Indian Ocean

IO:DIP
Indian Ocean: Delving Into the Past  

Aim and Scope of the Workshop

The proposed MagellanPlus workshop IO:DIP "Indian Ocean: Delving Into the Past" intends to gather resources and ideas to identify critical knowledge gaps and discuss the next phase of Indian Ocean scientific drilling. IO:DIP will achieve this by bringing together the "next generation" of Indian Ocean researchers with experienced IODP veterans. With this in mind, we designed IO:DIP as a forum to discuss and push the current state-of-the-art knowledge of Indian Ocean research based on data obtained from DSDP, ODP, and IODP cruises in the region over the last 52 years of ocean drilling.

Our workshop will build on the outcome of several recent Indian Ocean workshops (e.g., the 2020 Chapman Conference "On the Evolution of the Monsoon, Biosphere and Mountain Building in Cenozoic Asia"; the 2018 SPADE Workshop in Goa; the 2017 workshop "Land-Ocean Interactions Across the Indian Ocean: Toward Regional Integration of Recent Drilling Results" in Rhode Island; and the 2017 "Australasian IODP Regional Planning Workshop" in Sydney). Together with results from past IODP Expeditions in the region (EXPs 353 – 356, 359, 360 – 363, 369, and 371), these workshops have highlighted how little we know about the interior of the Indian Ocean basin, its link to the continental systems as well as the long term evolution of intermediate- and deep-water circulation. These currently unresolved factors are directly linked to how Indian Ocean water masses interrelate with the Asian Monsoon system, global climatic and tectonic changes, and thus, fundamentally, with the Indian Oceans connectivity to other basins through the global ocean circulation and the "super gyre" concept (Ridgway and Dunn, 2007; Geophys. Res. Lett., 34), or the contribution and role in AAIW on marine nutrient cycling (Laufkötter and Gruber, 2018; Science, 356). Answering these questions – which are at the core of the new IODP science plan – conclusively, however, is beyond the scope of stand-alone IODP expeditions as it requires a multi-expedition effort that runs complementary to individual expedition goals. IO:DIP will thus be a community-driven initiative to tackle open questions underpinning the Indian Ocean ocean-atmospheric circulation system's history.

Participants will define research questions in the Indian Ocean that contribute to the new IODP science plan's strategic objectives and discuss integrating existing proposal goals by defining research strategies. These strategies provide the basis to elucidate the relationship between climatically (Di Nezio et al., 2018; Sci. Adv., 12; Bialik et al., 2020; Paleoceanogr. Paleoclimatol., 35) and tectonically driven changes (Christensen et al., 2017; Geophys. Res. Lett., 44) in Indian Ocean circulation and on the influence, they have on the marine nutrient cycle (Laufkötter and Gruber, 2018), but also the history of the Indian Ocean oxygen minimum zone (Betzler et al., 2016; Sci. Adv., 6). The strategies defined in IO:DIP will thus link future IODP flagship initiatives 1 (Ground Truthing Future Climate Change) and 4 (Diagnosing Ocean Health). To achieve these goals IO:DIP will build upon recent data and model-driven studies (see above) and the framework of submitted pre-proposals to strategically tackle areas of interest in the Indian Ocean and integrate these with proposals in preparation.

Atmospheric and oceanographic currents
From Bialik et al. (2020) (https://doi.org/10.1029/2019PA003762): map of the Indian Ocean showing the prevailing atmospheric wind (Gadgil et al., 2018; Xue et al., 2004) and oceanographic current (Schott et al., 2009) conditions during Northern Hemisphere summer (JJA). Note the southwesterly Somali/Findlater jet (FJ) along the Horn of Africa. Major Indian Ocean surface currents shown are Indonesian Throughflow (ITF), Leeuwin Current (LC), South Equatorial Current (SEC), East Gyral Current (EGC), Equatorial Counter Current (ECC), South Java Current (SJC), Agulhas Current (AC), Mozambique Current (MC), Northeast and Southeast Madagascar Current (NEMC and SEMC), Southwest Monsoon Current (SMC), Southern Gyre (SG), and Great Whirl (GW) and associated upwelling wedges (green). The present‐day oxygen minimum zone in the northern Indian ocean is indicated as purple shaded area denoting oxygen concentrations <20 μmol/kg in 200‐m water depth (Garcia et al., 2018; McCreary et al., 2013). Cover image of Paleoceanography and Paleoclimatology Volume 35, Issue 2 (February 2020).

