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Structure and tectonic history of the eastern Panama Basin

1978; Geological Society of America; Volume: 89; Issue: 7 Linguagem: Inglês

10.1130/0016-7606(1978)89 2.0.co;2

1943-2674

Peter Lonsdale, Kim D. Klitgord,

Geological and Tectonic Studies in Latin America

Research Article| July 01, 1978 Structure and tectonic history of the eastern Panama Basin PETER LONSDALE; PETER LONSDALE 1University of California, San Diego, Marine Physical Laboratory of the Scripps Institution of Oceanography, La Jolla, California 92093 Search for other works by this author on: GSW Google Scholar KIM D. KLITGORD KIM D. KLITGORD 2U.S. Geological Survey, Woods Hole, Massachusetts 02543 Search for other works by this author on: GSW Google Scholar GSA Bulletin (1978) 89 (7): 981–999. https://doi.org/10.1130/0016-7606(1978)89 2.0.CO;2 Article history first online: 01 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation PETER LONSDALE, KIM D. KLITGORD; Structure and tectonic history of the eastern Panama Basin. GSA Bulletin 1978;; 89 (7): 981–999. doi: https://doi.org/10.1130/0016-7606(1978)89 2.0.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGSA Bulletin Search Advanced Search Abstract New marine geophysical data allow the preparation of revised bathymetric and magnetic anomaly charts of the Panama Basin and demonstrate that the eastern part of the basin, between the fracture zone at long 83°W and the Colombian continental margin, was formed by highly asymmetric sea-floor spreading along the boundary of the Nazca and Cocos plates 27 to 8 m.y. B.P. Lineated magnetic anomalies recording this history are oriented approximately east-west. The oldest set of north-flank anomalies overlaps in age with those adjacent to the Grijalva scarp, south of the western Panama Basin, where they are oriented 065°. Younger anomalies (5C to 5) in the eastern basin are approximately parallel to anomalies of this age identified on the Carnegie platform and the flanks of the Costa Rica rift. The eastern basin now contains a pattern of fossil spreading centers (including the Malpelo rift) and transform faults (including the Yaquina graben) that were abandoned 8 m.y. B.P. by a shift in plate boundaries that transferred a large section of the Cocos plate to the Nazca plate. Cessation of Nazca-Cocos spreading east of long 83°W was heralded by a 3-m.y. deceleration of spreading on the eastern segments, which created rough topography and axial rift valleys typical of slow-spreading ridges. Westward jumping of the Nazca-Cocos-Caribbean triple junction rejuvenated the northern segment of the fracture zone at long 83°W, causing uplift of the adjacent Coiba Ridge. Recently, active transform faulting has jumped farther west, from the foot of the Coiba Ridge to the Panama fracture zone.Apart from changes in plate boundaries, the main event in the tectonic evolution of the region was initiation about 22 to 20 m.y. B.P. of the hot spot that created the Malpelo, Cocos, and Carnegie Ridges. Precursors of effusive ridge-building volcanism included major fracturing of the oceanic crust to the north of the present Malpelo Ridge. Both processes hamper identification of magnetic anomalies in the vicinity of the ridges. Our interpretation of the tectonic history is also incomplete in the easternmost parts of the basin, where data are insufficient; this impairs our interpretation of the adjacent continental geology in terms of changing interaction between oceanic and continental plates. The geologic history of the Isthmus of Panama is compatible with our application of the plate-tectonic model. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.