Exp. 389 Hawaiian Drowned Reefs

航海概要

テーマ

Hawaiian Drowned Reefs

• プロポーザル #716
• Scientific Prospectus: To be published

ECORDのページ＞＞こちら

航海予定期間

Offshore (乗船): 2023年8月中旬～10月末 (最大60日間)
Onshore Science Party (航海後の陸上分析): 2024年早々（詳細な日程は未定） at MARUM（ドイツのブレーメン大学海洋環境科学センター）

※応募される際、「Onshoreのみ参加希望」もしくは「Offshoreとonshoreの両方に参加希望」をご記入ください。「Offshoreのみの参加」という選択肢はありませんのでご注意ください。

掘削船

Mission Specific Platform (TBD)

乗船/下船地

TBD

掘削地点

Hawaiian drowned reefs
ハワイ島近海　沈水サンゴ礁

科学目的

本航海では、ハワイ周辺の海底下134～1155mに存在する沈水サンゴ礁を掘削します。ハワイは過去に、1000年間で2.5～2.6cmという、急速な、しかしほぼ一定の速度で沈降しました。その結果、100～200mもの厚さにわたり浅部サンゴ礁の一連の層が、海底下に保存されています。これらのサンゴ礁は、地球の気候変動において重要な時期に生息していたと考えられます。掘削により、過去50万年間の古気候の解明、詳細な海水準曲線の復元、突然の気候変動に対するサンゴ礁の生態学的な応答、さらにはハワイの沈降と火山活動の歴史を解明することが目的です。

The overall goal of the drilling campaign is to sample a unique succession of drowned coral reefs around Hawaii now at -134 to -1155 m below sea level. As a direct result of Hawaii’s rapid (2.5-2.6/kyr) but nearly constant subsidence, a thick (100-200 m) expanded sequence of shallow coral reef dominated facies is preserved within the reefs. These reefs span important periods in Earth climate history, either not available or highly condensed on stable (Great Barrier Reef, Tahiti) and uplifted margins (Papua New Guinea, Barbados) due to a lack of accommodation space and/or unfavourable shelf morphology. Specifically, these data show that the reefs grew (for ~90-100 kyrs, albeit episodically) into, during and out of the majority of the last five to six glacial cycles.

Therefore, scientific drilling through these reefs will generate a new record of sea-level and associated climate variability during several controversial and poorly understood periods over the last 500 kyr.

The project has four major objectives:

1) To define the nature of sea level-change in the central Pacific over the last 500 kyr, we will construct a new, more complete sea level curve from the drowned Hawaiian reefs that will allow: a) more detailed testing of Milankovitch climate theory predictions and; b) improved constraints on millennial-scale sea-level changes over the last 500 kyr.

2) To identify critical processes that determine paleoclimate variability of the central Pacific over the last 500 kyr, we will: (a) reconstruct the mean and seasonal/interannual climate variability from massive coral samples; and (b) use these records to investigate how high latitude climate (e.g., ice sheet volume), pCO2, and seasonal solar radiation impact subtropical Pacific climate. This approach can be used to test theoretical predictions of climate response and sensitivity to changes in boundary conditions and climate forcing.

3) To establish the geologic and biologic response of coral reef systems to abrupt sea-level and climate changes, we will: (a) establish the detailed stratigraphic and geomorphic evolution of the reefs in response to these changes; (b) test ecologic theories about coral reef resilience and vulnerability to extreme, repeated environmental stress over interglacial/glacial to millennial time scales; and (c) establish the nature of living and ancient microbial communities in the reefs and their role in reef building.

4) To elucidate the subsidence and volcanic history of Hawaii, we will: (a) refine the variation through space and time of the subsidence of Hawaii, and; (b) improve the understanding of the volcanic evolution of the island.

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

共同首席研究者

Jody Webster and Christina Ravelo

J-DESCからの乗船研究者