Evaluation of Psychoacoustic Sound Parameters for Sonification

Sonification designers have little theory or experimental evidence to guide the design of data-to-sound mappings. Many mappings use acoustic representations of data values which do not correspond with the listener's perception of how that data value should sound during sonification. This research evaluates data-to-sound mappings that are based on psychoacoustic sensations, in an attempt to move towards using data-to-sound mappings that are aligned with the listener's perception of the data value's auditory connotations. Multiple psychoacoustic parameters were evaluated over two experiments, which were designed in the context of a domain-specific problem - detecting the level of focus of an astronomical image through auditory display. Recommendations for designing sonification systems with psychoacoustic sound parameters are presented based on our results

Thermochronology of the modern Indus River bedload: New insight into the controls on the marine stratigraphic record

The Indus River is the only major drainage in the western Himalaya and delivers a long geological record of continental erosion to the Arabian Sea, which may be deciphered and used to reconstruct orogenic growth if the modern bedload can be related to the mountains. In this study we collected thermochronologic data from river sediment collected near the modern delta. U-Pb ages of zircons spanning 3 Gyr show that only ∼5% of the eroding crust has been generated since India-Asia collision. The Greater Himalaya are the major source of zircons, with additional contributions from the Karakoram and Lesser Himalaya. The 39Ar/40Ar dating of muscovites gives ages that cluster between 10 and 25 Ma, differing from those recorded in the Bengal Fan. Biotite ages are generally younger, ranging 0–15 Ma. Modern average exhumation rates are estimated at ∼0.6 km/m.y. or less, and have slowed progressively since the early Miocene (∼20 Ma), although fission track (FT) dating of apatites may indicate a recent moderate acceleration in rates since the Pliocene (∼1.0 km/m.y.) driven by climate change. The 39Ar/40Ar and FT techniques emphasize the dominance of high topography in controlling the erosional flux to the ocean. Localized regions of tectonically driven, very rapid exhumation (e.g., Nanga Parbat, S. Karakoram metamorphic domes) do not dominate the erosional record

Thermochronology of mineral grains in the Red and Mekong Rivers, Vietnam: Provenance and exhumation implications for Southeast Asia

Sand samples from the mouths of the Red and Mekong Rivers were analyzed to determine the provenance and exhumation history of their source regions. U-Pb dating of detrital zircon grains shows that the main sources comprise crust formed within the Yangtze Craton and during the Triassic Indosinian Orogeny. Indosinian grains in the Mekong are younger (210-240 Ma) than those in the Red River (230-290 Ma), suggesting preferential erosion of the Qiangtang Block of Tibet into the Mekong. The Red River has a higher proportion of 700-800 Ma grains originally derived from the Yangtze Craton. 40Ar/ 39Ar dating of muscovite grains demonstrates that rocks cooled during the Indosinian Orogeny are dominant in both rivers, although the Mekong also shows a grain population cooling at 150-200 Ma that is not seen in the Red River and which is probably of original Qiangtang Block origin. Conversely, the Red River contains a significant mica population (350-500 Ma) eroded from the Yangtze Craton. High-grade metamorphic rocks exposed in the Cenozoic shear zones of southeast Tibet-Yunnan are minority sources to the rivers. However, apatite and zircon fission track ages show evidence for the dominant sources, especially in the Red River, only being exhumed through the shallowest 5-3 km of the crust since ̃25 Ma. The thermochronology data are consistent with erosion of recycled sediment from the inverted Simao and Chuxiong Basins, from gorges that incise the eastern flank of the plateau. Average Neogene exhumation rates are 104-191 m/Myr in the Red River basin, which is within error of the 178 ± 35 m/Myr estimated from Pleistocene sediment volumes. Sparse fission track data from the Mekong River support the Ar-Ar and U-Pb ages in favoring tectonically driven rock uplift and gorge incision as the dominant control on erosion, with precipitation being an important secondary influence. © 2006 by the American Geophysical Union

Evolution of the Kangmar Dome, southern Tibet: Structural, petrologic, and thermochronologic constraints

