Title: Data report: Site U1523 composite section and stratigraphic splice based on X-ray fluorescence data, IODP Expedition 374
Contribution of melting Antarctic Ice Sheets (AIS) to rising sea level remains one of the least quantified inputs to predictive models for the future. To improve these estimates, International Ocean Discovery Program Expedition 374 cored five sites in the Ross Sea, Antarctica, to examine the stability of the AIS to past intervals of global warmth. Site U1523 proved difficult to core because of the presence of gravel lags and indurated intervals; thus, we cored three holes with overlapping stratigraphy at that site to recover a more complete stratigraphic section. Given these challenges, no attempt was made to create a composite depth scale or stratigraphic splice during the expedition. Here we use a combination of physical property data (primarily magnetic susceptibility and natural gamma radiation), X-ray fluorescence core scanning, and visual core description to construct a core composite depth below seafloor (CCSF) depth scale to the base of Hole U1523B. This composite depth scale is discontinuous because of challenging coring conditions and variable core recovery, although there are several intervals of reasonably good stratigraphic continuity between 0 and 26 m CCSF and 82 and 96 m CCSF. We also created a stratigraphic splice from 0 to 93.95 m CCSF, although the splice is only continuous to 15.82 m CCSF. Additionally, we mapped the off-splice interval of Core 374-U1523E-1H to the composite depth scale over several intervals with significant core disturbance by stretching and squeezing to obtain a best fit. Development of the composite depth scale and stratigraphic splice will improve postcruise research results by allowing scientists to compare samples from different holes on the same depth scale. more »« less
Gong, L.; Lübbers, J.; Beil, S.; Holbourn, A.(
, Proceedings of the International Ocean Discovery Program)
null
(Ed.)
The shipboard sediment splice of International Ocean Discovery Program Expedition 363 Site U1483, drilled in 1733 m water depth on the Scott Plateau off Northwest Australia, was primarily based on a composite of the magnetic susceptibility records at 2.5 cm resolution from three holes drilled at this site. We performed X-ray fluorescence (XRF) core scanning at 2 cm intervals with overlaps of ~1–2 m at splice tie points and used these new data to verify the tie points along the original splice from 0 to 211.53 m core composite depth below seafloor (CCSF). Based on the XRF records, we revised the position of three original tie points and present a revised composite depth scale for Site U1483. These revisions resulted in shifts of up to 94 cm relative to the original shipboard offsets and a continuous section extending down to 211.62 m revised core composite depth below seafloor (r-CCSF).
Lübbers, J.; Holbourn, A.E.; Kuhnt, W.; Beil, S.(
, Proceedings of the International Ocean Discovery Program)
null
(Ed.)
International Ocean Discovery Program (IODP) Expedition 363 recovered extended Neogene to Quaternary carbonate- and clay-rich sedimentary successions at Site U1482 (15°3.32ʹS, 120°26.10ʹE; 1466 m water depth), drilled at the southwestern edge of the Indo-Pacific Warm Pool off northwest Australia (Rosenthal et al., 2018b). Four holes were drilled with the advanced piston corer (APC) system at this site and deepened with the half-length APC (HLAPC) and extended core barrel (XCB) systems. A shipboard splice, from 0 to 451.26 m core composite depth below seafloor (CCSF), was established. After the expedition, the cores were scanned at high-resolution (1–2 cm) using an Avaatech X-ray fluorescence (XRF) core scanner. Scanning was performed along the shipboard splice with approximately 1 m overlap at the splice tie points for verification. Based on this new data set, we revised nine of the original splice tie points. The revised splice for Site U1482 now extends to 445.11 m revised CCSF and is available from the IODP Laboratory Information Management System (LIMS) database.
Wilkens, R.H.; Drury, A.J.; Westerhold, T.; Röhl, U.(
, Proceedings of the International Ocean Discovery Program)
A near-complete sedimentary sequence was spliced together for the upper part of International Ocean Discovery Program (IODP) Holes U1553A, U1553B, and U1553E. Poor core recovery precluded a complete splice for the deeper section cored in Holes U1553C and U1553D. The history of Deep Sea Drilling Project Site 277, which was cored nearby, suggests that the Site U1553 splice will be heavily sampled and that eventually samples will be taken from intervals of core that are not included in the splice (i.e., off-splice). Although the depths of all cores have been shifted to a common scale during the splicing process by aligning significant features shared by cores from the different holes, core disturbance and natural variability often lead to misalignment between features in the splice and the same features in off-splice data. To remedy this problem for future sampling, data from off-splice intervals are squeezed or stretched to match spliced intervals using a set of tie points between the splice and off-splice data. The difference in depths can be significant when considering sedimentation rates and orbital periods of precession, obliquity, and eccentricity and sometimes even change the phase relationship compared to the splice. Results are presented as tables of tie points between each hole and the splice that can be used to interpolate the proper splice depth of off-splice samples.
Lyle, M.; Saraswat, R.(
, Proceedings of the International Ocean Discovery Program)
null
(Ed.)
