Volcanic iron fertilization of primary productivity at Kerguelen Plateau, Southern Ocean, through the Middle Miocene Climate Transition

Abrajevitch, Alexandra; Roberts, Andrew P.; Kodama, Kazuto

doi:10.1016/j.palaeo.2014.05.028

Cited by 11 publications

(11 citation statements)

References 88 publications

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“…Middle Miocene benthic foraminifera (and more specifically Cibicidoides) from Site 747 were previously described as well preserved (e.g., Abrajevitch et al, 2014;Billups and Schrag, 2002). Our examination appears to confirm the impression of relatively good preservation of middle Miocene Cibicidoides at Site 747 (see Figs.…”

Section: Sample Materialssupporting

confidence: 87%

“…At present, the site is situated south of the Polar Front and is bathed by Circumpolar Deep Water (CDW) with a temperature of ~1-2°C (Belkin and Gordon, 1996;Billups and Schrag, 2002). The middle Miocene geographic position of Site 747 relative to Antarctica was similar to today (e.g., Abrajevitch et al, 2014). The clumped isotope record generated in this study covers the depth interval from 62.64 m below sea floor (mbsf, Sample 747A-7H-5, 14-16 cm) to 85.36 mbsf (Sample 747A-9H-8, 75-77 cm) in Hole 747A.…”

Section: Site Detailsmentioning

confidence: 97%

“…191 samples (15-20 cm 3 , mostly calcareous nannofossil ooze with foraminifera) were taken continuously with a mean temporal resolution of ~20 kyr. We slightly rescaled the originally assigned shipboard sample depths to account for core expansion (Schlich et al, 1989), similar to previous studies focusing on the middle Miocene section of Hole 747A (e.g., Abrajevitch et al, 2014;Majewski and Bohaty, 2010).…”

Section: Site Detailsmentioning

confidence: 99%

“…We revised the Hole 747A age model by integrating six magnetostratigraphic tie points (Abrajevitch et al, 2014;Majewski and Bohaty, 2010) on the GTS2012 timescale (Gradstein et al, 2012), three benthic foraminiferal δ 13 C-based tie points associated with the "Monterey" carbon-isotope excursion (using the nomenclature of Holbourn et al 2007), and one peak warm event visible in benthic foraminiferal δ 13 C and δ 18 O (Kochhann et al, 2016) (Table S1). For the δ 13 C-based tie points, we used the high-resolution isotope stratigraphies of IODP Sites U1335, U1337 and U1338 in the eastern equatorial Pacific…”

Section: Age Modelsmentioning

confidence: 99%

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Southern Ocean bottom water cooling and ice sheet expansion during the middle Miocene climate transition

Leutert

Modestou

Bernasconi

et al. 2020

Preprint

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Abstract. The middle Miocene climate transition (MMCT, ~14.5–13.0 Ma) was associated with a significant expansion of Antarctic ice, but the mechanisms triggering the event remain enigmatic. We present a new clumped isotope (∆47) bottom water temperature (BWT) record from 16.0 Ma to 12.2 Ma from Ocean Drilling Program (ODP) Site 747 in the Southern Ocean, and compare it to existing BWT records. We show that BWTs in the Southern Ocean were ~8–10 °C during the middle Miocene greenhouse, and thus considerably warmer than today. Nonetheless, bottom water δ18O (calculated from foraminiferal δ18O and ∆47) suggests substantial amounts of land ice throughout the interval of the study. Our dataset demonstrates that BWTs at Site 747 decreased by ~3–5 °C across the MMCT. This cooling preceded the stepped main increase in global ice volume, and appears to have been followed by a transient bottom water warming starting during or slightly after the main ice volume increase. We speculate that a regional freshening of the upper water column at this time may have increased stratification and reduced bottom water heat loss to the atmosphere, counteracting global cooling in the bottom waters of the Southern Ocean and possibly even at larger scales. Additional processes and feedbacks required for substantial ice growth may have contributed to the observed decoupling of Southern Ocean BWT and global ice volume.