Structural, thermobarometric, and thermochronologic investigations of the Kangmar Dome, southern Tibet, suggest that both extensional and contractional deformational histories are preserved within the dome. The dome is cored by an orthogneiss which is mantled by staurolite + kyanite zone metasedimentary rocks; metamorphic grade dies out up section and is defined by a series of concentric kyanite-in, staurolite-in, garnet-in, and chloritoid-in isograds. Three major deformational events, two older penetrative events and a younger doming event, are preserved. The oldest event, D1, resulted in approximately E-W trending tight to isoclinal folds of bedding with an associated moderately to steeply north dipping axial planar foliation, S1. The second event, D2, resulted in a high strain mylonitic foliation, S2, which defines the domal structure, and an associated approximately N-S trending stretching and mineral alignment lineation. Shear sense during formation of S2 varied from dominantly top S shear on the south dipping flank of the dome to top N shear on the north dipping flank. The central part of the dome exhibits either opposing shear sense indicators or symmetric fabrics. Microtextural relations indicate that peak metamorphism occurred post-D1 and pre- to early D2 deformation. Quantitative thermobarometry yields peak metamorphic conditions of ∼445°C and 370 MPa in garnet zone rocks, increasing to 625°C and 860 MPa in staurolite + kyanite zone rocks. Pressures and temperatures increase with depth and northward within a single structural horizon across the dome and the apparent gradient in pressure is ∼20% of the expected gradient, suggesting that the rocks were subvertically shortened after the pressure gradient was frozen in. Mica 40Ar/39Ar thermochronology yields 15.24 ± 0.05 to 10.94 ± 0.30 Ma cooling ages that increase with depth and young northward within a single structural horizon across the dome. Diffusion modeling of potassium feldspar 40Ar/39Ar spectra yield rapid cooling rates (∼10–30°C/Myr) between ∼11.5 and 10 Ma and apatite fission track ages range from 7.9 ± 3.0 to 4.1 ± 1.9 Ma, with a mean age of ∼5.5 Ma. Both data sets show symmetric cooling across the dome between ∼11 and 5.5 Ma. The S2 mylonitic foliation, peak metamorphic isobars and isotherms, and mica 40Ar/39Ar isochrons are domed, whereas potassium feldspar 40Ar/39Ar and apatite fission track isochrons are not, suggesting that doming occurred at ∼11 Ma. Our data do not support simple, end-member metamorphic core complex-type extension, diapirism, or duplex models for gneiss dome formation. Rather, we suggest that the formation of extensional fabrics occurred within a zone of coaxial strain in the root zone of the Southern Tibetan Detachment System (STDS), implying that normal slip along the STDS and extensional fabrics within the Kangmar Dome were the result of gravitational collapse of overthickened crust. Subsequent doming during the middle Miocene is attributed to thrusting upward and southward over a north dipping ramp above cold Tethyan sediments. Middle Miocene thrust faulting in the Kangmar Dome region is synchronous with continued normal slip along the STDS and thrust motion along the Renbu Zedong thrust fault, suggesting that extension and contraction was occurring simultaneously within southern Tibet

Numerical evaluation of the vibration reduction index for structural joints

The present paper addresses the analysis of structural vibration transmission in the presence of structural joints. The problem is tackled from a numerical point of view, analyzing some scenarios by using finite element models. The numerical results obtained making use of this process are then compared with those evaluated using the EN 12354 standard vibration reduction index concept. It is shown that, even for the simplest cases, the behavior of a structural joint is complex and evidences the frequency dependence. Comparison with results obtained by empirical formulas reveals that those of the standards cannot accurately reproduce the expected behavior, and thus indicate that alternative complementary calculation procedures are required. A simple methodology to estimate the difference between numerical and standard predictions is here proposed allowing the calculation of an adaptation term that makes both approaches converge. This term was found to be solution-dependent, and thus should be evaluated for each structure.This work was supported by the Ministry of Science and Innovation (Spain) under the Project BIA2010-17723 and by the University of Alicante under the Project GRE10-29

Did the “Autochthonous” European foreland of Corsica Island (France) experience Alpine subduction?

Despite the important role played by the Sardinia-Corsica block in the reconstruction of the Western Mediterranean geodynamics, the extent of involvement of the “Autochthonous” European margin exposed in Corsica (France) (i.e., Hercynian Corsica) in the Alpine orogeny remains uncertain. Stratigraphic and sedimentological studies in the post-Variscan deposits on the Hercynian Corsica are scarce and even scarcer are the structural and metamorphic constraints. To face these uncertainties, we present new stratigraphic, structural and metamorphic data from the area of Razzo Bianco, Central Corsica, where a complete sequence belonging to the Europeancontinental margin is exposed. Field and structural investigations demonstrate that the sequence represents the easternmost edge of the downgoing European plate. Metamorphic studies on the Eocene deposits indicate that the margin was buried at depth up to blueschist facies conditions and, subsequently, it was progressively exhumed mainly through the activation of oblique top-to the NW shear zones