Distribution and geochronology of Oregon Plateau (U.S.A.) flood basalt volcanism: The Steens Basalt revisited

Brueseke, Matthew E.; Heizler, Matthew T.; Hart, William K.; Mertzman, Stanley A.

doi:10.1016/j.jvolgeores.2006.12.004

Cited by 85 publications

(44 citation statements)

References 43 publications

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“…Finally, we note that the region near the Steens Mountain escarpment is particularly intriguing. Dikes exposed in the Steens fault face show this area to be one of the major sources that fed Steens volcanism that erupted 50,000–65,000 km 3 of flood basalts beginning at 16.6 Ma [ Carlson and Hart , 1987; Brueseke et al , 2007]. The area surrounding the Steens escarpment is clearly reflected in the regional crustal structure, as both a zone of slightly thickened crust forming the boundary between the thinnest HLP crust and the “0.704 line” (Figure 8), and a zone of anomalously low Poisson's ratio (Figure 11).…”

Section: Discussionmentioning

confidence: 99%

Crustal structure beneath the High Lava Plains of eastern Oregon and surrounding regions from receiver function analysis

et al. 2011

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We analyze teleseismic P‐to‐S receiver functions to image crustal structure beneath the High Lava Plains (HLP) of eastern Oregon and surrounding regions. Coverage from 206 broadband seismic stations provides the first opportunity to resolve variations in crustal composition, thickness, and heterogeneity on scales of a few km in depth and tens of km laterally across the HLP region. We utilize both H − κ stacking and a new Gaussian‐weighted common conversion point stacking technique. We find crust that is ≥40 km thick beneath the Cascades, Idaho Batholith, and Owyhee Plateau and thinner (∼31 km) crust beneath the HLP and northern Great Basin. Low Poisson's ratios of ∼0.240 characterize the granitic crust beneath the Idaho Batholith, while the Owyhee Plateau exhibits values of ∼0.270, typical of average continental crust. The Owyhee Plateau is a thick simple crustal block with distinct edges at depth. The western HLP exhibits high average values of 0.304, typical for regions of widespread basaltic volcanism. Combined with other geological and geophysical observations, the areas of abnormally high Poisson's ratios (∼0.320) and low‐velocity zones in the crust beneath north‐central and southern Oregon are consistent with the presence of partial melt on either side of the HLP trend, suggesting a central zone where crustal melts have drained to the surface, perhaps enabled by the Brothers Fault Zone. Thicker crust and an anomalous N‐S band of low Poisson's ratios (∼0.252) skirting the Steens Mountain escarpment is consistent with residuum from a midcrustal magma source of the massive flood basalts, supporting the view of extensive mafic underplating and intraplating of the crust from Cenozoic volcanism.

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Section: Discussionmentioning

confidence: 99%

Crustal structure beneath the High Lava Plains of eastern Oregon and surrounding regions from receiver function analysis

et al. 2011

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“…1). New volcanic rock samples from the LMSR (Table DR1 in the GSA Data Repository 1 ) were analyzed by the 40 Ar/ 39 Ar geochronology step-heating method, mostly at the New Mexico Geochronology Research Laboratory (analytical methods in Heizler et al [1999] and Brueseke et al [2007]) and one Table 1 Smith and Ketner (1970); Carr et al (1997) 48 Oskin & Iriondo (2004) Tg Te Ts Tb Ta Tl QTph Tpr Tlr Tc Tpg Tp Tg Tpr Kr Ka Te Tb Ta Tl Tl Tl Tl Tl Tl Tb Tb Tg Tc Tc Te Te Hodges et al [1994] and Snyder and Hodges [2000]). A sample containing sanidine was analyzed by single crystal fusion.…”

Section: Geochronologymentioning

confidence: 99%

Evolution of the central Garlock fault zone, California: A major sinistral fault embedded in a dextral plate margin

Andrew¹,

Walker²,

Monastero³

2014

Geological Society of America Bulletin

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The Garlock fault is an integral part of the plate-boundary deformation system inboard of the San Andreas fault (California, USA); however, the Garlock is transversely oriented and has the opposite sense of shear. The slip history of the Garlock is critical for interpreting the deformation of the through-going dextral shear of the Walker Lane belt-Eastern California shear zone. The Lava Mountains-Summit Range (LMSR), located along the central Garlock fault, is a Miocene volcanic center that holds the key to unraveling the fault slip and development of the Garlock. The LMSR is also located at the intersection of the NNW-striking dextral Blackwater fault and contains several sinistral WSW-striking structures that provide a framework for establishing the relationship between the sinistral Garlock fault system and the dextral Eastern California shear zone. New fi eld mapping and geochronology data ( 40 Ar/ 39 Ar and U-Pb) show fi ve distinct suites of volcanic-sedimentary rock units in the LMSR overlain by Pliocene exotic-clast conglomerates. This stratigraphy coupled with fi fteen fault slip markers defi ne a three-stage history for the central Garlock fault system of 11-7 Ma, 7-3.8 Ma, and 3.8-0 Ma. Pliocene to recent slip occurs in a ~12-km-wide zone and accounts for ~33 km or 51% of the total 64 km of left-lateral offset on the Garlock fault in the vicinity of the LMSR since 3.8 Ma. This history yields slip rates of 6-9 mm/yr for the younger stage and slower rates for older stages. The LMSR internally accommodates northwest-directed dextral slip associated with the Eastern California shear zone-Walker Lane belt via multiple processes of lateral tectonic escape, folding, normal faulting, and the creation of new faults. The geologic slip rates for the Garlock fault in the LMSR match with and explain along-strike variations in neotectonic rates.

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“…Miocene lavas in the Warner Range and nearby to the south have a distinctly different composition and eruptive style from volcanic rocks of overlapping age erupted in the Basin and Range Province to the east, notably the Steens Basalt, with which they have some times been included on regional maps (e.g., Camp and Ross, 2004;Brueseke et al, 2007;Camp and Hanan, 2008). Miocene lavas in northeastern California erupted to form a chain of shield volcanoes, while the Steens Basalt Hooper et al, 2002).…”

Section: Miocene Volcanismmentioning

confidence: 99%

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et al. 2011

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Distribution and geochronology of Oregon Plateau (U.S.A.) flood basalt volcanism: The Steens Basalt revisited

Cited by 85 publications

References 43 publications

Crustal structure beneath the High Lava Plains of eastern Oregon and surrounding regions from receiver function analysis

Crustal structure beneath the High Lava Plains of eastern Oregon and surrounding regions from receiver function analysis

Evolution of the central Garlock fault zone, California: A major sinistral fault embedded in a dextral plate margin

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