The composition of fluids stored in the central Mexican lithospheric mantle: Inferences from noble gases and CO2 in mantle xenoliths

The heterogeneity of the Mexican lithospheric mantle: Clues from noble gas and CO2 isotopes in fluid inclusions

“…Mantle xenoliths and lavas were crushed for noble gas and CO 2 isotopic determinations following the same methods and analytical procedures described in Rizzo et al (2018), Rizzo et al (2021), Sandoval-Velasquez et al (2021a), and Sandoval-Velasquez et al (2021b. After crushing, samples were sieved with the aim of hand-picking crystals (with diameters >0.25 mm) of Ol, Opx, and Cpx from mantle xenoliths and only Ol crystals from lavas.…”

“…Like areas within the United States portion, the Mexican Basin and Range was accompanied by intraplate magmatism that generated several alkali basalt localities (Figure 1A; Basu, 1977;Gutmann, 1986;Aranda-Gómez and Ortega-Gutiérrez, 1987;Henry and Aranda-Gómez, 1992;Luhr and Aranda-Gomez, 1997). These volcanic fields represent a unique opportunity to study the characteristics of the local lithospheric mantle, since their deposits contain abundant mantle xenoliths (including both spinel peridotite varieties and pyroxenites; Basu, 1977;Gutmann, 1986;Aranda-Gómez and Ortega-Gutiérrez, 1987;Luhr et al, 1989;Pier et al, 1992;Luhr and Aranda-Gomez, 1997;Housh et al, 2010;Dávalos-Elizondo et al, 2016;Sandoval-Velasquez et al, 2021a); these (in view of the relatively rapid ascent of the host magma through the crust by short-lived monogenetic volcanic eruptions) are expected to retain the pristine mineralogy and geochemical/isotopic characteristics of the mantle source (Pier et al, 1989;Luhr and Aranda-Gomez, 1997;Jackson, 1998;Pearson et al, 2014).…”

“…In a previous work (Sandoval-Velasquez et al, 2021a), we investigated the isotopic composition of noble gases and CO 2 in fluid inclusions (FI) trapped in mantle xenoliths collected in the Ventura Espiritu Santo Volcanic Field (VESVF; Figure 1A). These results, integrated with information on petrography, mineral chemistry and fluid inclusion compositions from the same suite of samples, revealed a complex geological evolution, in which the central Mexican upper mantle was affected by metasomatism, refertilization and recycling of atmospheric noble gases and crustal carbon derived from the Farallon slab subduction.…”

“…Our hypothesis points to the existence of a refertilized mantle whose Ar-CO 2 systematics have been modified by the introduction of air-derived noble gases and crustal materials inherited from the extinct Farallon subduction. We rely on noble gas and CO 2 isotopes (coupled to petrological evidence), which are unique geodynamic tracers of the degassing history of the mantle, of the origin of Earth's volatiles, of the relationship between different mantle components, and of the nature and signature of metasomatic fluids in the mantle (Deines, 2002;Dunai and Porcelli, 2002;Gurenko et al, 2006;Dasgupta and Hirschmann, 2010;Day and Hilton, 2011;Day and Hilton, 2020;Correale et al, 2012, Correale et al, 2015Rizzo et al, 2018;Li et al, 2019;Sandoval-Velasquez et al, 2021a;Sandoval-Velasquez et al, 2021b;Bekaert et al, 2021).…”

“…Unlike the VESVF (see Sandoval-Velasquez et al, 2021a) and the DVF, the SQVF is situated in northwestern Mexico, in the Baja California state near the Mexico-USA border (Figure 1). The SQVF is the only mantle xenolith-bearing alkaline basalt complex identified in the Baja California Peninsula, and formed as consequence of opening of the Gulf of California (at 3.5 Ma) after subduction of the Farallon plate terminated at 12 Ma (Aranda-Gómez and Ortega-Gutiérrez, 1987;Luhr et al, 1995a;Luhr and Aranda-Gomez, 1997;Sedlock, 2003).…”