Dispersed remnants of a northeast Pacific fringing arc: Upper Paleozoic terranes of Permian McCloud Faunal affinity, western U.S.

Abstract

Two fragmentary, subparallel belts of terranes within the western North American Cordillera contain upper Paleozoic rocks and are characterized by contrasting lithotectonic assemblages and contrasting Permian faunal affinity. These two belts are (A) volcanic-arc related successions of Permian McCloud faunal affinity (McCloud belt) and (B)•bd•ctio•related accretionary complexes of Permian Tethyan faunal affinity (Cache Creek belt). This paper supports the hypothesis that the fragmentary terranes of the McCloud belt once constituted parts of a northeast Pacific fringing-arc system and, in constrast to some earlier interpretations, concludes that the volcanic arc evolved above an eastward dipping subduction zone. The absolute distance between this arc and western North America during the late Paleozoic cannot be constrained, however, there is little evidence to suggest closure of a major (> 103 kin) ocean basin or protracted periods of westward dipping subduction. Parts of Devonian to Permian volcanic island arc sequences of the western U.S. Cordillera are represented in the northern Sierra, eastern Klamath, Bilk Creek, Grindstone, and Chilliwack terranes. These scattered volcanic arc remnants share several fundamental characteristics: (1) The sequences were constructed across continental-affinity basement assemblages. (2) They underwent similar tectonic evolution during late Paleozoic time, such as coeval pulses in volcanism and related depositional histories. (3) They contain Early Permian McCloud-type fauna, of distinctive biogeographic affinity. (4) McCloud belt terranes are spatially and possibly genetically related to westward lying accretionary complexes of the Cache Creek belt which contain fragments of Upper Triassic blueschist and Permian limestone blocks bearing Tethyan Permian fusulinids and corals. Based on the presence of distinctive Early Permian McCloud fauna, the island arc remnants discussed in this paper are referred to as the McCloud belt. The similarities between McCloud belt terranes suggest that they were once parts of a long-lived late Paleozoic volcanic arc complex. The stratigraphy of these terranes records the tectonic evolution of the volcanic arc. Volcanism within the Paleozoic arc began as early as the Early Devonian, and was succeeded or accompanied by carbonate and epiclastic sedimentation during the Middle and Late Devonian. An influx of detritus derived from sedimentary and metasedimentary rocks during the Late Devonian and Mississippian records the uplift and erosion of arc basement sequences, an event that was, at least locally, accompanied by ongoing volcanism. A pulse in volcanism during the Pennsylvanian and coeval uplift led to the establishment of shallow marine and deltaic volcanogenic and carbonate sedimentation and, locally, subaerial exposure which persisted into the early Early Permian. Elsewhere during the Early Permian, shallow-water carbonate deposition was established, with only minor influx of volcanogenic debris. During the Late Permian, and locally as early as lat...

The odyssey of the Cache Creek terrane, Canadian Cordillera: Implications for accretionary orogens, tectonic setting of Panthalassa, the Pacific superwell, and break-up of Pangea

“…The McCloud Fauna is distinct from the fauna of coeval North American strata. The degree of separation required to produce this faunal provincialism is commonly assumed to have been b 1000 km [24,25], and the arcs are inferred to have been separated from the autochthon by a marginal basin [16] or to be autochthonous on North American basement [26] (Fig. 2).…”

The timing and provenance record of the Late Permian Klondike orogeny in northwestern Canada and arc‐continent collision along western North America

“…The Permian McCloud Limestone on the eastern Klamath terrane of northern California contains one of the defining fusulinid genera of the pericratonic biogeographic province, and Miller [1987] introduced the name "McCloud belt" to describe the known terranes associated with these faunas. Autochthonous occurrences of McCloud belt fusulinid species are recognized at paleoequatorial latitudes in west Texas, implying a more southerly latitude for the pericratonic terranes during the Permian [Stevens and Belasky, 2009].…”

“…The origin and evolution of the Klondike arc is interpreted to document the closure of a marginal ocean basin, the Slide Mountain ocean, and tectonic transport of the Yukon-Tanana terrane toward western North America. One of the better known aspects of the pericratonic arcs, including the YukonTanana terrane, is the presence of Permian rocks with marine fossils of the "McCloud belt" biogeographic province that are distinct from coeval fauna of the ancestral North American margin [Miller, 1987;. These fossils have greatly influenced ideas on Permian terrane transport and rates of plate convergence, implying that flare-up of the Klondike arc commenced 2000-3000 km west of the North American craton at a more southerly latitude than today [Belasky et al, 2002;Stevens and Belasky, 2009].…”

Structural analysis and ore controls in the Coeur D'Alene mining district, Idaho

“…A fourth hypothesis to generate the regional cleavage involves the docking of the Wallowa terrane (Jones and others, 1977;Mortimer, 1986;Miller, 1987;Coney, 1989) somewhere between 87-75 Ma (Criss and Fleck, 1987, p. 122). This terrane pushed eastward more than 80 miles in the later Cretaceous, produced sinistral slip along its northern margin (the Clearwater axis, 80 miles to the south), and slip was more or less easterly past rocks of the North American plate (Anderson, 1991).…”