Journal
JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH
Volume 117, Issue -, Pages -Publisher
AMER GEOPHYSICAL UNION
DOI: 10.1029/2011JB008959
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Funding
- Panama Canal Authority [SAA-199520-KRP]
- Senacyt [SUM-07-001, EST010-080 A]
- U.S. National Science Foundation (NSF) [0966884]
- Colciencias
- Swiss National Science Foundation [PBLA2-122660]
- NSF EAR [0824299]
- National Geographic
- Smithsonian Institution
- Ricardo Perez S.A.
- Division Of Earth Sciences
- Directorate For Geosciences [1032156, 0824299] Funding Source: National Science Foundation
- Office Of Internatl Science &Engineering
- Office Of The Director [0966884] Funding Source: National Science Foundation
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Closure of the Central American seaway was a local tectonic event with potentially global biotic and environmental repercussions. We report geochronological (six U/Pb LA-ICP-MS zircon ages) and geochemical (19 XRF and ICP-MS analyses) data from the Isthmus of Panama that allow definition of a distinctive succession of plateau sequences to subduction-related protoarc to arc volcaniclastic rocks intruded by Late Cretaceous to middle Eocene intermediate plutonic rocks (67.6 +/- 1.4 Ma to 41.1 +/- 0.7 Ma). Paleomagnetic analyses (24 sites, 192 cores) in this same belt reveal large counterclockwise vertical-axis rotations (70.9 degrees +/- 6.7 degrees), and moderate clockwise rotations (between 40 degrees +/- 4.1 degrees and 56.2 degrees +/- 11.1 degrees) on either side of an east-west trending fault at the apex of the Isthmus (Rio Gatun Fault), consistent with Isthmus curvature. An Oligocene-Miocene arc crosscuts the older, deformed and segmented arc sequences, and shows no significant vertical-axis rotation or deformation. There are three main stages of deformation: 1) left-lateral, strike-slip offset of the arc (similar to 100 km), and counterclockwise vertical-axis rotation of western arc segments between 38 and 28 Ma; 2) clockwise rotation of central arc segments between 28 and 25 Ma; and 3) orocline tightening after 25 Ma. When this reconstruction is placed in a global plate tectonic framework, and published exhumation data is added, the Central American seaway disappears at 15 Ma, suggesting that by the time of northern hemisphere glaciation, deep-water circulation had long been severed in Central America.
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