Cryptic alkaline magmatism in the oceanic Caribbean arc (Camagüey area, Cuba)
| Autor: | Lisard Torró, Manuel A. Iturralde-Vinent, Yamirka Rojas-Agramonte, Elena Piñero, Antonio García-Casco, Lidia Butjosa, Aitor Cambeses, Joaquín A. Proenza, Concepción Lázaro |
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| Přispěvatelé: | Ministerio de Economía y Competitividad (España), Ministerio de Ciencia e Innovación (España), European Commission, Universidad de Granada, Universidad de Barcelona |
| Rok vydání: | 2020 |
| Předmět: |
Basalt
geography Fractional crystallization (geology) geography.geographical_feature_category Magmatisme 010504 meteorology & atmospheric sciences Magmatism Partial melting Geochemistry Geology engineering.material 010502 geochemistry & geophysics 01 natural sciences Porphyritic Volcanic rock Geochemistry and Petrology Oceanic crust engineering Plagioclase Carib (Regió) Mafic Caribbean Area 0105 earth and related environmental sciences |
| Zdroj: | Dipòsit Digital de la UB Universidad de Barcelona Digital.CSIC. Repositorio Institucional del CSIC instname |
| Popis: | Mid and Late Cretaceous arc-related basaltic rocks in the Camagüey area, East Central Cuba, record an intriguing seemingly random enrichment in alkalis that suggests alkaline affinity, representing an oddity in the Greater Antilles. In this study, the petrology and geochemistry of volcanic rocks from the Camujiro, Piragua and La Mulata Formations have been investigated. The rocks bear a diverse mineral assemblage including feldspars (plagioclase and potassium feldspar), clinopyroxene, phlogopite and amphibole with both equilibrium and disequilibrium textures. Clinopyroxene porphyritic crystals show conspicuous oscillatory and convolute zoning and reveal events of mafic recharge and crystallization in equilibrium with alkaline and calc-alkaline basaltic magmas and their mixtures. Composition of fluorophlogopite xenocrystals is consistent with crystallization from mafic alkaline liquids. Unlike whole-rock major element composition, immobile trace element abundances suggest a systematic calc-alkaline affinity. Chondrite-normalized rare-earth element (REE) patterns are similar to those of calc-alkaline and high-K (and [sbnd]Th) calc-alkaline rocks from the Caribbean Antilles. Geochemical modelling indicates that the parental basic magmas formed by a 5–10% hydrous partial melting of spinel-facies depleted mantle fluxed by fluids evolved from subducted oceanic crust and pelagic sediments, as well as fractional crystallization. Random enrichment in alkalis in studied samples is attributed to the entrainment during ascent of material derived from mafic alkaline melts injected in the upper mantle or the root of the island-arc. Our new data establish a mature stage in the evolution of the Caribbean island-arc by Cenomanian times capable of sourcing alkaline melts and the existence of a thickened island arc crust that favored fractional crystallization and magma chamber recharge processes unlike in previous stages of the island-arc construction. his research has been supported financially by the Fondo Europeo de Desarrollo Regional (FEDER) Funds, the Spanish Projects CGL2015–65824 and PID2019-105625RB-C21 and the Universities of Barcelona and Granada (CIC). We thank Carl. E Nelson for scientific discussions, Xavier Llovet (CCiT-UB) for technical support during the acquisition of EPMA data and Steve Galer and Reimund Jotter (Max-Planck-Institut für Chemie) for their help during Pb isotope analysis and data reduction. We are grateful to Mathew Loewen, editor-in-chief Michael Roden and an anonymous reviewer for their constructive comments which significantly improved the manuscript. |
| Databáze: | OpenAIRE |
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