(U–Th)/He thermochronometry reveals Pleistocene punctuated deformation and synkinematic hematite mineralization in the Mecca Hills, southernmost San Andreas Fault zone

摘要: Abstract The timing, tempo, and processes of punctuated deformation in strike-slip fault systems are challenging to resolve the rock record. Faults Mecca Hills, adjacent southernmost San Andreas Fault, California, accommodate active exhumation Plio-Pleistocene sedimentary rocks underlying crystalline basement. We document spatiotemporal patterns Fault-related as recorded basement Hills using microstructural observations, geochemical data, hematite ( n = 24 ) apatite 44 (U–Th)/He (hematite He, He) thermochronometry data. Reproducible mean He dates from minor hematite-coated surfaces Painted Canyon Fault damage zone range ∼0.7–0.4 Ma younger than ∼1.2 host rock. These data reveal concomitant Pleistocene pulses slip, fluid flow, synkinematic mineralization. Hematite textures, crystal morphology, imply some occurred via cyclic crack-seal creep processes. Apatite define distinct date-eU indicate cooling across discrete blocks Hills. Uniform regardless eU located exclusively between Platform faults. Outside this block, samples yield individual ∼30–1 that a positive correlation. focused away main trace at Ma. Low-temperature fault-related provides an unprecedented window into 10 5 – 6 -yr record documents mechanisms may be operative other faults world-wide.