Experimental study of monazite/melt partitioning with implications for the REE, Th and U geochemistry of crustal rocks

Stepanov, Aleksandr S.; Hermann, Jörg; Rubatto, Daniela; Rapp, Robert P.

doi:10.1016/j.chemgeo.2012.01.007

Cited by 250 publications

(167 citation statements)

References 65 publications

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“…Richthofen stock, lending credence to a mixing origin for its compositional characteristics. We also note that the Nd isotopic composition of the mafic enclave (ε Nd ~ −2) is similar to Cenozoic basaltic rocks found elsewhere in the southern Rocky Mountain region (ε Nd ~ −2 to 0) and all Nash and Crecraft (1985), Sisson and Bacon (1992), Ewart and Griffin (1994), Hermann (2002), Prowatke and Klemme (2006), Bédard (2006), Stepanov et al (2012) 7 Page 18 of 23 may represent mafic magmas derived from the lithospheric mantle (Bailley 2010).…”

Section: Discussionmentioning

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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Section: Discussionmentioning

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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“…In fact, the recent study of Stepanov et al (2012) has determined monazite-melt partition coefficients that suggest D Th /D Nd > 1. Thus our finding that the Th/Nd melt > Th/Nd initial , further supports our conclusions from U-Th systematics that of a monazite-free, sediment melt residue is required.…”

Section: Control Of Accessory Phases On Fluid and Melt Componentsmentioning

confidence: 96%

Combined 238U–230Th and 235U–231Pa constraints on the transport of slab-derived material beneath the Mariana Islands

Avanzinelli

Prytulak

Skora

et al. 2012

Geochimica et Cosmochimica Acta

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“…The large size of the crystals compared to the MI, and the low solubility of these minerals in granitic melts (e.g. Watson and Harrison 1983;Montel 1993;Acosta-Vigil et al 2003;Stepanov et al 2012;Boehnke et al 2013), indicates that they are solid inclusions (i.e. were already present during the entrapment of the MI) and hence are not expected to dissolve into the melt during the experiments (Table 1).…”

Section: Microstructures Of Remelted Nanogranitoidsmentioning

confidence: 99%

The composition of nanogranitoids in migmatites overlying the Ronda peridotites (Betic Cordillera, S Spain): the anatectic history of a polymetamorphic basement

Acosta-Vigil

Barich

Bartoli

et al. 2016

Contrib Mineral Petrol

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The study of the composition of primary melts during anatexis of high-pressure granulitic migmatites is relevant to understand the generation and differentiation of continental crust.Peritectic minerals in migmatites can trap dropless of melt that forms via incongruent melting reactions during crustal anatexis. These melt inclusions commonly crystallize and form nanogranitoids upon slow cooling of the anatectic terrane. To obtain the primary compositions of crustal melts recorded in these nanogranitoids, including volatile concentrations and information on fluid regimes, they must be remelted and rehomogenize before analysis. A new occurrence of nanogranitoids was recently reported in garnets of mylonitic metapelitic gneisses (former high pressure granulitic migmatites) at the bottom of the prograde metamorphic sequence of Jubrique, located on top of the Ronda peridotite slab (Betic Cordillera, S Spain). Nanogranitoids within separated chips of cores and rims of large garnets from these former migmatites were remelted at 15 kbar and 850, 825 or 800 ºC and dry (without added H 2 O), during 24 hours, using a piston cylinder apparatus. Although all experiments show glass (former melt) within melt inclusions, the extent of rehomogenization depends on the experimental temperature. Experiments at 850-825 ºC show abundant disequilibrium microstructures, whereas those at 800 ºC show a relatively high proportion of rehomogenized nanogranitoids, indicating that anatexis and entrapment of melt inclusions in these rocks was likely close to 800 ºC. Electron microprobe and NanoSIMS analyses show that experimental glasses are leucogranitoid and peraluminous, though define two distinct compositional groups. Type I corresponds to K-rich, Ca-and H 2 O-poor leucogranitic melts, whereas type II represents K-poor, Ca-and H 2 O-rich granodioritic to tonalitic melts. Type I and II melt inclusions are found in most cases at the cores and rims of large garnets, respectively. We tentatively suggest that these former migmatites underwent two melting events under contrasting fluid regimes, possibly during two different orogenic periods. This 3 study demonstrates the strong potential of melt inclusions studies in migmatites and granulites in order to unravel their anatectic history, particularly in strongly deformed rocks where most of the classical anatectic microstructures have been erased during deformation.

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Experimental study of monazite/melt partitioning with implications for the REE, Th and U geochemistry of crustal rocks

Cited by 250 publications

References 65 publications

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

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

Combined 238U–230Th and 235U–231Pa constraints on the transport of slab-derived material beneath the Mariana Islands

The composition of nanogranitoids in migmatites overlying the Ronda peridotites (Betic Cordillera, S Spain): the anatectic history of a polymetamorphic basement

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