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Evaluating Complex Magma Mixing via Polytopic Vector Analysis (PVA) in the Papagayo Tuff, Northern Costa Rica: Processes that Form Continental Crust
Department of Natural and Applied Sciences, Bentley University, Waltham, MA 02452, USA
National Science Foundation, Arlington, VA 22230, USA
Department of Geological Sciences, Michigan State University, East Lansing, MI 48824, USA
Seismology and Volcanology Department, Costa Rica Institute of Electricity, Apdo. 10032-1000, San José, Costa Rica
* Author to whom correspondence should be addressed.
Received: 4 July 2013; in revised form: 19 August 2013 / Accepted: 23 August 2013 / Published: 29 August 2013
Abstract: Over the last forty years, research has revealed the importance of magma mixing as a trigger for volcanic eruptions, as well as its role in creating the diversity of magma compositions in arcs. Sensitive isotopic and microchemical techniques can reveal subtle evidence of magma mixing in igneous rocks, but more robust statistical techniques for bulk chemical data can help evaluate complex mixing relationships. Polytopic vector analysis (PVA) is a multivariate technique that can be used to evaluate suites of samples that are produced by mixing of two or more magma batches. The Papagayo Tuff of the Miocene-Pleistocene Bagaces Formation in northern Costa Rica is associated with a segment of the Central American Volcanic Arc. While this segment of the arc is located on oceanic plateau, recent (<8 Ma) ignimbrites bear the chemical signatures of upper continental crust, marking the transition from oceanic to continental crust. The Papagayo Tuff contains banded pumice fragments consistent with one or more episodes of mixing/mingling to produce a single volcanic deposit. The PVA solution for the sample set is consistent with observations from bulk chemistry, microchemistry and petrographic data from the rocks. However, without PVA, the unequivocal identification of the three end-member solution would not have been possible.
Keywords: Papagayo Tuff; Bagaces Formation; Central American Volcanic Arc; magma mixing; magma mingling; microchemistry; polytopic vector analysis; continental crust
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Szymanski, D.W.; Patino, L.C.; Vogel, T.A.; Alvarado, G.E. Evaluating Complex Magma Mixing via Polytopic Vector Analysis (PVA) in the Papagayo Tuff, Northern Costa Rica: Processes that Form Continental Crust. Geosciences 2013, 3, 585-615.
Szymanski DW, Patino LC, Vogel TA, Alvarado GE. Evaluating Complex Magma Mixing via Polytopic Vector Analysis (PVA) in the Papagayo Tuff, Northern Costa Rica: Processes that Form Continental Crust. Geosciences. 2013; 3(3):585-615.
Szymanski, David W.; Patino, Lina C.; Vogel, Thomas A.; Alvarado, Guillermo E. 2013. "Evaluating Complex Magma Mixing via Polytopic Vector Analysis (PVA) in the Papagayo Tuff, Northern Costa Rica: Processes that Form Continental Crust." Geosciences 3, no. 3: 585-615.