Cause of the middle/late Miocene carbonate crash; dissolution or low productivity?

Online Access: Get full text
doi: 10.2973/odp.proc.sr.206.013.2007
Author(s): Jiang, Shijun; Wise, Sherwood W., Jr.; Wang, Yang
Ocean Drilling Program, Leg 206, Shipboard Scientific Party, College Station, TX
Author Affiliation(s): Primary:
Florida State University, Department of Geological Sciences, Tallahasee, FL, United States
Other:
University of California, Santa Barbara, United States
Ocean Drilling Program, United States
University of Michigan, United States
University of Alberta, Canada
University of Leicester, United Kingdom
California Institute of Technology, United States
Universita di Genova, Italy
Université de Montpellier II, France
Florida State University, United States
Bundesanstalt für Geowissenschaften und Rohstoffe, Federal Republic of Germany
University of Utah, United States
Universitë de Aix-Marseille, France
Christian-Albrechts-Universität zu Kiel, Federal Republic of Germany
Macquarie University, Australia
Universita di Milano, Italy
Shizuoka University, Japan
Boston University, United States
Volume Title: Proceedings of the Ocean Drilling Program; volume 206; scientific results; an in situ section of the upper oceanic crust formed by superfast seafloor spreading; covering Leg 206 of the cruises of the drilling vessel JOIDES Resolution; Balboa, Panama to Balboa, Panama; Site 1256; 6 November 2002-4 January 2003
Volume Author(s): Teagle, Damon A. H.; Wilson, Douglas S.; Acton, Gary D.; Alt, Jeffrey C.; Banerjee, Neil R.; Barr, Samantha R.; Coggon, Rosalind; Cooper, Kari M.; Crispini, Laura; Einaudi, Florence; Jiang, Shijun; Kalberkamp, Ulrich; Kerneklian, Marcie J.; Laverne, Christine; Nichols, Holly J.; Sandwell, Rachel; Tartarotti, Paola; Umino, Susumu; Ziegler, Christa
Source: Proceedings of the Ocean Drilling Program; volume 206; scientific results; an in situ section of the upper oceanic crust formed by superfast seafloor spreading; covering Leg 206 of the cruises of the drilling vessel JOIDES Resolution; Balboa, Panama to Balboa, Panama; Site 1256; 6 November 2002-4 January 2003, Damon A. H. Teagle, Douglas S. Wilson, Gary D. Acton, Jeffrey C. Alt, Neil R. Banerjee, Samantha R. Barr, Rosalind Coggon, Kari M. Cooper, Laura Crispini, Florence Einaudi, Shijun Jiang, Ulrich Kalberkamp, Marcie J. Kerneklian, Christine Laverne, Holly J. Nichols, Rachel Sandwell, Paola Tartarotti, Susumu Umino and Christa Ziegler; Ocean Drilling Program, Leg 206, Shipboard Scientific Party, College Station, TX. Proceedings of the Ocean Drilling Program, Scientific Results (CD ROM), Vol.206, 24p. Publisher: Texas A&M University, Ocean Drilling Program, College Station, TX, United States. ISSN: 1096-2514
Note: In English. 102 refs.CD-ROM format, ISSN 1096-2514; WWW format, 1096-7451; illus., incl. sketch map
Summary: The middle/late Miocene "carbonate crash", a sharp decrease in carbonate mass accumulation rates in the eastern and central equatorial Pacific, as well as the Caribbean region, has previously been considered only a dissolution event associated with changes in global ocean chemistry, which is in turn believed to be tied to the production of the North Atlantic Bottom Water and/or ventilation via the Panama Seaway. δ13C data in the bulk-isotope record from Ocean Drilling Program Site 1256 show a close parallel with CaCO3 mass accumulation rates (MARs) in the 5- to 14-Ma interval (correlation coefficient = 0.87), suggesting a relationship likely coupled to surface water productivity by calcite-secreting organisms. The decoupling between δ13C and MARs after 5 Ma probably indicates a dominance of dissolution over carbonate production. Therefore, the coincidence in δ13C excursions with the stages of sharp reduction in CaCO3 MARs during the carbonate crash points to a causative mechanism induced by surface circulation-induced low productivity. We speculate that the major middle/late Miocene sea level drop may have caused the complete closure of the Indonesian Seaway. We propose a model wherein the blockage of Indonesian Throughflow would have resulted in a piling-up of surface warm water in the west Pacific, thereby strengthening the Equatorial Undercurrent system. The eastward spread of this nutrient-poor water then warmed sea-surface temperature and reduced upwelling in the central and eastern Pacific, reducing in turn biological productivity of phytoplankton. A coincident reduction in Central America and circum-Caribbean volcanism plus the deflection of the delivery of volcanic ash as a result of the then prevailing southeastern trade winds across the equator further deprived these regions of trace element nutrients, which added to lowered surface water carbonate production. Surface water warming and reduced upwelling is documented by negative excursions in δ18O values. The reduction in carbonate supply to the deep waters caused a rapid shoaling of the carbonate compensation depth and triggered the carbonate crash. The close correlation between CaCO3 mass accumulation rates and biological productivity suggests that the carbonate crash is best characterized as a low-productivity event.
Year of Publication: 2007
Research Program: ODP Ocean Drilling Program
Key Words: 02 Geochemistry; 12 Stratigraphy, Historical Geology and Paleoecology; Algae; Boreholes; C-13/C-12; Calcium carbonate; Carbon; Carbonate compensation depth; Cenozoic; Chemostratigraphy; Cores; Diagenesis; East Pacific; East Pacific Rise; Equatorial Pacific; Guatemala Basin; Isotope ratios; Isotopes; Leg 206; Lithofacies; Marine environment; Microfossils; Middle Miocene; Miocene; Nannofossils; Neogene; North Pacific; Northeast Pacific; O-18/O-16; ODP Site 1256; Ocean Drilling Program; Oxygen; Pacific Ocean; Paleo-oceanography; Plantae; Preservation; Productivity; Sea-level changes; Solution; Stable isotopes; Tertiary; Upper Miocene
Coordinates: N064400 N064400 W0915600 W0915600
Record ID: 2007124231
Copyright Information: GeoRef, Copyright 2019 American Geosciences Institute.