The Significance of the Cretaceous Kluane Schist in the Mesozoic Assembly of the North American Cordillera PDF Download
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Author: William F McKenzie Publisher: ISBN: Category : Languages : en Pages : 0
Book Description
The Cordillera of western North America is an archetypal accretionary orogen. During the Mesozoic, two significant periods of terrane accretion are recognised within the Canadian-Alaska ("Northern") Cordillera: 1) the accretion of the Intermontane terranes to the western Laurentian margin from ca. 200 to ca. 180 Ma and, (2) the subsequent accretion of the Insular terranes to the Intermontane terranes, possibly as early as ca. 174 Ma and as late as ca. 70 Ma. Information regarding the precise timing and tectonic drivers of this Mesozoic accretionary history is held within a series of inverted Jura-Cretaceous basins exposed at the interface between the pericratonic Intermontane and exotic Insular terranes. Of these inverted basins, the Kluane Schist, southwest Yukon, represents one of the largest and most continuous exposures. The Kluane Schist consists of metamorphosed and deformed low-Al pelites that were deposited during the very latest stages of Insular terrane accretion. Detrital zircon geochronology reveals a Late Cretaceous maximum depositional age for the Kluane Schist and Hafnium-isotope geochemistry provides strong provenance ties to Triassic-Cretaceous zircon sources currently exposed within the southern Yukon Tanana terrane. Detailed petrography, petrological modelling, and in-situ monazite petrochronology demonstrate the metamorphism of the Kluane Schist occurred during the override of the Yukon-Tanana terrane between ca. 70-55 Ma. This metamorphic evolution, combined with its continentally-dipping, Buchan-style inverted metamorphic sequence and tops-to-the-southwest shear structures are consistent with the Kluane Schist representing the uppermost part of a contractional forearc to an arc built upon the Yukon-Tanana terrane. This geodynamic setting for the Kluane Schist is most compatible with models of Insular terrane accretion that involve east-dipping subduction below a westward migrating North American continent during the Mesozoic.
Author: William F McKenzie Publisher: ISBN: Category : Languages : en Pages : 0
Book Description
The Cordillera of western North America is an archetypal accretionary orogen. During the Mesozoic, two significant periods of terrane accretion are recognised within the Canadian-Alaska ("Northern") Cordillera: 1) the accretion of the Intermontane terranes to the western Laurentian margin from ca. 200 to ca. 180 Ma and, (2) the subsequent accretion of the Insular terranes to the Intermontane terranes, possibly as early as ca. 174 Ma and as late as ca. 70 Ma. Information regarding the precise timing and tectonic drivers of this Mesozoic accretionary history is held within a series of inverted Jura-Cretaceous basins exposed at the interface between the pericratonic Intermontane and exotic Insular terranes. Of these inverted basins, the Kluane Schist, southwest Yukon, represents one of the largest and most continuous exposures. The Kluane Schist consists of metamorphosed and deformed low-Al pelites that were deposited during the very latest stages of Insular terrane accretion. Detrital zircon geochronology reveals a Late Cretaceous maximum depositional age for the Kluane Schist and Hafnium-isotope geochemistry provides strong provenance ties to Triassic-Cretaceous zircon sources currently exposed within the southern Yukon Tanana terrane. Detailed petrography, petrological modelling, and in-situ monazite petrochronology demonstrate the metamorphism of the Kluane Schist occurred during the override of the Yukon-Tanana terrane between ca. 70-55 Ma. This metamorphic evolution, combined with its continentally-dipping, Buchan-style inverted metamorphic sequence and tops-to-the-southwest shear structures are consistent with the Kluane Schist representing the uppermost part of a contractional forearc to an arc built upon the Yukon-Tanana terrane. This geodynamic setting for the Kluane Schist is most compatible with models of Insular terrane accretion that involve east-dipping subduction below a westward migrating North American continent during the Mesozoic.
Author: Robert S. Hildebrand Publisher: Geological Society of America ISBN: 0813724953 Category : Science Languages : en Pages : 182
Book Description
"In this well-illustrated book, Hildebrand expands upon his model for the development of the North American Cordillera detailed in Special paper 457. Starting with an overview of Cordilleran geology he goes on to provide an in depth look at how the Rubian ribbon continent was assembled. He integrates the complex geology of the Cordillera into an actualistic model involving arc magmatism, arc-continent collision, slab failure magmatism, and transcurrent motion in both Rubia and the western North American margin. While much of the focus is on the assembly of the Rubian ribbon continent, Hildebrand explores its interactions with North America during the Sevier and Laramide events and concludes that North America was the lower plate in both"--Provided by publisher.
Author: Robert S. Hildebrand Publisher: Geological Society of America ISBN: 0813724570 Category : Science Languages : en Pages : 80
Book Description
Within the Sonora segment to the south, break-off magmatism was also prevalent. Both the Canadian and Sonoran segments have abundant porphyry copper mineralization temporally and spatially associated with the break-off magmas, which suggests a genetic link between slab failure and porphyry copper mineralization. By 53 Ma, eastwardly dipping subduction of Pacific Ocean crust was generating arc magmatism on the amalgamated Cordilleran collision zone in both the Canadian and Sonoran segments. Oceanic schists, such as the Orocopia-Pelona-Rand, were formed in the ocean basin west of Rubia and accreted during initiation of the new easterly dipping subduction zone. A major transform fault, called the Phoenix fault, connects the Sevier fold-thrust belt at the California-Nevada border with that in eastern Mexico and separates the Great Basin and Sonoran segments. It juxtaposes the Sierra-Mojave-Sonora block alongside the Transition Zone of the Colorado Plateau. Cordilleran events affected the subsequent development of western North America. For example, the structural Basin and Range Province appears to coincide with the region where exotic allochthons sit atop North American crust in both the Great Basin and Sonoran segments. Also, within the triangular Columbia embayment, large segments of Rubia appear to have escaped laterally during the Cordilleran orogeny to create a lithospheric "hole" that was later filled by basalt of the Columbia River and Modoc plateaux.
Author: William F McKenzie
Author: William F McKenzie
Author: Robert S. Hildebrand
Author: Robert S. Hildebrand
Author: Patrick L. Abbott
Author: Spencer G. Lucas
Author: Samuel Almond Miller
Author: Ashu Khosla
Author: Samuel Almond Miller
Author: Edward Drinker Cope
Author: Charles Abiathar White