Magmatic arc asymmetry and distribution of anomalous plutonic belts in the batholiths of California: Effects of assimilation, crustal thickness, and depth of crystallization

Ague, Jay J.; Brimhall, George H.

doi:10.1130/0016-7606(1988)100<0912:maaado>2.3.co;2

Cited by 298 publications

(198 citation statements)

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“…This latter component most likely represents the Paleozoic North American metamorphic basement through which the Cretaceous batholith was emplaced (26,27). The protoliths of these metamorphic rocks were probably highly weathered sediments shed off the North American continent and later metamorphosed during subduction well before Cretaceous plutonism.…”

Section: Resultsmentioning

confidence: 99%

“…The PRB represents part of the north-south trending Cordilleran batholiths emplaced through the western margin of North America during Cretaceous subduction of the Farallon plate. The eastern PRB represents the part of the continental arc that was emplaced through the Paleozoic margin of North America and hence represents mixtures of juvenile magmas and melts of older metamorphic basement (27) (4,20,26). Despite the involvement of older, metamorphic basement, all of the granitic rocks studied here belong to the I-type granitic series (11).…”

Section: Application To Continental Arc Granitoidsmentioning

confidence: 99%

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The Mg isotopic systematics of granitoids in continental arcs and implications for the role of chemical weathering in crust formation

Shen

Jacobsen

Lee

et al. 2009

Proc. Natl. Acad. Sci. U.S.A.

114

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Continental crust is too Si-rich and Mg-poor to derive directly from mantle melting, which generates basaltic rather than felsic magmas. Converting basalt to more felsic compositions requires a second step involving Mg loss, which is thought to be dominated by internal igneous differentiation. However, igneous differentiation alone may not be able to generate granites, the most silicic endmember making up the upper continental crust. Here, we show that granites from the eastern Peninsular Ranges Batholith ( batholith ͉ granite ͉ isotope ͉ magnesium ͉ California

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Section: Resultsmentioning

confidence: 99%

Section: Application To Continental Arc Granitoidsmentioning

confidence: 99%

The Mg isotopic systematics of granitoids in continental arcs and implications for the role of chemical weathering in crust formation

Shen

Jacobsen

Lee

et al. 2009

Proc. Natl. Acad. Sci. U.S.A.

114

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“…Nevada although that "average arc" may be biased toward island arcs. The depth of crystallization exposed at the surface at the latitude of our cross section is 8 to 15 km [Ague and Brimhall, 1988 …”

mentioning

confidence: 99%

Three‐dimensional seismic model of the Sierra Nevada arc, California, and its implications for crustal and upper mantle composition

Fliedner¹,

Klemperer²,

Christensen³

2000

J. Geophys. Res.

116

101

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We display the velocity model in several cross sections a, nd maps of Moho depth and average crustal velocity. The measured velocities in the upper and mid crust of the Sierra Nevada batholith are in good agreement with laboratory measurements on Sierra Nevada tonalites after corrections for density a.nd temperature. Peridotite xenoliths from the eastern Sierra Nevada suggest strong upper mantle anisotropy, which could explain some of the velocity heterogeneity in the Sierra Nevada mantle. By the time Creta, ceous subduction-related magmatism ceased, the Sierra Nevada arc must have had a thick marie lower crust; yet a principal result of our work is that today the batholith has a crust of mainly felsic composition throughout.A subcrustal layer with velocities below normal P• velocities (<7.6 kin/s) may indicate the presence of lower crustal material in eclogite facies.

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“…In the Southern California segment of the batholith the depth of emplacement of all plutons, based on Al-in-hornblende barometry, increases from about 2 kbar or less in the west, to more than 5 kbar in the eastern zone (Ague and Brimhall 1988;Todd et al 2003). In the Sierra de San Pedro Mártir, farther south (Fig.…”

Section: Exhumationmentioning

confidence: 99%

“…6) represent an intense magmatic pulse ranging in age from 99-85 Ma (Silver and Chappell 1988;Walawender et al 1990;Kimbrough et al 2001;Premo et al 2014b). The plutons were emplaced at depths of 5-23 km into upper greenschist, but mainly amphibolite, grade wall rocks that are in many places migmatitic Ague and Brimhall 1988;Todd et al 1988Todd et al , 2003Grove 1993;Rothstein 1997;Rothstein and Manning 2003;Gastil et al 2014). The plutons were intruded during a period of exhumation when rocks at depths of 15-23 km were brought rapidly to the surface by detachment faulting and collapse (Krummenacher et al 1975;George and Dokka 1994;Ortega-Rivera et al 1997, Ortega-Rivera 2003Grove et al 2003;Miggins et al 2014).…”

Section: Exhumationmentioning

confidence: 99%

Arc and Slab-Failure Magmatism in Cordilleran Batholiths II – The Cretaceous Peninsular Ranges Batholith of Southern and Baja California

