Basanite to phonolite differentiation within 1550-1750 yr: U-Th-Ra isotopic evidence from the A.D. 1585 eruption on La Palma, Canary Islands

T. S. Johansen, F. Hauff, K. Hoernle, A. Klügel, T.F. Kokfelt

Publikation: Bidrag til tidsskriftArtikelForskningpeer review

19 Citationer (Scopus)

Abstrakt

U-Th-Ra disequilibria of basanites, tephrites, and phonolites from the A.D. 1585 eruption on La Palma, Canary Islands, constrain magma differentiation times in an ocean-island rift zone. The insignificant difference in (230Th)/(232Th) implies differentiation from basanite to phonolite in <15 k.y. 226Ra has a half-life of 1600 yr, however, and permits higher temporal resolution; (226Ra)/(230Th) disequilibria are highest in the phonolites (46%-54%) and basanites (44%-47%) and lowest in the tephrites (38%-41%). The higher 226Ra excesses in the end-member compositions model basanite-phonolite differentiation within 1550-1750 yr at a rate of 0.04% fractional crystallization per year. Such a short time interval is in sharp contrast to the ∼200 k.y. proposed for phonolite differentiation on the neighboring island of Tenerife and could reflect different volcanic systems, with a mantle-fed rift system on La Palma versus a crustal magma reservoir on Tenerife.

OriginalsprogEngelsk
Sider (fra-til)897-900
Antal sider4
TidsskriftGeology
Vol/bind33
Udgave nummer11
DOI
StatusUdgivet - nov. 2005
Udgivet eksterntJa

Emneord

  • La Palma
  • Canary Islands
  • Volcanic activity
  • Magma differentiation
  • Geochemistry and petrology
  • U-series disequilibria

Programområde

  • Programområde 4: Mineralske råstoffer

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