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  • Ocean Drilling Program; ODP  (11)
  • 04. Solid Earth::04.07. Tectonophysics::04.07.02. Geodynamics  (2)
  • PANGAEA  (11)
  • American Geophysical Union  (2)
  • Copernicus
  • Nature Publishing Group
  • 2015-2019  (13)
  • 1980-1984
  • 1935-1939
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  • 1
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    The protracted development of focused magmatic intrusion during continental rifting (2015)
    American Geophysical Union
    Details
    Publication Date: 2021-06-25
    Description: The transition from mechanical thinning toward focused magmatic intrusion during continental rifting is poorly constrained; the tectonically active Main Ethiopian Rift (MER) provides an ideal study locale to address this issue. The presence of linear magmatic-tectonic belts in the relatively immature central MER may indicate that the transition from mechanical to magmatic rifting is more spatially distributed and temporally protracted than has previously been assumed. Here we examine lava geochemistry and vent distribution of a Pliocene-Quaternary linear magmatic chain along the western margin of the central MER—the Akaki Magmatic Zone. Our results show limited variability in parental magma that evolve in a complex polybaric fractionation system that has not changed significantly over the past 3 Ma. Our results suggest the following: (1) channeling of plume material and the localization of shear- or topography-induced porosity modulates melt intrusion into the continental lithosphere. (2) Pre-existing lithospheric structures may act as catalysts for intrusion of magmas into the lithospheric mantle. (3) The midcrustal to upper crustal strain regime dictates the surface orientation of volcanic vents. Therefore, although linear magmatic belts like those in the central MER may young progressively toward the rift axis and superficially resemble oceanic style magmatism, they actually represent prebreakup magmatism on continental crust. The oldest linear magmatic belts observed seismically and magnetically at the edge of the ocean basins thus may not, as is often assumed, actually mark the onset of seafloor spreading.
    Description: Published
    Description: 875–897
    Description: 1T. Geodinamica e interno della Terra
    Description: JCR Journal
    Description: restricted
    Keywords: Precambrian lineaments control off-axis melt • Magmatic extension in Ethiopian rift is not ocean like • Magmatic belts at basins margins may not be seafloor spreading ; 04. Solid Earth::04.07. Tectonophysics::04.07.02. Geodynamics
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 2
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    The origin of along-rift variations in faulting and magmatism in the Ethiopian Rift (2015)
    American Geophysical Union
    Details
    Publication Date: 2021-06-25
    Description: The geological record at rifts and margins worldwide often reveals considerable along-strike variations in volumes of extruded and intruded igneous rocks. These variations may be the result of asthenospheric heterogeneity, variations in rate, and timing of extension; alternatively, preexisting plate architecture and/or the evolving kinematics of extension during breakup may exert first-order control on magmatism. The Main Ethiopian Rift (MER) in East Africa provides an excellent opportunity to address this dichotomy: it exposes, along strike, several sectors of asynchronous rift development from continental rifting in the south to incipient oceanic spreading in the north. Here we perform studies of volcanic cone density and rift obliquity along strike in the MER. By synthesizing these new data in light of existing geophysical, geochemical, and petrological constraints on magma generation and emplacement, we are able to discriminate between tectonic and mantle geodynamic controls on the geological record of a newly forming magmatic rifted margin. The timing of rift sector development, the three-dimensional focusing of melt, and the ponding of plume material where the rift dramatically narrows each influence igneous intrusion and volcanism along the MER. However, rifting obliquity plays an important role in localizing intrusion into the crust beneath en echelon volcanic segments. Along-strike variations in volumes and types of igneous rocks found at rifted margins thus likely carry information about the development of strain during rifting, as well as the physical state of the convecting mantle at the time of breakup.
