Isotope ratios of osmiun, carbon and oxygen of Miocene sediments and benthic foraminifera ...

• Main Authors: Reusch, Douglas N, Ravizza, Gregory E, Maasch, Kirk A, Wright, James D
• Format: Article in Journal/Newspaper
• Language: English
• Published: PANGAEA 1998
• Subjects: Drilling/drill rig; Leg73; Leg92; Glomar Challenger; Deep Sea Drilling Project DSDP; Pacific; Ice Sheet
• Online Access: https://dx.doi.org/10.1594/pangaea.711533; https://doi.pangaea.de/10.1594/PANGAEA.711533

Seawater 187Os/188Os ratios for the Middle Miocene were reconstructed by measuring the 187Os/188Os ratios of metalliferous carbonates from the Pacific (DSDP 598) and Atlantic (DSDP 521) oceans. Atlantic and Pacific 187Os/188Os measurements are nearly indistinguishable and are consistent with previously published Os isotope records from Pacific cores. The Atlantic data reported here provide the first direct evidence that the long-term sedimentary 187Os/188Os record reflects whole-ocean changes in the Os isotopic composition of seawater. The Pacific and the Atlantic Os measurements confirm a long-term 0.01/Myr increase in marine 187Os/188Os ratios that began no later than 16 Ma. The beginning of the Os isotopic increase coincided with a decrease in the rate of increase of marine 87Sr/86Sr ratios at 16 Ma. A large increase of 1 per mil in benthic foraminiferal delta18O values, interpreted to reflect global cooling and ice sheet growth, began approximately 1 million years later at 14.8 Ma, and the long-term ... : Supplement to: Reusch, Douglas N; Ravizza, Gregory E; Maasch, Kirk A; Wright, James D (1998): Miocene seawater 187Os/188Os ratios inferred from metalliferous carbonates. Earth and Planetary Science Letters, 160(1-2), 163-178 ...