Paleogeographic setting of the Schoonover sequence, Nevada, and implications for the late Paleozoic margin of western North America

Whiteford, W. B.

doi:10.1130/spe255-p115

Cited by 10 publications

(2 citation statements)

References 16 publications

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“…This conclusion has also been stressed by Miller et al [1982Miller et al [ , 1984Miller et al [ , 1991 and is supported by the observation that structures formed during back arc basin closure in the southern Andes are very similar to structures formed during arc-continent collision in New Guinea (Figure 4). This structural ambiguity underscores the importance of using other lines of evidence, such as stratigraphic, paleogeographic, and/or regional relations, in interpreting the Permo-Triassic development of the western U.S. Cordillera [e.g., Miller et al, 1984Miller et al, , 1991Tomlinson and Wright, 1986;Miller, 1987;Miller and Wright, 1987;Tomlinson, 1988Tomlinson, , 1990Harwood and Murchey, 1990;Stevens et al, 1990;Whiteford, 1990;Harwood et al, 1991;Miller and Saleeby, 1991 ]; at the present time, these latter relations collectively favor a model in which the McCloud arc was west facing and the Havallah basin was a back arc basin.…”

Section: Tectonics Of the Sonoma Orogenymentioning

confidence: 99%

Permo‐Triassic tectonism in volcanic arc sequences of the western U.S. Cordillera and implications for the Sonoma orogeny

Wyld¹

1991

Tectonics

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The Permo-Triassic Sonoma orogeny, western U.S. Cordillera, involved fight folding and imbricate thrust faulting of basinal strata of the Golconda allochthon. This event is generally interpreted in terms of accretion of upper Paleozoic volcanic arc rocks of the western U.S. Cordillera ("McCloud arc") to the North American continent, either via back arc basin closure or arc-continent collision. The structural history of the McCloud arc during the Sonoma orogeny is poorly understood, however, as are the implications of this history for tectonic models. This paper presents a synthesis of the Permian to Triassic stratigraphic and structural evolution of the McCloud arc, incorporating new data from the Pine Forest Range, northwest Nevada. The synthesis indicates that, on a regional scale, the arc was affected by widespread uplift but only local tilting, folding and faulting in the Late Permian to Early Triassic. The timing of Permo-Triassic tectonic activity in the McCloud arc is thus similar to the middle Permian to Early Triassic age of deformation in the Golconda allochthon but the structures produced in the two groups of rocks differ markedly. The significance of this contrasting structural response to Sonoma age tectonism can be evaluated by comparison with other better understood examples of arc-continent accretion (back arc basin closure in the southern Andes, "compressional" arc-continent collision in New Guinea and "extensional" arccontinent collision in the Mediterranean). This comparison indicates that the contrasting structural history of the McCloud arc and Golconda allochthon is entirely compatible with an arccontinent accretion model for the Sonoma orogeny and cannot be used as a basis for concluding that the McCloud arc was not involved in the orogenic event. The comparison further indicates that either back arc basin closure or "compressional" arc-continent collision are the most likely settings for the Sonoma orogeny. In contrast, an "extensional" Mediterraneanstyle arc-continent collision, as has been recently proposed for the earlier (middle Paleozoic) Antler orogeny, is probably not an appropriate analogue for the Sonoma orogeny. The weak structural response of the McCloud arc during Sonoman compression also provides new constraints on the specific processes involved in arc accretion, either via arc-continent collision or back arc basin closure. These constraints suggest that there may be few fundamental differences between the two models during the final stages of arc accretion. Regardless of tectonic setting, Permo-Triassic uplift and associated deformation in the McCloud arc should be considered as much a response to the Sonoma orogeny as is fight folding and imbricate faulting in the Golconda allochthon. A second model interprets the arc to have been east facing, and suggests that the Havallah sequence and related rocks were deformed as they were offscraped from the subducting edge of the North American plate and incorporated into a growing accretionary prism east of the arc [Speed, 1979; Snyd...

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Section: Tectonics Of the Sonoma Orogenymentioning

confidence: 99%

Permo‐Triassic tectonism in volcanic arc sequences of the western U.S. Cordillera and implications for the Sonoma orogeny

Wyld¹

1991

Tectonics

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“…This model is supported by the fact that initial stages of the development of the Havallah basin coincided with Late Devonian magmatism in the northern Sierra arc, as shown by the presence of Famennian fossils both in the Sierra Buttes Formation (Hanson and Schweickert, 1986) and in basal strata within the Havallah basin (Miller et al, 1984(Miller et al, , 1992. Placing the mid-Paleozoic northern Sierran arc directly outboard of the Havallah basin also provides a source for influx of significant amounts of arc-type volcaniclastic debris that was shed from the west in the early Mississippian (Kinderhookian) into parts of the Havallah basin (Miller et al, 1984(Miller et al, , 1992Harwood and Murchey, 1990;Whiteford, 1990).…”

