Multidimensional classification of magma types for altered igneous rocks and application to their tectonomagmatic discrimination and igneous provenance of siliciclastic sediments

Verma, Surendra P.; Rivera-Gómez, M. Abdelaly; Díaz-González, Lorena; Pandarinath, Kailasa; Amezcua-Valdez, Alejandra; Rosales-Rivera, Mauricio; Verma, Sanjeet K.; Quiroz-Ruiz, Alfredo; Armstrong‐Altrin, John S.

doi:10.1016/j.lithos.2017.02.005

Cited by 36 publications

(15 citation statements)

References 53 publications

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“…Using the traditional TAS diagram/method, 36 out of the 39 samples are classified as acid type, whereas the remaining three rocks E‐1, E‐2 and E‐4 were classified as basic, intermediate and basic types, respectively (Table S1). However, the new method for classification of altered rocks (by Verma, Rivera‐Gómez, et al, ), apart from classifying these three rock samples E‐1, E‐2 and E‐4 as basic, intermediate and basic types, respectively (as per the TAS method), additionally, it also classified another four rocks EAC‐RS‐3B, EAC‐RS‐5, EAC‐RS‐7 and EAC‐RS‐9, respectively, as inter, basic, basic and basic types (Table S1). Finally, to avoid any influence of the magma types on the element mobility and alteration processes, we have decided to include, 32 surface acid magmas.…”

Section: Resultsmentioning

confidence: 99%

“…Rock classification is carried out using two methods: (a) the commonly used total alkali–silica (TAS) classification (Le Bas, Le Maitre, Streckeisen, & Zanettin, ) with Fe 2 O 3 /FeO ratios adjusted depending on the rock type (Middlemost, ) using the computer programme IgRoCS (Verma & Rivera‐Gómez, ); and (b) a new classification method for magma type classification for altered igneous rocks recently proposed by Verma, Rivera‐Gómez, et al () and by applying the computer programme MagClaMSys_ilr (Magma Classification Major Element based System; Verma, Rosales‐Rivera, Díaz‐González, & Quiróz‐Ruíz, ). The traditionally applied TAS diagram/method is applicable only to fresh or relatively less altered igneous rocks.…”

Section: Sampling and Analytical Methodsmentioning

confidence: 99%

“…The rock samples of this study have undergone intensive alteration, and therefore, they do not meet this condition. For this reason, we have applied a new classification method for magma type classification for altered igneous rocks, recently proposed by Verma, Rivera‐Gómez, et al (). This new method is useful for the identification of magma types prior to the alteration and is proposed for the classification of igneous rocks in terms of four magma types: ultrabasic, basic, intermediate and acid.…”

Section: Sampling and Analytical Methodsmentioning

confidence: 99%

“…Some chemical elements (e.g., Ti, Nb and Zr) are usually considered as immobile during hydrothermal alteration, which can be used for normalising the concentration of other elements (MacLean, ; MacLean & Barrett, ; MacLean & Kranidiotis, ; Sturchio, Muehlenbachs, & Seitz, ). Because of their immobile geochemical nature (or less reactivity), some elements have been also used to develop tectonic discrimination diagrams for classifying tectonic setting of igneous rocks (Floyd & Winchester, ; Pearce & Cann, ; Verma & Agrawal, ; Verma, Pandarinath, Verma, & Agrawal, ; Verma, Rosales‐Rivera, Díaz‐González, & Quiróz‐Ruíz, ). Cann () and Field and Elliott () have reported that the elements Ti, Zr, Y, Nb, Ga and Ce are relatively immobile during post‐consolidation alteration processes, and therefore, the diagrams for identification of ancient volcanic suites based on these elements to other constituents may prove to be useful tools.…”

Section: Introductionmentioning

confidence: 99%

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Mineralogical and geochemical changes due to hydrothermal alteration of the volcanic rocks at Acoculco geothermal system, Mexico

