Os and Re concentrations and Os isotope ratios for DSDP and ODP metalliferous sediments from the Pacific Ocean (Table 1)

• Main Authors: Peucker-Ehrenbrink, Bernhard, Ravizza, Gregory E, Hofmann, Albrecht W
• Format: Dataset
• Language: English
• Published: PANGAEA 1995
• Subjects: 129-801A; 16-162; 20-196; 34-319; 35-323; 5-39; 8-74; 91-596; 92-597; 9-77B; AGE; Antarctic Ocean/PLAIN; Calculated; Deep Sea Drilling Project; DRILL; Drilling/drill rig; DSDP; DSDP/ODP/IODP sample designation; Elevation of event; Event label; Glomar Challenger; Inductively coupled plasma - mass spectrometry (ICP-MS); Joides Resolution; Latitude of event; Leg129; Leg16; Leg20; Leg34; Leg35; Leg5; Leg8; Leg9; Leg91; Leg92; Longitude of event; North Pacific/ABYSSAL FLOOR; North Pacific/CONT RISE; North Pacific/HILL; North Pacific Ocean; Ocean Drilling Program; ODP; Osmium; Osmium-187/Osmium-186; error; Osmium-187/Osmium-186 ratio; Osmium-187/Osmium-188; Osmium-187/Osmium-188 ratio; Rhenium; Rhenium-187/Osmium-186 ratio; Antarc*; Antarctic; Antarctic Ocean
• Online Access: https://doi.pangaea.de/10.1594/PANGAEA.712118; https://doi.org/10.1594/PANGAEA.712118

We report new 187Os/186Os data and Re and Os concentrations in metalliferous sediments from the Pacific to construct a composite Os isotope seawater evolution curve over the past 80 m.y. Analyses of four samples of upper Cretaceous age yield 187Os/186Os values of between 3 and 6.5 and 187Re/186Os values below 55. Mass balance calculations indicate that the pronounced minimum of about 2 in the Os isotope ratio of seawater at the K-T boundary probably reflects the enormous input of cosmogenic material into the oceans by the K-T impactor(s). Following a rapid recovery to 187Os/186Os of 3.5 at 63 Ma, data for the early and middle part of the Cenozoic show an increase in 187Os/186Os to about 6 at 15 Ma. Variations in the isotopic composition of leachable Os from slowly accumulating metalliferous sediments show large fluctuations over short time spans. In contrast, analyses of rapidly accumulating metalliferous carbonates do not exhibit the large oscillations observed in the pelagic clay leach data. These results together with sediment leaching experiments indicate that dissolution of non-hydrogenous Os can occur during the hydrogen peroxide leach and demonstrate that Os data from pelagic clay leachates do not always reflect the Os isotopic composition of seawater. New data for the late Cenozoic further substantiate the rapid increase in the 187Os/186Os of seawater during the past 15 Ma. We interpret the correlation between the marine Sr and Os isotope records during this time period as evidence that weathering within the drainage basin of the Ganges-Brahmaputra river system is responsible for driving seawater Sr and Os toward more radiogenic isotopic compositions. The positive correlation between 87Sr/86Sr and U concentration, the covariation of U and Re concentrations, and the high dissolved Re, U and Sr concentrations found in the Ganges-Brahmaputra river waters supports this interpretation. Accelerating uplift of many orogens worldwide over the past 15 Ma, especially during the last 5 Ma, could have contributed to ...