The tectonic significance of high-K2O volcanism in the Sierra Nevada, California

Putirka, Keith; Busby, Cathy J.

doi:10.1130/g23914a.1

Cited by 60 publications

(89 citation statements)

References 24 publications

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“…As noted in earlier studies (Putirka and Busby, 2007;, the Table Mountain Latite samples have high concentrations of incompatible trace elements, which can be attributed to low degrees of partial melting. However, the Table Mountain Latite and Eureka Valley Tuff also exhibit a distinct break in slope in TiO 2 (Fig.…”

Section: Geochemistrysupporting

confidence: 61%

“…3). Extreme transtension in the very large Sierra Crest-Little Walker pull-apart is inferred to have triggered rapid ascent of low-degree partial melts (Putirka and Busby, 2007), causing outpouring of high-K 2 O "andesite flood lavas" (Putirka and Busby, 2007;Busby et al, 2013b). The NE-striking fault zone in the northeast part of the Sierra Crest-Little Walker volcanic center mimics the right steps and NE-striking faults of the Carson domain and Mina deflection but on a smaller scale (Fig.…”

Section: Summary Of Structural Frameworkmentioning

confidence: 97%

“…Previous papers have presented small geochemical data sets in stratigraphic context (Ransome, 1898;Noble et al, 1976;Putirka and Busby, 2007; , 2008a, 2013bKoerner et al, 2009), or used those data sets as part of a regional-scale analysis du Bray et al, 2014). However, this is the first paper to present a large geochemical data set in stratigraphic and intrusive context (Table 1), plotted on maps (Fig.…”

Section: Field and Petrographic Characteristics And Newmentioning

confidence: 99%

“…The predicted volcanic expression, then, is an increase in the total volume of erupted volcanic materials, with geochemical trends that involve greater melt fractions and an increase in MORB-like (convective) geochemical signatures. However, none of the high-K 2 O lavas exhibits these characteristics: Both the central Sierra Nevada Stanislaus Group and the southern Sierra Nevada high-K 2 O suites are the products of very low degrees of melt fraction of typical continental mantle lithosphere, rather than a special enriched source (Putirka and Busby, 2007;. Worse still, lavas erupted after the presumed delamination event-including entrained mantle xenoliths (e.g., the Big Pine volcanic field)-have isotopic signatures that require an ancient continental mantle lithosphere source .…”

Section: Geochemistrymentioning

confidence: 99%

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A tale of two Walker Lane pull-apart basins in the ancestral Cascades arc, central Sierra Nevada, California

et al. 2018

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We integrate new geochronological, petrographic, and geochemical data with previously published (Sierra Crest-Little Walker volcanic center) and new (Ebbetts Pass volcanic center) structural and stratigraphic data to describe two deeply dissected, spectacularly well-exposed Walker Lane pull-apart basins in the ancestral Cascades arc. The Miocene (ca. 12-5 Ma) Sierra Crest-Little Walker arc volcanic center and the Miocene-Pliocene (ca. 6-4.6 Ma) Ebbetts Pass arc volcanic center formed in pull-apart basins in the Walker Lane, a NNW-trending zone of dextral strike-slip and oblique normal faults at the western edge of the Basin and Range Province. The Sierra Crest-Little Walker arc volcanic center is a transtensional arc volcanic field that is as areally extensive (~4000 km Volcano-tectonic activity continued for a longer period (ca. 12-6 Ma) in the northern half of the Sierra Crest-Little Walker volcanic center than it did in the southern half (ca. 12-9 Ma), overlapping for ~1 m.y. with the onset of volcano-tectonic activity at the Ebbetts Pass volcanic center to the north. This provides local-scale confirmation of the regional-scale interpretation that a transtensional rift tip propagated northward with time within the arc axis, in concert with northward migration of the Mendocino triple junction. Transtensional rift magmatism followed in its wake and continues today at various points along the length of the Walker Lane. "Tectono-stratigraphic recycling" was a key geologic process throughout the development of these ancestral Cascades arc pull-apart basins, and it consisted of the transfer of megaslide slabs, up to 2 km long and tens to hundreds of meters thick, from footwall to hanging-wall blocks in the transtensional rift. A time-slice series of block diagrams is used to illustrate the structural controls on arc volcanism in the early stages of Walker Lane transtensional faulting (ca. 12-4.6 Ma).

