Variations of the 187Os/186Os ratio of seawater over the past 28 million years as inferred from metalliferous carbonates

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doi: 10.1016/0012-821X(93)90177-B
Author(s): Ravizza, G.
Author Affiliation(s): Primary:
Woods Hole Oceanographic Institution, Woods Hole, MA 02543, United States
Volume Title: Earth and Planetary Science Letters
Source: Earth and Planetary Science Letters, 118(1-4), p.335-348. Publisher: Elsevier, Amsterdam, Netherlands. ISSN: 0012-821X CODEN: EPSLA2
Note: In English. Woods Hole Oceanographic Institution (WHOI) Contrib. No. 8349. 58 refs.; illus. incl. 2 tables
Summary: The Os concentration and isotopic composition of metalliferous carbonates deposited on the East Pacific Rise over the past 28 Ma are reported with complimentary Sr isotope data. Variations in the Os isotopic composition of these samples are interpreted as a record of past changes in the Os isotopic composition of seawater. These results are consistent with isotopic analyses of leachable Os in pelagic clays which have also been interpreted as a record of the 187Os/186Os ratio of seawater through time [1]. The metalliferous carbonate record clearly shows that seawater Os and Sr isotope systems are partially decoupled from one another over the past 28 Ma. Accelerated weathering of ancient organic-rich sediments is suggested as a possible mechanism to account for this decoupling and the rapid increase in the 187Os/186Os ratio of seawater over the past 15 Ma. This rapid increase suggests that the seawater Os record can potentially be used as a stratigraphic tool in some Neogene marine deposits.
Year of Publication: 1993
Research Program: DSDP Deep Sea Drilling Project
IPOD International Phase of Ocean Drilling
Key Words: 02 Geochemistry; 12 Stratigraphy, Historical Geology and Paleoecology; Algae; Alkaline earth metals; Biogenic processes; Biostratigraphy; Calcium carbonate; Carbonate sediments; Cenozoic; DSDP Site 597; DSDP Site 598; DSDP Site 599; DSDP Site 600; DSDP Site 601; Deep Sea Drilling Project; Diagenesis; East Pacific; East Pacific Rise; Geochemistry; IPOD; Iron oxides; Isotope ratios; Isotopes; Leg 92; Magnesium oxides; Metals; Microfossils; Nannofossils; Neogene; Os-187/Os-186; Osmium; Oxides; Pacific Ocean; Paleo-oceanography; Plantae; Platinum group; Quaternary; Radioactive isotopes; Sediments; Sr-87/Sr-86; Stable isotopes; Strontium; Tertiary; Thallophytes
Coordinates: S184823 S184822 W1294613 W1294614
S190017 S190016 W1244036 W1244037
S192706 S192705 W1195252 W1195253
S185545 S185544 W1165022 W1165023
S185514 S185513 W1165206 W1165207
Record ID: 1993033510
Copyright Information: GeoRef, Copyright 2017 American Geosciences Institute. Reference includes data from CAPCAS, Elsevier Scientific Publishers, Amsterdam, Netherlands