Major Late-Triassic strike-slip displacement in the Seven Devils terrane, Oregon and Idaho: A result of left-oblique plate convergence?

AvéLallemant, Hans G.; Schmidt, William; Kraft, Jamie L

doi:10.1016/0040-1951(85)90044-7

Cited by 19 publications

(9 citation statements)

References 41 publications

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“…Younger D2 deformation involved Late Triassic (ca. 229.43 ± 0.08 Ma to 229.13 ± 0.45 Ma) synmagmatic leftlateral, strikeslip mylonitic shearing associated with sinistraloblique sub duction (Avé Lallemant et al, 1985;Avé Lal lemant, 1995;Kurz and Northrup, 2008;Kurz et al, 2012). Middle to Late Triassic 40 Ar/ 39 Ar cooling ages have been interpreted as the mini mum age for peak metamorphism and deforma tion (Balcer, 1980;Walker, 1986;Avé Lallemant, 1995;Snee et al, 1995;Vallier, 1995;Gray and Oldow, 2005).…”

Section: Cougar Creek Complexmentioning

confidence: 99%

“…1 and 2). The OXC is lithologically and structur ally similar to the CCC; major rock types include basalt, rhyolite, diabase, gabbro, diorite, quartz diorite, tonalite, trondhjemite, and their meta morphosed and deformed equivalents (Vallier, 1967;Phelps, 1978;Balcer, 1980;Schmidt, 1980;Avé Lallemant et al, 1985;Avé Lallemant, 1995;Vallier, 1995). Like the CCC, the OXC is also inferred to be the basement to the WA (Avé Lal lemant, 1995;Vallier, 1995).…”

Section: Oxbow Complexmentioning

confidence: 99%

“…Tectonic fabrics in the OXC include well developed NESW-trending protomylonitic to ultramylonitic foliation that dips moderately to steeply to the NW or SE, and NESW-trend ing, horizontal to subhorizontal stretching linea tions defined by deformed and/or aligned min eral grains (Schmidt, 1980;Avé Lallemant, 1995;Vallier, 1995). Mesoscopic and microscopic analysis of mylonitic rocks indicated leftlateral transport analogous to the CCC (Schmidt, 1980;Avé Lallemant et al, 1985;Avé Lallemant, 1995).…”

Section: Oxbow Complexmentioning

confidence: 99%

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Isotopic compositions of intrusive rocks from the Wallowa and Olds Ferry arc terranes of northeastern Oregon and western Idaho: Implications for Cordilleran evolution, lithospheric structure, and Miocene magmatism

et al. 2016

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Late Paleozoic and Mesozoic intrusive rocks from the Wallowa and Olds Ferry arc terranes of the Blue Mountains Province, Oregon-Idaho, provide constraints on the paleogeographic and tectonic setting of magmatism preserved in both arcs. Sr, Nd, and Pb isotopic data show that the Wallowa terrane represents an isotopically depleted, juvenile intra-oceanic island arc. By contrast, isotopic data for intrusive rocks of the Olds Ferry arc are more isotopically enriched, and thereby establish a clear distinction between the two arcs. This distinction strengthens paleogeographic interpretation of the Olds Ferry terrane as a fringing continental arc, and it provides a basis for correlation to other inboard Cordilleran arc terranes including Quesnellia and Stikinia. The Wallowa terrane is by contrast more similar geologically and isotopically to the outboard Insular terranes. These isotopic data also constrain interpretations of regional lithospheric architecture. Isotopic profiles generated orthogonal to the inferred Wallowa-Olds Ferry terrane boundary and the western Idaho shear zone show abrupt increases in initial 87 Sr/ 86 Sr that mark the transitions between three geochemically distinct lithospheric columns. West-to-east spatial variability in the isotopic compositions of Neogene volcanic rocks is explained by the partial melting of these three geochemically distinct mantle reservoirs coupled to their respective crustal columns since the early Mesozoic, rather than alternative models of lithosphere-scale décollement offset during Sevier shortening. The inherited arcrelated mantle of the Olds Ferry arc may also have played a primary role in the petrogenesis of distinctive Neogene low-K, high-alumina olivine tholeiites of the High Lava Plains.

