Abstract: IGNEOUS PETROLOGY OF THE AVES RIDGE (GSA Annual Meeting in Denver, Colorado, USA

NICKE III, Bertram C., BONEY, Jacob, JENSEN, Kyle, ATLAS, Zachary and GERMA, Aurelie, Geology, University of South Florida, 4202 E. Fowler Ave, Tampa, FL 33620, bnicke@mail.usf.edu

The origin of the Aves Ridge formation, and its relationship to the Caribbean plate is enigmatic. It has been proposed that the Aves Ridge shows characteristics of both an island arc and traditional back arc spreading center (Bouysse, 1988). Spreading back arc volcanism, such as inthe Sea of Japan and Taiwan-Luzon arc, yield petrography similar to midocean ridge type basalts (Yang et al,.1996, Uyeda & Kanamori, 1979) . Front arc volcanism in the Lesser Antilles east of the Aves Ridge, produce a wide variety of igneous rocks. This work examines thin sections produced from dredged samples collected by the late Dr. F. Nagle in 1970.

These samples samples displayed a felty texture with abundant plagioclase and minor clinopyroxene. Where larger euhedral grains were observed, the plagioclase was reasonably evolved (An55-65) and atypical for midocean ridge magmas (Smith & Perfit, 2007). However, other samples showed degraded and serpentinized olivine. One particular sample exhibited an iron rich plagontized glass. Magnetite was discernible in some specimens. Quick cooling exhibited by fine grained plagioclase matrix and flow textures were apparent.

Combined, the abundance of plagioclase, clinopyroxene,olivine, and magnetite indicate that studied samples are more similar to midocean ridge pillow basalts rather than arc rocks. Additionally, the quick cooling, flowing textures with serpentinized olivine, and abundant benthic foraminifera point towards subaqueous eruptions and prolonged exposure to marine environments. Therefore the observed samples point toward the formation of the Aves Ridge being a spreading backarc similar to the Sea of Japan and Taiwan-Luzon arcs.

GSA Annual Meeting in Denver, Colorado, USA - 2016

IGNEOUS PETROLOGY OF THE AVES RIDGE