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Showing papers by "IPG Photonics published in 1993"


Journal ArticleDOI
TL;DR: In this article, the velocity field of present-day deformation in Central Asia is modelled using a set of four rotating blocks (Siberia, Tarim, Tibet, India) on a spherical earth.
Abstract: The velocity field of present‐day deformation in Central Asia is modelled using a set of four rotating blocks (Siberia, Tarim, Tibet, India) on a spherical earth. A best‐fit is inverted on the basis of estimated shortening‐rates across the main thrust zones (Himalayas, Tien Shan) and measured slip‐rates along the principal strike‐slip faults (Altyn Tagh and Karakorum) separating those blocks. The fit to the data implies that nearly all the present convergence between India and Asia can be accounted for by slip‐partitioning on these four zones, with as much as 50% absorbed by northeastwards extrusion of Tibet. This suggests that localised deformation governs the present mechanical behaviour of the Central Asian lithosphere.

881 citations


Journal ArticleDOI
TL;DR: In this article, the authors used X-ray Absorption Near Edge Structure (XANES) spectroscopy, Extended Xray Absorbption Fine Structure (EXAFS), and Optical Spectral Spectral Analysis (OSA) to investigate the presence of nickel in silicate and aluminosilicate glasses.

144 citations


Journal ArticleDOI
TL;DR: In this article, the authors have determined the omphacites δ18O and the abundance, δD and δ13C of hydrous and carbonaceous compounds present in whole rocks which are believed to trace the residual phases of what was mobilized in the original rocks during subduction.

135 citations


Journal ArticleDOI
TL;DR: In this article, the authors have sampled close to two summits of Teahitia, a submarine volcano from the southern extension of the Society volcanic chain, and the temperatures measured within two vents were 30°C.

79 citations


Journal ArticleDOI
TL;DR: Textural and petrological data are presented that record the formation of plagioclase-bearing wehrlites and peridotites at slow-spreading and fast spreading ridges that are comparable to those formed in ophiolitic complexes as discussed by the authors.

68 citations


Journal ArticleDOI
TL;DR: The Pallatanga right-lateral strike-slip fault as discussed by the authors runs across the Western Cordillera connecting N50°E-N70°E trending normal faults in the Gulf of Guayaquil with N-S reverse fault in the Interandean Depression.
Abstract: The northeast-trending Pallatanga right-lateral strike-slip fault runs across the Western Cordillera connecting N50°E-N70°E trending normal faults in the Gulf of Guayaquil with N-S reverse faults in the Interandean Depression Over most of its length, the fault trace has been partly obscured by erosional processes and can be inferred in the topography only at the large scale Only the northern fault segment, which follows the upper Rio Pangor valley at elevations above 3600 m, is prominent in the morphology Valleys and ridges cut and offset by the fault provide an outstanding record of right-lateral cumulative fault displacement The fault geometry and kinematics of this particular fault segment can be determined from detailed topographic levellings The fault strikes N30°E and dips 75° to the NW Depending on their size and nature, transverse morphological features such as tributaries of the Rio Pangor and intervening ridges, reveal right-lateral offsets which cluster around 27 ± 11m, 415 ± 4 m, 590 ± 65 m and 960 ± 70 m The slip vector deduced from the short-term offsets shows a slight reverse component with a pitch of about 115° SW The 415 ± 4 m displacements are assumed to be coeval with the last glacial termination, yielding a mean Holocene slip-rate of 29- 46 mm yr^(−1) Assuming a uniform slip rate on the fault in the long term, the 27 m offset appears to correlate with an identified middle Holocene morphoclimatic event, and the long term offsets of 590 m and 960 m coincide with the glacial terminations at the beginning of the last two interglacial periods

58 citations


Journal ArticleDOI
TL;DR: The two Ni coordination states put in evidence in Part 1 indicate distinct connections with the silicate glass structure, and their proportion only depends on glass composition as discussed by the authors, which is independent of the Ni content of the glass over more than two orders of magnitude (0.1-27 wt% NiO).

37 citations


Journal ArticleDOI
L Galoisy1, Georges Calas1
TL;DR: In this paper, the first spectroscopic data on KNiPO4 used as reference compound for 5-coordinated nickel in crystalline oxide compounds are presented, where the Ni-K edge X-ray Absorption Near Edge Structure (XANES) spectrum is compared to those of 4-and 6-coordinate Ni in NiCr2O4 and CaNiSi2O6, respectively.

19 citations


Journal ArticleDOI
TL;DR: Aged alumina refractories have been investigated by EPR (electron paramagnetic resonance) and EPMA (Electron Probe Micro-Analysis) as mentioned in this paper, which shows that Cr 3+ ions may be preferentially concentrated at the vicinity of extended lattice defects which help in accommodating the lattice strain due to the size difference between Al3+ and Cr3+ cations.
Abstract: Aged alumina refractories have been investigated by EPR (Electron Paramagnetic Resonance) and EPMA (Electron Probe Micro-Analysis). EPMA shows that Cr is homogeneously distributed inside the corundum grains within spatial resolution (1 μm). Cr3+ concentration at the atomic scale is obtained by EPR by the magnitude of dipolar broadening due to Cr-Cr interactions. This local concentration appears to be systematically higher (up to a factor of 10) than the average chromium content of the corundum crystals determined by EPMA. Cr3+ ions may be preferentially concentrated at the vicinity of extended lattice defects which help in accommodating the lattice strain due to the size difference between Al3+ and Cr3+ cations. A random location of these defects explains the apparent homogeneous chromium distribution found by EPMA in these aged refractories.

4 citations