IODP Expeditions 309 and 312 drill an intact section of upper oceanic basement into gabbros

The Integrated Ocean Drilling Program's (IODP) Expeditions 309 and 312 successfully completed the first sampling of an intact section of upper oceanic crust, through lavas and the sheeted dikes into the uppermost gabbros. Hole 1256D, which was initiated on the Ocean Drilling Program's (ODP) Leg 206, now penetrates to >1500 mbsf and >1250 m sub-basement. The first gabbroic rocks were encountered at 1407 mbsf. Below this, the hole penetrates 3c100 m into a complex zone of fractionated gabbros intruded into contact metamorphosed dikes

Hydrogeochemical and isotopic signatures for the identification of seawater intrusion in the paleobeach aquifer of Cox's Bazar city and its surrounding area, south-east Bangladesh

In order to better understand the encroachment of seawater into the groundwater system a total 115 groundwater samples were collected in an area of ∼7 km 2 in Cox's Bazar paleobeach and its vicinity, from different types of tubewells, which included hand pump fitted bore wells (&amp;lt;50 m depth), moderately deep energized bore wells (50 m–100 m depth) and deep bore wells (&amp;gt;100 m depth) during June 2013. A combined hydro-geochemical indicators, selected trace elements (Sr and B) and in addition to δ 18 O and δ 2 H were used in this study. Results show that the high values of EC (202 μS/cm to 6730 μS/cm) and TDS (135 mg/L to 4509 mg/L) are found in groundwater of wells closer to the coast and few wells from the northern and central part of the study area. The cross plot of HCO 3 /Cl and TDS shows that groundwater along the paleobeach and some isolated areas are saline with TDS &amp;gt; 1000 mg/L, associated with high ratios of Cl/TDS (0.065). The groundwater facies generally evolves from freshwater (Ca-Mg-HCO 3 ) to saline water (Na- Cl) type with an intermediate Ca-Mg-Cl type indicating that the aquifer system interacts with seawater and undergoes cation exchange. Results also reveal that the area affected by marine water intrusion has ionic ratios of Br/Cl (0.0006–0.0021) similar to seawater (0.0015) with some higher values. Groundwaters along the paleobeach and some isolated areas, low ionic ratios of SO 4 /Cl (0.01–6.53) and Na/Cl (0.20–152.09), relative to marine ratios (0.05 and 0.86 respectively), are also observed. Groundwaters with Seawater Mixing Index &amp;gt;1.0 and TDS &amp;gt;1000 mg/L constitute about 20% of the studied groundwaters and have relatively high δ 18 O (&amp;gt;- 4.0‰) values and the linear relationships between TDS and most of the ions, including B and Sr, and the chemical signature of the saline plumes (e.g., marine SO 4 /Cl, Na/Cl and Br/Cl ratios) suggest that mixing processes control the chemical composition of the seawater within the aquifers. However, these geochemical variations also reveal that the quality of potable water has deteriorated to a large extent due to seawater intrusion along the paleobeach, migrating inland toward the heavily groundwater exploited areas from the coast line and may entail various future health hazards.</p

Spectroscopic ellipsometry of TaNx and VN films

We report on spectro-ellipsometric investigations of reactively sputtered tantalum nitride (TaNx/SiO2) and vanadium nitride (VN/Si) films. Several TaNx layers with different deposition temperatures (200–400 °C) and a VN layer were prepared optically thick and analyzed using the bulk formula. For thin TaNx layers prepared with the same temperatures as thick layers, the Drude–Lorentz parameterization of dielectric functions was used by simultaneous fitting of ellipsometric and optical transmittance spectra. VN pseudo-dielectric functions show strong metallic character, which is typical for other transition metal nitrides. In contrast, the TaNx dielectric constants obtained here range from a metallic to a non-metallic character depending on substrate temperature, but independent of the film thickness. This substrate temperature dependence may be due to multiple phases in the TaNx films