Tsb Tb) and Precaldera Intermediate Lavas (Tpi)mentioning

confidence: 99%

“…Mountains, fit the formal definition of Camp et al (2013), and are here termed the Steens Basalt. We divide the Steens Basalt into two units based on stratigraphy and the presence of coarsely plagioclase-phyric lavas common to the Steens Basalt (Fig.…”

Section: Steens Basalt (Tsb Ts) Around the Mcdermitt Caldera Mafic mentioning

confidence: 99%

“…3). The tuff crops out locally in the northern caldera wall, and Minor et al (1989b) and Camp et al (2013) showed it capping the Steens Basalt at Catlow Peak northwest of the caldera. The tuff of Oregon Canyon is highly enriched in incompatible elements and depleted in compatible elements (Starkel, 2014).…”

Section: Distal Ash-flow Tuffsmentioning

confidence: 99%

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Geology and evolution of the McDermitt caldera, northern Nevada and southeastern Oregon, western USA

et al. 2017

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The McDermitt caldera (western USA) is commonly considered the point of origin of the Yellowstone hotspot, yet until now no geologic map existed of the caldera and its geology and development were incompletely documented. We developed a comprehensive geologic framework through detailed and re connaissance geologic mapping, extensive petrographic and chemical analy sis, and highprecision Eruption of the McDermitt Tuff generated the irregularly keyholeshaped, 40 × 30-22 km McDermitt caldera. Collapse occurred mostly along a narrow ringfault zone of discrete faults with variable downwarp into the caldera be tween faults. Minor parallel faults locally widen the zone to as much as 6 km. We find no evidence that the McDermitt caldera consists of multiple nested calderas, as previously postulated. Total collapse was no more than ~1 km, and total erupted volume was ~1000 km 3 , of which 50%-85% is intracaldera tuff. Uncertainties in these estimates arise because an intracaldera tuff section is exposed only along the western edge of the caldera, and outflow tuff is not completely mapped. Megabreccia and mesobreccia are common in intracal dera tuff in the complete section. Intracaldera tuff is strongly rheomorphic, scrambling the compositional zoning, which is locally better preserved in out flow sections. However, outflow tuff is also strongly rheomorphic where it was deposited over steep topography.The caldera underwent postcollapse resurgent uplift driven by intrusion of icelandite magma, which also erupted from two major vents and as wide spread lavas. Major igneous activity around the McDermitt caldera lasted from before 16.7 to 16.1 Ma, although minor highalumina olivine tholeiite lavas were emplaced ca. 14.9 Ma in the youngest recognized igneous activity.Tuffaceous sediments as much as 210 m thick filled the caldera, although whether deposition preceded, followed, or spanned resurgence is unresolved. Although formed during regional extension, the caldera is cut only at its west ern and eastern margins by much younger, highangle normal faults that re sulted in gentle (~10°) eastward tilting of the caldera.Numerous hydrothermal systems probably related to caldera magmatism and focused along caldera structures produced Hg, Zrrich U (some along the western caldera ring fracture dated as 16.3 Ma), Ga, and minor Au mineral ization. Lithium deposits formed throughout the intracaldera tuffaceous sedi ments, probably ca. 14.9 Ma.Silicic central Snake River Plain, which also erupted voluminous rhyolitic tuffs. How ever, the Snake River Plain ignimbrites are metaluminous and homogeneous in bulk chemistry, with plagioclase, sanidine, and minor quartz as common phenocrysts, and rarely contain pumice or lithics.

