Mafic injections, in situ hybridization, and crystal accumulation in the Pyramid Peak granite, California

Wiebe, Robert A.; Blair, K.D.; Hawkins, D. P.; Sabine, Charles

doi:10.1130/0016-7606(2002)114<0909:miisha>2.0.co;2

Cited by 134 publications

(73 citation statements)

References 39 publications

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“…That large silicic magma bodies accumulate continuously over time through injections of both mafic and silicic magma is also supported by studies of large granitic plutons, which may be associated with silicic volcanic rocks (e.g., Wiebe 1974Wiebe , 1993Wiebe , 1994Wiebe , 1996Michael 1991;Tait 1995, 1996;Wiebe and Collins 1998;Wiebe et al 2002). The issue of magma supply was apparently circumvented by Huppert and Sparks (1988) in their model of the rapid production of large quantities of silicic magma by wholesale melting of preheated crustal rocks immediately overlying basaltic sills.…”

Section: Magma Supply For Large Eruptionsmentioning

confidence: 96%

A model for the origin of large silicic magma chambers: precursors of caldera-forming eruptions

Jellinek

DePaolo

2003

Bulletin of Volcanology

385

373

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The relatively low rates of magma production in island arcs and continental extensional settings require that the volume of silicic magma involved in large catastrophic caldera-forming (CCF) eruptions must accumulate over periods of 10 5 to 10 6 years. We address the question of why buoyant and otherwise eruptible highsilica magma should accumulate for long times in shallow chambers rather than erupt more continuously as magma is supplied from greater depths. Our hypothesis is that the viscoelastic behavior of magma chamber wall rocks may prevent an accumulation of overpressure sufficient to generate rhyolite dikes that can propagate to the surface and cause an eruption. The critical overpressure required for eruption is based on the model of Rubin (1995a). An approximate analytical model is used to evaluate the controls on magma overpressure for a continuously or episodically replenished spherical magma chamber contained in wall rocks with a Maxwell viscoelastic rheology. The governing parameters are the long-term magma supply, the magma chamber volume, and the effective viscosity of the wall rocks. The long-term magma supply, a parameter that is not typically incorporated into dike formation models, can be constrained from observations and melt generation models. For effective wall-rock viscosities in the range 10 18 to 10 20 Pa s -1 , dynamical regimes are identified that lead to the suppression of dikes capable of propagating to the surface. Frequent small eruptions that relieve magma chamber overpressure are favored when the chamber volume is small relative to the magma supply and when the wall rocks are cool. Magma storage, leading to conditions suitable for a CCF eruption, is favored for larger magma chambers (>10 2 km 3 ) with warm wall rocks that have a low effective viscosity. Magma storage is further enhanced by regional tectonic extension, high magma crystal contents, and if the effective wall-rock viscosity is lowered by microfracturing, fluid infiltration, or metamorphic reactions. The longterm magma supply rate and chamber volume are important controls on eruption frequency for all magma chamber sizes. The model can explain certain aspects of the frequency, volume, and spatial distribution of smallvolume silicic eruptions in caldera systems, and helps account for the large size of granitic plutons, their association with extensional settings and high thermal gradients, and the fact that they usually post-date associated volcanic deposits.

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Section: Magma Supply For Large Eruptionsmentioning

confidence: 96%

A model for the origin of large silicic magma chambers: precursors of caldera-forming eruptions

Jellinek

DePaolo

2003

Bulletin of Volcanology

385

373

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“…In many continental magmatic systems, a complex interplay likely exists between mafic magmas injected into the crust from below, melts derived from crustal anatexis, and the crystallized products of both melt compositions, with this interplay varying in style with time, crustal depth, magma volume, and the overall heat budget of the system (McBirney et al 1987;Wiebe et al 2002;Acosta-Vigil et al 2010). Geochronological, chemical, and field studies of exposed continental igneous rocks are generally the only viable options for unraveling the plumbing and compositional evolution of melts in such magmatic systems.…”

Section: Introductionmentioning

confidence: 99%

Deep crustal anatexis, magma mixing, and the generation of epizonal plutons in the Southern Rocky Mountains, Colorado

Jacob

Farmer

Buchwaldt

et al. 2015

Contrib Mineral Petrol

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differentiated versions of the silicic melts parental to the Mt. Cumulus stock. Zircon U-Pb geochronology further reveals that the Mt. Richthofen stock was incrementally emplaced over a time interval from at least 28.975 ± 0.020 to 28.742 ± 0.053 Ma. Magma mixing could have occurred either in situ in the upper crust during basaltic underplating and remelting of an antecedent, incrementally emplaced, silicic intrusive body, or at depth in the lower crust prior to periodic magma ascent and emplacement in the shallow crust. Overall, the two stocks demonstrate that magmatism associated with the Never Summer igneous complex was fundamentally bimodal in composition. Highly silicic anatectic melts of the mafic lower crust and basaltic, mantle-derived magmas were the primary melts in the magma system, with mixing of the two producing intermediate composition magmas such as those from which Mt. Richthofen stock was constructed.

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“…Although several independent lines of evidence can be used to support a magmatic origin for the oldest Ag zircons captured in the supracrustals, the geochronological (degree of concordance), chemical (Th/U, REE) and isotopic (d 18 O Zr ) characters cited above do not separately provide the ''smoking gun'' for an origin as emplaced magmas. Yet, taken together, these results provide a self-consistent scenario in which (older) volcano-sedimentary packages are gradually invaded by granitoid sheets as the supracrustal rocks become merged into developing batholiths (Petford, 1996;Wiebe et al, 2002;Coleman et al, 2004).…”

Section: Igneous Zircons In Ttg-type Gneisses Within Supracrustal Encmentioning

confidence: 80%

Chemical and isotopic evidence for widespread Eoarchean metasedimentary enclaves in southern West Greenland

Cates

Mojzsis

2006

Geochimica et Cosmochimica Acta

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Mafic injections, in situ hybridization, and crystal accumulation in the Pyramid Peak granite, California

Cited by 134 publications

References 39 publications

A model for the origin of large silicic magma chambers: precursors of caldera-forming eruptions

A model for the origin of large silicic magma chambers: precursors of caldera-forming eruptions

Deep crustal anatexis, magma mixing, and the generation of epizonal plutons in the Southern Rocky Mountains, Colorado

Chemical and isotopic evidence for widespread Eoarchean metasedimentary enclaves in southern West Greenland

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