Exp. 401: Mediterranean-Atlantic Gateway Exchange

航海名

Expedition 401: Mediterranean-Atlantic Gateway Exchange
Investigating Miocene Mediterranean-Atlantic Gateway Exchange (IMMAGE)

• プロポーザル 895-Full3, 895-Add2
• Scientific Prospectus （準備中）

JRSOのページ ＞＞ こちら

航海予定期間

2023年12月10日～2024年2月9日

掘削船

JOIDES Resolution

乗船/下船地

Amsterdam, Netherlands to Napoli, Italy

掘削地点

科学目的

本航海は後期中新世の始まりから現在に至るまでの、大西洋と地中海間における海水の交換の完全な記録を復元することを目的とし、ジブラルタル海峡を挟んだ地中海と大西洋の計３地点での掘削を計画しています。

海峡は、大洋(ocean）と海(sea)の間の海水、熱、塩分、栄養塩の交換に重要な役割を果たしています。高塩分の海水の移動は、地球規模の熱塩循環を促進します。また、海洋は二酸化炭素の最大の貯蔵庫であるため、この流れは大気中の二酸化炭素濃度にも影響します。海峡の形状が変化すると、地球規模の海洋循環のパターンやそれに伴う熱輸送、気候が大きく変化するだけでなく、局所的にも大きな影響を与えることになります。ジブラルタル海峡を通って大西洋と地中海を行き来する海水の量は、地球上で最大級です。過去500万年にわたり、大西洋の中層に塩分を含んだプルームを生成し、カディス湾に独特の輪郭を持った堆積物を堆積させ、北大西洋深層水の形成に寄与してきました。

なお、本航海は、海洋掘削と陸上掘削を一貫したプロジェクトとして実施するLand-to-Seaプロジェクトとして行われ、国際陸上科学掘削計画（ICDP）での陸上掘削も予定されています。

Marine gateways play a critical role in the exchange of water, heat, salt and nutrients between oceans and seas. The advection of dense waters helps drive global thermohaline circulation and, since the ocean is the largest of the rapidly exchanging CO2 reservoirs, this advection also affects atmospheric carbon concentration. Changes in gateway geometry can therefore significantly alter both the pattern of global ocean circulation and associated heat transport and climate, as well as having a profound local impact.
Today, the volume of dense water supplied by Atlantic-Mediterranean exchange through the Gibraltar Strait is amongst the largest in the global ocean. For the past five million years this overflow has generated a saline plume at intermediate depths in the Atlantic that deposits distinctive contouritic sediments in the Gulf of Cadiz and contributes to the formation of North Atlantic Deep Water. This single gateway configuration only developed in the early Pliocene, however. During the Miocene, a wide, open seaway linking the Mediterranean and Atlantic evolved into two narrow corridors: one in northern Morocco; the other in southern Spain. Formation of these corridors permitted Mediterranean salinity to rise and a new, distinct, dense water mass to form and overspill into the Atlantic for the first time. Further restriction and closure of these connections resulted in extreme salinity fluctuations in the Mediterranean, leading to the formation of the Messinian Salinity Crisis salt giant.
IMMAGE is an amphibious drilling proposal designed to recover a complete record of Atlantic-Mediterranean exchange from its Late Miocene inception to its current configuration. This will be achieved by targeting Miocene offshore sediments on either side of the Gibraltar Strait with IODP and recovering Miocene core from the two precursor connections now exposed on land with ICDP. The scientific aims of IMMAGE are to constrain quantitatively the consequences for ocean circulation and global climate of the inception of Atlantic-Mediterranean exchange; to explore the mechanisms for high amplitude environmental change in marginal marine systems and to test physical oceanographic hypotheses for extreme high-density overflow dynamics that do not exist in the world today on this scale.

詳細については、Call for Applications、Additional Call for Applications、JRSOのページをご参照ください。

共同首席研究者

Rachel Flecker and Emmanuelle Ducassou

J-DESCからの乗船研究者

乗船者追加募集中