Sr, Nd, and Pb isotopic and trace element geochemical constraints for a veined-mantle source of magmas in the Michoacan-Guanajuato Volcanic Field, west-central Mexican Volcanic Belt

Abstract

This study reports new geochemical and radiogenic isotope data for Pliocene to Holocene (<2.8 Ma) alkaline (trachybasalt, basaltic trachyandesite, and trachyandesite) as well as subalkaline (basalt to dacite) volcanic rocks from the Michoacán-Guanajuato volcanic field (MGVF), located in the west-central part of the Mexican Volcanic Belt (MVB). There is no clear correlation of most geochemical parameters with differentiation indicators such as SiO 2. The rare-earth elements show light-REE enrichment, flat heavy-REE pattern, and absence of Eu anomaly. Depletion of Nb as compared to large ion lithophile elements such as Ba is observed for most rocks, probably suggesting involvement of subducted Cocos or Rivera plate. However, other HFSE such as Zr and Ti and key trace elements such as B and Be, and isotopic data do not support this conclusion. In most binary plots, the MGVF data lie at mantle compositions toward the lower end of subduction-input parameters, as is the case of magmas from well-known rifts; this contrasts with the data for subductionrelated Central American Volcanic Arc (CAVA) rocks that clearly show high values of subduction input. The average isotopic ratios of the MGVF rocks show the following ranges:

Continental Rift Setting for the Central Part of the Mexican Volcanic Belt: A Statistical Approach

“…Besides, the extensional tectonics in the western part of the MVB has played a significant role in the eruption of primitive magmas [35]. I, either alone [5,22,26,28,30,32,55,[69][70][71] or with colleagues [24,27,29,31,64,66,[182][183][184][185][186] published a series of papers on the MVB, involving major-and trace-elements and radiogenic isotopes. Some of them included petrogenetic modeling.…”

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

“…Sr, Nd, Pb, Os, Be, and Hf isotopes Isotopic compositions have proved to be extremely useful in petrogenetic studies of volcanic provinces (e.g., Best and Christiansen, 2001;Faure, 2001;McBirney, 2007), and the MVB has been no exception. Numerous studies have been published on the Sr, Nd, and Pb isotopes from the MVB (Verma, 1983(Verma, , 1999(Verma, , 2000a(Verma, , 2000b(Verma, , 2001a(Verma, , 2001b(Verma, , 2001c(Verma, , 2002(Verma, , 2003(Verma, , 2015aBoudal, 1985;Verma and Nelson, 1989;Verma et al, 1991;Nakagawa et al, 1998;Siebe et al, 1999Siebe et al, , 2004Blatter et al, 2001Blatter et al, , 2007Velasco-Tapia andVerma, 2001a, 2013;Aguirre-Díaz et al, 2002;Verma and Carrasco-Núñez, 2003;Martínez-Serrano et al, 2004;Verma and Hasenaka, 2004;Schaaf et al, 2005;Verma et al, 2005;Gómez-Tuena et al, 2007b;Mukasa et al, 2007;Meriggi et al, 2008;García Tovar, 2009;Agustín-Flores et al, 2011;Torres-Alvarado et al, 2011;Arce et al, 2013;Koloskov and Khubunaya, 2013;Cai et al, 2014), including the present work. The shift to the right of the mantl...…”

“…Schaaf et al Verma (1999Verma ( , 2000aVerma ( , 2001aVerma ( , 2001bVerma ( , 2002Verma ( , 2003; Verma and Carrasco-Núñez (2003); Verma and Hasenaka (2004); Verma et al (1991Verma et al ( , 2005; and Wallace and Carmichael (1999). The samples used for geochemical studies are seldom radiometrically dated, and no separation according to the age can, therefore, be easily done.…”

“…The shift to the right of the mantle array (Verma, 2006), towards and beyond the mean composition of subducted slab (Verma, 2000a(Verma, , 2002, commonly observed in all arcs around the world, has not been documented in the MVB, which makes this volcanic province atypical for it to be an arc. An important point to mention here is that the Sr and Nd isotopic data should be adjusted to given reference values for the standards used for estimating mass spectrometric bias, as has been done in all studies on the MVB published by our group (Verma and Nelson, 1989;Verma et al, 1991;Verma, , 1999Verma, , 2000aVerma, , 2000bVerma, , 2001aVerma, , 2001bVerma, , 2001cVerma, , 2002Verma, , 2003Verma, , 2015aVelasco-Tapia andVerma, 2001a, 2013;Verma and Carrasco-Núñez, 2003;Verma and Hasenaka, 2004;Verma et al, 2005;Torres-Alvarado et al, 2011;Velasco-Tapia and Verma, 2013). Most other scholars studying the MVB have unfortunately not followed this convention (e.g., Boudal, 1985;Nakagawa et al, 1998;Siebe et al, 1999Siebe et al, , 2004Blatter et al, 2001Blatter et al, , 2007Aguirre-Díaz et al, 2002;Martínez-Serrano et al, 2004;Schaaf et al, 2005;Mukasa et al, 2007;García-Tovar, 2009;Agustín-Flores et al, 2011;Arce et al, 2013;Koloskov and Khubunaya, 2013;Cai et al, 2014)<...>…”

“…Based on major-and trace-elements and radiogenic isotopes, I, either alone (Verma, 1983(Verma, , 1999(Verma, , 2000a(Verma, , 2000b(Verma, , 2001a(Verma, , 2001b(Verma, , 2001c(Verma, , 2002(Verma, , 2003(Verma, , 2004(Verma, , 2009(Verma, , 2015a or with colleagues (Verma et al, 1991;Márquez et al, 1999c;Sheth et al, 2000Sheth et al, , 2002Velasco-Tapia andVerma, 2001a, 2001b;Verma and Carrasco-Núñez, 2003;Verma and Hasenaka, 2004;Verma and Luhr, 2010), published a series of papers on the origin and evolution of the MVB; some of them also included petrogenetic modeling. As far back as in 1983 (Verma, 1983) for the Los Humeros caldera, in 1988 (Verma and Aguilar-Y-Vargas, 1988) for the MVB, and in 1999 (Márquez et al, 1999c;Verma, 1999) for the Sierra de Chichinautzin in the C-MVB (located in the area near the trench or at the volcanic front area), these studies showed that the MVB is atypical, and its origin can be best explained from the ongoing rifting or extensional processes rather than the ongoing subduction.…”