Hoernle, Kaj , Werner, Reinhard, Phipps Morgan, Jason, Garbe-Schönberg, Dieter, Bryce, Julie and Mrazek, Johann (2000) Existence of complex spatial zonation in the Galápagos plume. Geology, 28 (5). pp. 435-438. DOI 10.1130/0091-7613(2000)28<435:EOCSZI>2.0.CO;2.

Text Geology-2000-Hoernle-435-8.pdf - Published Version Restricted to Registered users only Download (143kB) | Contact

Abstract

Basalts from intraplate or hotspot ocean islands (e.g., the Hawaiian,
Galápagos, and Canary Islands) are believed to be formed by mantle
plumes, which emanate from mantle boundary layers such as the coremantle
boundary. The long-term chemical structure of mantle plumes,
however, remains poorly constrained. Spatial variation in the chemical
composition has long been recognized in lavas from the Galápagos
Islands: Enriched plume material forms a horseshoe-shaped region
with depleted mantle, similar in composition to mid-ocean ridge basalt,
in its inner part. The enriched horseshoe-shaped region can be subdivided
into three distinct geochemical domains. We show that these
same domains occur in the same relative positions with respect to morphology
in a geochemical profile across the Galápagos hotspot track off
the coast of Costa Rica, indicating that the asymmetrical spatial zonation
of the Galápagos hotspot has existed for at least 14 m.y. Combined
with published He isotope data, the results of this study imply that
plume material can ascend from the lower mantle, possibly from the
core-mantle boundary, with little stirring occurring during ascent, and
that zonation in hotspot lavas may in some cases reflect spatial heterogeneity
within the lower mantle source.

Actions (login required)

View Item