Fault Slip and Exhumation History of the Willard Thrust Sheet, Sevier Fold‐Thrust Belt, Utah: Relations to Wedge Propagation, Hinterland Uplift, and Foreland Basin Sedimentation

Zircon (U‐Th)/He (ZHe) and zircon fission track thermochronometric data for 47 samples spanning the areally extensive Willard thrust sheet within the western part of the Sevier fold‐thrust belt record enhanced cooling and exhumation during major thrust slip spanning approximately 125–90 Ma. ZHe and zircon fission track age‐paleodepth patterns along structural transects and age‐distance relations along stratigraphic‐parallel traverses, combined with thermo‐kinematic modeling, constrain the fault slip history, with estimated slip rates of ~1 km/Myr from 125 to 105 Ma, increasing to ~3 km/Myr from 105 to 92 Ma, and then decreasing as major slip was transferred onto eastern thrusts. Exhumation was concentrated during motion up thrust ramps with estimated erosion rates of ~0.1 to 0.3 km/Myr. Local cooling ages of approximately 160–150 Ma may record a period of regional erosion, or alternatively an early phase of limited... (see full abstract in article)

Detrital-zircon geochronology and provenance of the Ocloyic synorogenic clastic wedge, and Ordovician accretion of the Argentine Precordillera terrane

The Precordillera terrane in northwestern Argentina is interpreted to be anexotic (Laurentian) continental fragment that was accreted to western Gondwanaduring the Ordovician. One prominent manifestation of the subductionand collision process is a Middle?Upper Ordovician clastic wedge, which overliesa passive-margin carbonate-platform succession in the Precordillera. U/Pbages of detrital zircons from sandstones within the clastic wedge, as well as zirconsfrom clasts within conglomerates, provide documentation for the compositionof the sediment provenance. The ages of detrital zircons are consistentvertically through the succession, as well as laterally along and across strike ofthe Precordillera, indicating a single, persistent sediment source throughoutdeposition of the clastic wedge. The dominant mode (~1350?1000 Ma) of thedetrital-zircon ages corresponds to the ages of basement rocks in the WesternSierras Pampeanas along the eastern side of the Precordillera. A secondarymode (1500?1350 Ma) corresponds in age to the Granite-Rhyolite province ofLaurentia, an age range which is not known in ages of basement rocks of theWestern Sierras Pampeanas; however, detritus from Granite-Rhyolite-age rocksin the basement of the Precordillera was available through recycling of synriftand passive-margin cover strata. Igneous clasts in the conglomerates haveages (647?614 Ma) that correspond to the ages of minor synrift igneous rocks inthe nearby basement massifs; the same ages are represented in a minor mode(~750?570 Ma) of detrital-zircon ages. A quartzite clast in a conglomerate, aswell as parts of the population of detrital zircons, indicates the importanceof a source in the metasedimentary cover of the leading edge of the Precordillera.The Famatina continental-margin magmatic arc reflects pre-collisionsubduction of Precordillera lithosphere beneath the western Gondwana margin;however, no detrital zircons have ages that correspond to Famatina arcmagmatism, indicating that sedimentary detritus from the arc may have beentrapped in a forearc basin and did not reach the foreland. The indicators ofsedimentary provenance for the foreland deposits are consistent with subductionof the Precordillera beneath western Gondwana, imbrication of basementrocks from either the Precordillera or Gondwana into an accretionary complex,and recycling of deformed Precordillera cover rocks.Fil: Thomas, William A.. Geological Survey of Alabama; Estados UnidosFil: Astini, Ricardo Alfredo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Centro de Investigaciones en Ciencias de la Tierra. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Centro de Investigaciones en Ciencias de la Tierra; ArgentinaFil: Mueller, Paul A.. Florida State University; Estados UnidosFil: McClelland, William C.. University of Iowa; Estados Unido

Investigating the kinematics of mountain building in Taiwan from the spatiotemporal evolution of the foreland basin and western foothills

The Taiwanese range has resulted from the collision between the Luzon volcanic arc and the Chinese continental margin, which started about 6.5 Myr ago in the north, and has since propagated southward. The building of the range has been recorded in the spatiotemporal evolution of the foreland basin. We analyze this sedimentary record to place some constraints on the kinematics of crustal deformation. The flexure of the foreland under the load of the growing wedge started with a 1.5 Myr long phase of rapid subsidence and sedimentation, which has migrated southward over the last 3.5 Myr at a rate of 31 +10/−5 mm/yr, reflecting the structural evolution of the range and the growth of the topography during the oblique collision. Isopachs from the Toukoshan (~0 to 1.1 Ma) and Cholan (~1.1 to 3.3 Ma) formations, as well as the sedimentation rates retrieved from a well on the Pakuashan anticline, indicate that the foreland basement has been moving toward the center of mass of the orogen by ~45–50 mm/yr during the development of the basin. From there, we estimate the long-term shortening rate across the range to 39.5–44.5 mm/yr. By considering available data on the thrust faults of the foothills of central Taiwan, we show that most (if not all) the shortening across the range is accommodated by the most frontal structures, with little if any internal shortening within the wedge. The range growth appears therefore to have been essentially sustained by underplating rather than by frontal accretion. In addition, only the upper ~7 to 9 km of the underthrusted crust participates to the growth of the orogen. This requires that a significant amount of the Chinese passive margin crust is subducted beneath the Philippine Sea plate

