5 research outputs found
Recommended from our members
Triassic–Jurassic Accretionary History and Tectonic Origin of Stikinia From U-Pb Geochronology and Lu-Hf Isotope Analysis, British Columbia
The timing of assembly and tectonic origins of terranes in the northern Cordillera of Alaska, British Columbia, and the Pacific Northwest are debated. Stikinia, a long-lived arc terrane, has an enigmatic regional Mesozoic accretionary history and its tectonic origins remain unconstrained. Zircon U-Pb geochronology and Lu-Hf isotopic data on Triassic–Jurassic sedimentary and igneous rocks from central Stikinia shed light on the terrane-scale effects of a latest Triassic–Early Jurassic collision between Stikinia and pericratonic Yukon-Tanana terrane. Main age peaks from central Stikinia are 250–160 Ma, reflecting ongoing Mesozoic arc-related igneous activity within Stikinia. Comparison of isotopic evolution and unconformity development between central Stikinia and northern Stikinia (Whitehorse trough) provide new constraints on regional latest Triassic–earliest Jurassic deformation. We attribute the shortening-related deformation to variable along-strike interactions during end-on collision with the Yukon-Tanana terrane, with significant crustal thickening at the northern apex of Stikinia that did not persist farther south. A small pre-Devonian zircon population is significant, as the oldest exposed rocks in Stikinia are Early Devonian. Pre-Devonian age peaks differ from those of the northern Yukon-Tanana terrane, but resemble zircons from southern Wrangellia. These zircons are likely multi-cyclic, derived from crust that originated in the Arctic region near the northern end of the Caledonide orogeny. We suggest that Stikinia was an independent crustal block prior to latest Triassic onset of collision with Yukon-Tanana terrane. The ongoing, end-on collision in turn promoted oroclinal assembly of the peri-Laurentian terranes. © 2021. American Geophysical Union. All Rights Reserved.6 month embargo; first published: 10 March 2021This item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]
Recommended from our members
Where did the Arizona-Plano Go? Protracted Thinning Via Upper- to Lower-Crustal Processes
Mesozoic-Cenozoic subduction of the Farallon slab beneath North America generated a regionally extensive orogenic plateau in the southwestern US during the latest Cretaceous, similar to the modern Central Andean Plateau. In Nevada and southern Arizona, estimates from whole-rock geochemistry suggest crustal thicknesses reached ∼60–55 km by the Late Cretaceous. Modern crustal thicknesses are ∼28 km, requiring significant Cenozoic crustal thinning. Here, we compare detailed low-temperature thermochronology from the Catalina metamorphic core complex (MCC) to whole rock Sr/Y crustal thickness estimates across southern Arizona. We identify three periods of cooling. A minor cooling phase occurred prior to ∼40 Ma with limited evidence of denudation and ∼10 km of crustal thinning. Major cooling occurred during detachment faulting and MCC formation at 26–19 Ma, corresponding to ∼8 km of denudation and ∼8 km of crustal thinning. Finally, we document a cooling phase at 17–11 Ma related to Basin and Range extension that corresponds with ∼5 km of denudation and ∼9 km of crustal thinning. During the MCC and Basin and Range extension events, the amount of denudation recorded by low-temperature thermochronology can be explained by corresponding decreases in the crustal thickness. However, the relatively limited exhumation prior to detachment faulting at ∼26 Ma recorded by thermochronology is insufficient to explain the magnitude of crustal thinning (∼10 km) observed in the whole rock crustal thickness record. Therefore, we suggest that crustal thinning of the Arizona-plano was facilitated via ductile mid- to lower-crustal flow, and limited upper-crustal extension at 50–30 Ma prior to detachment faulting and Basin and Range extension. © 2022. American Geophysical Union. All Rights Reserved.6 month embargo; first published: 22 March 2022This item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]
The Wolf-Man and the Third World: Exploring Parallels between Psychoanalysis and 'Third World' Development
ABCC5, a Gene That Influences the Anterior Chamber Depth, Is Associated with Primary Angle Closure Glaucoma
10.1371/journal.pgen.1004089PLoS Genetics103e100408