Exp. 400 NW Greenland Glaciated Margin - J-DESC-日本地球掘削科学コンソーシアム

航海概要

J-DESCからの乗船研究者

氏名	所属	役職	乗船中の役割
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

航海名	Exp. 400: NW Greenland Glaciated Margin
プロポーザル／ Scientific Prospectus	・プロポーザル #909-Full2, #909-Add ・Scientific Prospectus
共同首席研究者	Paul Knutz and Anne Jennings
掘削船	JOIDES Resolution
航海期間	2023年8月12日~10月12日
乗船/下船地	Reykjavík to Reykjavík, Iceland
JRSOのページ	http://iodp.tamu.edu/scienceops/expeditions/nw_greenland_glaciated_margin.html
掘削地点	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)
科学目的	グリーンランド氷床史を理解し、北半球の氷河作用のメカニズムを解明することは、現代の気候温暖化システムを予測するための鍵となります。IODP 第400次研究航海では、北東バフィン湾の西グリーンランド縁辺域の7つの提案サイトにおいて、漸新世から完新世までの連続した厚い半遠洋性および氷河性海洋堆積物を掘削します。さまざまな時間スケールで氷床に影響を与える海洋、大気、軌道要素、地殻変動等とそのフィードバックを把握し、「氷床と海水準が温暖化する気候にどのように応答するのか？」という課題に取り組みます。 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.