Jordan, Benjamin R. et al. (2006): Geochemical correlation of Caribbean Sea tephra layers with ignimbrites in Central America

ODP 165


Jordan, Benjamin R.
United Arab Emirates University, Department of Geology, Al Ain, United Arab Emirates

Sigurdsson, Haraldur
Universidad Nacional Autonoma de Mexico, Juriquilla Campus, Mexico

Carey, Steven N.
University of Rhode Island, United States

Rogers, Robert
University of Puerto Rico, Puerto Rico

Ehrenborg, Jan
Revista del Centro de Investigaciones Geoscientificas, Nicaragua

Geochemical correlation of Caribbean Sea tephra layers with ignimbrites in Central America
In: Siebe, Claus (editor), Macias, Jose Luis (editor), Aguirre-Diaz, Gerardo J. (editor), Neogene-Quaternary continental margin volcanism; a perspective from Mexico
Geological Society of America (GSA), Boulder, CO, United States
Ignimbrites are deposits resulting from the eruption of volatile-rich, silicic magma. Few geochemical or petrological studies have been done concerning the Tertiary Ignimbrite Province of Central America in Honduras and Nicaragua. Previous work, using ages and geographical proximity, suggested that tephra layers recovered during Ocean Drilling Program (ODP) Leg 165 in the western Caribbean Sea were associated with deposits from explosive eruptions in Central America. A total of 112 marine tephra and 79 terrestrial samples from Nicaragua and Honduras were analyzed during this study. An electron microprobe was used for major oxides, and laser inductively coupled plasma-mass spectrometry (ICP-MS) was used for trace elements. The rare earth elements (REEs), due to their resistance to weathering, were used to correlate the marine tephra with the terrestrial samples. Cluster analysis resulted in the division of the samples into 6 geochemical groups. Visual inspection of these groups resulted in the reclassification of these 6 into 14 distinct geochemical groups. Each one of these geochemical groups displays unique REE trends relative to each other. The trends vary, relative to enriched mid-ocean-ridge basalt (EMORB), from strongly light (L) REE enriched with moderate to large, negative Eu anomalies, to nearly equal EMORB values without any Eu anomalies, to enriched REE with positive Eu anomalies. All but two groups consist of both marine and terrestrial samples. The geochemical correlation is strengthened using factor analysis, in which the REE values for each sample were reduced to two factors and replotted. Each group plots in a distinct field. The Lesser Antilles can be ruled out as contributing to the western Caribbean tephra due to the lack of any large-volume ignimbrite sheets within the arc, as well as the distinctly different REE trends of the magmas. The Sierra Madre Igneous Province in Mexico is also ruled out as a potential source, due mainly to a significant age difference between Sierra Madre ignimbrites and the Caribbean Sea tephra layers. Besides the strong similarities in REE patterns, several of the groups and subgroups are geographically limited in extent, which might imply a specific group source location.
Coverage:Geographic coordinates:
West:-89.0000East: -65.0000

Igneous and metamorphic petrology; algae; Atlantic Ocean; biostratigraphy; Caribbean Sea; Cenozoic; Central America; cluster analysis; correlation; eruptions; geochemistry; glasses; histograms; Honduras; ICP mass spectra; igneous rocks; ignimbrite; Leg 165; magmas; mass spectra; microfossils; Miocene; nannofossils; Neogene; Nicaragua; North Atlantic; Ocean Drilling Program; oxides; Plantae; pyroclastics; sampling; spectra; statistical analysis; Tertiary; volcanic ash; volcanic rocks; volcanism;