MELANGE AND LATE PALEOZOIC-TRIASSIC(?) CHERT, LIMESTONE, AND PILLOW BASALT ALONG A TERRANE SUTURE ZONE SOUTH OF THE DENALI FAULT, REINDEER HILLS, ALASKA
An increase in deformation intensity in the zone between the chert and melange is evidence that the chert-melange contact is a fault. The entire chert sequence is folded into a tight ENE-trending synform, parallel to the chert-melange fault contact and consistent with the NNW-SSE shortening recorded in the melange. If the flysch and conglomerate in the melange were derived from the adjacent Jurassic-Cretaceous Kahiltna assemblage, then the melange is post-early Late Cretaceous in age and probably formed in a suture zone between the Alaska margin and the accreting Wrangellia composite terrane. The exotic blocks may be fragments of the nearby Mystic or Dillinger terranes. The chert-pillow basalt sequence has oceanic affinity and could represent a seamount fragment or possibly a fragment of North American continental margin analogous to the Mystic or McKinley terranes, which both include Late Paleozoic radiolarian chert. The dextral strike-slip faults in the melange indicate that the late-stage NNW-SSE shortening was related to oblique-slip along the suture zone, consistent with Late Cretaceous-early Tertiary dextral simple shear along the Denali fault which trends ~E-W along the north side of the Reindeer Hills.