A comparative study of diagenetic pathways in sediments of the Caribbean Sea; highlights from pore-water results

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doi: 10.2973/odp.proc.sr.165.020.2000
Author(s): Lyons, Timothy W.; Murray, Richard W.; Pearson, D. Graham
Author Affiliation(s): Primary:
University of Missouri at Columbia, Department of Geological Sciences, Columbia, MO, United States
Other:
University of Rhode Island, United States
Ocean Drilling Program, United States
University of Puerto Rico, Puerto Rico
University of North Carolina at Chapel Hill, United States
Paleontological Research Institution, United States
Université de Lyon I, France
Rice University, United States
Université Pierre et Marie Curie, France
INGEOMINAS, Colombia
GEOMAR, Federal Republic of Germany
Teikoku Oil Company, Japan
Danmarks Tekniske Universitet, Denmark
Institut Mediterranéen de Technologie, France
University of Missouri, United States
Boston University, United States
Swiss Federal Institute of Technology, Switzerland
Lamont-Doherty Earth Observatory, United States
University of Southampton, United Kingdom
Durham University, United Kingdom
Rosenstiel School of Marine and Atmospheric Science, United States
Bremen University, Federal Republic of Germany
Volume Title: Proceedings of the Ocean Drilling Program, scientific results, Caribbean Ocean history and the Cretaceous/Tertiary boundary event; covering Leg 165 of the cruises of the drilling vessel JOIDES Resolution, Miami, Florida, to San Juan Puerto Rico, sites 998-1002, 19 December 1995-17 February 1996
Volume Author(s): Leckie, R. Mark; Sigurdsson, Haraldur; Acton, Gary D.; Abrams, Lewis J.; Bralower, Timothy J.; Carey, Steven N.; Chaisson, William P.; Cotillon, Pierre; Cunningham, Andrew D.; D'Hondt, Steven L.; Droxler, André W.; Galbrun, Bruno; Gonzalez, Juan; Haug, Gerald H.; Kameo, Koji; King, John W.; Lind, Ida L.; Louvel, Véronique; Lyons, Timothy W.; Murray, Richard W.; Mutti, Maria; Myers, Greg; Pearce, Richard B.; Pearson, D. Graham; Peterson, Larry C.; Röhl, Ursula; Garman, Phyllis
Source: Proceedings of the Ocean Drilling Program, scientific results, Caribbean Ocean history and the Cretaceous/Tertiary boundary event; covering Leg 165 of the cruises of the drilling vessel JOIDES Resolution, Miami, Florida, to San Juan Puerto Rico, sites 998-1002, 19 December 1995-17 February 1996, R. Mark Leckie, Haraldur Sigurdsson, Gary D. Acton, Lewis J. Abrams, Timothy J. Bralower, Steven N. Carey, William P. Chaisson, Pierre Cotillon, Andrew D. Cunningham, Steven L. D'Hondt, André W. Droxler, Bruno Galbrun, Juan Gonzalez, Gerald H. Haug, Koji Kameo, John W. King, Ida L. Lind, Véronique Louvel, Timothy W. Lyons, Richard W. Murray, Maria Mutti, Greg Myers, Richard B. Pearce, D. Graham Pearson, Larry C. Peterson, Ursula Röhl and Phyllis Garman. Proceedings of the Ocean Drilling Program, Scientific Results, Vol.165, p.287-298. Publisher: Texas A & M University, Ocean Drilling Program, College Station, TX, United States. ISSN: 0884-5891
Note: In English. 50 refs.CD-ROM format, ISSN 1096-2514; WWW format, ISSN 1096-7451; all chapters are also available on the included CD-ROM and on the Web in PDF format; illus., incl. 3 tables, sketch map
Summary: Leg 165 of the Ocean Drilling Program afforded a unique opportunity to investigate organic and inorganic geochemistry across a wide gradient of sediment compositions and corresponding chemical pathways. The solid fractions at Sites 998, 999, 1000, and 1001 reveal varying proportions of reactive carbonate species, a labile volcanic ash fraction occurring in discrete layers and as a dispersed component, and detrital fluxes that derive from continental weathering. The relative proportions and reactivities of these end-members strongly dictate the character of the diagenetic profiles observed during the pore-water work of Leg 165. In addition, alteration of the well-characterized basaltic basement at Site 1001 has provided a strong signal that is reflected in many of the dissolved components. The relative effects of basement alteration and diagenesis within the sediment column are discussed in terms of downcore relationships for dissolved calcium and magnesium. With the exception of Site 1002 in the Cariaco Basin, the sediments encountered during Leg 165 were uniformly deficient in organic carbon (typically <0.1 wt%). Consequently, rates of organic oxidation were generally low and dominated by suboxic pathways with subordinate levels of bacterial sulfate reduction and methanogenesis. The low rates of organic remineralization are supported by modeled rates of sulfate reduction. Site 1000 provided an exception to the generally low levels of microbially mediated redox cycling. At this site the sediment is slightly more enriched in organic phases, and externally derived thermogenic hydrocarbons appear to aid in driving enhanced levels of redox diagenesis at great depths below the seafloor. The entrapment of these volatiles corresponds with a permeability seal defined by a pronounced Miocene minimum in calcium carbonate concentration recognized throughout the basin and with a dramatic downcore increase in the magnitude of limestone lithification. The latter has been tentatively linked to increases in alkalinity associated with microbial oxidation of organic matter and gaseous hydrocarbons. Recognition and quantification of previously unconstrained large volumes and frequencies of Eocene and Miocene silicic volcanic ash within the Caribbean Basin is one of the major findings of Leg 165. High frequencies of volcanic ash layers manifest as varied but often dominant controls on pore-water chemistry. Sulfur isotope results are presented that speak to secondary metal and sulfur enrichments observed in ash layers sampled during Leg 165. Ultimately, a better mechanistic understanding of these processes and the extent to which they have varied spatially and temporally may bear on the global mass balances for a range of major and minor dissolved components of seawater.
Year of Publication: 2000
Research Program: ODP Ocean Drilling Program
Key Words: 02 Geochemistry; 07 Marine Geology and Oceanography; Alkaline earth metals; Atlantic Ocean; Basalts; Biogenic processes; Calcium; Caribbean Sea; Cenozoic; Chemical reactions; Concentration; Cores; Diagenesis; Eh; Eocene; Geochemistry; Halmyrolysis; Igneous rocks; Leg 165; Magnesium; Marine sediments; Metals; Mineralization; Miocene; Neogene; North Atlantic; Ocean Drilling Program; Oxidation; Paleogene; Pore water; Sediments; Tertiary; Volcanic ash; Volcanic rocks; Volcaniclastics; Water-rock interaction
Coordinates: N103000 N193000 W0650000 W0830000
Record ID: 2000062897
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