The chemically zoned 1949 eruption on La Palma (Canary Islands): Petrologic evolution and magma supply dynamics of a rift zone eruption.

Klügel, Andreas, Hoernle, Kaj A., Schmincke, Hans-Ulrich and White, James D. L. (2000) The chemically zoned 1949 eruption on La Palma (Canary Islands): Petrologic evolution and magma supply dynamics of a rift zone eruption. Open Access Journal of Geophysical Research: Solid Earth, 105 (B3). pp. 5997-6016. DOI 10.1029/1999JB900334.

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Abstract

The 1949 rift zone eruption along the Cumbre Vieja ridge on La Palma involved three eruptive centers, 3 km spaced apart, and was chemically and mineralogically zoned. Duraznero crater erupted tephrite for 14 days and shut down upon the opening of Llano del Banco, a fissure that issued first tephrite and, after 3 days, basanite. Hoyo Negro crater opened 4 days later and erupted basanite, tephrite, and phonotephrite, while Llano del Banco continued to issue basanite. The eruption ended with Duraznero erupting basanite with abundant crustal and mantle xenoliths. The tephrites and basanites from Duraznero and Llano del Banco show narrow compositional ranges and define a bimodal suite. Each batch ascended and evolved separately without significant intermixing, as did the Hoyo Negro basanite, which formed at lower degrees of melting. The magmas fractionated clinopyroxene +olivine±kaersutite±Ti-magnetite at 600–800 MPa and possibly 800–1100 MPa. Abundant reversely zoned phenocrysts reflect mixing with evolved melts at mantle depths. Probably as early as 1936, Hoyo Negro basanite entered the deep rift system at 200–350 MPa. Some shallower pockets of this basanite evolved to phonotephrite through differentiation and assimilation of wall rock. A few months prior to eruption, a mixing event in the mantle may have triggered the final ascent of the magmas. Most of the erupted tephrite and basanite ascended from mantle depths within hours to days without prolonged storage in crustal reservoirs. The Cumbre Vieja rift zone differs from the rift zones of Kilauea volcano (Hawaii) in lacking a summit caldera or a summit reservoir feeding the rift system and in being smaller and less active with most of the rift magma solidifying between eruptions.

Document Type: Article
Keywords: GREEN-CORE CLINOPYROXENES; BENEATH GRAN-CANARIA; PUU-OO ERUPTION; KILAUEA VOLCANO; TRACE-ELEMENT; PARTITION-COEFFICIENTS; OCEANIC-ISLAND; HIGH-PRESSURES; ASCENT RATES; CONSTRAINTS
Research affiliation: OceanRep > GEOMAR > FB4 Dynamics of the Ocean Floor > FB4-MUHS Magmatic and Hydrothermal Systems
Refereed: Yes
Open Access Journal?: No
DOI etc.: 10.1029/1999JB900334
ISSN: 0148-0227
Date Deposited: 25 Oct 2013 11:53
Last Modified: 25 Apr 2018 09:47
URI: http://oceanrep.geomar.de/id/eprint/22276

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