Site U1511

Sutherland, Rupert; Dickens, Gerald R.; Blum, Peter; Agnini, Claudia; Alegret, Laia; Bhattacharya, Joyeeta; Bordenave, A.; Chang, Liao; Collot, Julien; Cramwinckel, Margot J.; Dallanave, Edoardo; Drake, M. K.; Étienne, Samuel; Giorgioni, M.; Gurnis, Michael; Harper, D. T.; Huang, Huai-Hsuan May; Keller, A.L.; Lam, Adriane R.; Li, H.; Matsui, Hiroki; Morgans, Hugh E. G.; Newsam, Cherry; Park, Y.H.; Pascher, K.M.; Pekar, Stephen F.; Penman, Donald E.; Saito, S.; Stratford, W.; Westerhold, Thomas; Zhou, Xiaoli

doi:10.14379/iodp.proc.371.108.2019

Cited by 2 publications

(12 citation statements)

References 23 publications

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“…Litho-and magnetostratigraphy, and Magnetic Susceptibility (MS) of core U1511B-16R (from ref. 26 ); and main elements abundance analysed by XRF from ref. 46 .…”

Section: Resultsmentioning

confidence: 99%

“…kyr, considering the sedimentation rate of ref. 26 . Smectite, which represents 40-50% of the non-biogenic fraction, starts increasing, whereas all the other minerals decrease (Fig.…”

Section: Discussionmentioning

confidence: 99%

“…3. MECO (266.57-264.85 mbsf): Consists of 1.72 m of clay with biosilica, which is significantly less abundant than in the former intervals, and consists of sponge spicules and few radiolarians 26 . This indicates a decrease in the biosiliceous plankton productivity at the surface (diatoms and radiolarians), leaving only the contribution of the sponge spicules, delivered from shallower benthic environments.…”

Section: Discussionmentioning

confidence: 99%

“…1 and S3), indicating less dilution of the terrigenous fraction. Moreover, physical properties show higher sediment density, reflecting the drop of porous biosiliceous fragments and the consequent increase of clays, which are more compactable 26 . This change induces a decrease in sedimentation rate, explaining why, by applying the value of 10 m/Myr estimated by ref.…”

Section: Discussionmentioning

confidence: 99%

“…and increasing magnetic susceptibility (MS) and Natural Gamma Radiation (NGR) 26 . We present a multimethodological and multidisciplinary investigation aimed at providing new data about the environmental changes affecting this system during the MECO.…”

mentioning

confidence: 99%

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Abyssal oceanic circulation and acidification during the Middle Eocene Climatic Optimum (MECO)

Cornaggia

Bernardini

Giorgioni

et al. 2020

Sci Rep

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The Middle Eocene Climatic Optimum (MECO) is a global warming event that occurred at around 40 Ma and lasted about 500 kyr. We study this event in an abyssal setting of the Tasman Sea, using the IODP Core U1511B-16R, collected during the expedition 371. We analyse magnetic, mineralogical, and chemical parameters to investigate the evolution of the sea bottom conditions at this site during the middle Eocene. We observe significant changes indicating the response to the MECO perturbation. Mn oxides, in which Mn occurs under an oxidation state around +4, indicate a high Eh water environment. A prominent Mn anomaly, occurring just above the MECO interval, indicates a shift toward higher pH conditions shortly after the end of this event. Our results suggest more acid bottom water over the Tasman abyssal plain during the MECO, and an abrupt end of these conditions. This work provides the first evidence of MECO at abyssal depths and shows that acidification affected the entire oceanic water column during this event. The Eocene (~56-34 Ma) was characterized by a gradual climatic cooling, accompanied by decreasing atmospheric pCO 2 and culminating with the onset of the Antarctic glaciation in the early Oligocene (33 Ma) 1-5. This trend was interrupted during the middle Eocene by a warm period known as Middle Eocene Climatic Optimum (MECO), with duration of ~500 kyr and a warmth peak at ~40 Ma 6,7. The MECO has been identified in several sedimentary records around the globe, including the South Pacific Ocean 8,9. It is related to an increase in seawater temperature, from the surface to deep bathyal depths, and increasing pCO 2 in the atmosphere 10,11. Moreover, significant changes in atmospheric and oceanic circulation dynamics and in the patterns of continental rainfall are recorded 12,13. However, classic climatic models fail to explain how such conditions could persist for several hundreds of thousand years 14. Southern Ocean (SO) circulation is extremely important for understanding the climatic evolution during the Eocene, and particularly during the MECO. The separation of Australia from Antartica during the middle-late Eocene profoundly affected the circulation and made this region particularly sensitive to paleoceanographic changes 4,15. In this complex geological framework, the study of iron and manganese oxides in the sediments can provide important information, as they are strongly controlled by redox conditions and circulation 16. Manganese oxides typically occur as cryptocrystalline materials, in which Mn precipitates under different oxidation states: Mn 4+ , Mn 3+ and Mn 2+17. Moreover, Mn is more sensitive than Fe to pH, and requires more basic conditions to precipitate. Therefore, an environment may promote the oxidation and precipitation of iron and not of manganese, if the pH is not sufficiently high 18-21. Accordingly, relatively small shift in the redox conditions can change significantly the equilibrium solubility of these elements and thus their presence or absence in the geological record. Microorgani...

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“…Litho-and magnetostratigraphy, and Magnetic Susceptibility (MS) of core U1511B-16R (from ref. 26 ); and main elements abundance analysed by XRF from ref. 46 .…”

Section: Resultsmentioning

confidence: 99%

“…kyr, considering the sedimentation rate of ref. 26 . Smectite, which represents 40-50% of the non-biogenic fraction, starts increasing, whereas all the other minerals decrease (Fig.…”

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

See 3 more Smart Citations

Abyssal oceanic circulation and acidification during the Middle Eocene Climatic Optimum (MECO)

Cornaggia

Bernardini

Giorgioni

et al. 2020

Sci Rep

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Absolute Paleolatitude of Northern Zealandia From the Middle Eocene to the Early Miocene

et al. 2022

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The absolute position during the Cenozoic of northern Zealandia, a continent that lies more than 90% submerged in the southwest Pacific Ocean, is inferred from global plate motion models, because local paleomagnetic constraints are virtually absent. We present new paleolatitude constraints using paleomagnetic data from International Ocean Discovery Program Site U1507 on northern Zealandia and Site U1511 drilled in the adjacent Tasman Sea Basin. After correcting for inclination shallowing, five paleolatitude estimates provide a trajectory of northern Zealandia past position from the middle Eocene to the early Miocene, spanning geomagnetic polarity chrons C21n to C5Er (∼48–18 Ma). The paleolatitude estimates support previous works on global absolute plate motion where northern Zealandia migrated 6° northward between the early Oligocene and early Miocene, but with lower absolute paleolatitudes, particularly in the Bartonian and Priabonian (C18n–C13r). True polar wander (solid Earth rotation with respect to the spin axis), which only can be resolved using paleomagnetic data, may explain the discrepancy. This new paleomagnetic information anchors past latitudes of Zealandia to Earth's spin axis, with implications not only for global geodynamics, but also for addressing paleoceanographic and paleoclimate problems, which generally require precise paleolatitude placement of proxy data.

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Site U1511

Cited by 2 publications

References 23 publications

Abyssal oceanic circulation and acidification during the Middle Eocene Climatic Optimum (MECO)

Abyssal oceanic circulation and acidification during the Middle Eocene Climatic Optimum (MECO)

Absolute Paleolatitude of Northern Zealandia From the Middle Eocene to the Early Miocene

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