Magnetite (U–Th)/He dating and its application to the geochronology of intermediate to mafic volcanic rocks

Blackburn, Terrence; Stöckli, Daniel F.; Walker, J. Douglas

doi:10.1016/j.epsl.2007.04.044

Cited by 65 publications

(85 citation statements)

References 19 publications

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“…We suggest that these lavas are Pliocene in age because they are similar to ca. 3-4 Ma basalt lavas that occur in the Benton Range and throughout the Queen Valley area (Dalrymple and Hirooka, 1965;Crowder and Sheridan, 1972;Bradley, 2005;Blackburn et al, 2007;Tincher and Stockli, 2008). Locally overlying unit Tb, there is unit Trt, a quartz + feldspar, lithic-bearing rhyolite tuff.…”

Section: Tertiary Unitsmentioning

confidence: 97%

Quaternary faulting in Queen Valley, California-Nevada: Implications for kinematics of fault-slip transfer in the eastern California shear zone–Walker Lane belt

Lee

Garwood

Stöckli

et al. 2009

Geological Society of America Bulletin

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New geologic map, tectonic, geomorphologic, and terrestrial cosmogenic nuclide (TCN) geochronologic data document the geometry, style, kinematics, and slip rates on late Quaternary faults within the Queen Valley, California-Nevada area. These data provide important insight into the kinematics of fault-slip transfer from the dextral White Mountains fault zone northward into the Mina defl ection. Queen Valley is an ~16-kmlong, NE-trending basin bounded to the south by the White Mountains and underlain by four major Pleistocene to Holocene alluvialfan surfaces. Four different fault types and orientations cut and offset all but the youngest surfaces: (1) The normal-slip Queen Valley fault, which consists of a set of NE-striking, NW-and SE-dipping normal fault scarps that cut across the SE side of the valley and offset all but the youngest surfaces; (2) discontinuous NE-striking, sinistral faults exposed on the north side of the valley; (3) the NW-striking dextral Coyote Springs fault, which merges into (4) a set of E-W-striking thrust faults. Measured offsets across normal fault scarps developed within 10 Be TCN-dated surfaces yield minimum late Pleistocene horizontal extension rates of 0.1-0.3 mm/yr. Documented fault geometries and slip orientations across Queen Valley suggest that fault-slip transfer models, such as the extensional displacement transfer, block rotation, and simple shear models, within the dextral fault system proposed for the eastern California shear zoneWalker Lane belt are not applicable to this part of the Mina defl ection. Rather, dextral fault slip is transferred by both a restraining westward step and a releasing eastward step. Restraining and releasing bends have been extensively documented at a range of scales in strike-slip fault tectonic settings globally, and they have been simulated in analog models; thus, it is not surprising to document both within the ~630-km-long dextral shear zone that makes up the northern eastern California shear zone-Walker Lane belt. Our results, combined with published slip rates for the dextral White Mountain fault zone and the eastern sinistral Coaldale fault, suggest that transfer of dextral slip into the Mina defl ection is partitioned into three different components: horizontal extension along the Queen Valley fault, thrust faulting that merges into the dominantly dextral slip along the Coyote Springs fault, and dominantly sinistral slip along the Coaldale fault. A velocity vector diagram of fault-slip partitioning across Queen Valley predicts a small component of contraction across the Coyote Springs and western Coaldale faults. Contraction across the Mina defl ection is consistent with global positioning system data. An observed reduction in late Pleistocene fault-slip rates at the northern end of the eastern California shear zone and across the southwestern part of the Mina defl ection may be explained by distribution of slip across a much broader zone than generally thought.

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Section: Tertiary Unitsmentioning

confidence: 97%

Quaternary faulting in Queen Valley, California-Nevada: Implications for kinematics of fault-slip transfer in the eastern California shear zone–Walker Lane belt

Lee

Garwood

Stöckli

et al. 2009

Geological Society of America Bulletin

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“…Olivine grains in the size range 850 to 1000 μm were magnetically separated and handpicked. After picking, the olivine separates, approximately 1 g of material, were air abraded to remove the effects of alpha implantation from the decay of groundmass uranium on the helium concentration or alpha ejection loss from the phenocrysts (ACIEGO et al, 2007;BLACKBURN et al, 2007;MIN et al, 2006). Several attempts were made to separate enough microphenocrysts from samples AMK3, AMK11, AKA2, and AKA7, but the amount of material was not sufficient for helium and U-Th/He analysis.…”

Section: 2a U-th/hementioning

confidence: 99%

Combined U–Th/He and 40Ar/39Ar geochronology of post-shield lavas from the Mauna Kea and Kohala volcanoes, Hawaii

Aciego¹,

Jourdan²,

DePaolo³

et al. 2010

Geochimica et Cosmochimica Acta

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“…Among the acid-soluble and incongruently dissolved phases, phosphate minerals should be a major source of U, Th, and REE whereas olivine and titanomagnetite contribute less to the leachate trace element composition (Luhr et al, 1984;Green, 1994;Blackburn et al, 2007). The major source of Eu and alkaline and alkaline earth elements should be An-rich plagioclase, although enrichments of alkaline elements and Pb in the leachate solution of OA6-7 could be attributed to the contribution of dissolved nepheline and phlogopite (Larsen, 1979;Green, 1994).…”

Section: Resultsmentioning

confidence: 98%

Evaluation of the applicability of acid leaching for the 238U–230Th internal isochron method

et al. 2015

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Magnetite (U–Th)/He dating and its application to the geochronology of intermediate to mafic volcanic rocks

Cited by 65 publications

References 19 publications

Quaternary faulting in Queen Valley, California-Nevada: Implications for kinematics of fault-slip transfer in the eastern California shear zone–Walker Lane belt

Quaternary faulting in Queen Valley, California-Nevada: Implications for kinematics of fault-slip transfer in the eastern California shear zone–Walker Lane belt

Combined U–Th/He and 40Ar/39Ar geochronology of post-shield lavas from the Mauna Kea and Kohala volcanoes, Hawaii

Evaluation of the applicability of acid leaching for the 238U–230Th internal isochron method

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