Mechanisms controlling explosive-effusive transition of Teide-Pico Viejo complex dome eruptions.

摘要: The Teide-Pico Viejo (PT-PV) stratovolcanoes constitute one of the major potentially active volcanic complexes in Europe. PT-PV was traditionally considered as non-explosive system however, recent studies (ie. Garcia et al. 2014) have pointed out that explosive character phonolitic magmas, including plinian and subplinian eruptions generation pyroclastic density currents, also been significant within last 30 kyr volcanological record. This activity is mostly associated to satellite dome vents, like studied this work, Pico Cabras. Dome-forming usually present sudden transitions between effusive activity. A better knowledge type about main mechanisms controlling changes eruptive dynamics required undertake a comprehensive hazard assessment Tenerife Island. In study, we conduct petrological mineral characterization different eruption phases Cabras (pumice lava flow samples for activity, respectively) with aim determining factors control these Products were characterized Scanning Electrom Microscope, phases, glass volatile species (F, Cl) analysed electron microprobe micro-XRF. pre-eruptive conditions magma (pressure, temperature water dissolved magma) determined first by using available geothermobarometers, geohygrometers (Masotta al., 2013; Mollo 2015) compared those retrieved phase equilibria experiments from literature Andujar Scaillet, 2012). Our results suggest presence compositionally stratified chamber at 1 kbar±0.5kbar prior which differences styles are controlled amount volatiles melt. related upper part 725oC±25oC 3,5-5 wt% H 2 O body 880oC±30oC 2,5-3 O. Feldspar zonations show overturn events occurred layers chambers ("self-mixing") triggered underplating mafic without mixing. Chemical composition some feldspars equivalent found El Abrigo eruption, caldera-forming episode (ca. 190 ka), demonstrating still capable producing evolved very magmas.