Rise and fall of the Nevadaplano

Ernst, W. G.

doi:10.1080/00206810903063315

Cited by 13 publications

(7 citation statements)

References 17 publications

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“…The depth of the subduction channel was more than 45 km at the east margin of the Mesozoic arc. This fits the hypothesized ∼ 45-60 km thick crust of the Nevadaplano, which lasted well into Paleogene time (Ernst, 2009;Wernicke et al, 1996) and requires a minimum dip of 12.4 • for the subduction channel underneath the arc.…”

Section: Appendix B: Dip Of the Laramide Subduction Channelsupporting

confidence: 78%

“…Behr and Platt (2013) modified this formulation, so as to relate the viscosity to the maximum exhumation rate. The buoyancy contrast between the subducting material and the overlying upper plate has been proposed as the driving force for return flow (e.g., England and Holland, 1979;Ernst et al, 1997). The density of the Pelona Schist, which consists of 90 % metagreywacke, is ∼ 2700 kg m −3 .…”

Section: Topography-and Density-driven Return Flow Model Of Subductiomentioning

confidence: 99%

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Structural and rheological evolution of the Laramide subduction channel in southern California

Xia

Platt

2017

Solid Earth

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Abstract. The Pelona Schist in the San Gabriel Mountains, southern California, formed in the Laramide subduction channel, exhibits multiple phases of deformation/metamorphism and provides valuable insights into the rheological properties of the subduction channel. Petrological and microstructural analysis indicates that the Pelona Schist has undergone three major deformational/metamorphic events. Subduction of volcanic and sedimentary protoliths during D1 was recorded by aligned mineral inclusions in albite and epidote porphyroblasts. Metamorphic temperature and pressure at the end of subduction yielded by Raman spectroscopy of carbonaceous material and phengite barometry were 519 ± 20 °C and 10.5 ± 0.4 kbar, respectively. During D1 the dominant deformation mechanism was quartz pressure solution, and the estimated shear stress at the end of D1 was less than 10 MPa. D2, the first stage exhumation of the Pelona Schist along the upper section of the subduction channel during return flow, was recorded by retrogressive metamorphism, isoclinal folding, and a pervasive schistosity that wraps around earlier porphyroblasts. Metagreywacke was deformed mainly by quartz pressure solution and metachert was deformed dominantly by dislocation creep during D2. The shear stress in metagreywacke was less than 10 MPa and that in metachert was between 8.3 + 2.7/− 1.5 and 12.9 + .9/− 2.3 MPa, resulting in a strain rate of 1.4  ×  10−13 to 5.5  ×  10−13 s−1. A topography driven model is proposed as the main driving force of D2 exhumation. D3 records normal-sense movement on the Vincent Fault, which separates the schist from overlying arc and continental basement. This resulted in the second stage of exhumation, creating a major synform and associated mylonitic fabric in the upper section of the Pelona Schist. Conditions at the beginning of D3 were 390 ± 13 °C and 5.8 ± 0.8 kbar given by the TitaniQ thermometer and phengite geobarometer. The deformation was dominated by quartz dislocation creep with a strain rate of 4.5 ± 1.2  ×  10−13 s−1 at a shear stress of 20.1 + 7.3/− 4.0 MPa.

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Section: Appendix B: Dip Of the Laramide Subduction Channelsupporting

confidence: 78%

Section: Topography-and Density-driven Return Flow Model Of Subductiomentioning

confidence: 99%

Structural and rheological evolution of the Laramide subduction channel in southern California

Xia

Platt

2017

Solid Earth

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“…This synthesis is based on Great Basin research reports by numerous earth scientists as well as on a special issue of International Geology Review entitled, "Rise and Fall of the Nevadaplano" (Ernst, 2009). I thank the many contributors to that topical issue as well as earlier workers in the fi eld.…”

Section: Acknowledgmentsmentioning

confidence: 99%

Young convergent-margin orogens, climate, and crustal thickness—A Late Cretaceous–Paleogene Nevadaplano in the American Southwest?

