Cosmogenic ³He exposure dating of the Quaternary basalts from Fogo, Cape Verdes: implications for rift zone and magmatic reorganisation

Foeken, J. P.T., Day, S. and Stuart, F. M. (2009) Cosmogenic ³He exposure dating of the Quaternary basalts from Fogo, Cape Verdes: implications for rift zone and magmatic reorganisation. Quaternary Geochronology, 4(1), pp. 37-49. (doi: 10.1016/j.quageo.2008.07.002)

Abstract

We have used cosmogenic ³He to date pre- and post-collapse lava flows from southwestern Fogo, Cape Verdes, in order to date rift zone magmatic reorganisation following the lateral collapse of the flank of the Monte Amarelo volcano. The post-collapse flows have exposure ages ranging from 62 to 11 ka. The analysis of multiple flow tops on each lava flows, often at different elevations, provides an internal check for age consistency and the exposures ages conform with stratigraphic level. The exposure ages suggest that volcanic activity along the western branch of the triple-armed rift zone was more or less continuous from before 62 ka to approximately 11 ka. The absence of magmatic activity for the last 11 kyr reflects a structural reconfiguration of the volcano and may be related to renewed flank instability. This volcanic hiatus is similar in duration to that observed in the Canary Islands. Replicate ³He exposure ages of a pre-collapse flow (123.0 ± 5.2 ka) brackets the time of the Monte Amarelo collapse between 62 ka and 123 ka. Reproducible cosmogenic ³He exposure ages of less than 123 ka from flows away from major erosion features demonstrates that the technique is a viable alternative to the radiocarbon, K/Ar and ⁴⁰Ar/³⁹Ar chronometers for dating recent volcanism in arid climate zones.

• Item Type: Articles
• Keywords: Cosmogenic nuclide dating, exposure dating, lava, helium, natural hazard, volcano flank collapse.
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Stuart, Professor Fin and Foeken, Dr Jurgen
• Authors: Foeken, J. P.T., Day, S., and Stuart, F. M.
• Subjects: Q Science > QE Geology; G Geography. Anthropology. Recreation > GE Environmental Sciences
• College/School: College of Science and Engineering > Scottish Universities Environmental Research Centre
• Journal Name: Quaternary Geochronology
• Publisher: Elsevier
• ISSN: 1871-1014
• ISSN (Online): 1878-0350
• Published Online: 31 July 2008