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Section: Steens Basalt (Tsb Ts) Around the Mcdermitt Caldera Mafic mentioning

confidence: 55%

Section: Steens Basalt (Tsb Tb) and Precaldera Intermediate Lavas (Tpi)mentioning

confidence: 99%

Section: Steens Basalt (Tsb Tb) and Precaldera Intermediate Lavas (Tpi)mentioning

confidence: 99%

Section: Steens Basalt (Tsb Ts) Around the Mcdermitt Caldera Mafic mentioning

confidence: 99%

Section: Distal Ash-flow Tuffsmentioning

confidence: 99%

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Geology and evolution of the McDermitt caldera, northern Nevada and southeastern Oregon, western USA

et al. 2017

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A controlled‐source seismic and gravity study of the High Lava Plains (HLP) of Eastern Oregon

Cox

Keller

Harder

2013

Geochem Geophys Geosyst

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[1] This study employs data collected during the High Lava Plains (HLP) controlled-source seismic experiment conducted in September 2008. In this experiment, 2612 short-period seismic recorders and 120 3-component recorders were deployed across eastern Oregon and adjacent parts of Nevada and Idaho to record 15 seismic sources. Seismic and gravity data were integrated to create 2-D crustal scale P-wave velocity and density models for the 400 km long NW-SE and N-S profiles to provide a better understanding of the crustal and upper mantle structure and ultimately the magmatic and tectonic evolution of the region. These models are the first high-resolution images beneath the path of migratory, bi-modal volcanism that dotted the High Lava Plains beginning at 16 Ma. Our models show that the crustal structure across the HLP region is similar to that of the northern Basin and Range which has experienced extension since 35 Ma but with moderate magmatic modification of the crust. A thick layer (5-7 km) of sediments and volcanics extends over most of the area and is thickest in the Harney Basin area. We interpret denser/faster material in the lower to middle crust under the southern Harney Basin area to be mafic intraplating. We have also identified a region of denser/faster material in the upper crust in the vicinity of Oregon-Idaho border. The crust thickens from 34 to 37 km, and the lower crust increases in density (2.8-2.85 g/cm 3 ), from west to east across eastern Oregon in close proximity to the interpreted position of the 0.706 Sr isotope line, suggesting a decrease in extension. In the lowermost crust below the southeastern HLP, there is relatively high velocity (7.2-7.4 km/s) and density (2.95 g/ cm 3 ) that suggests the presence of underplating. The HLP region has undergone moderate extension, and the average crustal velocity is somewhat higher than in the adjacent Basin and Range, suggesting some magmatic modification in the lower crust, but not as much as might be expected given the voluminous surface volcanism.

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Testing fault growth models with low‐temperature thermochronology in the northwest Basin and Range, USA

2016

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Common fault growth models diverge in predicting how faults accumulate displacement and lengthen through time. A paucity of field‐based data documenting the lateral component of fault growth hinders our ability to test these models and fully understand how natural fault systems evolve. Here we outline a framework for using apatite (U‐Th)/He thermochronology (AHe) to quantify the along‐strike growth of faults. To test our framework, we first use a transect in the normal fault‐bounded Jackson Mountains in the Nevada Basin and Range Province, then apply the new framework to the adjacent Pine Forest Range. We combine new and existing cross sections with 18 new and 16 existing AHe cooling ages to determine the spatiotemporal variability in footwall exhumation and evaluate models for fault growth. Three age‐elevation transects in the Pine Forest Range show that rapid exhumation began along the range‐front fault between approximately 15 and 11 Ma at rates of 0.2–0.4 km/Myr, ultimately exhuming approximately 1.5–5 km. The ages of rapid exhumation identified at each transect lie within data uncertainty, indicating concomitant onset of faulting along strike. We show that even in the case of growth by fault‐segment linkage, the fault would achieve its modern length within 3–4 Myr of onset. Comparison with the Jackson Mountains highlights the inadequacies of spatially limited sampling. A constant fault‐length growth model is the best explanation for our thermochronology results. We advocate that low‐temperature thermochronology can be further utilized to better understand and quantify fault growth with broader implications for seismic hazard assessments and the coevolution of faulting and topography.

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The Steens Basalt: Earliest lavas of the Columbia River Basalt Group

Cited by 41 publications

References 100 publications

Geology and evolution of the McDermitt caldera, northern Nevada and southeastern Oregon, western USA

Geology and evolution of the McDermitt caldera, northern Nevada and southeastern Oregon, western USA

A controlled‐source seismic and gravity study of the High Lava Plains (HLP) of Eastern Oregon

Testing fault growth models with low‐temperature thermochronology in the northwest Basin and Range, USA

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