bluuebunny/crossref_metadata_2025_split huggingface dataset:
40
Ar/
39
Ar thermochronological constraints on the cooling and exhumation history of the South Tibetan Detachment System, Nyalam area, southern Tibet
Authors: Wang Yu , Li Qi , Qu Guosheng 
Published: April 2008

Abstract

The Nyalam detachment is part of the east-west striking South Tibetan Detachment System exposed in the Nyalam area, southern Tibet. Seventeen muscovite and biotite
40
Ar/
39
Ar age spectra and three K-feldspar multidiffusion domain modelling and cooling ages are presented for metamorphic rocks, leucogranite, granite and mylonite, collected from the Nyalam detachment and surrounding areas. The majority of the
40
Ar/
39
Ar results are cooling ages related to exhumation, which therefore place important constraints on formation of the Nyalam detachment and exhumation history of the region. Muscovite
40
Ar/
39
Ar ages from mylonite within the normal fault system and from the footwall of the fault are 16.1–15.2 Ma. Biotite
40
Ar/
39
Ar ages from the same samples are 15.6–14.8 Ma, slightly younger than the muscovite cooling ages. K-feldspar multidiffusion domain modelling suggests that samples collected from both mylonite on the fault surface and from footwall rocks underwent rapid cooling between 16.1 Ma and 11.7 Ma.

Ages and cooling histories in the Nyalam detachment and Greater Himalayan metamorphic sequence have similar characteristics and time constraints: the K-feldspar modelling indicates a sudden change in cooling rates for these regions during 15.5–14.0 Ma and
c.
12 Ma, respectively. Taking the regional thermal history into account, cooling could be associated with significant northward surface movement triggered by detachment normal faulting in the Nyalam area. The Nyalam detachment and Greater Himalayan metamorphic sequence experienced similar cooling and exhumation histories during
c.
17.0–11.7 Ma. Formation of the Nyalam detachment may have accompanied the southward extrusion of the Greater Himalaya zone along shear zones formed in response to underthrusting of the Indian plate beneath southern Tibet.
Crustal structure, restoration and evolution of the Greater Himalaya in Nepal-South Tibet: implications for channel flow and ductile extrusion of the middle crust
Authors: Searle M. P. , Law R. D. , Jessup M. J. 
Published: April 2008

Abstract
Recent suggestions that the Greater Himalayan Sequence (GHS) represents a mid-crustal channel of low viscosity, partially molten Indian plate crust extruding southward between two major ductile shear zones, the Main Central thrust (MCT) below, and the South Tibetan detachment (STD) normal fault above, are examined, with particular reference to the Everest transect across Nepal-south Tibet. The catalyst for the early kyanite ± sillimanite metamorphism (650–680°C, 7–8 kbar, 32–30 Ma) was crustal thickening and regional Barrovian metamorphism. Later sillimanite ± cordierite metamorphism (600–680°C, 4–5 kbar, 23–17 Ma) is attributed to increased heat input and partial melting of the crust. Crustal melting occurred at relatively shallow depths (15–19 km, 4–5 kbar) in the crust. The presence of highly radiogenic Proterozoic black shales (Haimanta-Cheka Groups) at this unique stratigraphic horizon promoted melting due to the high concentration of heat-producing elements, particularly U-bearing minerals. It is suggested that crustal melting triggered channel flow and ductile extrusion of the GHS, and that when the leucogranites cooled rapidly at 17–16 Ma the flow ended, as deformation propagated southward into the Lesser Himalaya. Kinematic indicators record a dominant south-vergent simple shear component across the Greater Himalaya. An important component of pure shear is also recorded in flattening and boudinage fabrics within the STD zone, and compressed metamorphic isograds along both the STD and MCT shear zones. These kinematic factors suggest that the ductile GHS channel was subjected to subvertical thinning during southward extrusion. However, dating of the shear zones along the top and base of the channel shows that the deformation propagated outward with time over the period 20–16 Ma, expanding the extruding channel. The last brittle faulting episode occurred along the southern (structurally lower) limits of the MCT shear zone and the northern (structurally higher) limits of the STD normal fault zone. Late-stage breakback thrusting occurred along the MCT and at the back of the orogenic wedge in the Tethyan zone. Our model shows that the Himalayan-south Tibetan crust is rheologically layered, and has several major low-angle detachments that separate layers of crust and upper mantle, each deforming in different ways, at different times.
Normal-sense shear zones in the core of the Higher Himalayan Crystallines (Bhutan Himalaya): evidence for extrusion?
Authors: Carosi R. , Montomoli C. , Rubatto D. , Visonà D. 
Published: April 2008

