Quick
Search: 		  
advanced search
 GSW Home   GeoRef Home   My GSW Alerts   Contact GSW   About GSW   Journals List   Help 
Geology Email Content Delivery
JOURNAL HOME HELP CONTACT PUBLISHER SUBSCRIBE ARCHIVE SEARCH TABLE OF CONTENTS
Geology; November 2005; v. 33; no. 11; p. 897-900; DOI: 10.1130/G21663.1
© 2005 Geological Society of America
This Article
Right arrow Figures Only
Right arrow Full Text
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Right arrow Citation Map
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in ISI Web of Science
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow reprints & permissions
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via ISI Web of Science (4)
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Johansen, T. S.
Right arrow Articles by Kokfelt, T.F.
Right arrow Search for Related Content
GeoRef
Right arrow GeoRef Citation

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. Johansen1, F. Hauff1, K. Hoernle1, A. Klügel2 and T.F. Kokfelt3

1 IFM-GEOMAR, Leibniz Institute for Marine Sciences, Wischhofstrasse 1-3, D-24148 Kiel, Germany
2 Department of Geology, University of Bremen, D-28334 Bremen, Germany
3 IFM-GEOMAR, Leibniz Institute for Marine Sciences, Wischhofstrasse 1-3, D-24148 Kiel, Germany

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.

Key Words: La Palma • A.D. 1585 eruption • ocean-island rift zone • U-series disequilibria • basanite-phonolite differentiation




This article has been cited by other articles:


Home page
 GeologyHome page
J.A. Vazquez, P.J. Shamberger, and J.E. Hammer
Plutonic xenoliths reveal the timing of magma evolution at Hualalai and Mauna Kea, Hawaii
Geology, August 1, 2007; 35(8): 695 - 698.
[Abstract] [Full Text] [PDF]

Home page
 J PetrologyHome page
T. Kuritani, T. Yokoyama, and E. Nakamura
Rates of Thermal and Chemical Evolution of Magmas in a Cooling Magma Chamber: a Chronological and Theoretical Study on Basaltic and Andesitic Lavas from Rishiri Volcano, Japan
J. Petrology, July 1, 2007; 48(7): 1295 - 1319.
[Abstract] [Full Text] [PDF]

Home page
 GeologyHome page
A. K. Schmitt
Laacher See revisited: High-spatial-resolution zircon dating indicates rapid formation of a zoned magma chamber
Geology, July 1, 2006; 34(7): 597 - 600.
[Abstract] [Full Text] [PDF]


JOURNAL HOME HELP CONTACT PUBLISHER SUBSCRIBE ARCHIVE SEARCH TABLE OF CONTENTS
Copyright © 2008 by Geological Society of America