Geochemical and isotopic composition of volcanic rocks of the heterogeneous Miocene (~ 23–19 Ma) Tepoztlán Formation, early Transmexican Volcanic Belt, Mexico

摘要: Abstract We present the first geochemical data (major and trace elements, as well Sr, Nd, Pb isotopes) on volcanic rocks from Tepoztlan Formation in central Transmexican Volcanic Belt. The is up to 800 m thick comprises a wide range of primary (lavas, pyroclastic density current deposits, fall deposits), their secondary reworked products due mass flow (lahars) fluvial processes. Magnetostratigraphy combined with K/Ar Ar/Ar geochronology suggests an age Early Miocene (23–19 Ma) for this Formation. Lava flows, rocks, dykes clasts basaltic andesite rhyolite, clear dominance andesites dacites. All samples are subalkaline hy-normative. These show homogeneous REE patterns LREE enrichment higher LILE concentrations respect HFSE, notably typical negative anomaly Nb, Ta, Ti, suggesting subduction-related magma genesis. Major element that either assimilation heterogeneous continental crust or crustal recycling by subduction erosion fractional crystallization important processes evolution magmas. Isotopic compositions (87Sr/86Sr) t  = 0.703693 0.704355 (143Nd/144Nd)  = 0.512751 0.512882, falling within mantle array. characteristics indicate these originated mantle, modified evolved through country rock upper crust.