|航海名||Exp. 400: NW Greenland Glaciated Margin|
|・プロポーザル #909-Full2, #909-Add|
|共同首席研究者||Paul Knutz and Anne Jennings|
|乗船/下船地||Reykjavík to Reykjavík, Iceland|
Bathymetric map (IBCAO v3; Jakobsson et al. 2012) showing study area of proposal 909 and the main ocean current systems in Baffin Bay. WGC = West Greenland Current. BC = Baffin lsland Current. Yellow star demarks the area of the North Water Polynia. Proposed sites along key transect (yellow) and existing wells/boreholes are indicated. West Greenland trough-mouth fans; Melville Bay (MB), Upernavik (Up), Umiivik (Um) and Disko Bay (DB), are shown. (https://iodp.tamu.edu/scienceops/precruise/southatlantic/900-Full2_Knutz_web.pdf)
Understanding the long-term history of the Greenland Ice Sheet (GrIS) is key to understanding northern hemisphere glaciation, to elucidating mechanisms underlying amplification of glacial cycles since the late Pliocene and to predicting how the GrIS will respond to modern climate warming. To address current knowledge gaps in the evolution and variability of the GrIS and its role in Earth's climate system, we propose to drill along a transect across the northwest Greenland margin extending from the shelf to Baffin Bay where thick Cenozoic sedimentary successions primarily reflect the evolution of the northern GrIS (NGrIS). The mission strategy is to retrieve a composite stratigraphic succession representing the Late Cenozoic era from Oligocene/early Miocene to Holocene. The proposed drill sites will specifically target high-accumulation- rate deposits associated with contourite drifts and potential interglacial deposits within a trough-mouth-fan system including proximal shelf deposits, all densely covered by excellent quality 2-D and 3-D seismic data. We seek to test if the NGRIS underwent near-complete deglaciations in the Pleistocene and assess recent models for the change in orbital cyclicities through the Mid-Pleistocene transition. Moreover, the proposal will examine a possible linkage between the general decrease in atmospheric CO2 from the Oligocene to the early Miocene and arrival of cold and possibly glacially-dominated environments in northwest Greenland and establish the timing for tectonic margin adjustments inferred from the seismic record. Finally, records will be produced that can test hypothesis that glacial expansion of the NGrIS is linked with intensification of northern hemisphere glaciations (3.3-2.8 Ma) and unravel marine heat transport through the western North Atlantic and Baffin Bay as a potential cause for the Pliocene high Arctic warmth. The detailed information obtained from these paleoclimate archives will be of great value for predictive models addressing how the GrIS may respond to global warming in the near future. The overall aim is to investigate the full range of forcing and feedbacks - oceanic, atmospheric, orbital, tectonic - that influence the GrIS over a range of time scales, as well as conditions prevailing at the time of glacial inception and deglacial to interglacial periods. The scientific objectives of this proposal are of key significance in addressing the challenges "How do ice sheets and sea level respond to a warming climate?" and "How does Earth's climate system respond to elevated levels of atmospheric CO2?" under the Climate and Ocean Change theme of the IODP science plan.
|関 宰||北海道大学||准教授||Organic Geochemist|
|横山 由香||東海大学||助教||Physical Properties Specialist|