Dating young basalt eruptions by (U-Th)/He on xenolithic zircons

Blondes, Madalyn S.; Reiners, Peter W.; Edwards, Benjamin R.; Biscontini, Adrian

doi:10.1130/g22956a.1

Cited by 40 publications

(32 citation statements)

References 20 publications

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“…Past geochronologic studies have established that BPVF volcanism is Pleistocene in age, with the most recent eruptions occurring during the late Pleistocene (12-126 ka), but a precise and reliable chronology for the youngest eruptions has not been constrained. Dating of BPVF lavas and lava-hosted xenoliths using K-Ar, 40 Ar/ 39 Ar, and (U-Th)/He methods has yielded dates between 1.2 Ma and <0.1 Ma [Cox et al, 1963a[Cox et al, , 1963bDalrymple, 1964;Gillespie, 1982;Gillespie et al, 1984;Turrin and Gillespie, 1986;Martel et al, 1987;Dorn et al, 1987;Blondes et al, 2007Blondes et al, , 2008; most of these reported K-Ar and 40 Ar/ 39 Ar dates are compiled by Connor and Conway [2000] and Bierman et al [1991]. Unfortunately, almost all of the reported K-Ar and 40 Ar/ 39 Ar dates are insufficiently precise to suitably resolve an eruption chronology for the youngest BPVF lavas (e.g., 70 6 40 ka, Gillespie [1982]; <300 ka, 130 6 25 ka, Dorn et al [1987]; Bierman et al [1991]; 1r errors), with an unclear role for excess argon because the analytical data for many of these dates are unpublished [e.g., Dorn et al, 1987].…”

Section: Previous Dating Of Bpvf Volcanismmentioning

confidence: 99%

Late Pleistocene ages for the most recent volcanism and glacial‐pluvial deposits at Big Pine volcanic field, California, USA, from cosmogenic ³⁶Cl dating

Woolford

2015

Geochem Geophys Geosyst

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The Big Pine volcanic field is one of several Quaternary volcanic fields that poses a potential volcanic hazard along the tectonically active Owens Valley of east-central California, and whose lavas are interbedded with deposits from Pleistocene glaciations in the Sierra Nevada Range. Previous geochronology indicates an 1.2 Ma history of volcanism, but the eruption ages and distribution of volcanic products associated with the most-recent eruptions have been poorly resolved. To delimit the timing and products of the youngest volcanism, we combine field mapping and cosmogenic 36 Cl dating of basaltic lava flows in the area where lavas with youthful morphology and well-preserved flow structures are concentrated. Field mapping and petrology reveal approximately 15 vents and 6 principal flow units with variable geochemical composition and mineralogy. Cosmogenic 36 Cl exposure ages for lava flow units from the top, middle, and bottom of the volcanic stratigraphy indicate eruptions at 17, 27, and 40 ka, revealing several different and previously unrecognized episodes of late Pleistocene volcanism. Olivine to plagioclase-pyroxene phyric basalt erupted from several vents during the most recent episode of volcanism at 17 ka, and produced a lava flow field covering 35 km 2 . The late Pleistocene 36 Cl exposure ages indicate that moraine and pluvial shoreline deposits that overlie or modify the youngest Big Pine lavas reflect Tioga stage glaciation in the Sierra Nevada and the shore of paleo-Owens Lake during the last glacial cycle.

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Section: Previous Dating Of Bpvf Volcanismmentioning

confidence: 99%

Late Pleistocene ages for the most recent volcanism and glacial‐pluvial deposits at Big Pine volcanic field, California, USA, from cosmogenic ³⁶Cl dating

Woolford

2015

Geochem Geophys Geosyst

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“…The chronology of eruptive volcanism in the Big Pine Volcanic Field is relatively well‐known from K‐Ar dating to range from ∼1.2 Ma to <0.1 Ma [ Connor and Conway , 2000; Turrin and Gillespie , 1986]. Although even higher precision ages are available from thermochronology of granitic xenoliths incorporated into magmas [ Blondes et al , 2007; Gillespie et al , 1984], the age of flows emanating from the Crater Mountain vent is not well‐known. A K/Ar age of 290 ± 40 ka was determined for flows west of the central vent [ Turrin and Gillespie , 1986], whereas unpublished 3 He exposure ages from flows on the SE corner of the cone cluster between 105 – 115 ka (J.…”