Section: Broader Tectonic Implicationsmentioning

confidence: 89%

Nature and timing of Late Devonian–early Mississippian island-arc magmatism in the Northern Sierra terrane and implications for regional Paleozoic plate tectonics

et al. 2019

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The Northern Sierra terrane is one of a series of Paleozoic terranes outboard of the western Laurentian margin that contain lithotectonic elements generally considered to have originated in settings far removed from their present relative locations. The Lower to Middle Paleozoic Shoo Fly Complex makes up the oldest rocks in the terrane and consists partly of thrust-imbricated deep-marine sedimentary strata having detrital zircon age signatures consistent with derivation from the northwestern Laurentian margin. The thrust package is structurally overlain by the Sierra City mélange, which formed within a mid-Paleozoic subduction zone and contains tectonic blocks of Ediacaran tonalite and sandstone with Proterozoic to early Paleozoic detrital zircon populations having age spectra pointing to a non–western Laurentian source. Island-arc volcanic rocks of the Upper Devonian Sierra Buttes Formation unconformably overlie the Shoo Fly Complex and are spatially associated with the Bowman Lake batholith, Wolf Creek granite stock, and smaller hypabyssal felsic bodies that intrude the Shoo Fly Complex. Here, we report new results from U-Pb sensitive high-resolution ion microprobe–reverse geometry (SHRIMP-RG) dating of 15 samples of the volcanic and intrusive rocks, along with geochemical studies of the dated units. In addition, we report U-Pb laser ablation–inductively coupled plasma–mass spectrometry ages for 50 detrital zircons from a feldspathic sandstone block in the Sierra City mélange, which yielded abundant Ordovician to Early Devonian (ca. 480–390 Ma) ages. Ten samples from the composite Bowman Lake batholith, which cuts some of the main thrusts in the Shoo Fly Complex, yielded an age range of 371 ± 9 Ma to 353 ± 3 Ma; felsic tuff in the Sierra Buttes Formation yielded an age of 363 ± 7 Ma; and three felsic hypabyssal bodies intruded into the Sierra City mélange yielded ages of 369 ± 4 Ma to 358 ± 3 Ma. These data provide a younger age limit for assembly of the Shoo Fly Complex and indicate that arc magmatism in the Northern Sierra terrane began with a major pulse of Late Devonian (Famennian) igneous activity. The Wolf Creek stock yielded an age of 352 ± 3 Ma, showing that the felsic magmatism extended into the early Mississippian. All of these rocks have similar geochemical features with arc-type trace-element signatures, consistent with the interpretation that they constitute a petrogenetically linked volcano-plutonic system. Field evidence shows that the felsic hypabyssal intrusions in the Sierra City mélange were intruded while parts of it were still unlithified, indicating that a relatively narrow time span separated subduction-related deformation in the Shoo Fly Complex and onset of Late Devonian arc magmatism. Following recent models for Paleozoic terrane assembly in the western Cordillera, we infer that the Shoo Fly Complex together with strata in the Roberts Mountains allochthon in Nevada migrated south along a sinistral transform boundary prior to the onset of arc magmatism in the Northern Sierra terrane. We suggest that the Shoo Fly Complex arrived close to the western Laurentian margin at the same time as the Roberts Mountains allochthon was thrust over the passive margin during the Late Devonian–early Mississippian Antler orogeny. This led to a change in plate kinematics that caused development of a west-facing Late Devonian island arc on the Shoo Fly Complex. Due to slab rollback, the arc front migrated onto parts of the Sierra City mélange that had only recently been incorporated into the accretionary complex. In the mélange, blocks of Ediacaran tonalite, as well as sandstones having detrital zircon populations with non–western Laurentian sources, may have been derived from the Yreka and Trinity terranes in the eastern Klamath Mountains, where similar rock types occur. If so, this suggests that these Klamath terranes were in close proximity to the developing accretionary complex in the Northern Sierra terrane in the Late Devonian.

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Permian of the Western United States

Wardlaw

Snyder

Spinosa

et al. 1995

The Permian of Northern Pangea

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Paleogeographic setting of the Schoonover sequence, Nevada, and implications for the late Paleozoic margin of western North America

Cited by 10 publications

References 16 publications

Permo‐Triassic tectonism in volcanic arc sequences of the western U.S. Cordillera and implications for the Sonoma orogeny

Permo‐Triassic tectonism in volcanic arc sequences of the western U.S. Cordillera and implications for the Sonoma orogeny

Nature and timing of Late Devonian–early Mississippian island-arc magmatism in the Northern Sierra terrane and implications for regional Paleozoic plate tectonics

Permian of the Western United States

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