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Section: Geochemistrysupporting

confidence: 61%

Section: Summary Of Structural Frameworkmentioning

confidence: 97%

Section: Field and Petrographic Characteristics And Newmentioning

confidence: 99%

Section: Geochemistrymentioning

confidence: 99%

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A tale of two Walker Lane pull-apart basins in the ancestral Cascades arc, central Sierra Nevada, California

et al. 2018

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“…This change in plate motion coincided with initiation of modern Walker Lane extensional tectonics in what has been interpreted as rift driven volcanism near Bridgeport, California [Putrika and Busby, 2007]. Extensional processes have more recently been recognized north of the Bridgeport area and interpreted as coinciding with northward evolution of the MTJ [Busby, 2013].…”

Section: Introductionmentioning

confidence: 98%

Evidence for Moho‐lower crustal transition depth diking and rifting of the Sierra Nevada microplate

Smith

Kent

Seggern

et al. 2016

Geophysical Research Letters

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Lithospheric rifting most often initiates in continental extensional settings where “breaking of a plate” may or may not progress to sea floor spreading. Generally, the strength of the lithosphere is greater than the tectonic forces required for rupture (i.e., the “tectonic force paradox”), and it has been proposed that rifting requires basaltic magmatism (e.g., dike emplacement) to reduce the strength and cause failure, except for the case of a thin lithosphere (<30 km thick). Here we isolate two very similar and unprecedented observations of Moho‐lower crustal transition dike or fluid injection earthquake swarms under southern Sierra Valley (SV: 2011–2012) and North Lake Tahoe (LT: 2003–2004), California. These planar distributions of seismicity can be interpreted to define the end points, and cover ~25% of the length, of an implied ~56 km long structure, each striking N45°W and dipping ~50°NE. A single event at ~30 km depth that locates on the implied dipping feature between the two swarms is further evidence for a single Moho‐transition depth structure. We propose that basaltic or fluid emplacement at or near Moho depths weakens the upper mantle lid, facilitating lithospheric rupture of the Sierra Microplate. Similar to the LT sequence, the SV event is also associated with increased upper crustal seismicity. An 27 October 2011, Mw 4.7 earthquake occurred directly above the deep SV sequence at the base of the upper crustal seismogenic zone (~15 km depth).

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Magmatic expressions of continental lithosphere removal

Wang

Currie

2015

JGR Solid Earth

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Gravitational lithosphere removal in continental interior has been inferred from various observations, including anomalous surface deflections and magmatism. We use numerical models and a simplified theoretical analysis to investigate how lithosphere removal can be recognized in the magmatic record. One style of removal is a Rayleigh‐Taylor‐type instability, where removal occurs through dripping. The associated magmatism depends on the lithosphere thermal structure. Four types of magmatism are predicted: (1) For relatively hot lithosphere (e.g., back arcs), the lithosphere can be conductively heated and melted during removal, while the asthenosphere upwells and undergoes decompression melting. If removal causes significant lithospheric thinning, the deep crust may be heated and melted. (2) For moderately warm lithosphere (e.g., average Phanerozoic lithosphere) in which the lithosphere root has a low density, only the lithosphere may melt. (3) If the lithosphere root has a high density in moderately warm lithosphere, only asthenosphere melt is predicted. (4) For cold lithosphere (e.g., cratons), no magmatism is induced. An alternate style of removal is delamination, where dense lithosphere peels along Moho. In most cases, the lithosphere sinks too rapidly to melt. However, asthenosphere can upwell to the base of the crust, resulting in asthenospheric and crustal melts. In delamination, magmatism migrates laterally with the detachment point; in contrast, magmatism in Rayleigh‐Taylor‐type instability has a symmetric shape and converges toward the drip center. The models may explain the diversity of magmatism observed in areas with inferred lithosphere removal, including the Puna Plateau and the southern Sierra Nevada.

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The tectonic significance of high-K2O volcanism in the Sierra Nevada, California

Cited by 60 publications

References 24 publications

A tale of two Walker Lane pull-apart basins in the ancestral Cascades arc, central Sierra Nevada, California

A tale of two Walker Lane pull-apart basins in the ancestral Cascades arc, central Sierra Nevada, California

Evidence for Moho‐lower crustal transition depth diking and rifting of the Sierra Nevada microplate

Magmatic expressions of continental lithosphere removal

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