Abstract
Recent fieldwork in western Bhutan, dedicated to unravelling the tectonic structure of the mid-crustal rocks, indicates a complex deformation pattern in the Greater Himalayan Slab (GHS). A system of normal shear zones, striking NE-SW and steeply to moderately dipping to the SE, has been recognized within this extruding slab or wedge of crystalline rocks. The zones are characterized by well developed shear-sense indicators pointing to a top-down-to-SE sense of shear. The main Barrovian metamorphic minerals are bent and stretched by extensional shear bands and associated deformation mechanisms indicate a range of brittle-ductile deformation conditions. Normal shear zones are concentrated in the middle-upper part of the GHS and indicate a thrust-transport-parallel lengthening of the core itself. Vorticity analysis highlights a non-coaxial flow with pure and simple shear acting together during deformation (mean vorticity number bracketed between 0.63 and 0.76). These data, when compared to available data near the tectonic boundaries of the GHS, indicate an increasing component of pure shear towards the interior of the GHS. The ages of zircon overgrowths and monazites from a slightly deformed granite, 20.5 ± 0.5 Ma, and a mylonitic granite deformed into the shear zones, 17.0 ± 0.2 Ma, bracket the age of shear zone formation at close to 17 Ma. According to our data, the normal shear zones could well accommodate the pure shear component of deformation localized in the inner part of the extruding wedge/slab and is compatible with a channel flow model.
Unrest in Long Valley Caldera, California, 1978–2004
Authors: Hill David P. 
Published: April 2008

Abstract

Long Valley Caldera and the Mono-Inyo Domes volcanic field in eastern California lie in a left-stepping offset along the eastern escarpment of the Sierra Nevada, at the northern end of the Owens Valley and the western margin of the Basin and Range Province. Over the last 4 Ma, this volcanic field has produced multiple volcanic eruptions, including the caldera-forming eruption at 760 000 a
bp
and the recent Mono-Inyo Domes eruptions 500–660 a
bp
and 250 a
bp
. Beginning in the late 1970s, the caldera entered a sustained period of unrest that persisted through the end of the century without culminating in an eruption. The unrest has included recurring earthquake swarms; tumescence of the resurgent dome by nearly 80 cm; the onset of diffuse magmatic carbon dioxide emissions around the flanks of Mammoth Mountain on the southwest margin of the caldera; and other indicators of magma transport at mid- to upper-crustal depths. Although we have made substantial progress in understanding the processes driving this unrest, many key questions remain, including the distribution, size, and relation between magma bodies within the mid-to-upper crust beneath the caldera, Mammoth Mountain, and the Inyo Mono volcanic chain, and how these magma bodies are connected to the roots of the magmatic system in the lower crust or upper mantle.
Faults and ground uplift at active calderas
Authors: Folch A. , Gottsmann J. 
Published: April 2008

Abstract
Subsurface volume and pressure increases triggering surface inflation at active calderas are generally deduced by inverting ground-deformation time-series using isotropic and homogeneous half-space models (IHM). These models represent simplified mathematical analogues of the mechanical behaviour of the Earth’s crust. Using three-dimensional numerical modelling, we show that lateral discontinuities such as intracaldera- or caldera-ring-faults can significantly amplify and distort the ground deformation pattern during unrest. As a consequence, data inversions using IHMs, which do not consider lateral discontinuities, can provide erroneous results on causative source parameters. We also find that the degree of amplification and distortion in the form of abrupt changes in displacement/distance gradients in proximity to faults is dependent on source geometry. Prolate bodies represent a particularly critical geometry for which pressure increases may be overestimated by a factor of up to three. Our 3D analysis suggests that amplification effects can be much larger than predicted by earlier 2D models. We validate theoretical results by applying our model to investigate the effect of boundary faults and source geometries on the displacement field during ground uplift at the restless calderas of Campi Flegrei (Italy) and Sierra Negra (Galapagos Islands, Ecuador). Based on the discrepancy in results from IHMs and our numerical model, we argue that employing IHMs for inversion of ground displacement and gravity time-series may in some cases lead to a biased assessment of hazards associated with ground uplift.
The search for magma reservoirs in Long Valley Caldera: single versus distributed sources
Authors: Battaglia M. , Vasco D. W. 
Published: April 2008

