Distinct mantle sources for Pliocene–Quaternary volcanism beneath the modern Sierra Nevada and adjacent Great Basin, northern California and western Nevada, USA

Cousens, Brian; Henry, Christopher D.; Gupta, Vishal

doi:10.1130/ges00741.1

Cited by 13 publications

(8 citation statements)

References 58 publications

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“…6 Ma Ebbetts Pass region (e.g., Hagan et al, 2009;Busby and Putirka, 2009) and Lake Mead (e.g., Weber and Smith, 1987) have been reported. In some cases, extension has thinned the lithosphere sufficiently that asthenosphere-derived magmatism allows alkali basalts with within-plate trace-element signatures to be emplaced (Reno-Fallon region, Buffalo Valley volcanic field, Lunar Craters volcanic field, and the Mojave Desert; Farmer et al, 1995;Cousens et al, 2012;Cousens et al, 2013;Rasoazanamparany et al, 2015).…”

Section: ■ Introductionmentioning

confidence: 99%

Geochemical study of Cenozoic mafic volcanism in the west-central Great Basin, western Nevada, and the Ancestral Cascades Arc, California

2020

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Processes linked to shallow subduction, slab rollback, and extension are recorded in the whole-rock major-, trace-element, and Sr, Nd, and Pb isotopic compositions of mafic magmatic rocks in both time and space over southwestern United States. Eocene to Mio-Pliocene volcanic rocks were sampled along a transect across the west-central Great Basin (GB) in Nevada to the Ancestral Cascade Arc (ACA) in the northern Sierra Nevada, California (~39°–40° latitude), which are interpreted to represent a critical segment of a magmatic sweep that occurred as a result of subduction from east-northeast convergence between the Farallon and North American plates and extension related to the change from a convergent to a transform margin along the western edge of North America. Mafic volcanic rocks from the study area can be spatially divided into three broad regions: GB (5–35 Ma), eastern ACA, and western ACA (2.5– 16 Ma). The volcanic products are dominantly calc-alkalic but transition to alkalic toward the east. Great Basin lavas erupted far inland from the continental margin and have higher K, P, Ti, and La/Sm as well as lower (Sr/P)pmn, Th/Rb, and Ba/Nb compared to ACA lavas. Higher Pb isotopic values, combined with lower Ce/Ce* and high Th/Nb ratios in some ACA lavas, are interpreted to come from slab sediment. Mafic lavas from the GB and ACA have overlapping 87Sr/86Sr and 143Nd/144Nd values that are consistent with mantle wedge melts mixing with a subduction-modified lithospheric mantle source. Eastern and western ACA lavas largely overlap in age and elemental and isotopic composition, with the exception of a small subset of lavas from the westernmost ACA region; these lavas show lower 87Sr/86Sr at a given 143Nd/144Nd. Results show that although extension contributes to melting in some regions (e.g., selected lavas in the GB and Pyramid Lake), chemical signatures for most mafic melts are dominated by subduction-related mantle wedge and a lithospheric mantle component.

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Section: ■ Introductionmentioning

confidence: 99%

Geochemical study of Cenozoic mafic volcanism in the west-central Great Basin, western Nevada, and the Ancestral Cascades Arc, California

2020

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“…The age of the youngest strata of the ancestral Cascades in any part of the Sierra is important, because the initiation of signifi cant incision followed the deposition of these units. Andesitic fl ows in the headwaters of the North Fork American River have K-Ar and Ar-Ar ages as young as 3.0 Ma (Harwood, 1981;Cousens et al, 2008Cousens et al, , 2012 data in Saucedo and Wagner, 1992); these are the youngest ages obtained from andesites south of the North Fork Feather River. Between these rocks and the North Fork Feather River, the youngest K-Ar age from andesitic rocks is 6.8 Ma (Saucedo and Wagner, 1992), but age data in this region are sparse.…”

Section: Introductionmentioning

confidence: 99%

Paleochannels, stream incision, erosion, topographic evolution, and alternative explanations of paleoaltimetry, Sierra Nevada, California

