skip to main content

Explore Research Products in the NSF-PAR

Title: Expedition 388 Scientific Prospectus: Equatorial Atlantic Gateway
International Ocean Discovery Program (IODP) Expedition 388 seeks to answer first-order questions about the tectonic, climatic, and biotic evolution of the Equatorial Atlantic Gateway (EAG). The scheduled drilling operations will target sequences of Late Cretaceous and Cenozoic sediments offshore northeast Brazil, just south of the theorized final opening point of the EAG. These sequences are accessible to conventional riserless drilling in the vicinity of the Pernambuco Plateau, part of the northeastern Brazilian continental shelf. This region was chosen to satisfy two key constraints: first, that some of the oldest oceanic crust of the equatorial Atlantic and overlying early postrift sediments are present at depths shallow enough to be recovered by riserless drilling, and second, Late Cretaceous and Paleogene sediments preserved on the Pernambuco Plateau are close enough to the continental margin and at shallow enough paleowater depths (<2000 m) to provide well-preserved organic biomarkers and calcareous microfossils for multiproxy studies of greenhouse climate states. New records in this region will allow us to address major questions in four key objectives: the early rift history of the equatorial Atlantic, the biogeochemistry of the restricted equatorial Atlantic, the long-term paleoceanography of the EAG, and the limits of tropical climates and ecosystems under conditions of extreme warmth. Tackling these major questions with new drilling in the EAG region will advance our understanding of the long-term interactions between tectonics, oceanography, ocean biogeochemistry, and climate and the functioning of tropical ecosystems and climate during intervals of extreme warmth.  more » « less
Award ID(s):
1326927
NSF-PAR ID:
10229909
Author(s) / Creator(s):
; ;
Date Published:
Journal Name:
Scientific prospectus
Volume:
388
ISSN:
2332-1385
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
More Like this
  1. ; ; ( , Proceedings of the International Ocean Discovery Program)
    null (Ed.)
    The tectonic and paleoceanographic setting of the Great Australian Bight (GAB) and the Mentelle Basin (adjacent to Naturaliste Plateau) offered an opportunity to investigate Cretaceous and Cenozoic climate change and ocean dynamics during the last phase of breakup among remnant Gondwana continents. Sediment recovered from sites in both regions during International Ocean Discovery Program Expedition 369 will provide a new perspective on Earth’s temperature variation at subpolar latitudes (60°–62°S) across the extremes of the mid-Cretaceous hot greenhouse climate and the cooling that followed. Basalts and prebreakup sediments were also recovered and will provide constraints regarding the type and age of the Mentelle Basin basement and processes operating during the break up of Gondwana. The primary goals of the expedition were to 1. Investigate the timing and causes for the rise and collapse of the Cretaceous hot greenhouse climate and how this climate mode affected the climate–ocean system and oceanic biota; 2. Determine the relative roles of productivity, ocean temperature, and ocean circulation at high southern latitudes during Cretaceous oceanic anoxic events (OAEs); 3. Investigate potential source regions for deep-water and intermediate-water masses in the southeast Indian Ocean and how these changed during Gondwana breakup; 4. Characterize how oceanographic conditions at the Mentelle Basin changed during the Cenozoic opening of the Tasman Gateway and restriction of the Indonesian Gateway; and 5. Resolve questions on the volcanic and sedimentary origins of the Australo-Antarctic Gulf and Mentelle Basin and provide stratigraphic control on the age and nature of the prebreakup successions. Hole U1512A in the GAB recovered a 691 m thick sequence of black claystone ranging from the lower Turonian to the lower Campanian. Age control is primarily based on calcareous nannofossils, but the presence of other microfossil groups provided consistent low-resolution control. Despite the lithologic uniformity, long- and short-term variations in natural gamma radiation and magnetic susceptibility show cyclic alternations that suggest an orbital control of sediment deposition, which will be useful for developing an astrochronology for the sequence. Sites U1513, U1514, U1515, and U1516 were drilled in water depths between 850 and 3900 m in the Mentelle Basin and penetrated 774, 517, 517, and 542 meters below seafloor, respectively. Under a thin layer of Pleistocene to upper Miocene sediment, Site U1513 cored a succession of Cretaceous units from the Campanian to the Valanginian, as