Ernst

2010

Lithosphere

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The N-S-trending Andes surmount South American lithosphere above the east-descending Nazca plate. The highest mountains, underlain by ~70-km-thick crust, cap the Cordillera at 25°S, an extremely arid region. In contrast, the precipitation-drenched fjordland at 45°S is supported by ~35-km-thick crust. The Cascade and Sierra Nevada ranges in the western United States display comparable N-S trends and latitudinal rainfall patterns. Westerly winds supply abundant moisture to the northwest, but precipitation diminishes southward, producing increased aridity where the Sierra achieves its maximum regional elevation around Mount Whitney. Overthickened, now delaminating, ~42-55-km-thick crust of the southern Sierra exceeds that of the ~35-km-thick northern Sierra and the active Cascade arc. Contrasts in orogenic crustal thickness in California are not as marked as in the Andes because Sierran arc construction ceased near the end of Cretaceous time. Geologic, geochemical, and stable isotopic data suggest that a Nevadaplano occupied central + southern Nevada + western Utah in the rain shadow of the Late Cretaceous-Paleogene arc. The ~40-45-km-thick Colorado Plateau crust lies well downwind from the southern Sierra, and, depending on when it became elevated, it might represent part of a broader highland that collapsed during Neogene Basin and Range extension.

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“…Protracted partial melting and zircon preservation are frequently connected to strain softening and promotion of detachment faulting (e.g., Hollister and Crawford, 1986;Wells, 2001;Whitney et al, 2013;Howlett et al, 2021;others). In the North American Cordillera and the Cordillera Blanca, these processes precede extension of distributed high topography in orogenic collapse-type geodynamic models (e.g., Dalmayrac and Molnar, 1981;Ernst, 2009;Molnar, 2010;Jepson et al, 2022). The correlation of magmatism, high topography, and orogenic extension implores exploration of the role that protracted magmatism may play in rheologic modification of the crust, strain localization in pre-and synextensional terranes, and the initiation of low-angle detachment faults during stress switching in Cordilleran-style orogenies.…”

Section: Importance Of End-miocene Magmatism For Initiating and Local...mentioning

confidence: 99%

Magmatic conditions aiding synconvergent extension above the Peruvian flat slab

Grambling,

Jessup,

Newell

et al. 2024

Geosphere

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The Cordillera Blanca and Cordillera Huayhuash contain some of the highest topography in the Andes and provide insight into tectonomagmatic processes associated with the onset of flat-slab subduction. These adjacent ranges shared a similar history of deformation and exhumation prior to the late Miocene, when synconvergent extension began in the Cordillera Blanca. Magmatism in the Cordillera Huayhuash has been inferred as coeval with magmatism in the Cordillera Blanca. Yet, extension, which has been correlated with magmatic heat flow, is limited to the Cordillera Blanca. New zircon U-Pb dates and trace and rare earth element concentrations from the Cordillera Blanca batholith and the Huayllapa pluton in the Cordillera Huayhuash and reassessment of existing zircon data help to characterize regional magmatic processes prior to the establishment of flat-slab subduction. Two compositionally distinct samples of the Huayllapa pluton yielded mean ages of 24.8 ± 0.4 Ma and 25.4 ± 0.8 Ma. In contrast, the Cordillera Blanca batholith has a protracted crystallization history postdating that of the Cordillera Huayhuash by up to 20 m.y. Miocene magmatism in the Cordillera Blanca began at 19 Ma and ended with injection of large volumes of geochemically distinct, mantle-derived magma from 10 to 5 Ma. We suggest that 6–5 Ma magmatism in the Cordillera Blanca promoted elevated heat flow and reduced shear strength, which facilitated extensional shearing along the western slopes of the range, whereas colder amagmatic crust in the Cordillera Huayhuash inhibited southward propagation of faulting. Our data demonstrate that the linkages between magmatism and elevated heat flow identified in the Cordillera Blanca are important driving processes in initiating extension in cordilleran-style orogenies.

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Rise and fall of the Nevadaplano

Cited by 13 publications

References 17 publications

Structural and rheological evolution of the Laramide subduction channel in southern California

Structural and rheological evolution of the Laramide subduction channel in southern California

Young convergent-margin orogens, climate, and crustal thickness—A Late Cretaceous–Paleogene Nevadaplano in the American Southwest?

Magmatic conditions aiding synconvergent extension above the Peruvian flat slab

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