Wakabayashi

2013

Geosphere

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Geologic relationships in the Sierra Nevada, California, show negligible stream incision between Eocene and Late Miocene-Pliocene time. Stream incision of up to ~1 km began at (from south to north) ca. 20 Ma in the Kern to Kings River drainages, between 6 and 10 Ma in the San Joaquin River drainage, 3.6-4 Ma in the Stanislaus and Mokelumne River drainages, and ca. 3 Ma in the American and Feather River drainages. These differences in incision timing greatly exceed the time of knickpoint retreat, based on the example of the North Fork Feather River, where the knickpoint may have retreated over 100 km in less than 300 k.y. based on ages of interfl uve-capping andesites and an inset basalt fl ow. The knickpoint in the Stanislaus River may have retreated over 50 km in less than 400 k.y. based on somewhat looser constraints. Eocene paleochannels show lowest gradients parallel to the range axis, steepest ones perpendicular, and reaches with signifi cant "uphill" gradients that rise in the paleo-downstream direction. Modern Sierran rivers lack this relationship. The azimuth-gradient relationships of paleochannels, especially the uphill gradients, require late Cenozoic tilting and uplift. Incision began in spite of decreasing discharge and increasing sediment load and must have resulted from steepening associated with tilting and uplift. Stable-isotope paleoaltimetry apparently records a profi le similar to that of the modern range and areas east of it, in spite of signifi cant vertical deformation that postdates the age of the sampled deposits, suggesting fairly recent reequilibration, in contrast to the published interpretations of closed-system behavior since the Oligocene or Eocene. Such apparent opensystem behavior agrees with studies showing progressive hydration of volcanic glass and the correspondence between weathering and erosion rates. Northward-younging initiation of late Cenozoic uplift and stream incision suggests a relationship with triple-junction migration, possibly associated with slab window development, with a second uplift pulse related to delamination and limited to the southern Sierra (San Joaquin River drainage and southward). Basement features may have signifi cantly infl uenced along-and across-strike differences in Cenozoic tectonics and geomorphic response. GENERAL GEOLOGIC FRAMEWORK AND TECTONIC HISTORY The 600-km-long Sierra Nevada is the most prominent mountain range in California. The Sierra Nevada and the Central Valley belong to the Sierra Nevada microplate, an element of

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“…Extensive Cenozoic volcanic and sedimentary rocks, excellent exposure, and abundant previous geological mapping in the Walker Lane make it an excellent region in which to study rifting processes (e.g., Fig. 2; Henry and Perkins, 2001;Trexler et al, 2012;Putirka and Busby, 2007;Busby et al, 2008aBusby et al, , 2008bFaulds and Henry, 2008;Busby and Putirka, 2009;Cashman et al, 2009Cashman et al, , 2012Jayko, 2009aJayko, , 2009bNorton, 2011;Cousens et al, 2012;Jayko and Bursik, 2012;Putirka and Platt, 2012;Riley et al, 2012;Trexler et al, 2012;Wakabayshi, 2013).…”

Section: Introductionmentioning

confidence: 99%

Birth of a plate boundary at ca. 12 Ma in the Ancestral Cascades arc, Walker Lane belt of California and Nevada

Busby

2013

Geosphere

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The Walker Lane belt of eastern California and western Nevada is the northernmost extension of the Gulf of California transtensional rift, where the process of continental rupture has not yet been completed, and rift initiation can be studied on land. GPS and earthquake focal mechanism studies demonstrate that the Walker Lane belt currently accommodates NW-SE-directed movement between the Sierra Nevada microplate and the North American plate, but the timing and nature of rift initiation remains unclear. I present a model for plate-margin-scale initiation of the Gulf of California and Walker Lane transtensional rifts at ca. 12 Ma; localization of rifting in both was initiated by thermal weakening in the axis of a subduction-related arc undergoing extension due to slab rollback, and thermal weakening in the arc was enhanced by stalling of the trenchward-migrating precursor arc against a thick Cretaceous batholithic lithospheric profi le on its western margin. Rifting succeeded very quickly in the Gulf of California, due to stalling of Farallon slabs, but the Walker Lane transtensional rift has been unzipping northward along the axis of the Cascades arc, following the Mendocino triple junction. I infer that plate-margin-scale Walker Lane transtension was signaled by the development of an unusually large and voluminous transtensional arc volcanic center, the ca. 11.5-9 Ma Sierra Crest-Little Walker arc volcanic center. I show that the style of faulting in this large Miocene arc volcanic center closely matches that of Quaternary transtensional structures in the central Walker Lane, where it lies, and that it differs from southern and northern Walker Lane structures. This indicates that the temporal transition from E-W Basin and Range extension to NW-SEWalker Lane transtension occurred earlier than most workers have inferred. I also summarize new data which show that the central Sierra Nevada range front (from Long Valley to the Tahoe Basin) lies squarely within the Walker Lane belt, not to the west of it as previous workers have inferred.The leading tip of Walker Lane transtension is marked by large arc volcanic centers sited in transtensional stepovers; these include the ca. 11.5-9 Ma Sierra Crest-Little Walker volcanic center; north of that, the ca. 6.3-4.8 Ma Ebbetts Pass volcanic center; and north of that, the active Lassen volcanic center. In its wake, large rift volcanic centers are sited on transtensional stepovers or bends; these include the Long Valley and Coso volcanic fi elds. I predict that any <12 Ma large volcanic centers identifi ed by future workers in the Sierra Nevada-Walker Lane region, or in the Gulf of California, will prove to be sited at major releasing bends or stepovers.

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Distinct mantle sources for Pliocene–Quaternary volcanism beneath the modern Sierra Nevada and adjacent Great Basin, northern California and western Nevada, USA

Cited by 13 publications

References 58 publications

Geochemical study of Cenozoic mafic volcanism in the west-central Great Basin, western Nevada, and the Ancestral Cascades Arc, California

Geochemical study of Cenozoic mafic volcanism in the west-central Great Basin, western Nevada, and the Ancestral Cascades Arc, California

Paleochannels, stream incision, erosion, topographic evolution, and alternative explanations of paleoaltimetry, Sierra Nevada, California

Birth of a plate boundary at ca. 12 Ma in the Ancestral Cascades arc, Walker Lane belt of California and Nevada

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