Publication Date:
2021-12-13
Description:
Submarine massive sulfide deposits on slow-spreading ridges are larger and longer-lived than deposits at fast-spreading ridges 1,2 , likely due to more pronounced tectonic faulting creating stable preferential fluid pathways 3,4 . 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 5-7 . It has formed through distinct phases of high-temperature fluid discharge lasting 10s to 100s of years throughout at least the last 50,000 years 8 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 up to 1800 MW 9 remain poorly understood. Previous concepts involved long-distance channelized high-temperature fluid upflow along the detachment 5,10 but that circulation mode is thermodynamically unfavorable 11 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 sub-vertical discharge and recharge along the detachment. This revised flow regime reconciles problematic aspects of previously inferred circulation patterns and can be used as guidance to one critical combination of parameters that can generate substantive mineral systems.
Type:
Article
,
NonPeerReviewed
,
info:eu-repo/semantics/article
Format:
text
DOI:
10.21203/rs.3.rs-1030743/v1
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