Computer Science
Scientific paper
Sep 1988
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1988gecoa..52.2235a&link_type=abstract
Geochimica et Cosmochimica Acta, vol. 52, Issue 9, pp.2235-2249
Computer Science
3
Scientific paper
Trace-element and Sr and Nd isotopic compositions have been determined for a suite of calc-alkaline rocks from southeastern Arizona. The suite consists of andesitic and rhyolitic rocks (67 m.y. old) intruded by granodiorite and granite (58-62 m.y. old). It is situated within Proterozoic basement of 1.7 to 1.65 Ga age. Isotopic composition and chemical evolution are well correlated throughout the suite. The andesite has the least negative Nd ( t igneous ) = -4.3) and smallest 87 Sr / 86 Sr 0 (0.7069). It is also the oldest and chemically most primitive, having the lowest concentrations of Rb, SiO 2 , and highest concentrations of the transition elements. These parameters change through the system to the youngest unit (granite) which has the most negative Nd (-8.5), the greatest 87 Sr / 86 Sr 0 (0.7092), and is most chemically evolved. We interpret these trends as resulting from a continuous process of progressive assimilation in which mafic magmas invade and incorporate continental crust. The assimilated continental crust was probably intermediate to mafic in composition and of amphibolite grade. Phase relations among minerals indicate that it was hydrous and oxidizing. Also, if the granite is in isotopic equilibrium with the basement, its Nd of -8.5 implies a 147 Sm / 144 Nd of 0.13 to 0.14 for the assimilant, characteristic of intermediate to mafic rather than felsic rocks. Inverse methods have been applied to equations for assimilation and fractional crystallization whose use assumes periodic tapping of a single magma body. Such modelling yields insight into the size and chemistry of the magma system.
Anthony Elizabeth Y.
Titley Spencer R.
No associations
LandOfFree
Progressive mixing of isotopic reservoirs during magma genesis at the Sierrita porphyry copper deposit, Arizona: Inverse solutions does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Progressive mixing of isotopic reservoirs during magma genesis at the Sierrita porphyry copper deposit, Arizona: Inverse solutions, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Progressive mixing of isotopic reservoirs during magma genesis at the Sierrita porphyry copper deposit, Arizona: Inverse solutions will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-913289