The influences of incremental pluton growth on magma crystallinity and aureole rheology: numerical modeling of growth of the Papoose Flat pluton, California

Post-Archean granitic rocks: contrasting petrogenetic processes and tectonic environments

“…Moreover, during its construction, a granitic pluton may also incorporate extra material either from the country rock (xenocrysts) or the previous pulses of the same magmatism (antecrysts) (Streck 2008;Jerram et al 2018). A distinct (third) possibility remains of mixing or mingling with some other magma pulse(s), either broadly cogenetic, during incremental construction commonly invoked for the granitic plutons (Bartley et al 2006;Farina et al 2012;Chen & Nabelek 2017;Hines et al 2018), or even coming from a contrasting, mantle source (Hibbard 1995;Perugini & Poli 2000;Didier & Barbarin 1991). Last, but not least, granitic plutons are commonly associated with hydrothermal systems, and the water-rich fluid unmixed during crystallization inevitably results in alterations.…”

Numerical Modeling of Dike Propagation Out of Continuously and Episodically Growing Midcrustal Magma Chambers

“…de Saint-Blanquat et al (2001) estimated that the Papoose Flat pluton took no more than 20 to 30 kyr to fill, based on summation of 1-D cooling times of emplaced sills and thermal constraints from mineralogy of the aureole and solid-state deformation fabrics of the pluton's margins. Chen and Nabelek (2017) showed that during continuous melt injections over 10 and 20 kyr time periods, the Papoose Flat laccolith would always have a molten portion at the bottom. Therefore, here we show models for 10 and 20 kyr time periods of construction.…”

“…Thus, the elastic modulus of a crystal mush with 50% crystals is~30 GPa. According to Chen and Nabelek (2017), the upper ductile portion of the model Papoose Flat pluton had a lithostatic pressure of~340 MPa, which is higher than the pressure condition used in Caricchi et al (2008). Experimental measurements of the elastic properties of granite have been done under brittle conditions (e.g., Blake & Faulkner, 2016;Gautam et al, 2018;Spencer & Nur, 1976;Villeneuve et al, 2018;Wang et al, 2014).…”

“…However, the eruptible magma volume needs to be at least several hundreds of cubic kilometers, which within a thermal structure of an arc crust (Peacock, 2003(Peacock, , 2009) would require extremely rapid melt accumulation to prevent significant crystallization prior to eruption. In a pluton with the size of the Papoose Flat, considering its evolving thermal structure, such a large volume of mobile magma cannot be sustained (Chen & Nabelek, 2017). Thus, overpressure from buoyancy in such a magma chamber is unlikely to exceed the critical overpressure for dike formation during either continuous or episodic melt injections into the chamber.…”

“…The critical overpressures are calculated for ranges of magma viscosities and elastic moduli that are likely to exist in an arc crust. The exploration of magma supply that is required to generate dikes is based on the modeled thermal and rheological evolution of the Papoose Flat pluton and its aureole in the White-Inyo Range, eastern California, USA (Chen & Nabelek, 2017). The size and the laccolithic shape of this pluton are typical of other plutons in upper plates of arc systems.…”