well as a succession of basalts. Site U1514 sampled an expanded Pleistocene to Eocene sequence and terminated in the upper Albian. The Cenomanian to Turonian interval at Site U1514 is represented by deformed sedimentary rocks that probably represent a detachment zone. Site U1515 is located on the west Australian margin at 850 m water depth and was the most challenging site to core because much of the upper 350 m was either chert or poorly consolidated sand. However, the prebreakup Jurassic(?) sediments interpreted from the seismic profiles were successfully recovered. Site U1516 cored an expanded Pleistocene, Neogene, and Paleogene section and recovered a complete Cenomanian/Turonian boundary interval containing five layers with high organic carbon content. Study of the well-preserved calcareous microfossil assemblages from different paleodepths will enable generation of paleotemperature and biotic records that span the rise and collapse of the Cretaceous hot greenhouse (including OAEs 1d and 2), providing insight to resultant changes in deep-water and surface water circulation that can be used to test predictions from earth system models. Measurements of paleotemperature proxies and other data will reveal the timing, magnitude, and duration of peak hothouse conditions and any cold snaps that could have allowed growth of a polar ice sheet. The sites contain a record of the mid-Eocene to early Oligocene opening of the Tasman Gateway and the Miocene to Pliocene restriction of the Indonesian Gateway; both passages have important effects on global oceanography and climate. Advancing understanding of the paleoceanographic changes in a regional context will provide a global test on models of Cenomanian to Turonian oceanographic and climatic evolution related both to extreme Turonian warmth and the evolution of OAE 2. The Early Cretaceous volcanic rocks and underlying Jurassic(?) sediments cored in different parts of the Mentelle Basin provide information on the timing of different stages of the Gondwana breakup. The recovered cores provide sufficient new age constraints to underpin a reevaluation of the basin-wide seismic stratigraphy and tectonic models for the region. 
    more » « less
  2. ; ; ; ( , Scientific prospectus)
    null (Ed.)
    International Ocean Discovery Program (IODP) Expedition 387 aims to recover sediments at two sites located in shallow water (~350 to 450 m) on the uppermost continental slope west of the Amazon Fan, northwest of the mouth of the Amazon River. These sediments were deposited in the upper part of the long-lived Foz do Amazonas Basin of the equatorial margin of Brazil. These two sites will recover a sedimentary sequence that spans much of the Cenozoic but with variable provenance and highly variable sedimentation rates. By virtue of their location, the Quaternary sediments will recover an abundance of terrigenous materials including pollen, organic matter, zircon grains, and clay minerals, allowing detailed reconstruction of the biodiversity, climate, and hydrology of the adjacent tropical South American continent. At the same time, an abundance of well-preserved marine microfossils and organic matter will allow accurate determination of the age and oceanographic conditions of the western equatorial Atlantic that partly forced the climate of the adjacent continent. However, our reconstructions of the spatial patterns of biodiversity and climate through time must be interpreted with the knowledge that the geometry of the watersheds that contributed water and sediment to the coastal Atlantic was itself rearranged through time. For example, a transcontinental proto-Amazon river did not likely reach the Atlantic until somewhere between 11 and 2 Ma, a date that we expect to more accurately determine from these new cores. Prior to that event, terrigenous sediments at our sites would have been derived from smaller coastal rivers draining watersheds limited to the eastern tropics of northeastern South America. The planned drill sites of Expedition 387 will be the marine complement to a transect of continental drill sites. Together, the marine and continental sites form the Trans-Amazon Drilling Project (TADP), a project that is partly funded by the International Continental Drilling Program (ICDP). The TADP addresses fundamental questions about the Cenozoic climatic evolution of the Amazon region, the origins and evolution of the neotropical rain forest and its biodiversity, and the origins and rearrangements of the transcontinental Amazon River. Together, we expect that these IODP and ICDP projects will transform our understanding of Amazonian geological, climatic, biological, and paleoceanographic history. 
    more » « less
  3. ; ; ( , Preliminary report)
    null (Ed.)
