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Site U1455 (proposed Site MBF-1A) is the last site drilled during Expedition 354 in the Bengal Fan. It is a reoccupation of Deep Sea Drilling Project (DSDP) Site 218 (see Figure F11 in the Expedition 354 summary chapter [France-Lanord et al., 2016e]) (von der Borch, Sclater, et al., 1974), which was the first attempt to drill the Bengal Fan and was only spot cored with the rotary core barrel (RCB) system to 773 meters below seafloor (mbsf). The site is above the eastern flank of the 85°E Ridge at 8°0.42′N, 86°16.97′E at 3743 m water depth. Site U1455 is one of three deep-penetration sites along the Expedition 354 transect dedicated to reveal Neogene fan evolution and Himalayan erosion. This site will also document Pleistocene fan architecture when integrated into the complete seven-site transect. Coring to 900 mbsf was planned to determine Miocene to Pliocene accumulation rates and changes related to Himalayan erosion and environment. The deeper part of the site will extend the existing Site 218 record back into the middle Miocene. Because of time constraints at the end of the expedition, we focused coring on three objectives: the Pleistocene (0–122 mbsf), the late Miocene terrestrial vegetation transition from C3 to C4 plants (360–431 mbsf), and the middle Miocene (773–949 mbsf) to extend the existing core record of Site 218.
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This content will become publicly available on March 24, 2026
Site U1607
Site U1607 (proposed Site MB-07B), the easternmost site in the Expedition 400 site transect, was cored at 74°29.5499′N, 60°34.9900′W at 739 meters below sea level (mbsl) on the middle shelf (Figure F1). Extensive seismic and limited borehole data indicate that this site captures Megaunits C, D1, and D2, interpreted as a middle–late Miocene sediment drift that overlies a succession of mainly hemipelagic strata, possibly of early Miocene to Oligocene age (Knutz et al., 2022b) (Figures F2, F3). Accordingly, Site U1607 may capture the time period from 6 to 30 Ma.
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- PAR ID:
- 10579120
- Author(s) / Creator(s):
- ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; more »
- Publisher / Repository:
- International Ocean Discovery Program
- Date Published:
- Journal Name:
- Proceedings of the International Ocean Discovery Program Expedition reports
- Volume:
- 400
- Issue:
- 107
- ISSN:
- 2377-3189
- ISBN:
- 978-1-954252-93-6
- Subject(s) / Keyword(s):
- International Ocean Discovery Program IODP JOIDES Resolution Expedition 400 NW Greenland Glaciated Margin Site U1607 Baffin Bay hemipelagic glauconite ikaite glendonite ice-rafted debris IRD continental shelf
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Abstract Oscillations in ice sheet extent during early and middle Miocene are intermittently preserved in the sedimentary record from the Antarctic continental shelf, with widespread erosion occurring during major ice sheet advances, and open marine deposition during times of ice sheet retreat. Data from seismic reflection surveys and drill sites from Deep Sea Drilling Project Leg 28 and International Ocean Discovery Program Expedition 374, located across the present-day middle continental shelf of the central Ross Sea (Antarctica), indicate the presence of expanded early to middle Miocene sedimentary sections. These include the Miocene climate optimum (MCO ca. 17–14.6 Ma) and the middle Miocene climate transition (MMCT ca. 14.6–13.9 Ma). Here, we correlate drill core records, wireline logs and reflection seismic data to elucidate the depositional architecture of the continental shelf and reconstruct the evolution and variability of dynamic ice sheets in the Ross Sea during the Miocene. Drill-site data are used to constrain seismic isopach maps that document the evolution of different ice sheets and ice caps which influenced sedimentary processes in the Ross Sea through the early to middle Miocene. In the early Miocene, periods of localized advance of the ice margin are revealed by the formation of thick sediment wedges prograding into the basins. At this time, morainal bank complexes are distinguished along the basin margins suggesting sediment supply derived from marine-terminating glaciers. During the MCO, biosiliceous-bearing sediments are regionally mapped within the depocenters of the major sedimentary basin across the Ross Sea, indicative of widespread open marine deposition with reduced glacimarine influence. At the MMCT, a distinct erosive surface is interpreted as representing large-scale marine-based ice sheet advance over most of the Ross Sea paleo-continental shelf. The regional mapping of the seismic stratigraphic architecture and its correlation to drilling data indicate a regional transition through the Miocene from growth of ice caps and inland ice sheets with marine-terminating margins, to widespread marine-based ice sheets extending across the outer continental shelf in the Ross Sea.more » « less
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Elucidating the geologic history of the Greenland ice sheet (GrIS) is essential for understanding glacial instability thresholds, identified as major climate system tipping points, and how the cryosphere will respond to anthropogenic greenhouse gas emissions. To address current knowledge gaps in the evolution and variability of the GrIS and its role in Earth’s climate system, International Ocean Discovery Program (IODP) Expedition 400 obtained sedimentary records from Sites U1603–U1608 across the northwest Greenland margin into Baffin Bay where thick Cenozoic sedimentary successions can be directly linked to the evolution of the northern GrIS (NGrIS). The strategy of drilling along this transect was to retrieve a composite stratigraphic succession representing the late Cenozoic era from the Oligocene/early Miocene to the Holocene. The proposed sites targeted high–accumulation rate deposits associated with contourite drifts and potential interglacial deposits within a trough mouth fan system densely covered by seismic data. The principal objectives were to (1) test if the NGrIS underwent near-complete deglaciations in the Pleistocene and assess the ice sheet’s response to changes in orbital cyclicities through the mid-Pleistocene transition, (2) ascertain