56
views
0
recommends
+1 Recommend
1 collections
    0
    shares
      • Record: found
      • Abstract: found
      • Article: found
      Is Open Access

      Expedition 371 summary

      Read this article at

      ScienceOpenPublisher
      Bookmark
          There is no author summary for this article yet. Authors can add summaries to their articles on ScienceOpen to make them more accessible to a non-specialist audience.

          Abstract

          International Ocean Discovery Program (IODP) Expedition 371 drilled six sites (U1506–U1511) in the Tasman Sea, southwest Pacific, between 27 July and 26 September 2017. The primary goal was to understand Tonga-Kermadec subduction initiation through recovery of Paleogene sediment records. Secondary goals were to understand regional oceanography and climate through intervals of the Cenozoic, especially the Eocene. We recovered 2506 m of cored sediment and volcanic rock in 36.4 days of on-site drilling over a total expedition length of 58 days. The ages of strata at the base of each site were middle Eocene to Late Cretaceous. The cored intervals at five sites (U1506–U1510) sampled mostly nannofossil and foraminiferal ooze or chalk that contained volcanic or volcaniclastic intervals with variable clay content. Paleocene and Cretaceous sections at Site U1509 also contain calcareous clay and claystone. At Site U1511, a sequence of abyssal clay and diatomite was recovered with only minor amounts of carbonate. Wireline logs were collected at Sites U1507 and U1508. Our results provide the first firm basis for correlating lithostratigraphic units across a substantial part of northern Zealandia, including ties to onshore geology in New Caledonia and New Zealand. All six sites provide new stratigraphic and paleogeographic information that can be put into context through regional seismic stratigraphic interpretation and hence provide constraints on geodynamic models of subduction zone initiation. Evidence from Site U1507 suggests the northern New Caledonia Trough formed during an early stage of Paleogene tectonic change (before 44 Ma). Paleowater depth estimates from Site U1509 indicate that the Cretaceous Fairway-Aotea-Taranaki Basin dramatically deepened (~2000 m) at a similar time. Northern Lord Howe Rise at Site U1506 rose to sea level at ~50 Ma and subsided back to bathyal depths (600–1000 m) by 45 Ma. In contrast, southern Lord Howe Rise, at least near Site U1510, experienced its peak of transient uplift at ~40–30 Ma. A pulse of convergent plate failure took place across the southern part of the region (Sites U1508–U1511) between 45 and 35 Ma. Uplift of Lord Howe Rise was associated with intraplate volcanism, whereas volcanic activity on Norfolk Ridge near Site U1507 started at ~38 Ma and may relate to subduction. Shipboard observations made using cores and logs represent a substantial gain in fundamental knowledge about northern Zealandia. Prior to Expedition 371, only Deep Sea Drilling Project Sites 206, 207, and 208 had penetrated beneath upper Eocene strata in the region. Our samples and results provide valuable new constraints on geodynamic models of subduction initiation because they reveal the timing of plate deformation, the magnitude and timing of vertical motions, and the timing and type of volcanism. Secondary drilling objectives focused on paleoclimate topics were not fully completed, but significant new records were obtained that should contain information on Cenozoic oceanography and climate in the southwest Pacific.

          Related collections

          Most cited references153

          • Record: found
          • Abstract: not found
          • Article: not found

          Global continental and ocean basin reconstructions since 200Ma

            Bookmark
            • Record: found
            • Abstract: found
            • Article: not found

            Rapid acidification of the ocean during the Paleocene-Eocene thermal maximum.

            The Paleocene-Eocene thermal maximum (PETM) has been attributed to the rapid release of approximately 2000 x 10(9) metric tons of carbon in the form of methane. In theory, oxidation and ocean absorption of this carbon should have lowered deep-sea pH, thereby triggering a rapid ( 100,000 years). These findings indicate that a large mass of carbon (>2000 x 10(9) metric tons of carbon) dissolved in the ocean at the Paleocene-Eocene boundary and that permanent sequestration of this carbon occurred through silicate weathering feedback.
              Bookmark
              • Record: found
              • Abstract: found
              • Article: not found

              Rapid Cenozoic glaciation of Antarctica induced by declining atmospheric CO2.

              The sudden, widespread glaciation of Antarctica and the associated shift towards colder temperatures at the Eocene/Oligocene boundary (approximately 34 million years ago) (refs 1-4) is one of the most fundamental reorganizations of global climate known in the geologic record. The glaciation of Antarctica has hitherto been thought to result from the tectonic opening of Southern Ocean gateways, which enabled the formation of the Antarctic Circumpolar Current and the subsequent thermal isolation of the Antarctic continent. Here we simulate the glacial inception and early growth of the East Antarctic Ice Sheet using a general circulation model with coupled components for atmosphere, ocean, ice sheet and sediment, and which incorporates palaeogeography, greenhouse gas, changing orbital parameters, and varying ocean heat transport. In our model, declining Cenozoic CO2 first leads to the formation of small, highly dynamic ice caps on high Antarctic plateaux. At a later time, a CO2 threshold is crossed, initiating ice-sheet height/mass-balance feedbacks that cause the ice caps to expand rapidly with large orbital variations, eventually coalescing into a continental-scale East Antarctic Ice Sheet. According to our simulation the opening of Southern Ocean gateways plays a secondary role in this transition, relative to CO2 concentration.
                Bookmark

                Author and article information

                Journal
                10.14379/iodp.proc.371.2019
                Proceedings of the International Ocean Discovery Program
                International Ocean Discovery Program
                2377-3189
                2 February 2019
                Article
                10.14379/iodp.proc.371.101.2019
                69f6c51c-e87a-422b-a4f7-5ea2db8bd66b

                This work is licensed under a Creative Commons Attribution 4.0 Unported License. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/

                History

                Earth & Environmental sciences,Oceanography & Hydrology,Geophysics,Chemistry,Geosciences

                Comments

                Comment on this article