ORCID

Abstract

International Ocean Discovery Program (IODP) Expedition 399 collected new cores from the Atlantis Massif (30°N; Mid-Atlantic Ridge), an oceanic core complex that hosts the Lost City hydrothermal field (LCHF). Studies of the Atlantis Massif and the LCHF have transformed our understanding of tectonic, magmatic, hydrothermal, and microbial processes at slow-spreading ridges. The Atlantis Massif was the site of four previous expeditions (Integrated Ocean Drilling Program Expeditions 304, 305, and 340T and IODP Expedition 357) and numerous dredging and submersible expeditions. The deepest IODP hole in young (<2 My) oceanic lithosphere, Hole U1309D, was drilled ~5 km north of the LCHF and reached 1415 meters below seafloor (mbsf) through a series of primitive gabbroic rocks. A series of 17 shallow (<16.4 mbsf) holes were also drilled at 9 sites across the south wall of the massif during Expedition 357, recovering heterogeneous rock types including hydrothermally altered peridotites, gabbroic, and basaltic rocks. The hydrologic regime differs between the two locations, with a low-permeability conductive regime in Hole U1309D and a high- (and possibly deep-reaching) permeability regime along the southern wall.

Publication Date

2025-05-03

Publication Title

Proceedings of the International Ocean Discovery Program

Volume

399

ISSN

2377-3189

Acceptance Date

2025-05-03

Deposit Date

2025-10-14

Keywords

abiotic organic synthesis, Biosphere Frontiers, Building Blocks of Life, Atlantis Massif, carbon budget, deep biosphere, detachment fault, Earth Connections, Earth in Motion, Expedition 399, geomicrobiology, International Ocean Discovery Program, IODP, JOIDES Resolution, Lost City hydrothermal field, mantle, peridotite, serpentinization, Site U1309, Site U1601, ultramafic, wireline logging

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