Activation of slip systems in Sn-bearing sphalerite and its consequences for trace element mobility during fluid-assisted overprinting

Abstract

Critical metals (Ga, Ge, In, Sn) frequently occur as impurities in common sulfides like sphalerite, (Zn,Fe)S. Integrated micron- to nanoscale structural analysis enables reconstruction of trace element mobility during protracted geological events. Evolving chemical patterns at the grain-scale inform on different slip responses induced by oriented stress. Disrupted chemical oscillatory zoning patterns are examined across an individual Sn-bearing sphalerite crystal. Results show activation of two distinct slip systems, {101} and {111}, characterized by dislocation glide and creep, respectively. Tin is preserved in domains of {101} slip, while {111} slip causes complete Sn removal. Oscillatory zoning is associated with fine particles of stannite within bands of alternating orientation throughout {101} slip domains. Activation of slip systems is estimated to occur at ∼300 °C. A strain hardening effect, likely accentuated during Ostwald ripening is evidenced by short <111>ZnS stacking faults. Slip systems stresses (53.9‒110 MPa) are derived from dislocation density values extracted from microstructural maps, fluid fluxes are calculated using Darcy velocity. Rapid Sn mobilization (days to years) is estimated for fluid fluxes that preferentially remove Sn from {111} slip domains. Small-scale processes play decisive roles in dictating whether an ore deposit is created, modified, or rendered economically insignificant.