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Section: Cougar Creek Complexmentioning

confidence: 99%

Section: Oxbow Complexmentioning

confidence: 99%

Section: Oxbow Complexmentioning

confidence: 99%

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Isotopic compositions of intrusive rocks from the Wallowa and Olds Ferry arc terranes of northeastern Oregon and western Idaho: Implications for Cordilleran evolution, lithospheric structure, and Miocene magmatism

et al. 2016

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“…Previously, the timing of magmatic activity in the Wallowa terrane was based on limited geochronologic, thermo chrono logic, and paleontologic data (Vallier, 1977;Balcer, 1980;Avé Lallemant et al, 1980, 1985Walker, 1986Walker, , 1995Schwartz et al, 2010). Furthermore, the major-and trace-element geochemistry of igneous rocks from the Wallowa arc terrane remains inadequately characterized.…”

Section: Introductionmentioning

confidence: 97%

U-Pb geochronology and geochemistry of intrusive rocks from the Cougar Creek Complex, Wallowa arc terrane, Blue Mountains Province, Oregon-Idaho

Kurz

Schmitz

Northrup

et al. 2011

Geological Society of America Bulletin

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“…Existing Juro-Cretaceous plate tectonic models based on regional structures in various terranes throughout the western North American Cordillera propose conflicting overall plate kinematics including sinistral, orthogonal, and dextral convergence (e.g., Oldow et al, 1984;Avé Lallemant et al, 1985;McClelland et al, 2000;Umhoefer, 2003;Ernst et al, 2008;Saleeby and Dunne, 2015). On the other hand, paleomagnetic and ocean-floor age data indicate a significant kinematic switch during Late Jurassic to Early Cretaceous as the Pacific, Kula, and Farallon plates changed their drift from southward to northward with respect to the cratonal North America.…”

Section: Introductionmentioning

confidence: 99%

Magnetic fabrics of arc plutons reveal a significant Late Jurassic to Early Cretaceous change in the relative plate motions of the Pacific Ocean basin and North America

et al. 2016

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Contrasting magnetic fabrics in five successively emplaced syntectonic plutons reveal temporal and spatial variations in tectonic strain in the oceanic terranes of the Blue Mountains province, northeastern Oregon, during the Late Jurassic to Early Cretaceous. The inferred strain regimes changed from: (1) thrusting and sinistral shearing at ca. 160 Ma, to (2) horizontal stretching at ca. 147 Ma (in the forearc-accretionary wedge Baker terrane), to (3) dextral transpression that started from ca. 140 Ma onward and was associated with progressive anticlockwise rotation of the principal horizontal shortening direction from ca. 130 Ma to ca. 126 Ma (in the Wallowa oceanic arc terrane). These progressive strain reorientations are interpreted in terms of an outboard Wallowa-Baker terrane collision, lateral extrusion, docking of the amalgamated Blue Mountains superterrane into a continental-margin reentrant, and onset of oroclinal bending, respectively. The changes in crustal strains are then interpreted as recording a progressive change in relative motions between the Pacific Ocean basin and North America and suggest a transition from Late Jurassic sinistral deformation to Early Cretaceous dextral terrane translations along the paleo-Pacific margin. We speculate that these events may have been linked along large portions of the North American Cordillera, from central California to Blue Mountains, and may have culminated in the onset of accretion in the Franciscan complex and voluminous plutonism in the Sierra Nevada magmatic arc. A similar plate-kinematic change is inferred to have occurred in British Columbia several tens of millions of years later (at ca. 100 Ma), implying that these kinematic transitions may have varied in space and time along the length of the Cordilleran orogen.

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Major Late-Triassic strike-slip displacement in the Seven Devils terrane, Oregon and Idaho: A result of left-oblique plate convergence?

Cited by 19 publications

References 41 publications

Isotopic compositions of intrusive rocks from the Wallowa and Olds Ferry arc terranes of northeastern Oregon and western Idaho: Implications for Cordilleran evolution, lithospheric structure, and Miocene magmatism

Isotopic compositions of intrusive rocks from the Wallowa and Olds Ferry arc terranes of northeastern Oregon and western Idaho: Implications for Cordilleran evolution, lithospheric structure, and Miocene magmatism

U-Pb geochronology and geochemistry of intrusive rocks from the Cougar Creek Complex, Wallowa arc terrane, Blue Mountains Province, Oregon-Idaho

Magnetic fabrics of arc plutons reveal a significant Late Jurassic to Early Cretaceous change in the relative plate motions of the Pacific Ocean basin and North America

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