Nicaraguan volcanoes record paleoceanographic changes accompanying closure of the Panama gateway
- 1Department of Earth Sciences, Boston University, Boston, Massachusetts 02215, USA, and Department of Geology, University of Kansas, Lawrence, Kansas 66044, USA
- 2Department of Geology, University of Kansas, Lawrence, Kansas 66044, USA, and Department of Geology, Oregon State University, Corvallis, Oregon 97331, USA
- 3Department of Geological Sciences, Rutgers University, Piscataway, New Jersey 08854, USA
Abstract
A major oceanographic event preserved in the Cocos plate sedimentary column survived subduction and is recorded in the changing composition of Nicaraguan magmas. A uranium increase in these magmas since the latest Miocene (after 7 Ma) resulted from the “carbonate crash” at 10 Ma and the ensuing high organic carbon burial in the sediments. The response of the arc to this paleoceanographic event requires near steady-state sediment recycling at this margin since 20 Ma. This relative stability in sediment subduction invites one of the first attempts to balance sedimentary input and arc output across a subduction zone. Calculations based on Th indicate that as much as 75% of the sedimentary column was subducted beneath the arc. The Nicaraguan margin is one of the few places to observe such strong links between the oceans and the solid earth.
Footnotes
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↵GSA Data Repository item 2002128, Age data, geochemistry of sediments and volcanic rocks, and bulk sediment flux calculations, is available from Documents Secretary, GSA, P.O. Box 9140, Boulder, CO 80301–9140, editinggeosociety.org, or at www.geosociety.org/pubs/ft2002.htm.
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- Accepted August 20, 2002.
- Received May 6, 2002.
- Revision received August 16, 2002.
- Geological Society of America
