Exp. 390/393 South Atlantic Transect

航海概要

航海名	Exp. 390/393: South Atlantic Transect
プロポーザル／ Scientific Prospectus	・プロポーザル #853-Full2, #853-Add ・Scientific Prospectus ・Preliminary Report
共同首席研究者	Exp. 390: Rosalind Coggon and Jason Sylvan Exp. 393: Damon Teagle and Gail Christeson
掘削船	JOIDES Resolution
航海期間	Exp. 390: 2022年4月7日~6月7日 Exp. 393: 2022年6月7日~8月7日
乗船/下船地	Exp. 390: Cape Town, South Africa to Cape Town, South Africa Exp. 393:Cape Town, South Africa to Cape Town, South Africa
JRSOのページ	http://iodp.tamu.edu/scienceops/expeditions/south_atlantic_transect.html
掘削地点
科学目的	South Atlantic Transect Expeditions 390 and 393 (based on IODP Proposals 853-Full2 and 853-Add) are a multidisciplinary and joint scientific ocean drilling project that aims to recover complete sedimentary sections and ~200 m of oceanic crust along a crustal age transect at ~31°S across the South Atlantic Ocean to (1) investigate the history of low-temperature hydrothermal interactions between the aging ocean crust and the evolving South Atlantic Ocean; (2) quantify past hydrothermal contributions to global geochemical cycles; (3) investigate sediment and basement-hosted microbial community variation with substrate composition and age in the low energy South Atlantic Gyre subseafloor biosphere; and (4) investigate the responses of Atlantic Ocean circulation patterns and the Earth’s climate system to rapid climate change, including elevated CO2 during the Cenozoic. The South Atlantic Transect expeditions will target six primary sites on 7, 15, 31, 48, and 63 Ma ocean crust. The proposed transect, which follows a Mid-Atlantic Ridge crustal flow-line, will fill critical gaps in our sampling of intact in-situ ocean crust with regards to crustal age, spreading rate, and sediment thickness. The transect traverses the previously unexplored sediment- and basalt-hosted deep biosphere beneath the South Atlantic gyre, samples of which are essential to refine global biomass estimates and investigate microbial ecosystems’ responses to variable conditions in a low energy gyre and aging ocean crust. The transect is located near World Ocean Circulation Experiment (WOCE) line A10, providing access to records of carbonate chemistry and deep-water mass properties across the western South Atlantic through key Cenozoic intervals of elevated atmospheric CO2 and rapid climate change. Reconstruction of the history of the deep western boundary current and deep-water formation in the Atlantic basins will yield crucial data to test hypotheses regarding the role of evolving thermohaline circulation patterns in climate change, and the effects of tectonic gateways and climate on ocean acidification. 詳細についてはJRSOのページをご参照ください。 下記にCOVID-19に関する対応事項がございます： COVID-19 Protocol: The JRSO has created a protocol to safely operate during the COVID-19 pandemic. If pandemic conditions have not improved by early-mid 2022, one or both expeditions may need to sail with a reduced shipboard contingent. However, all participants will maintain their designation as science party members regardless of whether they sail or not, and will have equal access to all expedition data and core materials. The protocol is available here: http://iodp.tamu.edu/scienceops/JR_COVID-Mitigation-Protocols.pdf

J-DESCからの乗船研究者

Exp. 390 South Atlantic Transect 1

氏名	所属	役職	乗船中の役割
相澤　正隆	琉球大学	博士課程	Inorganic Geochemist
高田　真子	東京大学	修士課程	Organic Geochemist Microbiologis

Exp. 393 South Atlantic Transect 2

氏名	所属	役職	乗船中の役割
土井　信寬	千葉大学	博士課程	Micropaleontologist (nannofossils)
桑野　太輔	千葉大学	博士課程	Micropaleontologist (nannofossils)