Magma felsic

There is another opinion on the origin of Kuroko ore fluids. Sawkins (1982) thought that intrusive felsic magmas were the source of the metals and heat in Kuroko hydrothermal systems. He stressed the contributions of magmatic fluid and seawater in... 

Rapp R.P. and Watson E.B. (1986) Monazite solubility and dissolution kinetics implications for the thorium and light rare Earth chemistry of felsic magmas. Contrib. Mineral. Petrol. 94, 304-316. 

Mafic Describes a magma, lava, or igneous rock that is generally richer in magnesium and iron than intermediate and felsic varieties, but has less silica (45-52 wt%) than intermediate and felsic magmas, lavas, and rocks (Hyndman, 1985), 42 (Press and Siever, 2001), 74. 

Variation diagrams of major and trace elements vs. SiC>2 (Fig. 8.13) show a bimodal distribution between basalts and rhyolites, with a gap for intermediate compositions (Daly gap). Such a distribution of rock types is typical of volcanoes from continental rift settings (see Peccerillo et al. 2003 and references therein). A few intermediate samples have been found as xenoliths, and these have been suggested to represent hybrids between mafic and felsic magmas (e.g. Mahood and Baker 1986). 

Coleman D. S., Glazner A. F., Miller J. S., Bradford K. J., Frost T. P., Joye J. L., and Bachl C. A. (1995) Exposure of a late cretaceous layered mafic-felsic magma system in the Central Sierra-Nevada batholith, California. Contrib. Mineral. Petrol. 120, 129-136. 

Vigneresse J. L., Barbey P., and Cuney M. (1996) Rheological transitions during partial melting and crystallization with application to felsic magma segregation and transfer. J. Petrol. 37, 1579-1600. 

The dominant rocks of the Earth s early continental crust are the felsic magmas of the tonalite-trondhjemite-granodiorite suite, or the TTG suite, as it is known (Rollinson, 2006). Compared to average crust TTGs are more felsic, more sodic and have a lower mg-number, and are clearly different from average "andesitic" crust (Table 4.2, Fig. 4.10). This implies that the magmatic flux across the Moho has changed with time (Kemp St Hawkesworth, 2003). 

Rapp RP and Watson EB (1986) Monazite solubihty and dissolution kinetics Implications for the thorium and light rare earth chemistry of felsic magmas. Contrib Mineral Petrol 94 304-316 Rapp RP, Ryerson FJ, Miller CF (1987) Experimental evidence bearing on the stability of monazite during crystal anatexis. Geophys. Res Letters 14 307-310... 

For metaluminous systems, apatite crystallizes relatively early in the crystallization sequence of felsic magmas, and crystallizes comparatively later in more mafic melts. For example, it was estimated that apatite is a near liquidus phase in the Johnson Granite Porphyry, but began to crystallize after about 1/3 of the Kuna Crest (quartz diorite) magma crystallized (Piccoli and Candela 1994). Ultimately, apatite often first appears as an intercumulus phase in gabbros and related rocks (e g., Boudreau et al. 1986). 

Pyle JM, Spear FS, Rudnick RL, McDonough WF (2001) Morrazite-xenotime-gamet eqtrihbritrm in metapelites and a new morrazite-gamet thermometer. J Petrol 42 2083-2107 Rapp R (1985) An experimental investigation of the solubility and dissolution kinetics of morrazite and its implications for the thorirrm and rare earth element chemistry of felsic magmas. MS thesis, Rertsselaer Polytechnic Irrst, Troy, New York... 

Europium anomalies are chiefly controlled by feldspars, particularly in felsic magmas, for Eu (present in the divalent state) is compatible in plagiocase and... 

The best available evidence for the age of the Patuxent Formation (as redefined by Rowell et al. 2001) arises from age determinations of the Gorecki Rhyolite in the Schmidt Hills. If the Gorecki Rhyolite consists of lava flows or other kinds of volcanogenic surface deposits that are interbedded with the Patuxent Formation at Mount Gorecki and elsewhere, then age determinations of these rhyolites also date the time of deposition of the local Patuxent Formation. On the other hand, if the felsic magma of the Gorecki Rhyolite intruded the Patuxent Formation in the form of sills or small plu-tons, then the Patuxent Formation is older than isotopic dates of the felsites in the Schmidt Hills. 

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