et al. 2020

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Most of the volcanic rocks in the Acoculco geothermal system (AGS), near to the surface manifestations, are intensively altered. Thirty‐four surface volcanic rocks and five rocks from outcrop sections are considered in this work. Silica polymorphs (quartz, cristobalite and tridymite) are the dominant hydrothermal minerals in almost all the rock samples. The following other minerals are present in minor concentrations: alkali‐feldspars (sanidine potassic, anorthoclase and microcline), plagioclase feldspars (albite and anorthite), clay minerals (illite, kaolinite and montmorillonite), anhydrite, buddingtonite, titanoaugite, magnetite and anatase. This type of mineral assemblage of the rocks indicates an intensive silicic and argillic alteration. Comparison of the elemental concentrations of the surface acid rocks of the AGS with that of the precursor rock has indicated alteration‐induced changes in (a) chemical mobility in the concentrations of major element oxides, with an increase in the concentrations of SiO2, and TiO2, loss in those of Al2O3, Fe2O3, MnO, MgO, CaO, Na2O and K2O, and no statistically significant changes in those of P2O5, (b) no significant changes in the concentrations of LREE and MREE (except Dy and Ho), however, less but significant loss in the concentrations of Dy and Ho, and HREE, and (c) there is an enrichment in the concentrations of Nd, Sr, Sc, V, Nb, Ag, Sn, Pb, Tl, Ta, U and Th; and depletion in Be, Co, Zn, Ga, Ge, Rb, Y, Zr, Mo, Cs, Ba and Hf compared to those of the precursor rock. This type of distribution of the elements may indicate (a) an intense silicic alteration; and (b) REEs might have been leached from the original rocks because of hydrothermal alteration processes, but only LREEs, and MREEs (except Dy and Ho) can be redistributed and accommodated in the hydrothermal minerals, providing them with somewhat inert (immobile) behaviour. The mass change calculations have indicated that MnO and Sr have experienced the greatest and smallest mass changes, respectively. The identification of outliers in chemical data has revealed the presence of two distinctive groups of rocks. Ten out of the total 27 acid volcanic rocks with several elements as outlier data are negligibly to moderately altered (Group‐1), and the remaining 17 acid rocks without outlier data are intensively altered rocks (Group‐2).

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Section: Resultsmentioning

confidence: 99%

Section: Sampling and Analytical Methodsmentioning

confidence: 99%

Section: Sampling and Analytical Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Mineralogical and geochemical changes due to hydrothermal alteration of the volcanic rocks at Acoculco geothermal system, Mexico

et al. 2020

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“…Compositional variations in whole‐rock chemistry over continuous or discrete bodies have been investigated by many studies, especially for igneous rocks (e.g. Batchelor & Bowden, ; Brandmeier & Wörner, ; Maier, Arndt, & Curl, ; Verma et al., ). Previous publications have focused mainly on empirically established characteristics (e.g.…”

Section: Methodsmentioning

confidence: 99%

Progressive evolution of whole‐rock composition during metamorphism revealed by multivariate statistical analyses

Yoshida

Kuwatani

Hirajima

et al. 2017

Journal Metamorphic Geology

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The geochemical evolution of metamorphic rocks during subduction-related metamorphism is described on the basis of multivariate statistical analyses. The studied data set comprises a series of mapped metamorphic rocks collected from the Sanbagawa metamorphic belt in central Shikoku, Japan, where metamorphic conditions range from the pumpellyite-actinolite to epidote-amphibolite facies. Recent progress in computational and information science provides a number of algorithms capable of revealing structures in large data sets. This study applies k-means cluster analysis (KCA) and non-negative matrix factorization (NMF) to a series of metapelites, which is the main lithotype of the Sanbagawa metamorphic belt. KCA describes the structures of the high-dimensional data, while NMF provides end-member decomposition which can be useful for evaluating the spatial distribution of continuous compositional trends. The analysed data set, derived from previously published work, contains 296 samples for which 14 elements (Si, Ti, Al, Fe, Mn, Mg, Ca, Na, K, P, Rb, Sr, Zr and Ba) have been analysed. The KCA and NMF analyses indicate five clusters and four end-members, respectively, successfully explaining compositional variations within the data set. KCA indicates that the chemical compositions of metapelite samples from the western (Besshi) part of the sampled area differ significantly from those in the east (Asemigawa). In the west, clusters show a good correlation with the metamorphic grade. With increasing metamorphic grade, there are decreases in SiO 2 and Na 2 O and increases in other components. However, the compositional change with metamorphic grade is less obvious in the eastern area. End-member decomposition using NMF revealed that the evolutional change of whole-rock composition, as correlated with metamorphic grade, approximates a stoichiometric increase of a garnet-like component in the whole-rock composition, possibly due to the precipitation of garnet and effusion of other components during progressive dehydration. Thermodynamic modelling of the evolution of the whole-rock composition yielded the following results: (1) the whole-rock composition at lower metamorphic grade favours the preferential crystallization of garnet under the conditions of the garnet zone, with biotite becoming stable together with garnet in higher-grade

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Multidimensional Techniques for Compositional Data Analysis

Verma

2019

Road From Geochemistry to Geochemometrics

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Multidimensional classification of magma types for altered igneous rocks and application to their tectonomagmatic discrimination and igneous provenance of siliciclastic sediments

Cited by 36 publications

References 53 publications

Mineralogical and geochemical changes due to hydrothermal alteration of the volcanic rocks at Acoculco geothermal system, Mexico

Mineralogical and geochemical changes due to hydrothermal alteration of the volcanic rocks at Acoculco geothermal system, Mexico

Progressive evolution of whole‐rock composition during metamorphism revealed by multivariate statistical analyses

Multidimensional Techniques for Compositional Data Analysis

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