The former Piemont–Liguria Ocean, which separated Europe from Africa–Adria in the Jurassic, opened as an arm of the central Atlantic. Using plate reconstructions and geodynamic modeling, we show that the ocean reached only 250 km width between Europe and Adria. Moreover, at least 65 % of the lithosphere subducted into the mantle and/or incorporated into the Alps during convergence in Cretaceous and Cenozoic times comprised highly thinned continental crust, while only 35 % was truly oceanic.
Helen Eri Amsler, Lena Mareike Thöle, Ingrid Stimac, Walter Geibert, Minoru Ikehara, Gerhard Kuhn, Oliver Esper, and Samuel Laurent Jaccard
Clim. Past Discuss., https://doi.org/10.5194/cp-2021-29,https://doi.org/10.5194/cp-2021-29, 2021
Preprint under review for CP
We present sedimentary redox-sensitive trace metal records from five sediment cores retrieved from the SW Indian Ocean. These records are indicative of oxygen-depleted conditions during cold periods and enhanced oxygenation during interstadials. Our results thus suggest that deep ocean oxygenation changes were mainly controlled by ocean ventilation and that a generally more sluggish circulation contributed to sequester remineralized carbon away from the atmosphere during glacial periods.
A record of past sea temperature in the Indian sector of the Southern Ocean, spanning the last 14 200 years, has been developed by analysis of fossil diatoms in marine sediment. During the late deglaciation the reconstructed temperature changes were highly similar to those over Antarctica, most likely due to a reorganisation of global ocean and atmospheric circulation. During the last 11 600 years temperatures gradually cooled and became increasingly variable.
Robert McKay, Neville Exon, Dietmar Müller, Karsten Gohl, Michael Gurnis, Amelia Shevenell, Stuart Henrys, Fumio Inagaki, Dhananjai Pandey, Jessica Whiteside, Tina van de Flierdt, Tim Naish, Verena Heuer, Yuki Morono, Millard Coffin, Marguerite Godard, Laura Wallace, Shuichi Kodaira, Peter Bijl, Julien Collot, Gerald Dickens, Brandon Dugan, Ann G. Dunlea, Ron Hackney, Minoru Ikehara, Martin Jutzeler, Lisa McNeill, Sushant Naik, Taryn Noble, Bradley Opdyke, Ingo Pecher, Lowell Stott, Gabriele Uenzelmann-Neben, Yatheesh Vadakkeykath, and Ulrich G. Wortmann
Ariadna Salabarnada, Carlota Escutia, Ursula Röhl, C. Hans Nelson, Robert McKay, Francisco J. Jiménez-Espejo, Peter K. Bijl, Julian D. Hartman, Stephanie L. Strother, Ulrich Salzmann, Dimitris Evangelinos, Adrián López-Quirós, José Abel Flores, Francesca Sangiorgi, Minoru Ikehara, and Henk Brinkhuis
Here we reconstruct ice sheet and paleoceanographic configurations in the East Antarctic Wilkes Land margin based on a multi-proxy study conducted in late Oligocene (26–25 Ma) sediments from IODP Site U1356. The new obliquity-forced glacial–interglacial sedimentary model shows that, under the high CO2 values of the late Oligocene, ice sheets had mostly retreated to their terrestrial margins and the ocean was very dynamic with shifting positions of the polar fronts and associated water masses.
Subduction zones intersecting buried carbonate platforms liberate significant atmospheric CO2 and have the potential to influence global climate. We model the spatio-temporal distribution of carbonate platform accumulation within a plate tectonic framework and use wavelet analysis to analyse linked behaviour between atmospheric CO2 and carbonate-intersecting subduction zone (CISZ) lengths since the Devonian. We find that increasing CISZ lengths likely contributed to a warmer Palaeogene climate.
We summarize the findings of the IODP Workshop Tracking the Tsunamigenic slips Across and Along the Japan Trench (JTRACK) held in Tokyo, May 2014. The workshop recommended a program of drilling to investigate the physical and chemical controls on coseismic slip in the 2011 Tohoku-oki earthquake and to develop new methods for determining the recurrence interval of tsunamigenic earthquakes in the sediment record. One full- and one pre-proposal with these goals were recently submitted to IODP.
The IODP scientific ocean drilling program drilled into the sediments of the Bengal–Nicobar submarine fan system west of Sumatra, Indonesia. Within the cores, a large piece of fossilized wood was discovered, 9 million years in age and buried beneath 800 m of sediment; it is thought to be the largest wood fragment found in scientific ocean drilling boreholes. The wood is believed to be a species of flowering plant and may have originated from the north, east, or even as a result of a tsunami.
The Toarcian Oceanic Anoxic Event (T-OAE) was cored at Colle di Sogno and Gajum in the Lombardy Basin (northern Italy), where pelagic successions guarantee a continuous record of this paleoenvironmental perturbation. The Sogno and Gajum cores recovered high-quality sediments deposited prior to, during, and after the T-OAE. Ongoing research is devoted to reconstructing the marine ecosystem dynamics and resilience under short- and long-term perturbations analogous to current global changes.
This brief paper reports on a workshop held last September in Shanghai to promote global monsoon research in the paleoclimate community. In the framework of the international ocean drilling program, seven expeditions have been completed within the last years to recover long-term records of the global monsoon, and forty-eight scientists from 12 countries exchanged scientific findings based on the expeditions. The workshop came up with four recommendations for the future ocean drillings.