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U-Pb age spectra of detrital zircons in samples from the Paleogene Colton Formation in the Uinta Basin of northeastern Utah and the Late Cretaceous McCoy Mountains Formation of southwestern Arizona (United States) are statistically indistinguishable. This finding refutes previous inferences that arkosic detritus of the Colton was derived from cratonic basement exposed by Laramide tectonism, and instead establishes the Cordilleran magmatic arc (which also provided sediment to the McCoy Mountains Formation) as the primary source. Given the existence of a north-south-trending drainage divide in eastern Nevada and the north-northeast direction of Laramide paleoflow throughout Arizona and southern Utah, we infer that a large river system headed in the arc of the Mojave region flowed northeast ~700 km to the Uinta Basin. Named after its source area, this Paleogene California River would have been equal in scale but opposite in direction to the modern Green River-Colorado River system, and the timing and causes of the subsequent drainage reversal are important constraints on the tectonic evolution of the Cordillera and the Colorado Plateau. © 2010 Geological Society of America.

Drawing on data from seven European countries (Czech Republic, Finland, France, Germany, Ireland, Italy and the United Kingdom), this article seeks to identify how young migrant men engage with authority and avoid conflict against a backdrop of increasing hostility towards migrants in many European countries. As this article contends, even those with permanent residency status in the host country often find themselves having to justify their legitimacy to carry out daily tasks, resulting in many young male migrants living with feelings of perpetual insecurity. As such, a number of coping strategies are employed by young migrant men in order to assuage such feelings and mitigate potential risks. Focusing on the lived experiences of this group, as described in narrative interviews, our study found that many young migrant men are required to enter into negotiations with authority figures, where there is a considerable power differential. Acting as risk assessors, they find themselves forced to navigate complex and challenging social relations and support networks. We show how self-limiting behaviour intended to avoid or control interactions with authority and the negotiations conducted to minimize the risk of 'trouble' by young migrant men not only are problematic in the context of day-to-day activities but can very often have a detrimental impact on their lives. [ABSTRACT FROM AUTHOR]

The Santa Catalina Mountains, SE Arizona, was one of the first metamorphic core complexes to be described. Despite its status as a type example, relatively little is known about precise ages and origins of the intrusive rocks that make up most of the crystalline core. U-Pb and Hf isotopic data by laser ablation-inductively coupled plasma-mass spectrometry from zircons and Nd isotopic results from whole rocks were obtained for 12 granitoids ranging from 1,440 to 26 Ma. Results confirm that the 1.44-Ga Oracle Granite extends through the Catalina Range as variably mylonitic granite and banded gneiss. Laramide intrusions (67-73 Ma) display initial [ζ.sub.Nd] values -5to -8 and [ζ.sub.Hf] from -7.5 to -9. Magmatic ages for the prominent white granite sills of the Wilderness suite are 46-57 Ma, in agreement with Terrien (2012), and these granites have initial [ζ.sub.Nd] values -8 to -10 and [ζ.sub.Hf] from -7 to -14. Lastly, the undeformed Catalina Granite has an age of 26 Ma, with an initial [ζ.sub.Nd] and [ζ.sub.Hf] of -6 and -8, respectively. Our Nd results agree with limited results from Farmer and DePaolo (89:10141-10160, 1984). Although the Catalina Granite seems to have a significant juvenile component based on Nd and Hf, most of the Laramide and Wilderness intrusions contain Nd and Hf compositions lying close to the evolution of 1.44-Ga Oracle Granites, a fact that is confirmed by the U-Pb data, which show both 1.7- and 1.4-Ga zircon cores in these samples, with 1.4 Ga as the dominant core age. In order to become the dominant source of most of the 72-45-Ma magmas, the Oracle pluton must not only extend across the whole Catalina region, but also have abundant deep-seated equivalents to provide magma sources. Keywords Santa Catalina metamorphic core complex * Granite origins * U-Pb ages * Hafnium isotopes * Neodymium isotopes, Introduction The Santa Catalina metamorphic core complex (Fig. 1), part of a chain of NW-trending metamorphic core complexes stretching across Arizona (Banks 1980; Davis 1980), is among the first occurrence [...]

Although the importance of ocular pressure was recognized as early as 1875, the first truly practical instrument for its measurement was patented in 1905 by the Norwegian ophthalmologist Hjalmar Schiotz. [...]

