Crustal structure of the Trans-Atlantic Geotraverse (TAG) segment (Mid-Atlantic Ridge, 26°10′N) : implications for the nature of hydrothermal circulation and detachment faulting at slow spreading ridges
MetadataShow full item record
KeywordTAG hydrothermal field; Crustal structure; Detachment faulting; Mid-Atlantic Ridge; Slow spreading ridge
New seismic refraction data reveal that hydrothermal circulation at the Trans-Atlantic Geotraverse (TAG) hydrothermal field on the Mid-Atlantic Ridge at 26°10′N is not driven by energy extracted from shallow or mid-crustal magmatic intrusions. Our results show that the TAG hydrothermal field is underlain by rocks with high seismic velocities typical of lower crustal gabbros and partially serpentinized peridotites at depth as shallow as 1 km, and we find no evidence for low seismic velocities associated with mid-crustal magma chambers. Our tomographic images support the hypothesis of Tivey et al. (2003) that the TAG field is located on the hanging wall of a detachment fault, and constrain the complex, dome-shaped subsurface geometry of the fault system. Modeling of our seismic velocity profiles indicates that the porosity of the detachment footwall increases after rotation during exhumation, which may enhance footwall cooling. However, heat extracted from the footwall is insufficient for sustaining long-term, high-temperature, hydrothermal circulation at TAG. These constraints indicate that the primary heat source for the TAG hydrothermal system must be a deep magma reservoir at or below the base of the crust.
Author Posting. © American Geophysical Union, 2007. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Geochemistry Geophysics Geosystems 8 (2007): Q08004, doi:10.1029/2007GC001629.
Suggested CitationGeochemistry Geophysics Geosystems 9 (2007): Q08004
Showing items related by title, author, creator and subject.
Three-dimensional seismic structure of a Mid-Atlantic Ridge segment characterized by active detachment faulting (Trans-Atlantic Geotraverse, 25°55′N-26°20′N) Zhao, Minghui; Canales, J. Pablo; Sohn, Robert A. (American Geophysical Union, 2012-11-02)We use air gun shots recorded by ocean bottom seismometers (OBSs) to generate a three-dimensional (3D) P-wave tomographic velocity model of the Trans-Atlantic Geotraverse (TAG) segment of the Mid-Atlantic Ridge, and to ...
Parnell-Turner, Ross; Sohn, Robert A.; Peirce, Christine; Reston, Tim J.; MacLeod, Christopher J.; Searle, Roger C.; Simão, Nuno Mendes (Geological Society of America, 2020-11-04)At slow-spreading ridges, plate separation is commonly partly accommodated by slip on long-lived detachment faults, exposing upper mantle and lower crustal rocks on the seafloor. However, the mechanics of this process, the ...
Nonvolcanic seafloor spreading and corner-flow rotation accommodated by extensional faulting at 15°N on the Mid-Atlantic Ridge : a structural synthesis of ODP Leg 209 Schroeder, Timothy; Cheadle, Michael J.; Dick, Henry J. B.; Faul, Ulrich; Casey, John F.; Kelemen, Peter B. (American Geophysical Union, 2007-06-28)Drilling during ODP Leg 209, dredging, and submersible dives have delineated an anomalous stretch of the Mid-Atlantic Ridge north and south of the 15°20′N Fracture Zone. The seafloor here consists dominantly of mantle ...