Extension-related origin of magmas from a garnet-bearing source in the Los Tuxtlas volcanic field, Mexico

Abstract

The Los Tuxtlas volcanic field (

New critical values for F and their use in the ANOVA and Fisher’s F tests for evaluating geochemical reference material granite G-2 (U.S.A.) and igneous rocks from the Eastern Alkaline Province (Mexico)

“…In summary, from all three sets of diagrams the results of an extensional or a continental rift setting for this area can be inferred, which is fully consistent with earlier conclusions by Verma (2006) for Rg8 and S.K. for Rg8 and some other regions of the EAP from a limited compilation of data.…”

Present state of knowledge and new geochemical constraints on the central part of the Mexican Volcanic Belt and comparison with the Central American Volcanic Arc in terms of near and far trench magmas

“…"; 2) "Where is the volcanism or plutonism associated with this middle Miocene collision event in southern Mexico?" -it is certainly not in the LTVF (Figure 1) because this Neogene volcanism is not of an arctype (Verma, 2006); 3) as suggested by Kim et al (2011), the Chiapas fold and thrust belt could be taken as the product of this collision provided there were evidence of the syncollision and postcollision igneous activity, which is not known; 4) even when volcanism is documented from the Chiapas belt, it must be shown to be of collision type; 5) these authors themselves admit that they have no paleomagnetic evidence to support their model; 6) "Why did the oceanic slab attached to the Yucatán block continue to grow even after this collision (see their Figure 10)? "; 7) the horizontal and vertical scales in their Figure 10 are not provided, and irrespective of this shortcoming the proportions of different geological identities seem to be incorrect; 8) "Why did the subducted slab corresponding to the Yucatán block remain intact but cause the Cocos slab to break off?…”

“…Surprisingly, the deeper contours of 80 to 100 km (if any, in southern Mexico) corresponding to the subduction of the Cocos plate ( Figure 1) suddenly terminate between the volcanic front of the E-MVB and the Los Tuxtlas volcanic field (LTVF). The inference of the depth contours from the seismic data close to the LTVF (Figure 1) has been criticized; from geochemical evidence, the LTVF is shown to have a solely extension-related origin (Verma, 2006). No deep earthquakes (>60 km depth) have ever been recorded beneath the C-MVB (Figure 2), nor beneath the E-MVB (Figure 1).…”

“…The study of primitive or at least basic or ultrabasic magmas is a fundamental requirement if one wishes to conclude about the deeper mantle sources and processes (e.g., Verma, 2006;Luhr, 2007).…”

“…The new discriminant function-based tectonic discrimination diagrams Agrawal et al, 2008;Verma and Agrawal, 2011) (Hofmann and Feigenson, 1983;Hofmann et al, 1984;McKenzie and O'Nions, 1991;Ormerod et al, 1991;Feigenson and Carr, 1993;Maaløe, 1994;Velasco-Tapia andVerma, 2001a, 2013;Feigenson et al, 2003;Verma, 2004Verma, , 2006. Basic magmas with characteristics of primitive, little-differentiated magmas are present throughout the MVB (e.g., Luhr et al, 1989;Luhr, 1997;Wallace and Carmichael, 1999;Verma, 2000aVerma, , 2002Verma, , 2004, as well as in the LTVF (Verma et al, 1993a;Nelson et al, 1995;Verma, 2006). The geochemical data from the MVB have been subjected to inverse modeling.…”