    Description: Published
    Description: 467-477
    Description: 1T. Geodinamica e interno della Terra
    Description: JCR Journal
    Description: restricted
    Keywords: Variationsinmeltproductioncausedby asynchronous rift sector development • Where the rift narrows, ponding of plume material may enhance melting • Three-dimensional migration of melt along the LAB focuses magma supply ; 04. Solid Earth::04.07. Tectonophysics::04.07.02. Geodynamics
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 3
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    Ostracoda counts and coarse fraction analysis from the Paleocene-Eocene samples at ODP Site 865 (2015)
    PANGAEA
    In:  Supplement to: Yamaguchi, Tatsuhiko; Norris, Richard D (2015): No place to retreat: Heavy extinction and delayed recovery on a Pacific guyot during the Paleocene-Eocene Thermal Maximum. Geology, 43(5), 443-446, https://doi.org/10.1130/G36379.1
    Details
    Publication Date: 2024-01-09
    Description: Modern global change threatens alpine ecosystems by forcing species to migrate to higher elevations and potentially eliminating alpine habitat altogether. Here we show that an analogous restriction of suitable habitat operates on submarine mountains. During the Paleocene–Eocene Thermal Maximum (PETM, ca. 55.96 Ma), ostracodes underwent local extinction on the crest of Allison Guyot in the central Pacific Ocean, which lost 64% of its ostracode species richness (14 species reduced to three species) and as much as 94% of ostracode abundance for ~1.1 m.y., before recolonization rebuilt biodiversity and abundance over the next 200 k.y. Biotic changes may reflect an increase in current speeds, acidification, and a decrease in food supply owing to a temperature-driven increase in metabolic rates. Notably, continental margin ostracodes also underwent extinction during the PETM (25%–38% loss) but, unlike Allison Guyot faunas, could quickly repopulate the continental slope. The absence of refugia for isolated seamounts prolonged the reduction in biodiversity initiated by the PETM, a pattern that may be expected for modern seamount faunas in an era of future global change.
    Keywords: Ocean Drilling Program; ODP
    Type: Dataset
    Format: application/zip, 3 datasets
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  • 4
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    Synchronizing early Eocene deep-sea and continental records from the Bighorn Basin Coring Project (2017)
    PANGAEA
    In:  Supplement to: Westerhold, Thomas; Röhl, Ursula; Wilkens, Roy H; Gingerich, Philip D; Clyde, William C; Wing, Scott L; Bowen, Gabriel J; Kraus, Mary J (2018): Synchronizing early Eocene deep-sea and continental records - cyclostratigraphic age models for the Bighorn Basin Coring Project drill cores. Climate of the Past, 14(3), 303-319, https://doi.org/10.5194/cp-14-303-2018
    Details
    Publication Date: 2024-01-09
    Description: A consistent chronostratigraphic framework is required to understand the effect of major paleoclimate perturbations on both marine and terrestrial ecosystems. Transient global warming events in the early Eocene, 56-54 Ma ago, show the impact of large scale carbon input into the ocean-atmosphere system. Here we provide the first time-scale synchronization of continental and marine deposits spanning the Paleocene-Eocene Thermal Maximum (PETM) and the interval just prior to the Eocene Thermal Maximum 2 (ETM-2). Cyclic variations in geochemical data come from continental drill cores of the Bighorn Basin Coring Project (BBCP, Wyoming, USA) and from marine deep-sea drilling deposits retrieved by the Ocean Drilling Program (ODP). Both are dominated by eccentricity modulated precession cycles used to construct a common cyclostratigraphic framework. Integration of age models results in a revised astrochronology for the PETM in deep-sea records that is now generally consistent with independent 3He age models. The duration of the PETM is estimated at ~200 kyr for the CIE and ~120 kyr for the associated pelagic clay layer. A common terrestrial and marine age model shows a concurrent major change in marine and terrestrial biotas ~200 kyr before ETM-2. In the Bighorn Basin, the change is referred to as Biohorizon B, and represents a period of significant mammalian turnover and immigration, separating the upper Haplomylus-Ectocion Range Zone from the Bunophorus Interval Zone and approximating the Wa-4-Wa-5 land mammal zone boundary. In sediments from ODP Site 1262 (Walvis Ridge), major changes in the biota at this time are documented by the radiation of a "2nd generation" of apical spine-bearing sphenoliths species (e.g., S. radians and S. editus), the emergence of T. orthostylus, and the marked decline of D. multiradiatus.
