40Ar-39Ar incremental heating experiments and electron microprobe analyses were performed on basaltic rocks recovered from Site 1001 during Ocean Drilling Program Leg 165. The lower Nicaraguan Rise, on which Site 1001 lies, appears to be part of a larger Caribbean oceanic plateau that makes up the core of the Caribbean plate. Our results indicate an eruption age of 81 ± 1 Ma. A single flow-rim glass is tholeiitic and almost identical to the shipboard X-ray fluorescence analyses of the whole rock. The slightly porphyritic basalts have at least two populations of plagioclase, groundmass, and glomerocrystic plagioclase laths that appear to be in equilibrium with the surrounding melt and corroded tabular phenocrysts that have a higher An content (An84-86).
1Leckie, R.M., Sigurdsson, H., Acton, G.D., and Draper, G. (Eds.), 2000. Proc. ODP, Sci. Results, 165 [Online]. Available from World Wide Web: <http://www-odp.tamu.edu/publications/165_SR/165TOC.HTM>. [Cited YYYY-MM-DD]
2Graduate School of Oceanography, University of Rhode Island, Narragansett, RI 02882, U.S.A. (Present address: New York State College of Ceramics, Alfred University, Alfred, NY 14802, U.S.A.) sintoncw@alfred.edu
3College of Oceanic and Atmospheric Sciences, Oregon State University, Corvallis, OR 97331, U.S.A.
Date of
initial receipt: 24 June 1998
Date of acceptance: 29 March 1999
Ms 165SR-029