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Expedition 374 Methods
No full textThis chapter documents the procedures and methods employed during drilling operations and in the shipboard laboratories on the R/V JOIDES Resolution during International Ocean Discovery Program (IODP) Expedition 374. This information applies only to the shipboard work described in the Expedition Reports section of the Expedition 374 Proceedings of the International Ocean Discovery Programvolume. Methods used by investigators for shore-based analyses of Expedition 374 data and samples will be described in separate individual publications. This introductory section provides an overview of drilling and coring operations, core handling, curatorial conventions, depth scale terminology, and the sequence of shipboard analyses. Subsequent sections of this chapter describe specific laboratory procedures and instruments in more detail.
The nomenclature of many geographic features on the Antarctic continent is aligned to the geographic coordinate system (e.g., the East and West Antarctic Ice Sheets), in which 0° of longitude represents grid north on a universal polar stereographic projection. However, in the Ross Sea, true direction is generally opposite to the geographic coordinates: the eastern Ross Sea is the area located between 160°W and 180° longitude (see Figure F2 in the Expedition 374 summary chapter [McKay et al., 2019a]), and the western Ross Sea is the area between 160°E and 180° of longitude (see Figure F2 in the Expedition 374 summary [McKay et al., 2019a]). In this volume, descriptors of directional orientation (e.g., west versus east) are based on true directions within the Ross Sea and not the geographical coordinate system
Bulletin No. 374 - Crop and Livestock Costs in Northcentral Wyoming
No full textBulletin No. 374 - Crop and Livestock Costs in Northcentral Wyomin
Aristófanes, Paz, 374-375
No full textReference to initiatory cults in Peace 374-5 can be interpreted as a sexual allusion, as wc can deduce froin the comparison with Frogs 337-8 and Acharnians 736 ss. The author o
Gemeindenachrichten Ottensheim 2015 / 374 (2015 / 374)
No full textGEMEINDENACHRICHTEN OTTENSHEIM 2015 / 374
Gemeindenachrichten Ottensheim (-)
Gemeindenachrichten Ottensheim 2015 / 374 (2015 / 374) ([1]
Expedition 374 Summary
No full textThe 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 Evaluate the contribution of West Antarctica to far-field ice volume and sea level estimates; Reconstruct ice-proximal oceanic and atmospheric temperatures to quantify past polar amplification; Assess the role of oceanic forcing (e.g., temperature and sea level) on AIS variability; Identify the sensitivity of the AIS to Earth’s orbital configuration under a variety of climate boundary conditions; and Reconstruct Ross Sea paleobathymetry to examine relationships between seafloor geometry, ice sheet variability, and global climate.
To achieve these objectives, postcruise studies will Use data and models to reconcile intervals of maximum Neogene and Quaternary ice advance and retreat with far-field records of eustatic sea level; Reconstruct past changes in oceanic and atmospheric temperatures using a multiproxy approach; Reconstruct Neogene and Quaternary sea ice margin fluctuations and correlate these records to existing inner continental shelf records; Examine relationships among WAIS variability, Earth’s orbital configuration, oceanic temperature and circulation, and atmospheric pCO2; and 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
EPMA data from tephra layer in IODP 374 Expedition Site U1524
No full textMajor-element data of single glass shards (raw data, normalized, and from U1524 tephra found in the U1524 from IODP Expedition 374 sites. Analyses were carried out with a JEOL JXA 8230 electron probe microanalyzer (EPMA) at Victoria University of Wellington using wavelength dispersive spectrometry techniques. Data includes calibrated international standards including ATHO-G, T1-G (Jochum et al., 2006), and VG-568 (USNM 72854) analyzed to monitor instrumental drift as well as the precision and accuracy of the analyses
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Chemical and isotope compositions of interstitial water in sediments from Mediterranean basin at DSDP Sites 42-372 and 42-374
No full textThe Br/Cl, Li/Cl and B/Cl ratios and boron isotope compositions of hypersaline pore fluids from DSDP Sites 372 and 374 were measured in an attempt to evaluate the origin of the brines. In Site 374 the relationships between the Cl concentrations (up to 5000 mM) and Br/Cl (~0.012), Na/Cl (as low as 0.1), B/Cl (0.0025), and d11B values (43-55 per mil ) of the deep pore water between 380 and 405 mbsf, located within the Messinian sediments, reflect remnants of ~65-fold evaporated sea water. The original evaporated sea water was modified by: (1) dilution with overlying or less saline water by about 30%; and (2) slight dissolution of NaCl evaporites. The variations in d11B show a continuous increase in d11B values with depth in Site 374, up to 66.7 per mil at a depth of 300 mbsf (Upper Pliocene marl sediments). The conspicuous 11B enrichment trend is consistent with elemental boron depletion, which was calculated from the expected boron concentrations of evaporated sea water with corresponding Br/Cl and Na/Cl ratios. Li/Cl variations also show a depletion of Li relative to evaporated sea water. The apparent depletions of B and Li, as well as the 11B enrichment, reflect uptake of these elements by clay minerals at low water/sediment ratios
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