Heavy-mineral provenance signatures during the infill and uplift of a foreland basin : An example from the Jaca basin (southern Pyrenees, Spain)

In the Jaca foreland basin (southern Pyrenees), two main sediment routing systems merge from the late Eocene to the early Miocene, providing an excellent example of interaction of different source areas with distinct petrographic signatures. An axially drained fluvial system, with its source area located in the eastern Central Pyrenees, is progressively replaced by a transverse-drained system that leads to the recycling of the older turbiditic foredeep. Aiming to provide new insights into the source-area evolution of the Jaca foreland basin, we provide new data on heavy-mineral suites, from the turbiditic underfilled stage to the youngest alluvial-fan systems of the Jaca basin, and integrate the heavy-mineral signatures with available sandstone petrography. Our results show a dominance of the ultrastable Ap-Zrn-Tur-Rt assemblage through the entire basin evolution. However, a late alluvial sedimentation stage brings an increase in other more unstable heavy minerals, pointing to specific source areas belonging to the Axial and the North Pyrenean Zone and providing new insights into the response of the heavy-mineral suites to sediment recycling. Furthermore, we assess the degree of diagenetic overprint vs. provenance signals and infer that the loss of unstable heavy minerals due intrastratal dissolution is negligible at least in the Peña Oroel and San Juan de la Peña sections. Finally, we provide new evidence to the idea that during the late Eocene the water divide of the transverse drainage system was located in the North Pyrenean Zone, and areas constituted by the Paleozoic basement were exposed in the west-Central Pyrenees at that time. Our findings provide new insights into the heavy-mineral response in recycled foreland basins adjacent to fold-and-thrust belts

Influence of porosity on the critical currents of trifluoroacetate-MOD YBa2Cu3O7 films

The influence of porosity on the superconducting properties have been investigated on YBa/sub 2/Cu/sub 3/O/sub 7/ thin films deposited on LaAlO/sub 3/ [100] substrates by the so-called Trifluoroacetate (TFA) route. Micro-Raman spectroscopy have been used to determine the concentration of c-axis grains /spl delta/ in different samples and their influence on the final film porosity as observed from SEM imaging. This has been compared with measurements of resistivity and critical currents in the same samples. We prove that this /spl delta/ fraction is the main parameter controlling the porosity and hence the normal-state resistivity of the thin films. The optimization of the microstructure of these YBa/sub 2/Cu/sub 3/O/sub 7/ TFA films allow to have high critical currents : J/sub c/ = 3 /spl times/ 10/sup 6/ A/cm/sup 2/ at 77 K

Multiwavelength excitation Raman scattering analysis of bulk and 2 dimensional MoS2: vibrational properties of atomically thin MoS2 layers

In order to deepen the knowledge of the vibrational properties of two-dimensional (2D) MoS2 atomic layers, a complete and systematic Raman scattering analysis has been performed using both bulk single-crystal MoS2 samples and atomically thin MoS2 layers. Raman spectra have been measured under non-resonant and resonant conditions using seven different excitation wavelengths from near-infrared (NIR) to ultraviolet (UV). These measurements have allowed us to observe and identify 41 peaks, among which 22 have not been previously experimentally observed for this compound, and characterize the existence of different resonant excitation conditions for the different excitation wavelengths. This has also included the first analysis of resonant Raman spectra that are achieved using UV excitation conditions. In addition, the analysis of atomically thin MoS2 layers has corroborated the higher potential of UV resonant Raman scattering measurements for the non-destructive assessment of 2D MoS2 samples. Analysis of the relative integral intensity of the additional first- and second-order peaks measured under UV resonant excitation conditions is proposed for the non-destructive characterization of the thickness of the layers, complementing previous studies based on the changes of the peak frequencies

The Ardon L6 ordinary chondrite: A long-hidden Spanish meteorite fall

We report and describe an L6 ordinary chondrite fall that occurred in Ardon, Leon province, Spain (longitude 5.5605 degrees W, latitude 42.4364 degrees N) on July 9th, 1931. The 5.5 g single stone was kept hidden for 83 yr by Rosa Gonzalez Perez, at the time an 11 yr old who had observed the fall and had recovered the meteorite. According to various newspaper reports, the event was widely observed in Northern Spain. Ardon is a very well-preserved, fresh, strongly metamorphosed (petrologic type 6), and weakly shocked (S3) ordinary chondrite with well-equilibrated and recrystallized minerals. The mineral compositions (olivine Fa(23.7 +/- 0.3), low-Ca pyroxene Fs(20.4 +/- 0.2)Wo(1.5 +/- 0.2), plagioclase An(10.3 +/- 0.5)Ab(84.3 +/- 1.2)), magnetic susceptibility (log chi = 4.95 +/- 0.05 x10(-9) m(3) kg(-1)), bulk density (3.49 +/- 0.05 g cm(-3)), grain density (3.58 +/- 0.05 g cm(-3)), and porosity (2.5 vol%) are typical for L6 chondrites. Short-lived radionuclides confirm that the meteorite constitutes a recent fall. The Ne-21 and Ar-38 cosmic ray exposure ages are both about 20-30 Ma, similar to values for many other L chondrites. The cosmogenic Ne-22/Ne-21 ratio indicates that preatmospheric Ardon was a relatively large body. The fact that the meteorite was hidden in private hands for 83 yr makes one wonder if other meteorite falls may have experienced the same fate, thus possibly explaining the anomalously low number of falls reported in continental Spain in the 20th century

