Detachment-parallel recharge can explain high discharge fluxes at the TAG hydrothermal field

Submarine massive sulfide deposits on slow-spreading ridges are larger and longer-lived than deposits at fast-spreading ridges, likely due to more pronounced tectonic faulting creating stable preferential fluid pathways. The TAG hydrothermal mound at 26∘N on the Mid-Atlantic Ridge (MAR) is a typical...

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Bibliographic Details
Published in:Earth and planetary science letters 2023-09, Vol.617, p.118245, Article 118245
Main Authors: Guo, Zhikui, Rüpke, Lars, Petersen, Sven, German, Christopher R., Ildefonse, Benoit, Hasenclever, Jörg, Bialas, Jörg, Tao, Chunhui
Format: Article
Language:English
Subjects:
3D modeling
black smoker
detachment
Earth Sciences
Geophysics
hydrothermal system
Sciences of the Universe
TAG
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Summary:Submarine massive sulfide deposits on slow-spreading ridges are larger and longer-lived than deposits at fast-spreading ridges, likely due to more pronounced tectonic faulting creating stable preferential fluid pathways. The TAG hydrothermal mound at 26∘N on the Mid-Atlantic Ridge (MAR) is a typical example located on the hanging wall of a detachment fault. It has formed through distinct phases of high-temperature fluid discharge lasting 10s to 100s of years throughout at least the last 50,000 yrs and is one of the largest sulfide accumulations on the MAR. Yet, the mechanisms that control the episodic behavior, keep the fluid pathways intact, and sustain the observed high heat fluxes of possibly up to 1700 MW remain poorly understood. Previous concepts involved long-distance channelized high-temperature fluid upflow along the detachment but that circulation mode is thermodynamically unfavorable and incompatible with TAG's high discharge fluxes. Here, based on the joint interpretation of hydrothermal flow observations and 3-D flow modeling, we show that the TAG system can be explained by episodic magmatic intrusions into the footwall of a highly permeable detachment surface. These intrusions drive episodes of hydrothermal activity with vertical discharge and recharge along the detachment. The numerical simulations reveal that the high-temperature circulation system at TAG may be confined to a vertical zone of enhanced permeability that channelizes upflow and a recharge system that is hosted by the detachment surface with a high permeability of 2×10−13 to 10−12m2. This revised flow regime reconciles problematic aspects of previously inferred circulation patterns and allows to identify the prerequisites for generating substantive seafloor mineral systems. •A new hydrothermal circulation mode that can explain the prolific TAG-like systems.•Detachment-parallel recharge helps sustaining high discharge hydrothermal fluxes.•Heat source should be close to the circulation pathways to sustain high heat fluxes.•Models and data suggest that TAG system is driven by episodic footwall intrusions.
ISSN:0012-821X
1385-013X
DOI:10.1016/j.epsl.2023.118245