Abstract

Long Valley Caldera and the Mono-Inyo Craters chain form a large volcanic complex in eastern California that has experienced persistent earthquake activity and ground uplift over the past 25 years. The central part of Long Valley Caldera (an area of more than 100 square km) has been slowly rising since 1980 at an average rate of 3 cm a
−1
. Inversion of micro-gravimetry and deformation data using a single vertical prolate ellipsoid source has helped to define the existence of a relatively shallow (5–8 km) silicic magma intrusion of 0.11–0.19 km
3
beneath the caldera’s resurgent dome. We use the information from the single-source inversion to constrain a more general three-dimensional distribution of volume changes in the subsurface. The distributed inversion identifies two main inflation areas beneath the resurgent dome: one following the regional trend of north-south faults, and another in the dome’s southern section, parallel to a strike-slip fault that is responsible for most of the seismic activity in the caldera’s south moat.
Evaluating the impact of quarrying on karst aquifers of Salento (southern Italy)
Authors: Delle Rose M. , Parise M. , Andriani G. F. 
Published: April 2008

Abstract
This paper describes a case study in the Salento karst (Apulia, southern Italy) in a site that has been intensively used to quarry limestones in the last 30 years. After quarrying activity had stopped, the site was transformed into legal and illegal landfills where solid and liquid wastes have been repeatedly dumped, with serious consequences for the groundwater resources. In this paper, through a geological, petrographical and hydrogeological approach, we attempt to assess the consequences of the anthropogenic activities on the local hydrogeology, with particular regard to the surficial aquifer that is contained in the Plio-Quaternary calcarenites cropping out in the area. Application of some well-known methods to assess the vulnerability of aquifer systems to contamination by human activities (DRASTIC, SINTACS, LeGrand and GOD) highlights the limits of such an approach in karst environment, and the necessity to include in the methods data strictly related to the peculiarity of karst. This is further evidenced by application of the EPIK method, specifically designed for karst areas. The final part of the paper focuses on the need of a thorough understanding of the hydrogeological setting for a better management and policy action of karst environments.
Biotic versus abiotic calcite formation on prehistoric cave paintings: the Arcy-sur-Cure ‘Grande Grotte’ (Yonne, France) case
Authors: Chalmin E. , d'Orlyé F. , Zinger L. , Charlet L. , Geremia R. A. , Orial G. , Menu M. , Baffier D. , Reiche I. 
Published: April 2008

Abstract
The ‘Grande Grotte’ cave at Arcy-sur-Cure (Yonne, France) with its prehistoric paintings shows important calcite concretions. Two types of calcite have been observed on the wall: translucent yellowish layers and opaque white or grey layers that completely obstruct the paintings. Other calcite types are present in the lakes of the cave (floating calcite rafts at the surface of the lake and soft calcite at the bottom of the lake).
The morphology of the different calcites was observed at different scales by optical microscopy with normal and polarized light, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The elemental composition was measured by using particle-induced X-ray emission (micro-PIXE) and the structure by X-ray diffraction (XRD), infrared (FT-IR) and Raman spectroscopy. The bacterial diversity and its role in calcite formation were assessed by culture and 16S-SSCP in order to distinguish and to assess various abiotic and biotic formation mechanisms.
The investigation of calcite characteristics enables conclusions on the formation mechanism and on a biotic or abiotic origin of the calcites. The change of calcite types on the walls reveals changes of the environmental cave parameters. In addition, interactions of calcites with the prehistoric paint layer could be evaluated.
Magnetic prospection as an efficient tool for doline detection: a case study in the central Ebro Basin (northern Spain)
Authors: Mochales T. , Pueyo E. L. , Casas A. M. , Soriano M. A. 
Published: April 2008