    Keywords: Ocean Drilling Program; ODP
    Type: Dataset
    Format: application/zip, 11 datasets
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  • 5
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    Carbonate weight percentages, XRF Ca/Ti ratios and foraminifer δ¹⁸O records from TN057-21, TN057-10 and from ODP Site 1089 (2018)
    PANGAEA
    In:  Supplement to: Gottschalk, Julia; Hodell, David A; Skinner, Luke C; Crowhurst, Simon J; Jaccard, Samuel L; Charles, Christopher D (2018): Past carbonate preservation events in the deep Southeast Atlantic Ocean (Cape Basin) and their implications for Atlantic overturning dynamics and marine carbon cycling. Paleoceanography and Paleoclimatology, 33(6), 643-663, https://doi.org/10.1029/2018PA003353
    Details
    Publication Date: 2024-02-23
    Description: Micropaleontological and geochemical analyses reveal distinct millennial-scale increases in carbonate preservation in the deep Southeast Atlantic (Cape Basin) during strong and prolonged Greenland interstadials that are superimposed on long-term (orbital-scale) changes in carbonate burial. These data suggest carbonate oversaturation of the deep Atlantic and a strengthened Atlantic Meridional Overturning Circulation (AMOC) during the most intense Greenland interstadials. However, proxy evidence from outside the Cape Basin indicate that AMOC changes also occurred during weaker and shorter Greenland interstadials. Here we revisit the link between AMOC dynamics and carbonate saturation in the deep Cape Basin over the last 400 kyr (sediment cores TN057-21, TN057-10 and ODP Site 1089) by reconstructing centennial changes in carbonate preservation using mm-scale X-ray fluorescence (XRF) scanning data. We observe close agreement between variations in XRF Ca/Ti, sedimentary carbonate content and foraminiferal shell fragmentation, reflecting a common control primarily through changing deep-water carbonate saturation. We suggest that the high-frequency (sub-orbital) component of the XRF Ca/Ti records indicates the fast and recurrent redistribution of carbonate ions in the Atlantic basin via the AMOC during both long/strong- and short/weak North Atlantic climate anomalies. In contrast, the low-frequency (orbital) XRF Ca/Ti component is interpreted to reflect slow adjustments through carbonate compensation, and/or changes in the deep-ocean respired carbon content. Our findings emphasize the recurrent influence of rapid AMOC variations on the marine carbonate system during past glacial periods, providing a mechanism for transferring the impacts of North Atlantic climate anomalies to the global carbon cycle via the Southern Ocean.
    Keywords: Ocean Drilling Program; ODP
    Type: Dataset
    Format: application/zip, 5 datasets
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  • 6
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    Calcium isotope ratios from marine barite and carbonate over Paleocene-Eocene Boundary (ODP Sites 1212 and 1221) (2015)
    PANGAEA
    In:  Supplement to: Griffith, Elizabeth M; Fantle, Matthew S; Eisenhauer, Anton; Paytan, Adina; Bullen, Thomas D (2015): Effects of ocean acidification on the marine calcium isotope record at the Paleocene–Eocene Thermal Maximum. Earth and Planetary Science Letters, 419, 81-92, https://doi.org/10.1016/j.epsl.2015.03.010
    Details
    Publication Date: 2024-01-09
    Description: Carbonates are invaluable archives of the past, and have been used extensively to reconstruct paleoclimate and paleoceanographic conditions over geologic time scales. Such archives are susceptible to diagenetic alteration via dissolution, recrystallization and secondary precipitation, particularly during ocean acidification events when intense dissolution can occur. Despite the importance of diagenesis on proxy fidelity, the effects of diagenesis on the calcium isotopic composition (d44Ca) of carbonates are unclear. Accordingly, bulk carbonate d44Ca was measured at high resolution in two Pacific deep sea sediment cores (ODP Sites 1212 and 1221) with considerably different dissolution histories over the Paleocene-Eocene Thermal Maximum (PETM, ~55 Ma). The d44Ca of marine barite was also measured at the deeper Site 1221, which experienced severe carbonate dissolution during the PETM. Large (~0.8 per mil) variations in bulk carbonate d44Ca occur in the deeper site near the peak carbon isotope excursion, and are correlated with a large drop in carbonate weight percent. Such an effect is seen in neither the 1221 barite record nor the bulk carbonate record at the shallower, less dissolved Site 1212. We contend that ocean chemical changes associated with the abrupt and massive carbon release into the ocean-atmosphere system and subsequent ocean acidification at the PETM affected the bulk carbonate d44Ca record via diagenesis in the sedimentary column. Such changes are considerable, and need to be taken into account when interpreting and modeling Ca isotope data over extreme climatic events associated with ocean chemical evolution.
    Keywords: Ocean Drilling Program; ODP
    Type: Dataset
    Format: application/zip, 3 datasets
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  • 7
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    Ichthyolith abunances, morphotypes and accumulation rates across the PETM (2015)
    PANGAEA
    Details
    Publication Date: 2024-01-09
    Description: Ichthyolith abundances and accumulation rates for ODP 1209, ODP 1220, and ODP 1260. Ichthyolith morphotype relative abundances for ODP 1209, ODP 1220, and ODP 1260. Isotopic carbon data and ages for ODP 1209, ODP 1220, and ODP 1260
    Keywords: Ocean Drilling Program; ODP
    Type: Dataset
    Format: application/zip, 8 datasets
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  • 8
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    Benthic foraminiferal I/Ca, fish teeth Ce anomaly, and Mn enrichment factor of bulk sediment during the late Paleocene-early Eocene (2016)
    PANGAEA
    In:  Supplement to: Zhou, Xiaoli; Thomas, Ellen; Winguth, Arne M E; Ridgwell, Andy; Scher, Howie D; Hoogakker, Babette A A; Rickaby, Rosalind E M; Lu, Zunli (2016): Expanded oxygen minimum zones during the late Paleocene-early Eocene: Hints from multiproxy comparison and ocean modeling. Paleoceanography, https://doi.org/10.1002/2016PA003020
    Details
    Publication Date: 2024-01-09
    Description: Important insight into the relationship between de-oxygenation and warming can be obtained from the geological record, but evidence is limited because few ocean oxygenation records are available for past greenhouse climate conditions. We use I/Ca in benthic foraminifera to reconstruct late Paleocene through early Eocene bottom and pore-water redox conditions in the South Atlantic and Southern Indian Oceans, and compare our results with those derived from Mn speciation and the Ce anomaly in fish teeth.
