Precessional changes in the western equatorial Pacific Hydroclimate: A 240 kyr marine record from the Halmahera Sea, East Indonesia

• Published in: Geochemistry, geophysics, geosystems : G3 geophysics, geosystems : G3, 2015-01, Vol.16 (1), p.148-164
• Main Authors: Dang, Haowen, Jian, Zhimin, Kissel, Catherine, Bassinot, Franck
• Format: Article
• Language: English
• Subjects: Atmospheric convection; Autumn; Climate change; Climatology; Earth Sciences; El Nino; Geological time; Hydroclimate; Marine; Marine sediments; Ocean, Atmosphere; Paleoclimate science; precession; Sciences of the Universe; Sedimentary geology; Southern Oscillation; Summer; Trace elements; western equatorial Pacific
• ISSN: 1525-2027; 1525-2027
• DOI: 10.1002/2014GC005550

Within the precession band, an interhemispheric antiphase pattern in the tropical hydroclimate is supported by many paleorecords, and optimally explained by the forcing of precessional insolation change. However, scenarios within the western equatorial Pacific (WEP), which plays the role of the ascending center of atmospheric convection, remain poorly determined. In this study, a marine sediment core from the Halmahera Sea, East Indonesia, was analyzed with high‐resolution XRF scanning, quantitative discrete XRF, and ICP‐AES/MS measurements. The terrigenous fractions in this core are constrained by their trace elemental characteristics to be locally sourced from Halmahera Island, and hence reflect variations in the local riverine runoff and precipitation. On this basis, a continuous record of precipitation changes of the western equatorial Pacific was reconstructed with multidecadal resolution over the last ∼240 ka, using an age model established by the correlation between an adjusted ice volume model and benthic δ18O constrained by 14C dating. The records of terrigenous input show a dominant ∼23 kyr periodicity with a 90°∼100° phase lag to the boreal summer (i.e., in‐phase with the boreal autumn) insolation change. This pattern can be explained by the variability in the convective activity over the WEP, which might be primarily controlled by precessional changes in the El Niño and Southern Oscillation (ENSO) system. A dynamic linkage is implied between the precessional variations in the convective activity in the WEP and the East Asian and Australia‐Indonesian summer monsoons (EASM and AISM), in the sense of their distinct stable phase relationship to precession. Key Points: The age model is established with reliability on precession band The provenance of sediment is determined to be mainly locally derived The terrigenous fraction varies in‐phase with boreal autumn insolation