Sediment cores from adjacent holes at a drill site are typically spliced to make a continuous sediment record that spans sediment gaps that occur between sediment cores within each hole. The splice also provides a template for later sampling. During International Ocean Discovery Program Expedition 355, we made such a splice for both Sites U1456 and U1457 using shipboard Whole-Round Multisensor Logger and Section Half Multisensor Logger data. The shipboard-spliced sediment section at Site U1457 was constructed for the advanced piston corer interval to an age of about 1.5 Ma. Additional postexpedition planktonic foraminifer stable isotope data (Globigerinoides ruber δ18O) show that the shipboard stratigraphic tie between Cores 355-U1457B-1H and 355-U1457A-1H was wrong. This paper describes a revised splice that appends Core 355-U1457A-1H to the base of Core 355-U1457B-1H. The core composite depth below seafloor depths of the remaining splice have been revised because of this change. The revised splice interval is also longer by 1.2 m to accommodate the lower part of Core 355-U1457B-1H. In addition, a break of unknown thickness is present between Cores 355-U1457B-1H and 355-U1457A-1H. The revised splice interval table is included in this report.
McKay, R.M.; De Santis, L.; Kulhanek, D.K.(
, Proceedings of the International Ocean Discovery Program)
null
(Ed.)
The marine-based West Antarctic Ice Sheet (WAIS) is currently locally retreating because of shifting wind-driven oceanic currents that transport warm waters toward the ice margin, resulting in ice shelf thinning and accelerated mass loss. Previous results from geologic drilling on Antarctica’s continental margins show significant variability in ice sheet extent during the late Neogene and Quaternary. Climate and ice sheet models indicate a fundamental role for oceanic heat in controlling ice sheet variability over at least the past 20 My. Although evidence for past ice sheet variability is available from ice-proximal marine settings, sedimentary sequences from the continental shelf and rise are required to evaluate the extent of past ice sheet variability and the associated forcings and feedbacks. International Ocean Discovery Program Expedition 374 drilled a latitudinal and depth transect of five sites from the outer continental shelf to rise in the central Ross Sea to resolve Neogene and Quaternary relationships between climatic and oceanic change and WAIS evolution. The Ross Sea was targeted because numerical ice sheet models indicate that this sector of Antarctica responds sensitively to changes in ocean heat flux. Expedition 374 was designed for optimal data-model integration to enable an improved understanding of Antarctic Ice Sheet (AIS) mass balance during warmer-than-present climates (e.g., the Pleistocene “super interglacials,” the mid-Pliocene, and the Miocene Climatic Optimum). The principal goals of Expedition 374 were to: 1. Evaluate the contribution of West Antarctica to far-field ice volume and sea level estimates; 2. Reconstruct ice-proximal oceanic and atmospheric temperatures to quantify past polar amplification; 3. Assess the role of oceanic forcing (e.g., temperature and sea level) on AIS variability; 4. Identify the sensitivity of the AIS to Earth’s orbital configuration under a variety of climate boundary conditions; and 5. Reconstruct Ross Sea paleobathymetry to examine relationships between seafloor geometry, ice sheet variability, and global climate. To achieve these objectives, postcruise studies will: 1. Use data and models to reconcile intervals of maximum Neogene and Quaternary ice advance and retreat with far-field records of eustatic sea level; 2. Reconstruct past changes in oceanic and atmospheric temperatures using a multiproxy approach; 3. Reconstruct Neogene and Quaternary sea ice margin fluctuations and correlate these records to existing inner continental shelf records; 4. Examine relationships among WAIS variability, Earth’s orbital configuration, oceanic temperature and circulation, and atmospheric pCO2; and 5. Constrain the timing of Ross Sea continental shelf overdeepening and assess its impact on Neogene and Quaternary ice dynamics. Expedition 374 departed from Lyttelton, New Zealand, in January 2018 and returned in March 2018. We recovered 1292.70 m of high-quality core from five sites spanning the early Miocene to late Quaternary. Three sites were cored on the continental shelf (Sites U1521, U1522, and U1523). At Site U1521, we cored a 650 m thick sequence of interbedded diamictite and diatom-rich mudstone penetrating seismic Ross Sea Unconformity 4 (RSU4). The depositional reconstructions of past glacial and open-marine conditions at this site will provide unprecedented insight into environmental change on the Antarctic continental shelf during the late early and middle Miocene. At Site U1522, we cored a discontinuous late Miocene to Pleistocene sequence of glacial and glaciomarine strata from the outer shelf with the primary objective of penetrating and dating RSU3, which is interpreted to reflect the first continental shelf–wide expansion of East and West Antarctic ice streams. Site U1523, located on the outer continental shelf, targeted a sediment drift beneath the westward-flowing Antarctic Slope Current (ASC) to test the hypothesis that changes in ASC vigor regulate ocean heat flux onto the continental shelf and thus ice sheet mass balance. We also cored two sites on the continental rise and slope. At Site U1524, we recovered a Plio–Pleistocene sedimentary sequence from the levee of the Hillary Canyon, one of the largest conduits of Antarctic Bottom Water from the continental shelf to the abyssal ocean. Site U1524 was designed to penetrate into middle Miocene and older strata, but coring was initially interrupted by drifting sea ice that forced us to abandon coring in Hole U1524A at 399.5 m drilling depth below seafloor (DSF). We moved to a nearby alternate site on the continental slope (Site U1525) to core a single hole designed to complement the record at Site U1524. We returned to Site U1524 after the sea ice cleared and cored Hole U1524C with the rotary core barrel system with the intention of reaching the target depth of 1000 m DSF. However, we were forced to terminate Hole U1524C at 441.9 m DSF because of a mechanical failure with the vessel that resulted in termination of all drilling operations and forced us to return to Lyttelton 16 days earlier than scheduled. The loss of 39% of our operational days significantly impacted our ability to achieve all Expedition 374 objectives. In particular, we were not able to recover continuous middle Miocene sequences from the continental rise designed to complement the discontinuous record from continental shelf Site U1521. The mechanical failure also meant we could not recover cores from proposed Site RSCR-19A, which was targeted to obtain a high-fidelity, continuous record of upper Neogene and Quaternary pelagic/hemipelagic sedimentation. Despite our failure to recover a continental shelf-to-rise Miocene transect, records from Sites U1522, U1524, and U1525 and legacy cores from the Antarctic Geological Drilling Project (ANDRILL) can be integrated to develop a shelf-to-rise Plio–Pleistocene transect.