the timing of the NGrIS expansion and examine a hypothesized linkage between marine heat transport through Baffin Bay and high Arctic warmth during the Pliocene, and (3) provide new understandings of climate-ecosystem conditions in Greenland during the geologic periods with increased atmospheric CO2 compared to preindustrial values, encompassing the last 30 My. The deep time objective was attained by coring at Site U1607 on the inner shelf to 978 meters below seafloor, capturing a succession of mainly Miocene and Oligocene age. The six sites drilled during Expedition 400 resulted in 2299 m of recovered core material, and wireline downhole logging was completed at Sites U1603, U1604, U1607, and U1608. This unique archive will provide the basis for understanding the full range of forcings and feedbacks—oceanic, atmospheric, orbital, and tectonic—that influence the GrIS over a range of timescales, as well as conditions prevailing at the time of glacial inception and deglacial to interglacial periods. We anticipate that the shipboard data and further analytical work on Expedition 400 material can constrain predictive models addressing the GrIS response to global warming and its impending effects on global sea levels.more » « less
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Elucidating the geologic history of the Greenland ice sheet (GrIS) is essential for understanding glacial instability thresholds, identified as major climate system tipping points, and how the cryosphere will respond to anthropogenic greenhouse gas emissions. To address current knowledge gaps in the evolution and variability of the GrIS and its role in Earth’s climate system, International Ocean Discovery Program (IODP) Expedition 400 obtained sedimentary records from Sites U1603–U1608 across the northwest Greenland margin into Baffin Bay where thick Cenozoic sedimentary successions can be directly linked to the evolution of the northern GrIS (NGrIS). The strategy of drilling along this transect was to retrieve a composite stratigraphic succession representing the late Cenozoic era from the Oligocene/early Miocene to the Holocene. The proposed sites targeted high–accumulation rate deposits associated with contourite drifts and potential interglacial deposits within a trough mouth fan system densely covered by seismic data. The principal objectives were to (1) test if the NGrIS underwent near-complete deglaciations in the Pleistocene and assess the ice sheet’s response to changes in orbital cyclicities through the mid-Pleistocene transition, (2) ascertain the timing of the NGrIS expansion and examine a hypothesized linkage between marine heat transport through Baffin Bay and high Arctic warmth during the Pliocene, and (3) provide new understandings of climate-ecosystem conditions in Greenland during the geologic periods with increased atmospheric CO2 compared to preindustrial values, encompassing the last 30 My. The deep time objective was attained by coring at Site U1607 on the inner shelf to 978 meters below seafloor, capturing a succession of mainly Miocene and Oligocene age. The six sites drilled during Expedition 400 resulted in 2299 m of recovered core material, and wireline downhole logging was completed at Sites U1603, U1604, U1607, and U1608. This unique archive will provide the basis for understanding the full range of forcings and feedbacks—oceanic, atmospheric, orbital, and tectonic—that influence the GrIS over a range of timescales, as well as conditions prevailing at the time of glacial inception and deglacial to interglacial periods. We anticipate that the shipboard data and further analytical work on Expedition 400 material can constrain predictive models addressing the GrIS response to global warming and its impending effects on global sea levels.more » « less
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Elucidating the geologic history of the Greenland Ice Sheet (GrIS) is essential for understanding glacial instability thresholds, identified as major climate system tipping points, and how the cryosphere will respond to anthropogenic greenhouse gas emissions. To address current knowledge gaps in the evolution and variability of the GrIS and its role in Earth's climate system, International Ocean Discovery Program (IODP) Expedition 400 obtained sedimentary records from Sites U1603–U1608 across the northwest Greenland margin into Baffin Bay where thick Cenozoic sedimentary successions can be directly linked to the evolution of the northern GrIS (NGrIS). The strategy of drilling along this transect was to retrieve a composite stratigraphic succession representing the late Cenozoic era from the Oligocene/early Miocene to Holocene. The proposed sites targeted high–accumulation rate deposits associated with contourite drifts and potential interglacial deposits within a trough mouth fan system densely covered by seismic data. The principal objectives were to (1) test if the NGrIS underwent near-complete deglaciations in the Pleistocene and assess the ice sheet’s response to changes in orbital cyclicities through the mid-Pleistocene transition; (2) ascertain the timing of the NGrIS expansion and examine a hypothesized linkage between marine heat transport through Baffin Bay and high Arctic warmth during the Pliocene; and (3) provide new understandings of climate-ecosystem conditions in Greenland during the geologic periods with increased atmospheric CO2 compared to preindustrial values, encompassing the last 30 My. The deep time objective was attained by coring at Site U1607 on the inner shelf to 978 meters below seafloor, capturing a succession of mainly Miocene and Oligocene age. The six sites drilled during Expedition 400 resulted in 2299 m of recovered core material, and wireline downhole logging was completed at Sites U1603, U1604, U1607, and U1608. This unique archive will provide the basis for understanding the full range of forcings and feedbacks—oceanic, atmospheric, orbital, and tectonic—that influence the GrIS over a range of timescales, as well as conditions prevailing at the time of glacial inception and deglacial to interglacial periods. We anticipate that the shipboard data and further analytical work on Expedition 400 material can constrain predictive models addressing the GrIS response to global warming and its impending effects on global sea levels.more » « less