We report strontium isotopic results for the late Miocene Hualapai Limestone of the Lake Mead area (Arizona-Nevada) and the latest Miocene to early Pliocene Bouse Formation and related units of the lower Colorado River trough (Arizona-California-Nevada), together with parallel oxygen and carbon isotopic analyses of Bouse samples, to constrain the lake-overflow model for integration of the Colorado River. Sr isotopic analyses on the basal 1-5 cm of marl, in particular along a transect over a range of altitude in the lowest-altitude basin that contains freshwater, brackish, and marine fossils, document the [sup.87]Sr/[sup.86]Sr of first-arriving Bouse waters. Results reinforce the similarity between the [sup.87]Sr/[sup.86]Sr of Bouse Formation carbonates and present-day Colorado River water, and the systematic distinction of these values from Neogene marine Sr. Basal Bouse samples show that [sup.87]Sr/[sup.86]Sr decreased from 0.7111 to values in the range 0.7107-0.7109 during early basin filling, [sup.87]Sr/[sup.86]Sr values from a recently identified marl in the Las Vegas area are within the range of Bouse Sr ratios. [sup.87]Sr/[sup.86]Sr values from the Hualapai Limestone decrease upsection from 0.7195 to 0.7137, in the approach to a time soon after 6 Ma when Hualapai deposition ceased and the Colorado River became established through the Lake Mead area. Bouse Formation [delta][sup.18]O values range from-12.9[per thousand] to +1.0[per thousand] Vienna Pee Dee belemnite (VPDB), and [delta][sup.13]C between -6.5[per thousand] and +3.4[per thousand] VPDB. Negative [delta][sup.18]O values appear to require a continental origin for waters, and the trend to higher [delta][sup.18]O suggests evaporation in lake waters. Sr and stable isotopic results for sectioned barnacle shells and from bedding planes of the marine fish fossil Colpichthys regis demonstrate that these animals lived in saline freshwater, and that there is no evidence for incursions of marine water, either long-lived or brief in duration. Lack of correlation of Sr and O isotopic variations in the same samples also argue strongly against systematic replacement of Sr in Bouse carbonates after deposition. Our results reinforce the conclusion that the Bouse Formation was deposited in a descending series of basins connected by overflow of Colorado River water. The Hualapai Limestone records a separate and earlier lake that may have been progressively influenced by Colorado River water as the time of river integration approached. doi: 10.1130/B30186.1

Hundreds of circular features on Venus known as coronae are characterized by annular fractures and commonly associated radial fractures and lava flows. Coronae are thought to have been produced by buoyant mantle diapirs that flatten and spread at the base of the lithosphere and cause fracturing, uplift, and magmatism. The interior of Artemis Corona, by far the largest corona at 2100 km diameter, is divided in half by a northeast-trending deformation belt that contains numerous rounded ridges resembling antiforms. The largest of these ridges, located at the center of Artemis Corona, is ~5 km high on its steep northwest flank where it is adjacent to a flat-bottomed, 10-km-wide trough interpreted as a rift valley. The 280-km-long anti-formal ridge is marked by perpendicular grooves that cross the ~50-km-wide ridge and extend southeastward as far as 120 km across adjacent plains. The grooves abruptly terminate northwestward at the rift trough. The large antiformal ridge terminates southwestward at a transform shear zone that parallels the grooves. These features--rift valley, antiformal uplift, grooves, and transform shear zone--are morphologically and geometrically similar to grooved, elevated, submarine metamorphic core complexes on the inside corners of ridge-transform intersections of slow-spreading ridges on Earth. As with submarine core complexes, the grooved surface on Venus is interpreted as the footwall of a large-displacement normal fault, and the grooves are inferred to be the product of plastic molding of the footwall to irregularities on the underside of the hanging wall followed by tectonic exhumation of the molded grooves and conveyer-belt--like transport up and over the large antiform and across the southeastern plains. According to this interpretation, the trend of the grooves records the direction of extension, which is perpendicular to the thrusts at the leading edge of the annular thrust belt 1000 km to the southeast. Both may have formed at the same time as a result of uniform southeastward displacement of the southeastern half of the interior of Artemis Corona. The location of this grooved core complex at the center of Artemis Corona may reflect genesis above the buoyant, ascending tail of the corona-producing mantle diapir. Keywords: coronae, extension tectonics, metamorphic core complexes, Venus, Venus radar mapper.

In one common type of industrial continuous casting, partially molten metal is extruded from a vessel through a shaped orifice called a mold in which the metal assumes the cross-sectional form of the mold as it cools and solidifies. Continuous casting can be sustained as long as molten metal is supplied and thermal conditions are maintained. I propose that a similar process produced parallel sets of grooves in three geologic settings, as follows: (1) corrugated metamorphic core complexes where mylonitized mid-crustal rocks were exhumed by movement along low-angle normal faults known as detachment faults; (2) corrugated submarine surfaces where ultramafic and mafic rocks were exhumed by normal faulting within oceanic spreading centers; and (3) striated magma extrusions exemplified by the famous grooved outcrops at the Inca fortress of Sacsayhuaman in Peru. In each case, rocks inferred to have overlain the corrugated surface during corrugation genesis molded and shaped a plastic to partially molten rock mass as it was extruded from a moderate- to high-temperature reservoir.

The conclusion of T. Parsons and J. McCarthy on their seismic study of the Colorado Plateau is problematic. One problem is that the elevation map of the northeast-southwest line and the digital-elevation database used were erroneously transposed. Another is the failure to include a large part of the Colorado Plateau interior, which includes the reference column, in their lithospheric-mass calculations.