Dataset Information

Narduzzi, Francesco; ORCID: 0000-0003-4257-2229
Tribuzio, Riccardo
Cannaò, Enrico
Mariani, Davide
Tiepolo, Massimo
Zanetti, Alberto

How fluids penetrate and initiate hydration within the lower oceanic crust during detachment-driven exhumation remains poorly understood. Here, we constrain this process through a petrological and geochemical study of brown amphibole veins, brown amphibole mylonites, and coeval late-stage magmatic felsic veins from the upper ~240 m of IODP Hole U1473A (Atlantis Bank, Southwest Indian Ridge). Amphibole and plagioclase (An27-37) in amphibole veins and mylonites yield overlapping compositions, recording crystallization temperatures clustering at ~790 °C. Specifically, amphibole is Cl-rich and plagioclase exhibits a uniform ⁸⁷Sr/⁸⁶Sr ratio of ~0.7028. In contrast, late-stage felsic veins display distinct chemical signatures, including Cl-poor and REE-rich amphibole, while the 87Sr/86Sr ratio of plagioclase (An16-33) remains nearly constant (~0.7029). Crystallization temperatures of the felsic veins (860-670 °C) reflect fractional crystallization of plagioclase and minor amphibole from residual melts following oxide gabbro crystallization. The geochemical features of amphibole veins rule out direct seawater-gabbro interaction or fluid mixing with late-stage felsic melts. Instead, we propose that seawater ingress via flexural faulting in the uppermost exhuming footwall triggered partial melting of low-solidus oxide gabbros. Strain localized within these domains to form amphibole mylonites, whereas the migration and interaction of H2O-rich anatectic melts with host gabbros generated the amphibole veins.

Narduzzi, F., Tribuzio, R., Cannaò, E., Mariani, D., Tiepolo, M., Zanetti, A., 2027. Mineral major and trace element contents, plagioclase Sr isotopes and temperature estimates of brown amphibole veins and their reconstructed bulk compositions from Atlantis Bank oceanic core complex, IODP Hole U1473A, Southwest Indian Ridge, Version 1.0. Interdisciplinary Earth Data Alliance (IEDA). https://doi.org/10.60520/IEDA/114624. Accessed 2026-10-12.

2026-10-06

Creative Commons Attribution 4.0 International [CC-BY-4.0]

Coverage Scope: Regional (Continents, Oceans)

Amphibole, Atlantis Bank, Fluid-rock interaction, Oceanic core complex, In situ trace element geochemistry

2027-09-07

Collection