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Section: Sample Materialssupporting

confidence: 87%

Section: Site Detailsmentioning

confidence: 97%

Section: Site Detailsmentioning

confidence: 99%

Section: Age Modelsmentioning

confidence: 99%

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Southern Ocean bottom water cooling and ice sheet expansion during the middle Miocene climate transition

Leutert

Modestou

Bernasconi

et al. 2020

Preprint

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“…The coercivity and DP of component 1 of the IRM acquisition might suggest the presence of detrital iron oxides (e.g., Maher, 1988;Moskowitz et al, 1989;Kruiver et al, 2001;Egli, 2004;Font et al, 2011, Font et al, 2014Savian et al, 2014), whereas those of components 2 and 3 are indicative of SD biogenic soft (BS) and biogenic hard (BH) magnetic particles produced by MTB (Kruiver and Passier, 2001;Egli, 2004;Yamazaki, 2012). Ancient sediments also show these components Kodama, 2009, Abrajevitch andKodama, 2011;Roberts et al, 2013;Abrajevitch et al, 2014;Heslop et al, 2014;Savian et al, 2014, which can be different in terms of median coercivity due to differences in magnetosome morphology (Egli, 2004;Yamazaki, 2012;Heslop et al, 2014). The high-coercivity of component 5 suggests the presence of hematite (Kruiver et al, 2001;Savian et al, 2014), but cannot also exclude some fraction of goethite due to the similar coercivity.…”

Section: Magnetotactic Bacteriamentioning

confidence: 99%

Paleoenvironmental signature of the Selandian-Thanetian Transition Event (STTE) and Early Late Paleocene Event (ELPE) in the Contessa Road section (western Neo-Tethys)

Coccioni

Frontalini

Catanzariti

et al. 2019

Palaeogeography, Palaeoclimatology, Palaeoecology

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Sedimentary records of the Early Cenozoic indicate a series of events with climatic and carbon cycle variability known as hyperthermals. A ~350-kyr-long event of environmental disruption during the Paleocene, not described before and here named Selandian-Thanetian Transition Event (STTE), has been recognized and well constrained in the western Tethys Contessa Road section (Gubbio, Italy) through high-resolution biostratigraphic, geochemical, and rock-magnetic data. The STTE exhibits peculiar stressed ecological responses among calcareous nannofossils and foraminifera, which highlight marked environmental perturbation affecting the biosphere. The environmental instability is not confined within the photic zone but extends to the seafloor leading to little more trophic conditions of the sea surface waters with an enhanced, but of short measure, nutrient availability on the seafloor conditions and marked rise of lysocline. Magnetic Susceptibly (MS) is dominantly controlled by the balance between carbonate productivity and detrital supply, as evidenced by the strong correlation between MS and CaCO3 (%) (r2 = −0.72). However, we also document two components in the isothermal remanent magnetization (IRM) and first-order reversal curves (FORC) diagrams that prove the occurrence of biogenic magnetite throughout the STTE. Systematic variations in bio-geochemical and magnetic parameters show the relative abundance of carbonate production (or inversely dissolution of carbonate) versus detrital supply during the STTE, which induced higher populations of magnetotactic bacteria through increased terrigenous input and, therefore, increased nutrient supply. Noteworthy, the uppermost part of the STTE includes the equivalent of the suspected hyperthermal, short-lived Early Late Paleocene Event (ELPE). The ELPE event shows an episode of increase in magnetic properties of the sediments, including an increase in magnetofossil concentration, as indicated by IRM components and FORC diagrams. The comparison of biotic and abiotic records throughout the STTE at Contessa Road section with available data across the ELPE from former investigated ocean and land-based sites provides lines of evidence that this latter event might be indeed only the terminal part of a long-lasting environmental change than hitherto supposed.

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Environmental conditions for the presence of magnetofossils in the Last Glacial Maximum inferred from magnetic parameters of sediments from the Ulleung Basin, East Sea

Suk

2016

Marine Geology

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Volcanic iron fertilization of primary productivity at Kerguelen Plateau, Southern Ocean, through the Middle Miocene Climate Transition

Cited by 11 publications

References 88 publications

Southern Ocean bottom water cooling and ice sheet expansion during the middle Miocene climate transition

Southern Ocean bottom water cooling and ice sheet expansion during the middle Miocene climate transition

Paleoenvironmental signature of the Selandian-Thanetian Transition Event (STTE) and Early Late Paleocene Event (ELPE) in the Contessa Road section (western Neo-Tethys)

Environmental conditions for the presence of magnetofossils in the Last Glacial Maximum inferred from magnetic parameters of sediments from the Ulleung Basin, East Sea

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