The tenuous connection between high-silica rhyolites and granodiorite plutons 
Reference Number:
Publication Year:
GeoREF Number:
2008-062604 (View Original Data File)
Glazner, Allen F; Coleman, Drew S; Bartley, John M
aplite, California, dikes, feldspar group, framework silicates, geochemistry, granites, granodiorites, igneous rocks, intrusions, magmas, major elements, metals, nesosilicates, orthosilicates, plutonic rocks, plutons, rare earths, rhyolites, Sierra Nevada, Sierra Nevada Batholith, silica, silicates, titanite, titanite group, trace elements, United States, volcanic rocks
Geology (Boulder)36.2 (February 2008): 183-186
The trace element compositions of aplite dikes in the Sierra Nevada batholith of California differ profoundly from high-silica rhyolites (HSRs) and contradict a genetic connection to them. The aplites are strongly depleted in all middle rare earth elements (REEs), whereas HSRs are strongly depleted only in Eu and enriched in other REEs; the aplites are strongly depleted in Y and variably enriched in Sr, whereas HSRs are enriched in Y and strongly depleted in Sr. Volcanic rocks with the trace element characteristics of these aplites are rare to absent in the geologic record. Aplite REE patterns are likely controlled by titanite, which has large distribution coefficients for REEs, whereas HSRs cannot have equilibrated with titanite. Titanite may crystallize late in dacitic magma and thus HSR may be extracted before titanite saturation is reached; aplites would form after titanite appears, but when the melt percentage is too low and the water content of the melt too high (at fluid saturation) for the magma to ascend without rapid crystallization, thus preventing eruption. HSRs could also form by low-degree partial melting of granodiorite plutons in which titanite melts out early. Alternatively, HSRs may be extracted from silica-rich plutons that lack titanite; leucogranite plutons with REE contents that could be complementary to HSRs are present but uncommon in the Sierra Nevada.
GeoRef, Copyright 2008, American Geological Institute. Reference includes data from GeoScienceWorld, Alexandria, VA, United States | Reference includes data supplied by the Geological Society of America, Boulder, CO, USA, United States

Sample Summary:
Sample ID: Major Data: Trace Data: Isotope Data:
21-C Yes Yes No
29-0 Yes Yes No
49C Yes Yes No
81C Yes Yes No
97A Yes Yes No
104-A Yes Yes No
121-B Yes Yes No
HD01-42 Yes Yes No
HD01-62 Yes Yes No
JBTIS04-1 Yes Yes No
KR04-13 Yes Yes No
KR04-15 Yes Yes No
KR04-16 Yes Yes No
Y06-33 Yes Yes No
Y06-39 Yes Yes No
Y06-40 Yes Yes No
AP-DSC-02 Yes Yes No
16BRJ06 Yes Yes No
21BRJ06 Yes Yes No
08BRJ06 Yes Yes No
HD01-78 Yes Yes No
AFGWH03-2 Yes Yes No
AFGWH03-7 Yes Yes No
SEKI06-01 Yes Yes No
JP-ap Yes Yes No
AFGWH03-8 Yes Yes No
AFGWH03-9 Yes Yes No
JBAS07-1 Yes Yes No
JBAS07-2 Yes Yes No
JBLCS07-1 Yes Yes No
JBLCS07-2 Yes Yes No
BP07-1 Yes Yes No
BP07-2 Yes Yes No