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Percorrer por autor "Xuan, Chuang"

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  • Depth fluctuations of mediterranean outflow water along its northward propagation during the late pleistocene
    Publication . Chen, Xinyang; Wu, Jiawang; Pang, Xiaolei; Dang, Haowen; Zhong, Lifeng; Yu, Jimin; Colin, Christophe; Liu, Zhifei; Lange, Gert J. de; Kaboth‐Bahr, Stefanie; Xuan, Chuang; Ikeda, Hisashi; Herbert, Timothy D.; Huang, Huai‐Hsuan May; Zarikian, Carlos A. Alvarez; Abrantes, Fatima; Hodell, David A.
    Mediterranean Outflow Water (MOW) critically influences the Atlantic Meridional OverturningCirculation, yet its northward transport dynamics along the Iberian Margin remain unclear. Using terrigenousgrain‐size sortable silt and benthic foraminiferal carbon isotopes from two depth‐strategic sites (U1389:644 m vs. U1588: 1,339 m), we constrain MOW's northward depth fluctuations over the last 250 kyr. Resultsshow that MOW progressively deepened from ∼100 to 60 ka, then stabilized—synchronized with theprevalence of millennial‐scale climate variability. During interglacials, MOW directly influenced U1588,while deepened below this site during glacials. Flow speed gradients between Sites U1389 and U1588 showpronounced precession cycles. At precession maxima—Northern Hemisphere summer insolation minima—when flow intensified, MOW underwent enhanced mixing and dilution during northward transport. Thisresults from increased density contrasts between MOW and ambient waters, indicating deeper MOWpenetration. We demonstrate precessional forcing on both the strength and depth of MOW's northward propagation.
    2025-07-11Artigo científico Acesso aberto Ver mais
  • Early Pleistocene (1.94–1.46 Ma) records for the upper mediterranean outflow Water branch reveal low and high latitude climate influences
    Publication . Voelker, Antje; Ducassou, Emanuelle; Balestra, Barbara; Flores, Jose Abel; Acton, Gary D.; Richter, Carl; Xuan, Chuang; Lofi, Johanna; Alberto, Ana; Kuhnert, Henning; Zarikian, Carlos A. Alvarez
    The Mediterranean Outflow Water (MOW), modified by paleoceanographic conditions and tectonic processes, played a significant role in the formation of sediments drifts along the Iberian Margin. Using sediment samples from IODP Hole U1387C, we explore the Early Pleistocene history of the upper MOW core above the central Faro Drift in the Gulf of Cadiz. The time series of benthic foraminifer stable isotope and grain size related data have a rigorous stratigraphic framework consisting of nannofossil biostratigraphy and paleomagnetic and delta 18O stratigraphy. The paleoenvironmental records are supplemented by natural gamma ray downhole logging data. Above the hiatus associated with the youngest dolostone, sandy to muddy contourite sedimentation started at 1.946 Ma, i.e., within Marine Isotope Stage (MIS) 74, at IODP Site U1387, slightly younger than at IODP Site U1389. Formation of contourite layers, reflected in the sortable silt and sand percentage records, strongly reacted to precession forcing, including semi- and quarter-precession cycles. The majority of the contourite beds developed during stadial (colder) climate periods, like previous observations from the Early to Late Pleistocene. Formation of contourite layers within MIS 53, MIS 55 and MIS 65, however, appear to be linked to the prevailing atmospheric conditions over North Africa. Periods of poor ventilation in the upper MOW were linked to insolation maxima and reduced ventilation in the Mediterranean Sea. Here, MIS 51 presents a peculiar case as poor ventilation reached from the surface to the lower North Atlantic Deep Water range, reflecting unique interglacial conditions that merit future exploration.
    2026-02Artigo científico Acesso aberto Ver mais