Hildebrand

Whalen

2014

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Ever since the late 1960s when Warren Hamilton proposed that the great Cordilleran batholiths of the western Americas are the roots of volcanic arcs like the Andes and were generated by longstanding eastward subduction, most geologists have followed suit, despite the evergrowing recognition that many Cordilleran batholiths are complex, composite bodies that developed with intervals of intense shortening and exhumation between and during periods of magmatism. The Peninsular Ranges batholith of Southern and Baja California provides a superb place to unravel the complexities because there is a lot of data and because it is longitudinally composed of two parts: an older western portion of weakly to moderately deformed, low-grade volcanic and epizonal plutonic rocks ranging in age from ~128–100 Ma; and a more easterly sector of deformed amphibolite grade rocks cut by compositionally zoned, mesozonal plutonic complexes of the La Posta suite, emplaced from 99–86 Ma. While plutons of the La Posta suite are generally considered to be the product of continued eastward subduction, they are enigmatic, because they and their wall rocks were rapidly exhumed from as deep as 23 km and eroded during, and just after, their emplacement, unlike plutons in magmatic arcs, which are generally emplaced in zones of subsidence. Here we resolve the enigma with a model where westward-dipping subduction led to arc magmatism of the western sector, the Santiago Peak–Alisitos composite arc, during the period ~128–100 Ma. Arc magmatism shut down when the arc collided with a west-facing Early Cretaceous passive margin at about 100 Ma. During the collision the buoyancy contrast between the continental crust of the eastern block and its attached oceanic lithosphere led to failure of the subducting slab. The break-off allowed subjacent asthenosphere to upwell, adiabatically melt, and rise into the upper plate to create the large zoned tonalite–granodiorite–granite complexes of the La Posta suite. While compositionally similar to arc plutons in many respects, the examples from the Southern California and Baja segments of the batholith have geochemistry that indicates they were derived from partial melting of asthenosphere at deeper levels in the mantle than typical arc magmas, and within the garnet stability field. This is consistent with asthenosphere upwelling through the torn lower-plate slab. We identify kindred rocks with similar geological relations in other Cordilleran batholiths of the Americas, such as the Sierra Nevada, which lead us to suggest that slab failure magmatism is common, both spatially and temporally.SOMMAIREDepuis la fin des années 1960, Warren Hamilton a proposé que les grands batholites de la Cordillère de l'ouest des Amériques sont les racines d’arcs volcaniques andéens issus de la subduction vers l'est de longue durée, et depuis la plupart des géologues ont emboîté le pas, bien qu’un nombre croissant d’indications montrent que de nombreux batholites de la Cordillère sont des entités composites complexes qui se sont développés lors d’intervalles intenses de contraction et d’exhumation, durant et entre les périodes de magmatisme. Le batholite Peninsular Ranges du Sud de la Californie et de Baja California est un excellent endroit permettant de démêler les choses parce qu'il y a beaucoup de données et parce qu'il est composé longitudinalement de deux parties: une partie occidentale plus ancienne, faiblement à modérément déformée, de roches volcaniques de faible métamorphisme et de roches plutoniques épizonales âgées d’environ 128 Ma à 100 Ma; et, d’un segment plus à l'est de roches amphiboliques déformées recoupées par des roches de composition zonée des complexes mésozonaux plutoniques de la suite de la Posta, mises en place entre 99 Ma et 86 Ma. Bien que les plutons de la suite La Posta sont généralement considérés comme le produit d’une subduction soutenue vers l’est, ils posent problème, parce qu'avec leurs roches encaissantes, ils ont été rapidement exhumés de profondeurs aussi grandes que 23 km, et érodées durant et juste après leur mise en place, contrairement aux plutons des arcs magmatiques, qui sont généralement mis en place dans les zones de subsidence. Dans le présent article, nous proposons une solution à ce problème, avec un modèle de subduction vers l'ouest qui conduit à un magmatisme d'arc du secteur ouest, l'arc composite de Santiago Peak-Alisitos, durant la période d’environ 128 Ma à 100 Ma. Le magmatisme d’arc s’est arrêté lorsque l'arc est entré en collision avec une marge passive à pendage ouest du début du Crétacé, il y a environ 100 Ma. Lors de la collision, le contraste de flottabilité entre la croûte continentale du bloc de est et la lithosphère océanique qui y est rattachée a conduit à l'avortement de la plaque plongeante. La cassure a entrainé la remontée de l’asthénosphère sous-jacente, sa fusion adiabatique, et sa remontée dans la plaque supérieure pour former les grands complexes zonés de tonalite-granodiorite-granite de La Posta. Bien que de composition similaire aux plutons d'arc à bien des égards, les exemples des segments de batholites de Californie du Sud et de Baja ont une géochimie qui indique qu'ils proviennent de la fusion partielle de l’asthénosphère à des niveaux plus profonds dans le manteau que les magmas d'arc typiques, à l’intérieur du domaine de stabilité du grenat. Ce qui correspond à une remontée d’asthénosphère à travers une dalle de plaque inférieure cassée. Nous connaissons des roches semblables avec les relations géologiques similaires dans d'autres batholites de la Cordillère des Amériques, tel celles de la Sierra Nevada, ce qui nous amène à penser que le magmatisme de cassure de plaque est commun, tant spatialement et temporellement.

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Magmatic arc asymmetry and distribution of anomalous plutonic belts in the batholiths of California: Effects of assimilation, crustal thickness, and depth of crystallization

Cited by 298 publications

References 0 publications

The Mg isotopic systematics of granitoids in continental arcs and implications for the role of chemical weathering in crust formation

The Mg isotopic systematics of granitoids in continental arcs and implications for the role of chemical weathering in crust formation

Three‐dimensional seismic model of the Sierra Nevada arc, California, and its implications for crustal and upper mantle composition

Arc and Slab-Failure Magmatism in Cordilleran Batholiths II – The Cretaceous Peninsular Ranges Batholith of Southern and Baja California

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