Hydrothermal silicification and active extensional faulting: Insights from the Kornos-Aghios Ioannis fault, Lemnos Island, Greece

• DOI: 10.1130/b37810.1
• Publication Date: 2025-04-07T20:11:19Z
• Authors: L.R. Berio; F. Balsamo; A. Lucca; M. Pizzati; F. Storti; L. Aldega; A. Cipriani; L. Dallai; F. Lugli; L. Mantovani; V. Moretto; T. Trua; S. Zanchetta; G. Viola
• Keywords: Extensional fault

Fault-related diagenesis critically influences the petrophysical and mechanical properties of fault zones, affecting fluid circulation seismicity in upper crust. Questions remain about composition mineralizing fluids role architecture controlling distribution hydrothermal silicification. This study addressed these questions by establishing source documenting spatial variability synkinematic products along Kornos-Aghios Ioannis (Lemnos, Greece). The is an ∼10-km-long extensional system that deforms, at shallow depth (<1 km), Eocene−Miocene sandstone turbidites volcanic rocks. Our multidisciplinary approach, combining structural analysis, petrography, mineralogy, geochemistry, inclusion microthermometry, revealed silicification occurred epithermal environment assisted acid-sulfate (temperature ∼160−170 °C). Mineralizing were predominantly meteoric origin, with a possible residual magmatic component. intensity decreases distance from principal slip surface, forming up to 250-m-thick rock volumes that, locally, outsize width damage zone. Along strike, only ∼4-km-long segment exhibits silica cementation. along-strike best explained long-term evolution system. Kilometer-scale soft- hard-linkage patterns combined second-order geometric complexities (e.g., breached relay ramps tips) localized flow promoted extensive alteration. findings have implications for understanding permeability structure silica-cemented relevance assessment seismic hazards exploration natural resources siliciclastic