Abstract

The presence of alluvial dolines in the Ebro Basin causes problems to both agricultural and urban areas. At present, new urbanization of former farming areas requires new tools to detect karst zones and so diminish the hazard linked to collapses. In the surroundings of Zaragoza, dolines (developed mainly on Quaternary alluvial terraces covering a Tertiary gypsum substratum) are commonly filled with alluvial deposits, agricultural soils, urban debris, etc. Measurements of magnetic susceptibility show a remarkable contrast between host rocks and cavity fillings, demonstrating the value of magnetic surveying. A field test was made in a recently collapsed (September 2003) doline filled currently with urban debris. A magnetic survey was carried out following a 130 m
2
grid, with 1–10 m spacing between profiles. A proton magnetometer with gradiometer was utilized, and the total field intensity and gradient measurements were taken. The magnetic survey demonstrated a strong anomaly with a dipole defined by more than 650 nT and a gradient of about 100 nT m
−1
. The 2.5-dimensional (2.5D) modelling of the magnetic anomaly fits well with the known geometrical data. Two other dolines (that are not clearly defined at the surface) were also detected during the survey. These results validate the starting hypothesis and open a new research approach to the problem. The magnetic survey output allows the construction of realistic geological models.
Coastal karst geomorphosites at risk? A case study: the floods of 6–11 December 2004 in central-east Sardinia
Authors: Cossu A. , De Waele J. , Di Gregorio F. 
Published: April 2008

Abstract
Extreme rainfall causing floods and great damage occurred in many areas of central-east Sardinia in the period 6–11 December 2004. A total of approximately 700 mm of rain was measured during this extreme event, with a maximum reaching 510 mm of rainfall in 1 day at the rain gauge of Villagrande (Ogliastra). During and immediately after the event all fluviokarstic canyons were activated for at least 1 week, reaching the highest water levels in at least 50 years and reversing great quantities of sediment-loaded water onto the coast and with important geomorphical modifications. There was public fear that serious damage to the natural resources would occur, such as the famous Cala Luna beach that was almost completely destroyed by the flooding of the Codula Ilune River and by the coinciding sea storm. The river, in fact, eroded the longshore bar (beach) and destroyed the small backshore lagoon. A monitoring study has been initiated in order to analyse the natural evolution of this littoral system and to define the resilience of this interesting geomorphosite. The observations have shown that the flood, albeit impacting negatively in the moments immediately after the disaster, almost completely restored the natural equilibrium of this coastal karst geo-ecosystem within a season.
Contributory area definition for groundwater source protection and hazard mitigation in carbonate aquifers
Authors: Gunn J. 
Published: April 2008

Abstract
Carbonate aquifers provide important sources of potable water but are known to be particularly prone to pollution owing to rapid transfer of pollutants from the surface to springs or boreholes. Source protection zones and groundwater vulnerability maps are commonly used to mitigate against the pollution hazard but cannot be applied simplistically to carbonate aquifers, which are usually highly heterogeneous with overlapping groundwater divides that may vary with water levels. Divergent flow and disjunct contributory areas provide further complexity. Under these conditions, water-tracing experiments, repeated under different flow conditions, are the only tool capable of identifying those areas that contribute recharge to a particular source. Examples of water pollution affecting disjunct and overlapping source contributory areas are presented from the Waitomo area (New Zealand), Cuilcagh Mountain (Ireland) and the Peak District (UK). Source protection zones (SPZ), that have been defined by the Environment Agency in the Buxton area of the Peak District using equivalent porous medium models, are shown to be deficient. Further water-tracing experiments are essential if carbonate aquifers are to be adequately protected from pollution.
Evolution of the Microstructure and Performance of Pd/Ag ‐ BasedThick Conductors
Authors: Prudenziati Maria , Morten Bruno , Brigatti Maria Franca 
Published: April 2008

