Glass Buttes Research Articles

Oblique incidence of ultrafast laser for glass butt welding.

Lap welding restricts the connection state of glasses by vertically incident ultrafast laser at the interface to be welded, which cannot meet the increasingly flexible welding needs. In this Letter, glass butt welding is achieved by oblique incidence of an ultrafast laser, expanding the applicability of ultrafast laser glass welding. Furthermore, the propagation path of the laser beam after oblique incidence into a glass is solved based on geometric optics, the dynamic development of the molten pool in a glass is observed through a high-speed camera, and the mechanism of glass butt welding is elucidated. Finally, the influence of laser pulse energy, glass tilt angle, and defocus amount on welding strength is investigated, achieving a maximum shear strength of 11.5 MPa.

Reassessing obsidian field relationships at Glass Buttes, Oregon

The Glass Buttes complex in the High Lava Plains of Oregon produced obsidians during a series of rhyolitic eruptions circa 5.8 to 6.5Ma. These obsidians have been used to craft stone tools for millennia, from Clovis peoples to modern knappers, and have been recovered at sites throughout the Pacific Northwest. Glass Buttes is also the origin of much obsidian used for lithic replication experiments and to test new techniques for sourcing. Paradoxically, the spatial distributions of chemically distinct obsidians at this complex have received comparatively little attention. The only published study to connect obsidian compositional differences to the Glass Buttes landscape is Ambroz et al. (2001), who reported seven discrete, spatially constrained obsidian “chemical groups” based on clustered data in elemental scatterplots. Since its publication, their paper has been cited as an example of successful obsidian “subsource” characterization. During the course of a wider research program, we collected 337 specimens at Glass Buttes from loci originally sampled by Ambroz et al. (2001). While we could replicate the “chemical groups” observed by Ambroz et al. (2001), we were unable to reproduce the reported spatial distribution of sources across the landscape. Almost half of the resampled loci exhibited intermingled populations of chemical types due to their locations on alluvial–colluvial deposits. We also identified five additional obsidian chemical types at the complex; however, geochemically significant elements suggest that only a subset of these eleven types correspond to different flows and domes at Glass Buttes. A few appear to reflect chemical zoning within flows, whereas two other types may be exogenous, moved from nearby obsidian sources via secondary transport. Thus, we demonstrate here that the discrete subsource zones demarcated by Ambroz et al. (2001) do not reflect reality on the landscape. This, in turn, alters how artifact sourcing results are interpreted with respect to how mobile foraging groups interacted with the landscape and made choices regarding resource acquisition, toolstone provisioning, and land use.

THE ORIGIN OF COLOR IN "FIRE" OBSIDIAN

A variety of obsidian from Glass Buttes, Oregon, known as “fire” obsidian and named for thin layers showing various colors, was investigated with field-emission scanning electron microscopy, X-ray energy-dispersive spectroscopy, electron back-scatter diffraction, and optical spectroscopy methods. Our study reveals that the thin layers mainly consist of concentrated nanometric crystals of magnetite. The thin layers, which have a thickness of 300 to 700 nm, give rise to brilliant colors in reflection. The color is caused by thin-film optical interference, in which the thin layers have a higher calculated index of refraction (1.496 < n < 1.519) than that of the host glass (n = 1.481).

Structural use of adhesives for the construction of frameless glass shells

The author has investigated the mechanical properties of glass butt joints to be used in the design of glass roofs in architecture. Thanks to adhesive joining, it is possible to design self-bearing structural glass shells without using any metal frame or connection, thus increasing the degree of transparency. After the selection of an adhesive by means of tests on the mechanical properties, a prototype of a frameless structural glass shell has been designed and built in order to show the high potential of such a solution.

Chemical Differentiation of Obsidian within the Glass Buttes Complex, Oregon

Two hundred twenty-five source samples from the multi-component obsidian source at Glass Buttes, Oregon were characterized by neutron activation analysis to determine the number of chemical groups present. Seven geochemical groups were found within the Glass Buttes complex. An abbreviated neutron activation analysis procedure previously used to differentiate between obsidian sources in Mesoamerica was also successful in separating obsidian from different outcrops at Glass Buttes. Thirty-one artifacts from the Robins Spring site on Glass Buttes were also analysed. The abbreviated NAA procedure was also successful at assigning the artifacts to the different subsources at Glass Buttes.

