Figure F75. Several faults cut a contact between a leucrocratic material and granoblastic basaltic material but have been later mineralized with vein materials, indicating that the timing of faulting postdated the contact but was followed by a lower temperature stage of alteration (Sample 335-1256D-236R-1, 0–4 cm; Thin Section 4). The alteration halo around the contact contains evidence of semibrittle deformation. A. Close-up image. B. Hand-drawn sketch. C, D. Thin section images of orange box in B in (C) plane-polarized and (D) cross-polarized light. E. Brittle shear vein filling prehnite (V1). F. Prehnite diffuse vein crosscuts the amphibole vein. G. Amphibole vein crosscuts the prehnite vein.
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