    The tectonic and paleoceanographic setting of the Great Australian Bight (GAB) and the Mentelle Basin (MB; adjacent to Naturaliste Plateau) offered an outstanding opportunity to investigate Cretaceous and Cenozoic climate change and ocean dynamics during the last phase of breakup among remnant Gondwana continents. Sediment recovered from sites in both regions during International Ocean Discovery Program Expedition 369 will provide a new perspective on Earth’s temperature variation at sub-polar latitudes (60°–62°S) across the extremes of the mid-Cretaceous hot greenhouse climate and the cooling that followed. The primary goals of the expedition were to • Investigate the timing and causes for the rise and collapse of the Cretaceous hot greenhouse climate and how this climate mode affected the climate-ocean system and oceanic biota; • Determine the relative roles of productivity, ocean temperature, and ocean circulation at high southern latitudes during Cretaceous oceanic anoxic events (OAEs); • Identify the main source regions for deep-water and intermediate-water masses in the southeast Indian Ocean and how these changed during Gondwana breakup; • Characterize how oceanographic conditions at the MB changed during the Cenozoic opening of the Tasman Passage and restriction of the Indonesian Gateway; • Resolve questions on the volcanic and sedimentary origins of the Australo-Antarctic Gulf and Mentelle Basin and provide stratigraphic control on the age and nature of the prebreakup successions. Hole U1512A in the GAB recovered a 691 m thick sequence of black claystone ranging from the early Turonian to the early Campanian. Age control is primarily based on calcareous nannofossils, but the presence of other microfossil groups provided consistent but low-resolution control. Despite the lithologic uniformity, long- and short-term variations in natural gamma ray and magnetic susceptibility intensities show cyclic alternations that suggest an orbital control of sediment deposition that will be useful for developing an astrochronology for the sequence. Sites U1513–U1516 were drilled between 850 and 3900 m water depth in the MB and penetrated 774, 517, 517, and 542 meters below seafloor (mbsf), respectively. Under a thin layer of Pleistocene–upper Miocene sediment, Site U1513 cored a succession of Cretaceous units from the Campanian to the Valanginian. Site U1514 sampled an expanded Pleistocene–Eocene sequence and terminated in the upper Albian. The Cenomanian–Turonian interval at Site U1514 recovered deformed sedimentary rocks that probably represent a detachment zone. Site U1515 is located on the west Australian margin at 850 m water depth and was the most challenging site to core because much of the upper 350 m was either chert or poorly consolidated sand. However, the prebreakup Jurassic(?) sediments interpreted from the seismic profiles were successfully recovered. Site U1516 cored an expanded Pleistocene, Neogene, and Paleogene section and recovered a complete Cenomanian/Turonian boundary interval containing five layers with high total organic carbon content. Recovery of well-preserved calcareous microfossil assemblages from different paleodepths will enable generation of paleotemperature and biotic records that span the rise and collapse of the Cretaceous hot greenhouse (including OAEs 1d and 2), providing insight to resultant changes in deep-water and surface water circulation that can be used to test predictions from earth system models. Paleotemperature proxies and other data will reveal the timing, magnitude, and duration of peak hothouse temperatures and any cold snaps that could have allowed growth of a polar ice sheet. The sites will also record the mid-Eocene–early Oligocene opening of the Tasman Gateway and the Miocene–Pliocene restriction of the Indonesian Gateway; both passages have important effects on global oceanography and climate. Understanding the paleoceanographic changes in a regional context provides a global test on models of Cenomanian–Turonian oceanographic and climatic evolution related both to extreme Turonian warmth and the evolution of OAE 2. The Early Cretaceous volcanic rocks and underlying Jurassic(?) sediments cored in different parts of the MB provide information on the timing of different stages of the Gondwana breakup. The recovered cores provide sufficient new age constraints to underpin a reevaluation of the basin-wide seismic stratigraphy and tectonic models for the region. 
