Early Ordovician volcanism in the Iberian Chains (NE Spain) and its influence on the preservation of shell concentrations

• DOI: 10.2113/gssgfbull.179.6.569
• Publication Date: 2009-01-01T01:57:46Z
• Authors: Jose Javier Álvaro; Hassan Ezzouhairi; M. Luisa Ribeiro; J. Farinha Ramos; A. Rita Solá
• Keywords: Felsic

Abstract Research is described to evaluate the influence of volcanic activity on studies shell-concentration taphonomy and biodiversity patterns in strata that commonly display poor densities skeletal debris. Two episodes are recorded Lower Ordovician Iberian Chains: (i) a succession Tremadocian-earliest “Arenig”, eruptive felsic products, expelled explosively characterized by onset rhyolitic dacitic tuffs embedded Borrachón Santed formations; (ii) an effusive basaltic episode, represented single lava flow Armorican Quartzite. The reflects change from sub-alkaline alkaline geochemical affinities, related Early magmatism southwestern Europe attributed opening Rheic Ocean. explosive associated with two ecosystem disturbance events: short-term colonization event opportunistic linguliformean brachiopods proliferated aftermath multi-event pyroclastic surge deposit; several single-event mass-mortality horizons flows responsible for preservation high-diverse allochthonous coquinas. Our knowledge achieved benthic communities preserved poorly fossiliferous, siliciclastic Chains is, as result, strongly biased presence tuffs, directly controlled neighbouring explosions.