The Ardon L6 ordinary chondrite: A long-hidden Spanish meteorite fall

We report and describe an L6 ordinary chondrite fall that occurred in Ardon, Leon province, Spain (longitude 5.5605 degrees W, latitude 42.4364 degrees N) on July 9th, 1931. The 5.5 g single stone was kept hidden for 83 yr by Rosa Gonzalez Perez, at the time an 11 yr old who had observed the fall and had recovered the meteorite. According to various newspaper reports, the event was widely observed in Northern Spain. Ardon is a very well-preserved, fresh, strongly metamorphosed (petrologic type 6), and weakly shocked (S3) ordinary chondrite with well-equilibrated and recrystallized minerals. The mineral compositions (olivine Fa(23.7 +/- 0.3), low-Ca pyroxene Fs(20.4 +/- 0.2)Wo(1.5 +/- 0.2), plagioclase An(10.3 +/- 0.5)Ab(84.3 +/- 1.2)), magnetic susceptibility (log chi = 4.95 +/- 0.05 x10(-9) m(3) kg(-1)), bulk density (3.49 +/- 0.05 g cm(-3)), grain density (3.58 +/- 0.05 g cm(-3)), and porosity (2.5 vol%) are typical for L6 chondrites. Short-lived radionuclides confirm that the meteorite constitutes a recent fall. The Ne-21 and Ar-38 cosmic ray exposure ages are both about 20-30 Ma, similar to values for many other L chondrites. The cosmogenic Ne-22/Ne-21 ratio indicates that preatmospheric Ardon was a relatively large body. The fact that the meteorite was hidden in private hands for 83 yr makes one wonder if other meteorite falls may have experienced the same fate, thus possibly explaining the anomalously low number of falls reported in continental Spain in the 20th century

Enabling electromechanical transduction in silicon nanowire mechanical resonators fabricated by focused ion beam implantation

We present the fabrication of silicon nanowire (SiNW) mechanical resonators by a resistless process based on focused ion beam local gallium implantation, selective silicon etching and diffusive boron doping. Suspended, doubly clamped SiNWs fabricated by this process presents a good electrical conductivity which enables the electrical read-out of the SiNW oscillation. During the fabrication process, gallium implantation induces the amorphization of silicon that, together with the incorporation of gallium into the irradiated volume, increases the electrical resistivity to values higher than 3 Ω m, resulting in an unacceptably high resistance for electrical transduction. We show that the conductivity of the SiNWs can be restored by performing a high temperature doping process, which allows us to recover the crystalline structure of the silicon and to achieve a controlled resistivity of the structures. Raman spectroscopy and TEM microscopy are used to characterize the recovery of crystallinity, while electrical measurements show a resistivity of 10 Ω m. This resistivity allows to obtain excellent electromechanical transduction, which is employed to characterize the high frequency mechanical response by electrical methods

Influence of porosity on the critical currents of trifluoroacetate-MOD YBa2Cu3O7 films

The influence of porosity on the superconducting properties have been investigated on YBa/sub 2/Cu/sub 3/O/sub 7/ thin films deposited on LaAlO/sub 3/ [100] substrates by the so-called Trifluoroacetate (TFA) route. Micro-Raman spectroscopy have been used to determine the concentration of c-axis grains /spl delta/ in different samples and their influence on the final film porosity as observed from SEM imaging. This has been compared with measurements of resistivity and critical currents in the same samples. We prove that this /spl delta/ fraction is the main parameter controlling the porosity and hence the normal-state resistivity of the thin films. The optimization of the microstructure of these YBa/sub 2/Cu/sub 3/O/sub 7/ TFA films allow to have high critical currents : J/sub c/ = 3 /spl times/ 10/sup 6/ A/cm/sup 2/ at 77 K

Magnetic vortex evolution in self-assembled La₀.₇Sr₀.₃MnO₃ nanoislands under in-plane magnetic field

The magnetic vortex formation at room temperature and its evolution under in-plane magnetic field is studied in chemically grown self-assembled La₀.₇Sr₀.₃MnO₃ nanoislands of less than 200 nm in width. We use variable field magnetic force microscopy and numerical simulations to confirm that the vortex state is ubiquitous in these square-base pyramid shape epitaxial LaSrMnO nanostructures, and that it requires in-plane magnetic fields below 40 kA/m to be annihilated

Magnetic vortex evolution in self-assembled La₀.₇Sr₀.₃MnO₃ nanoislands under in-plane magnetic field

The magnetic vortex formation at room temperature and its evolution under in-plane magnetic field is studied in chemically grown self-assembled La₀.₇Sr₀.₃MnO₃ nanoislands of less than 200 nm in width. We use variable field magnetic force microscopy and numerical simulations to confirm that the vortex state is ubiquitous in these square-base pyramid shape epitaxial LaSrMnO nanostructures, and that it requires in-plane magnetic fields below 40 kA/m to be annihilated