    more » « less
  4. ; ; ( , Scientific prospectus)
    The Iberian margin is a well-known source of rapidly accumulating sediment that contains a high-fidelity record of millennial climate variability (MCV) for the late Pleistocene. The late Sir Nicholas (Nick) Shackleton demonstrated that piston cores from the region can be correlated precisely to polar ice cores in both hemispheres. Moreover, the narrow continental shelf off Portugal results in the rapid delivery of terrestrial material to the deep-sea environment, thereby permitting correlation of marine and ice core records to European terrestrial sequences. Few places exist in the world where such detailed marine-ice-terrestrial linkages are possible. The continuity, high sedimentation rates, and fidelity of climate signals preserved in Iberian margin sediments make this region a prime target for ocean drilling. During Integrated Ocean Drilling Program Expedition 339 (Mediterranean Outflow), one of the sites proposed here was drilled to a total depth of 155.9 meters below seafloor in multiple holes. At Site U1385 (the “Shackleton site”) a complete record of hemipelagic sedimentation was recovered for the last 1.45 My corresponding to Marine Isotope Stage 47 with sedimentation rates of 10–20 cm/ky. Preliminary results from Site U1385 demonstrate the great promise of the Iberian margin to yield long records of millennial-scale climate change and land–sea comparisons. International Ocean Discovery Program (IODP) Expedition 397 will extend this remarkable sediment archive through the Pliocene and expand the depth range of available sites by drilling additional sequences in water depths from 1304 to 4686 meters below sea level (mbsl). This depth transect is designed to complement those sites drilled during Expedition 339 (560–1073 mbsl) where sediment was recovered at intermediate water depth under the influence of Mediterranean Outflow Water (MOW). Together, the sites recovered during Expeditions 339 and 397 will constitute a complete depth transect with which to study past variability of all the major subsurface water masses of the eastern North Atlantic. Because most of the mass, thermal inertia, and carbon in the ocean-atmosphere system is contained in the deep ocean, well-placed depth transects in each of the major ocean basins are needed to understand the underlying mechanisms of glacial–interglacial cycles and MCV. We have identified four primary sites (SHACK-4C, SHACK-10B, SHACK-11B, and SHACK-14A) at which multiple holes will be drilled to ensure complete recovery of the stratigraphic sections at each site, ranging in age from the latest Miocene to Holocene. Building on the success of Site U1385 and given the seminal importance of the Iberian margin for paleoclimatology and marine-ice-terrestrial correlations, the cores recovered during Expedition 397 will provide present and future generations of paleoceanographers with the raw material needed to reconstruct the North Atlantic climate at high temporal resolution for the entire Quaternary and Pliocene. 
    more » « less
  5. ; ; ( , Scientific prospectus)
    null (Ed.)
    The unique tectonic and paleoceanographic setting of the Naturaliste Plateau (NP) and Mentelle Basin (MB) offers an outstanding opportunity to investigate a range of scientific issues of global importance with particular relevance to climate change. Previous spot-core drilling at Deep Sea Drilling Project Site 258 in the western MB demonstrates the presence of an expanded upper Albian–lower Campanian chalk, marl, and claystone sequence that is nearly complete stratigraphically and yields calcareous microfossils that are mostly well preserved. This sediment package and the underlying Albian volcanic claystone unit extend across most of the MB and are targeted at the primary sites, located between 850 and 3900 m water depth. Coring the Cretaceous MB sequence at different paleodepths will allow recovery of material suitable for generating paleotemperature and biotic records that span the rise and collapse of the Cretaceous hothouse (including oceanic anoxic Events [OAEs] 1d and 2), providing insight to resultant changes in deep-water and surface water circulation that can be used to test predictions from earth system models. The high-paleolatitude (60°–62°S) location of the sites is especially important because of the enhanced sensitivity to changes in vertical gradients and surface water temperatures. Paleotemperature proxies and other data will reveal the timing, magnitude, and duration of peak hothouse temperatures and whether there were any cold snaps that would have allowed growth of a polar ice sheet. The sites are also well-positioned to monitor the mid-Eocene–early Oligocene opening of the Tasman Gateway and the Miocene–Pliocene restriction of the Indonesian Gateway; both passages have important effects on global oceanography and climate. Comparison of the Cenomanian–Turonian OAE 2 interval that will be cored on the Great Australian Bight will establish whether significant changes in ocean circulation were coincident with OAE 2, and over what depth ranges, and whether OAE 2 in the high-latitude Southern Hemisphere was coincident with major changes in sea-surface temperature. Understanding the paleoceanographic changes in a regional context will provide a global test on models of Cenomanian–Turonian oceanographic and climatic evolution related both to extreme Turonian warmth and the evolution of OAE 2. Drilling of Early Cretaceous volcanic rocks and underlying Jurassic(?) sediments in different parts of the MB will provide information on the timing of different stages of the Gondwana breakup and the nature of the various phases of volcanism, which will lead to an improved understanding of the evolution of the NP and MB. 
    more » « less
  • Citation Formats
  • MLA
  • APA
  • Chicago
  • BibTeX
  • Save / Share this Record
  • Send to Email