Structural aspects of diapiric mélange emplacement: the Duck Creek diapir

摘要: Abstract The Duck Creek melange is one of a series diapiric mud intrusions into the slope cover sequence Cascadia Accretionary Wedge. diapir originated deep within accreted Hoh sequences and has intruded approximately 1 km up 2–3 thick Pliocene Quinault at its current level exposure in coastal seacliffs. Analyses geometry kinematic indicators strongly suggest that this part low angle to form an inclined sill or dyke-like body least 0.5 diameter. Microstructural analysis indicates zonation deformational features between core margins resulting from evolving fabrics increasing concentration strain towards margins. Specifically, we interpret early independent particulate flow (IPF) as indicating deformation effective stress environment with possibility turbulence during initial mobilization intrusion. subsequent transition cataclastic occurring presence stress, creation broad marginal shear zones suggests hardening. final IPF limited narrow softened zone decreasing stresses latest intrusion phase. In addition, abundance veining phases associated latter history became major fluid conduit for mineralizing fluids toward end emplacement history.