Section: Millennial Slip Rate Of the Owens Valley Faultmentioning

confidence: 99%

Late Pleistocene slip rate along the Owens Valley fault, eastern California

Kirby¹,

Anandakrishnan²,

Phillips³

et al. 2008

Geophysical Research Letters

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The Owens Valley fault zone (OVF) is one of the primary structures accommodating dextral shear across the Eastern California shear zone (ECSZ). Previous estimates of the Holocene slip rate along this structure rely on paleoseismic data and yield rates 2–3 times lower than those implied by geodetic velocities. Using displaced lava flows along the flank of Crater Mountain, we present the first estimate of slip rate along the OVF during the late Pleistocene. Subsurface characterization of the flow margin using a ground‐penetrating radar (GPR) allows for relatively precise determination of dextral displacement, and terrestrial cosmogenic 36Cl exposure ages of samples from the flow surface yield slip rates between ∼2.8 – 4.5 mm/yr over the past 55–80 kyr. Our results suggest either that paleoseismic slip‐rate estimates underestimate the long‐term slip rate or that rates of strain release have not been steady during the latter part of the Quaternary.

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“…The middle temperature (150-4008C) geochronometers of the (U-Th)/He system have the potential to avoid some of the challenges outlined above. Many (U-Th)/He thermochronologic applications are aimed at deciphering the cooling history of rocks during exhumation [e.g., Ehlers, 2005;Reiners and Shuster, 2009], but for fast-cooled volcanic rocks the cooling date may be equivalent to the eruption age [e.g., Tagami et al, 2003;Blondes et al, 2007;Blackburn et al, 2008]. Previous (U-Th)/He study of multiple phases (zircon, titanite, magnetite, garnet, and apatite) from several kimberlites in Kansas showed that He dating of kimberlites has promise, although the results were characterized by variable age dispersion [Blackburn et al, 2008].…”

Section: Introductionmentioning

confidence: 99%

Dating kimberlite emplacement with zircon and perovskite (U‐Th)/He geochronology

Stanley

Flowers

2016

Geochem Geophys Geosyst

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Kimberlites provide rich information about the composition and evolution of cratonic lithosphere. Accurate geochronology of these eruptions is key for discerning spatiotemporal trends in lithospheric evolution, but kimberlites can sometimes be difficult to date with available methods. We explored whether (U-Th)/He dating of zircon and perovskite can serve as reliable techniques for determining kimberlite emplacement ages. We obtained zircon and/or perovskite (U-Th)/He (ZHe, PHe) dates from 16 southern African kimberlites. Most samples with abundant zircon yielded reproducible ZHe dates ( 15% dispersion) that are in good agreement with published eruption ages. The majority of dated zircons were xenocrystic. Zircons with reproducible dates were fully reset during eruption or resided at temperatures above the ZHe closure temperature prior to entrainment in the kimberlite magma. Not dating hazy and radiation damaged grains can help avoid anomalous results for more shallowly sourced zircons that underwent incomplete damage annealing and/or partial He loss during the eruptive process. All seven kimberlites dated with PHe yielded reproducible ( 15% dispersion) and reasonable results. We conducted two preliminary perovskite 4 He diffusion experiments, which suggest a PHe closure temperature of >3008C. Perovskite in kimberlites is unlikely to be xenocrystic and its relatively high temperature sensitivity suggests that PHe dates will typically record emplacement rather than postemplacement processes. ZHe and PHe geochronology can effectively date kimberlite emplacement and provide useful complements to existing techniques.

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Dating young basalt eruptions by (U-Th)/He on xenolithic zircons

Cited by 40 publications

References 20 publications

Late Pleistocene ages for the most recent volcanism and glacial‐pluvial deposits at Big Pine volcanic field, California, USA, from cosmogenic ³⁶Cl dating

Late Pleistocene ages for the most recent volcanism and glacial‐pluvial deposits at Big Pine volcanic field, California, USA, from cosmogenic ³⁶Cl dating

Late Pleistocene slip rate along the Owens Valley fault, eastern California

Dating kimberlite emplacement with zircon and perovskite (U‐Th)/He geochronology

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Dating young basalt eruptions by (U-Th)/He on xenolithic zircons

Cited by 40 publications

References 20 publications

Late Pleistocene ages for the most recent volcanism and glacial‐pluvial deposits at Big Pine volcanic field, California, USA, from cosmogenic 36Cl dating

Late Pleistocene ages for the most recent volcanism and glacial‐pluvial deposits at Big Pine volcanic field, California, USA, from cosmogenic 36Cl dating

Late Pleistocene slip rate along the Owens Valley fault, eastern California

Dating kimberlite emplacement with zircon and perovskite (U‐Th)/He geochronology

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Product

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Late Pleistocene ages for the most recent volcanism and glacial‐pluvial deposits at Big Pine volcanic field, California, USA, from cosmogenic ³⁶Cl dating

Late Pleistocene ages for the most recent volcanism and glacial‐pluvial deposits at Big Pine volcanic field, California, USA, from cosmogenic ³⁶Cl dating