    Keywords: Ocean Drilling Program; ODP
    Type: Dataset
    Format: application/zip, 3 datasets
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  • 9
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    Tropical SSTs over the past 3.5 million years (2017)
    PANGAEA
    In:  Supplement to: Herbert, Timothy D; Peterson, Laura C; Lawrence, Kira T; Liu, Zhonghui (2010): Tropical Ocean Temperatures Over the Past 3.5 Million Years. Science, 328(5985), 1530-1534, https://doi.org/10.1126/science.1185435
    Details
    Publication Date: 2024-01-09
    Description: Determining the timing and amplitude of tropical sea surface temperature (SST) change is an important part of solving the puzzle of the Plio-Pleistocene ice ages. Alkenone-based tropical SST records from the major ocean basins show coherent glacial-interglacial temperature changes of 1° to 3°C that align with (but slightly lead) global changes in ice volume and deep ocean temperature over the past 3.5 million years. Tropical temperatures became tightly coupled with benthic d18O and orbital forcing after 2.7 million years. We interpret the similarity of tropical SST changes, in dynamically dissimilar regions, to reflect "top-down" forcing through the atmosphere. The inception of a strong carbon dioxide-greenhouse gas feedback and amplification of orbital forcing at ~2.7 million years ago connected the fate of Northern Hemisphere ice sheets with global ocean temperatures since that time.
    Keywords: Ocean Drilling Program; ODP
    Type: Dataset
    Format: application/zip, 5 datasets
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  • 10
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    Elements and Sr-Nd-Pb isotopic evidences of the residual fractions from ODP Hole 195-1202B (2017)
    PANGAEA
    In:  Supplement to: Dou, Yanguang; Yang, Shouye; Shi, Xuefa; Clift, Peter D; Liu, Shengfa; Liu, Jihua; Li, Chao; Bi, Lei; Zhao, Yun (2016): Provenance weathering and erosion records in southern Okinawa Trough sediments since 28ka: Geochemical and Sr–Nd–Pb isotopic evidences. Chemical Geology, 425, 93-109, https://doi.org/10.1016/j.chemgeo.2016.01.029
    Details
    Publication Date: 2024-01-09
    Description: Geochemical and Sr-Nd-Pb isotopic compositions of the detrital sediments from ODP Hole 1202B and Taiwan rivers were measured in this study, aiming to reveal changes in sediment provenance in the southern Okinawa Trough (SOT) since 28 ka, and to examine the weathering and sediment transport processes in response to monsoon climate variability. Large variations in Sr-Nd-Pb isotopic ratios at 11?9 ka suggest changes in detrital sediment provenance in the SOT from a dominance of the paleo-Changjiang (Yangtze River) and/or continental shelf sediment during the late deglaciation and to west Taiwan rivers since 9.5 ka. Volcanic rocks and eastern Taiwan sediments have not significantly contributed to the SOT. The large shift in sediment provenance during the early Holocene marks a major change in oceanic circulation, mainly caused by the intrusion of the Kuroshio Current into the trough. Clay mineral and geochemical proxies suggest that the Taiwan-derived sediments accumulated during the early-mid ?Holocene climate optimum? (ca. 9.5-4 ka) might be tightly related to the reworking of older altered sediments from terraces and floodplains, rather than having experienced more intense silicate weathering than in the late Holocene (~ 4-0 ka). Overall, silicate weathering in Taiwan was greatly inhibited by accelerating sediment production and transfer from land to ocean caused by monsoon intensification in Holocene. Our study illustrates that the radiogenic isotopic and geochemical compositions of fine-grained detrital sediments are sensitive tools for fingerprinting sediment sources and for reconstructing changes in oceanic currents and monsoon climate in river-dominated East Asian continental margin.
    Keywords: Ocean Drilling Program; ODP
    Type: Dataset
    Format: application/zip, 2 datasets
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