scholarly journals Origin of alkali olivine basalts and hawaiites in the western Mexican arc: Evidence of rapid phenocryst growth and magma mixing during ascent along fractures

Geosphere ◽  
2021 ◽  
Author(s):  
Juliana Mesa ◽  
Rebecca A. Lange
Keyword(s):  
Magma Mixing ◽  
Olivine Basalt ◽  
Volcanic Belt ◽  
Prolonged Storage ◽  
Compositional Zoning ◽  
Mexican Volcanic Belt ◽  
Alkali Olivine Basalt ◽  
Mafic Lavas ◽  
Unique Composition ◽  
Mafic Lower Crust

A detailed petrological study is presented to constrain the origin of a suite of alkali olivine basalt and hawaiite (>5 wt% MgO) lavas that were erupted in a rift zone within the western Mexican arc (Trans-Mexican Volcanic Belt), adjacent to the Sangangüey andesitic stratovolcano, together with more evolved lavas (mugearites and benmoreites; <5 wt% MgO). As previously documented in the literature, the Sangangüey mafic lavas are devoid of any arc geochemical signature, despite their location within an arc. In this study, a new olivine-melt thermometer/hygrometer, based on the partition­ing behavior of Ni2+ and Mg2+, was applied to the Sangangüey basalts (SB). The results show that the high-MgO (>9 wt%) SB crystallized at higher temperatures and lower melt-water contents (0–1.3 wt%) compared to high-MgO arc basalts (≤5.7 wt% H2O) erupted in the west-central Mexican arc. The Sangangüey lavas with 5–8 wt% MgO display evidence of mixing between high-MgO alkali olivine basalts and low-MgO mugearites. It is proposed that the unique composition of the mugearites (i.e., low SiO2 contents and elevated FeO and TiO2 contents) is the result of partial melting of mafic lower crust driven by the influx of high-MgO intraplate basalts under relatively hot, dry, and reduced conditions. On the basis of crystal textures and compositional zoning patterns, it is shown that both phenocryst growth and magma mixing occurred rapidly, most likely during ascent along fractures, and not slowly during prolonged storage in a crustal magma chamber.

scholarly journals Multivariate Analysis, Mass Balance Techniques, and Statistical Tests as Tools in Igneous Petrology: Application to the Sierra de las Cruces Volcanic Range (Mexican Volcanic Belt)

2014 ◽  
Vol 2014 ◽  
pp. 1-32 ◽  
Author(s):  
Fernando Velasco-Tapia
Keyword(s):  
Multivariate Analysis ◽  
Mass Balance ◽  
Magma Mixing ◽  
Statistical Tests ◽  
Tectonic Setting ◽  
Volcanic Rocks ◽  
Volcanic Belt ◽  
Cocos Plate ◽  
Igneous Petrology ◽  
Mexican Volcanic Belt

Magmatic processes have usually been identified and evaluated using qualitative or semiquantitative geochemical or isotopic tools based on a restricted number of variables. However, a more complete and quantitative view could be reached applying multivariate analysis, mass balance techniques, and statistical tests. As an example, in this work a statistical and quantitative scheme is applied to analyze the geochemical features for the Sierra de las Cruces (SC) volcanic range (Mexican Volcanic Belt). In this locality, the volcanic activity (3.7 to 0.5 Ma) was dominantly dacitic, but the presence of spheroidal andesitic enclaves and/or diverse disequilibrium features in majority of lavas confirms the operation of magma mixing/mingling. New discriminant-function-based multidimensional diagrams were used to discriminate tectonic setting. Statistical tests of discordancy and significance were applied to evaluate the influence of the subducting Cocos plate, which seems to be rather negligible for the SC magmas in relation to several major and trace elements. A cluster analysis following Ward’s linkage rule was carried out to classify the SC volcanic rocks geochemical groups. Finally, two mass-balance schemes were applied for the quantitative evaluation of the proportion of the end-member components (dacitic and andesitic magmas) in the comingled lavas (binary mixtures).

The Cheslatta Lake suite: Miocene mafic, alkaline magmatism in central British Columbia

2001 ◽  
Vol 38 (4) ◽  
pp. 697-717 ◽  
Author(s):  
Robert G Anderson ◽  
Jonah Resnick ◽  
James K Russell ◽  
G J Woodsworth ◽  
Michael E Villeneuve ◽  
...  
Keyword(s):  
British Columbia ◽  
Olivine Basalt ◽  
Volcanic Belt ◽  
Primitive Mantle ◽  
Alkaline Magmatism ◽  
Type Area ◽  
Late Tertiary ◽  
Alkali Olivine Basalt ◽  
Trace Element Contents ◽  
Geochemical Studies

New mapping, mineralogical, and geochemical studies help characterize late Tertiary primitive, alkaline, sodic basanite, alkali olivine basalt, transitional basalt, and diabase in the Nechako River, Whitesail Lake, and McLeod Lake map areas of central British Columbia and distinguish the Miocene Cheslatta Lake suite. The suite encompasses scattered erosional remnants of topographically distinct, columnar-jointed, olivine-phyric basalt and diabase volcanic necks, dykes, and associated lava flows north of the Anahim volcanic belt and west of the Pinchi Fault. Volcanic centres at Alasla Mountain and at Cutoff Creek, near Cheslatta Lake, are proposed as type areas. Olivine, plagioclase, and pyroxene phenocrysts, megacrysts, and (or) xenocrysts; common ultramafic xenoliths; and rare but significant plutonic and metamorphic xenoliths are characteristic. Basanite, transitional basalt, and alkali olivine basalt groundmass contain plagioclase, clinopyroxene, Fe-Ti oxides, feldspathoid, olivine, and apatite. The Cheslatta Lake suite is characterized by its alkaline character, olivine-rich (>10 wt.%) normative mineralogy, and silica-undersaturated nature (>1 wt.% normative nepheline; hypersthene-normative rocks are uncommon). Mg numbers vary between 72–42. Some samples encompass near-primitive mantle melt compositions. Cheslatta Lake suite rocks in the Nechako River area are distinguished from the underlying Eocene Endako and stratigraphically higher Neogene Chilcotin groups basaltic andesite lavas within the study area, and from the Chilcotin Group basalt in the type area south of the Anahim volcanic belt, by form, preserved thickness, phenocryst–xenocryst mineralogy, amygdule abundance, included xenoliths, isotopic age, and major and incompatible, high field strength, and rare-earth trace element contents.

scholarly journals Geochemical Evidence for Slab Melting in the Trans-Mexican Volcanic Belt

2006 ◽  
Vol 48 (3) ◽  
pp. 537-562 ◽  
Author(s):  
A. Gomez-Tuena ◽  
C. H. Langmuir ◽  
S. L. Goldstein ◽  
S. M. Straub ◽  
F. Ortega-Gutierrez
Keyword(s):  
Volcanic Belt ◽  
Slab Melting ◽  
Geochemical Evidence ◽  
Mexican Volcanic Belt ◽  
Trans Mexican Volcanic Belt

scholarly journals Evidence for geomagnetic excursions recorded in Brunhes and Matuyama Chron lavas from the trans-Mexican volcanic belt

2013 ◽  
Vol 118 (6) ◽  
pp. 2648-2669 ◽  
Author(s):  
Daniel M. Michalk ◽  
Harald N. Böhnel ◽  
Norbert R. Nowaczyk ◽  
Gerardo J. Aguírre-Diaz ◽  
Margarita López-Martínez ◽  
...  
Keyword(s):  
Volcanic Belt ◽  
Matuyama Chron ◽  
Mexican Volcanic Belt ◽  
Trans Mexican Volcanic Belt
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