Precious-Metal Deposits in Relation to Volcanic and Sedimentary Stratigraphy: Examples from the Oregon Plateau, U.S.A.: ABSTRACT

Miocene to Recent volcanic and sedimentary rocks of the Oregon Plateau host precious-metal deposits. The deposits, formed within an extensional tectonic setting, illustrate the relation among volcanic and sedimentary stratigraphy, regional structural development, and hydrothermal systems. Gold deposits hosted in felsic volcaniclastic sediments in the Owyhee region formed during or shortly after sedimentation. Uniformly silicified tuffaceous mudstone and siltstone interbedded with siliceous and sulfide-rich sediments and bedded hydrathermal breccia, hydrothermal explosion craters infilled by breccia fragments, and stacked buried sinter deposits attest to mineralization near the time of sedimentation. The regional structures that controlled the distribution of volcanic activity and location of sedimentary basins changed through time. In the middle Miocene, basin-and range faults controlled the location of basalt and rhyolitic volcanism and fluvial and lacustrine basins. In the late Miocene and Pliocene, faults parallel to those of the Western Snake River Plain are more prominent and interfingering volcanic and volcaniclastic sedimentary deposits characterize the stratigraphic section. Fault-controlled mercury mineralization in quartz within opalized high-silica rhyolite flow-domes produces an obscure precious-metal prospect at Glass Buttes in the High Lava Plains. Glassy high-silica rhyolite flow-domes were erupted between 5.8 and 5.0 ma but alteration and mineralization occur along faults of themore » Brothers fault zone that cut the high-silica rhyolite sequence. Younger porphyritic rhyolite to dacite domes, spines, and intrusions controlled by faults of the Brothers fault zone are believed to be the heat source for the hydrothermal system. Precious-metal mineralization may occur in the subsurface where hydrothermal solutions boiled beneath the paleowater table.« less

Mineralogy and Geochemistry of Hydrothermal Alteration at Glass Buttes, South-Central Oregon

Mineralogy and Geochemistry of Hydrothermal Alteration at Glass Buttes, South-Central Oregon

Obsidian Collecting at Oregon's Glass Buttes

(1974). Obsidian Collecting at Oregon's Glass Buttes. Rocks & Minerals: Vol. 49, No. 11, pp. 651-654.

The Effects of High Contact Pressures and Temperatures on the Adhesion of Amorphous Polystyrene to Borosilicate (Pyrex) Glass

Abstract The effects on adhesive joint strength of four pressure-temperature histories, each over the range of pressures from 1 to 1500 bars and temperatures from 25 to 200°C, has been investigated with polystyrene-Pyrex glass butt joint specimens. The various pressure-temperature histories were designed to show the separate effects of permanent stresses, transient stresses and interfacial contact on joint strength. This strength increased as the number of stress concentration loci were reduced through application of high contact pressures on the melt. However, isobaric solidification of the polymer led to a maximum in fracture stress as a function of applied molding pressure because of the existence of a critical pressure at which permanent thermal stresses were minimized. A series of isothermal compression-decompression molding operations showed fracture stress to increase with interfacial contact area until maximum contact was achieved. A 100 per cent gain in bond strength was realized when interfacial...

Theory of stresses in glass butt seals

Theory of stresses in glass butt seals

Theory of stresses in glass butt seals

Theory of stresses in glass butt seals

Reply to theory of stresses in glass butt seals

Reply to theory of stresses in glass butt seals

A theory of stresses in glass butt seals

A series of equations are derived which may be used for the calculation of the stresses in glass butt seals and three component graded seals between materials of differing expansion coefficients. Stress determinations were made by the photoelastic method and good agreement was found between the theoretical and experimental values.

A Structural and Petrographic Study of the Glass Buttes, Lake County, Oregon

The Glass Buttes, a small mountain range composed entirely of volcanic rocks, have as their dominant structural feature an anticline. This anticline has been very greatly modified by a multitude of normal faults. The lavas of the district represent three periods of extrusion. The older flows of basalt were followed by a series of acidic lavas which were, in turn, partially covered by a later series of basalts.