Early Carboniferous synorogenic basins evolution of the Ossa-Morena and

The stratigraphic record of the Early Carboniferous in Iberia reveals that synorogenic deposition was important and occurred simultaneously in basins influenced by extension and contraction with gravitational instability. In NW Iberia (Galicia – Trás-os-Montes Zone) contraction was dominant and the deposition took place in a forebulge outwards from the nappe stacking front. Here, synorogenic deposits were strongly affected by folding and thrusting as they were imbricated and incorporated in the allochthonous pile. In a different way, in SW Iberia (Ossa-Morena Zone) synorogenic deposition was influenced by extension and happened simultaneously with the onset of significant magmatism

On the origin of the North Pacific arcs

We present a new hypothesis that relates global plate tectonics to the formation of marginal basins, island arcs, spreading ridges and arc-shaped mountain belts around the North Pacific Ocean. According to our model, the ellipsoidal-shaped Paleogene basins of the South China Sea, Parece-Vela Basin, Shikoku Basin, Sea of Japan and the Sea of Okhotsk in addition to those of the North American Cordillera can be attributed to the change in plate convergence direction at 42 Ma between the Indoaustralian and Eurasian plates. The new direction of convergence was parallel to the eastern continental margin of Asia and resulted in widespread extension perpendicular to this margin and to the western margin of North America. Both margins form part of a circle parallel to the Indoaustralian-Eurasian direction of convergence

Synorogenic evolution of large-scale drainage patterns: Isotope paleohydrology of sequential Laramide basins

In the past decade, we and others have compiled an extensive dataset of O, C and Sr isotope stratigraphies from sedimentary basins throughout the Paleogene North American Cordillera. In this study, we present new results from the Piceance Creek Basin of northwest Colorado, which record the evolving hydrology of the Eocene Green River Lake system. We then place the new data in the context of the broader Cordilleran dataset and summarize implications for understanding the synorogenic evolution of large-scale drainage patterns. The combined data reflect (1) a period of throughgoing foreland rivers heading in the Sevier fold-and-thrust belt and flowing east, (2) ponding of freshwater lakes in the foredeep as Laramide uplifts blocked drainage, (3) hydrologic closure that led to both intensive evaporation in the terminal sink of the Piceance Creek Basin and integration of catchments over length-scales \u3e1000 km, (4) infilling of basin accommodation by southward migrating magmatism in distal catchments, leading to the freshening and demise of intraforeland lakes that also stepped south over time

Influence of pre-Andean history over Andean foreland deformation: structural styles in the Malargüe fold-and-thrust belt at 35ºS, Andes of Argentina

We present the first complete balanced cross-section of the Argentinean Andes at 35ºS. Based on an extensive field survey and limited sub-surface information, we constructed a structural model in which both the tectonic inversion of Mesozoic normal faults and the formation of Cenozoic Andean thrusts play a role in the deformation. We obtained a shortening of 26.2 km, equivalent to 22% of the initial length. This value is lower than previous estimates obtained from partial cross-sections using non-inversion structural models. Comparison of our results with a geophysical model of the crust indicates that: (i) crustal thickness was not constant across the orogen before Andean shortening, but a thick (~45 km) crustal block was interpreted? in the west as a remnant of a Late Paleozoic orogeny, and a thinner sector (~32 km) was located in the east as a result of Mesozoic stretching; and (ii) the structural model presented in this work is more consistent with the regional shortening and crustal thickness trends than models which do not take into account tectonic inversion.Fil: Mescua, Jose Francisco. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Provincia de Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Universidad Nacional de Cuyo. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales; ArgentinaFil: Giambiagi, Laura Beatriz. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Provincia de Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Universidad Nacional de Cuyo. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales; ArgentinaFil: Tassara Oddo, Andres Humberto. Universidad de Concepción; ChileFil: Gimenez, Mario Ernesto. Universidad Nacional de San Juan. Facultad de Ciencias Exactas, Físicas y Naturales. Instituto Geofísico Sismológico Volponi; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Ramos, Victor Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Estudios Andinos "Don Pablo Groeber". Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Estudios Andinos "Don Pablo Groeber"; Argentin

Preface: Palaeozoic geodynamics of the southwestern margin of Gondwana: controls on the present architecture of the Argentine-Chilean Andes

Palaeozoic geodynamics of the southwestern margin of Gondwana: controls on the present architecture of the Argentine-Chilean Ande