Working hypotheses:

The Indian Ocean has a paucity of high-resolution marine data, hampering our understanding of several critical aspects of the Indian Ocean circulation system, even though it represents an integral part of the global thermohaline circulation. Furthermore, there is no high-resolution data on how the closure and opening of critical oceanic gateways may have affected oceanic and atmospheric (i.e., Monsoonal) circulation patterns. The paucity of Data in the Indian Ocean thus leaves several key questions about the Indian Ocean as of yet unanswered.  

  1. How did changing gateway connectivity affect biogeographic (and thus stratigraphic) distribution patterns of planktonic organisms in the past? Is there a link between these tectonic events and large-scale evolutionary and faunal exchange patterns?
  2. Closing (equatorial) oceanic gateways lead to significant climate-tectonic interactions that substantially impacted ocean circulation. Indeed, recent modeling studies show that the shoaling of ocean passages may have played a key role in developing the unique ocean-atmospheric circulation pattern that prevails in the Indian Ocean and fuels the Indian and Southeast Asian Monsoon.
  3. Ocean-atmospheric interactions: It is well known that monsoons, upwelling, and the expansion of the oxygen minimum zones are tightly linked phenomena. However, there is still a paucity of data detailing how these systems interacted with past climate change. Understanding how these significant wind-driven upwelling cells interact with the global climate and nutrient cycles may be crucial in predicting future climate patterns.
  4. The southern high latitude climate and its effect on deep and intermediate water circulation are still poorly constrained in the Indian Ocean. State of the art high-resolution drill cores in the southern mid-latitudes are thus necessary to trace intermediate water masses from the northern branch of the Antarctic divergence.
  5. How does the unique seafloor topography of the Indian Ocean affect deep-water circulation and exchange between the Atlantic and the Pacific Ocean?
  6. There is, as of yet, no long-term data that could elucidate the temporal evolution and climatic impact of the global "southern hemisphere super gyre".
  7. We still lack sufficient data to fully establish the causes and effects of the "carbonate crash" in the Indian Ocean. In particular, the depth extent and variability through time (= 4D evolution) are poorly constrained in the region. Constraining such boundary conditions will be essential to establish a link to changes in global thermohaline circulation and the "biogenic bloom".

Predicted Outcomes

IO:DIP aims to define a set of community goals and directions that advance our understanding of the Indian Ocean's role in the global ocean and atmospheric circulation system and as an integral "switchboard" in the late Mesozoic (Cretaceous) to Cenozoic evolution of the earth's climate. These goals will be achieved by the definition of overarching community-driven research goals for the Indian Ocean region. These research goals will directly link to the new IODP Science Plan and serve as a guideline to strategically strengthen forthcoming Indian Ocean drilling proposals. The workshop thus expressly aims to:

  1. Advance existing Indian Ocean preproposals and proposal ideas by firmly anchoring them within the new IODP Science Plan and community-driven research question in the region.
  2. Develop research questions that benefit from latitudinal and depth transects in the Indian Ocean.
  3. Gather interested ECSs and involve this "next generation" in IODP and proposal development.

Targeted Audience

The workshop Indian Ocean: Delving Into the Past aims to bring together experienced researchers with Early Career Scientists (ECS) in order to generate networks and teams capable of shaping the future of ship-based Indian Ocean drilling within ECORD member countries, with a focus on Cenozoic to late Mesozoic Indian Ocean paleoceanography, paleoclimatology, sedimentology, stratigraphy. In particular, we hope to gather contributions/ideas as scientific posters to stimulate discussion during IO:DIP. The posters, detailing past achievements and fresh ideas for future Indian Ocean drilling and research, will be displayed for the workshop's duration.

Authors

Gerald Auer1, Sietske J. Batenburg2, David De Vleeschouwer3, Anna Joy Drury4, Beth A. Christensen5

  1. University of Graz, Institute of Earth Sciences (Geology and Paleontology), NAWI Graz Geocenter, Graz, Austria
  2. Géosciences Rennes, UMR 6118, Université de Rennes 1, 35042 Rennes, France
  3. MARUM–Center for Marine and Environmental Sciences, University of Bremen, Bremen, Germany
  4. Department of Earth Science, University College London, London, UK
  5. Department of Environmental Science, Rowan University, Glassboro, NJ, USA  

 

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