Geochemistry of Eocene felsic volcanic rocks from the Mesa Virgen-Calerilla, Zacatecas, Mexico: Implications for the magma source and tectonic setting,Geological Journal

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Geochemistry of Eocene felsic volcanic rocks from the Mesa Virgen-Calerilla, Zacatecas, Mexico: Implications for the magma source and tectonic setting
Geological Journal ( IF 1.4 ) Pub Date : 2021-03-30 , DOI: 10.1002/gj.4133
Sanjeet K. Verma ₁ , Darío Torres‐Sánchez ₂ , Karla R. Hernández‐Martínez ₂ , Vivek P. Malviya ₃ , Pradip K. Singh ₄ , José R. Torres‐Hernández ₅ , Beatriz A. Rivera‐Escoto ₆

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The Mesa Virgen Calerilla (MVC) is located in the state of Zacatecas, Mexico. The most intense volcanism, which occurred during the Eocene, formed extensive ignimbrite deposits exposed in some parts as lava spills of rhyolitic (felsic) composition. This felsic volcanism may represent much of the MVC. This study describes whole-rock geochemistry and mineralogy data from felsic volcanic rocks in the MVC to address their petrogenesis and tectonic setting. The MVC covers a compositional spectrum ranging from trachyte, dacite, to high-silica rhyolite. The petrography and mineral assemblages indicate that the felsic rocks are composed of K-feldspar (sanidine), quartz, plagioclase, and biotite. The felsic volcanic rocks have a composition of 64.08–78.17 wt% (SiO₂)_adj, 0.14–0.69 wt% (TiO₂)_adj, and 0.11–0.62 wt% (MgO)_adj with 12–54 Mg number [Mg# = 100 × (Mg²⁺/[Mg²⁺ + Fe²⁺])]. These felsic volcanic rocks showed enrichment in light rare earth elements (LREE; [La/Sm]_N = 3.80–7.19), and are depleted in heavy rare earth elements [HREE; (Tb/Yb)_N ratios 0.35–1.84], along with negative Ba, Nb, Sr, P, Eu, and Ti anomalies. The geochemical characteristics and petrogenetic modelling indicate that felsic volcanic rocks are derived from partial melting process of an upper-middle continental crust. The tectono-magmatic model and multidimensional tectonic discrimination diagram indicate that an extensional-related setting prevails for the MVC.

中文翻译：

墨西哥萨卡特卡斯 Mesa Virgen-Calerilla 始新世长英质火山岩的地球化学：对岩浆源和构造环境的影响

Mesa Virgen Calerilla (MVC) 位于墨西哥萨卡特卡斯州。最强烈的火山活动发生在始新世期间，形成了大量的火山灰沉积物，在某些部分暴露为流纹质（长英质）成分的熔岩溢出。这种长英质火山作用可能代表了 MVC 的大部分。本研究描述了 MVC 中长英质火山岩的全岩地球化学和矿物学数据，以解决它们的岩石成因和构造环境。MVC 涵盖了从粗面岩、英安岩到高硅流纹岩的组成范围。岩石学和矿物组合表明长英质岩石由钾长石（砂质）、石英、斜长石和黑云母组成。长英质火山岩的成分为 64.08–78.17 wt% (SiO ₂ ) _adj , 0.14–0.69 wt% (TiO₂ ) _adj和 0.11–0.62 wt% (MgO) _adj，Mg 数为 12–54 [Mg# = 100 × (Mg ²⁺ /[Mg ²⁺ + Fe ²⁺ ])]。这些长英质火山岩显示出富含轻稀土元素（LREE；[La/Sm] _N = 3.80–7.19），并缺乏重稀土元素 [HREE；(Tb/Yb) _N0.35–1.84]，以及负的 Ba、Nb、Sr、P、Eu 和 Ti 异常。地球化学特征和成岩模型表明，长英质火山岩来源于中上陆地壳的部分熔融过程。构造-岩浆模型和多维构造判别图表明，MVC 具有伸展相关的背景。

更新日期：2021-03-30

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