Kulhanek, D.K., Prunella, C., McLaughlin, J.R., Griffin, B., McKay, R.M., Patterson, M.O., Gales, J., Shevenell, A.E., and van Peer, T.E. Data report: Site U1523 composite section and stratigraphic splice based on X-ray fluorescence data, IODP Expedition 374. Retrieved from https://par.nsf.gov/biblio/10357017. Proceedings of the International Ocean Discovery Program 374.202 Web. doi:10.14379/iodp.proc.374.202.2022.
Kulhanek, D.K., Prunella, C., McLaughlin, J.R., Griffin, B., McKay, R.M., Patterson, M.O., Gales, J., Shevenell, A.E., & van Peer, T.E. Data report: Site U1523 composite section and stratigraphic splice based on X-ray fluorescence data, IODP Expedition 374. Proceedings of the International Ocean Discovery Program, 374 (202). Retrieved from https://par.nsf.gov/biblio/10357017. https://doi.org/10.14379/iodp.proc.374.202.2022
Kulhanek, D.K., Prunella, C., McLaughlin, J.R., Griffin, B., McKay, R.M., Patterson, M.O., Gales, J., Shevenell, A.E., and van Peer, T.E.
"Data report: Site U1523 composite section and stratigraphic splice based on X-ray fluorescence data, IODP Expedition 374". Proceedings of the International Ocean Discovery Program 374 (202). Country unknown/Code not available. https://doi.org/10.14379/iodp.proc.374.202.2022.https://par.nsf.gov/biblio/10357017.
@article{osti_10357017,
place = {Country unknown/Code not available},
title = {Data report: Site U1523 composite section and stratigraphic splice based on X-ray fluorescence data, IODP Expedition 374},
url = {https://par.nsf.gov/biblio/10357017},
DOI = {10.14379/iodp.proc.374.202.2022},
abstractNote = {Contribution of melting Antarctic Ice Sheets (AIS) to rising sea level remains one of the least quantified inputs to predictive models for the future. To improve these estimates, International Ocean Discovery Program Expedition 374 cored five sites in the Ross Sea, Antarctica, to examine the stability of the AIS to past intervals of global warmth. Site U1523 proved difficult to core because of the presence of gravel lags and indurated intervals; thus, we cored three holes with overlapping stratigraphy at that site to recover a more complete stratigraphic section. Given these challenges, no attempt was made to create a composite depth scale or stratigraphic splice during the expedition. Here we use a combination of physical property data (primarily magnetic susceptibility and natural gamma radiation), X-ray fluorescence core scanning, and visual core description to construct a core composite depth below seafloor (CCSF) depth scale to the base of Hole U1523B. This composite depth scale is discontinuous because of challenging coring conditions and variable core recovery, although there are several intervals of reasonably good stratigraphic continuity between 0 and 26 m CCSF and 82 and 96 m CCSF. We also created a stratigraphic splice from 0 to 93.95 m CCSF, although the splice is only continuous to 15.82 m CCSF. Additionally, we mapped the off-splice interval of Core 374-U1523E-1H to the composite depth scale over several intervals with significant core disturbance by stretching and squeezing to obtain a best fit. Development of the composite depth scale and stratigraphic splice will improve postcruise research results by allowing scientists to compare samples from different holes on the same depth scale.},
journal = {Proceedings of the International Ocean Discovery Program},
volume = {374},
number = {202},
author = { Kulhanek, D.K. and Prunella, C. and McLaughlin, J.R. and Griffin, B. and McKay, R.M. and Patterson, M.O. and Gales, J. and Shevenell, A.E. and van Peer, T.E.},
}
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