Pd/Ag‐based inks are probably the most commonly used conductors in thick‐film hybrid technology. The
evolution of the microstructure of these films was studied on samples fired with isochronal cycles at a
peak temperature in the range from 300℃ up to 850℃. The samples were investigated by means of X‐ray
diffraction, SEM and EDAX analysis techniques; the results of these analyses as well as those of
thermogravimetry (TG, DTG) and differential thermal analysis (DTA), enable one to obtain a clear
picture of the complex evolution of the microstructure of these conductors, which correlates quite strictly
with the performance of the films in terms of resistivity and adhesion.The relevance and limitations of each analytical technique for the examination of thick‐film conductors
are emphasized.
Preparation and Properties of a New Thick Film System
Authors: Inokuma T. , Taketa Yoshiaki , Haradome Miyoshi 
Published: April 2008

Work has been carried out to develop a new ruthenium oxide based thick film resistor whose resistance is
independent of the contact area of the conductor to the resistor. Such a resistor can then be combined with a
low cost silver conductor.It has been found that such a resistor can be made by doping a ruthenium oxide based thick film resistor
with up to several percent of gold. With such a material it is possible to use silver or palladium silver
(containing only very small amounts of palladium) as an electrode material and very few interactions have
been found to occur between the resistor and electrode. Such a gold doped ruthenium oxide thick film resistor
using silver electrodes has some major advantages as follows:‐1. The resistor size can be made much smaller than normal.2. The design of a thick film hybrid circuit becomes easier.3. The resistor cost can be reduced.
Statistical Analysis of Data From Electronic Component Lifetests (ATutorial Paper)
Authors: Møltoft J. 
Published: April 2008

Methods of statistically analysing data from electronic component lifetests are discussed. Particular emphasis is given to
analysis techniques using the assumptions of constant hazard rate (Exponential distribution), the Weibull distribution
and mixed Weibull distributions. The methods used for analysing Weibull data when the data itself is non‐uniform due
to both removal of test samples during test and also the non‐continuance of surveillance of components under test are
discussed. Attention is finally given to the effect of two or more failure mechanisms which can produce S‐shaped
patterns when data is plotted on Weibull Graph paper.Numerous examples are given, mainly from the field of analysis of CMOS circuit components.
Similarity Criteria of EHF Physical Model of Long Distance Transmission Line with Plate Phases
Authors: Hamed M. 
Published: April 2008

Carson′s equations for computation of frequency dependent parameters of overhead
transmission line are modified. The earth is considered to be homogenous. The
optimal required number of terms of Carson′s series for applications on computer is
determined. Accurate mathematical expressions for resistance and inductance of
overhead transmission lines are obtained.Different arrangements of conductors for double circuit transmission lines are
studied. The mutual inductance and potential coefficient (mutual capacitance) of such
arrangements are computed. Double voltage class type double circuit transmission
lines are suggested. The plate type double circuit lines are proposed for power transmission
over long distances.This paper presents a mathematical analysis in order to determine the coefficients
of similarity criteria of EHF physical model for the given long distance transmission
line. The integral analogue method and PI‐theorem are used. The independent
parameters of EHF physical model are formulated. The scales of four independent
parameters of the designed EHF physical model are obtained.
Analysis of Multi‐Pin Modular Daughterboard‐to‐BackplaneConnectors at High Bit Rate Signals
Authors: Capsalis C. N. , Chronopoulos C. P. , Tigelis J. G. , Uzunoglu N. K. 
Published: April 2008

A theoretical model for the electrical characterization of multi‐pin modular daughterboard‐to‐backplane
connectors at high bit rate signals is developed. The fundamental field equations are transformed into
a linear system of equations for the currents and voltages at the edges of the pins of the connector.Efficient formulaes for the calculation of self and mutual inductances and capacitances between the
pins which are involved in the linear system of equations are obtained. Using the previous developed
theoretical model the connector′s performance can be examined in both the frequency and the time
domain.Numerical calculations are performed for three types of existing connectors. Furthermore, they are
compared to each other for bit‐rates in the range of 100 Mbits/sec up to 500 Mbits/sec.