Im Herzen Afrikas

T – Goldschmidt Abstracts 2013

“…Finally, the correlation between the spatial distribution of lithology of the sub-watersheds and their corresponding 87 Sr /86 Sr ratio of river water, the correlation between NO 3 -/HCO 3 -, Cl -/HCO 3 -, SO 4 2-/HCO 3 -and anthropogenic activities respectively, and the correlation between the fraction of green vegetation of the sub-watershed and their corresponding flux of TDS (total dissolved solids) were analyzed quantitatively. The results justify that the 87 Sr/ 86 Sr ratio of river water is highly dependent on the lithologic feature of the watershed and indicate that anthropogenic activities are one of the main sources of NO 3 -and SO 4 2-of river waters, the output of TDS is highly dependent on the percentage of vegetation cover of the watershed. The Mongol-Okhotsk suture belt is located between the North Asian and the North China cratons and played an important role in the formation and tectonic evolution of eastern part of the Eurasian continent during Mesozoic.…”

“…A core interval (70 cm) of the residual harzburgite cut by gabbro recovered from the Atlantis Massif, Mid-Atlantic Ridge 30°N shows inhomogeneous compositions caused by reaction with melt forming the gabbro [4]. Pargasitic amphibole inclusions in concentric spinel grains are only observed in the harzburgite near the gabbro contact (10 cm) where depleted residual harzburgite reacted with N-MORBlike melt beneath the ridge.…”

“…Though the glass series of NIST SRM 61x have been the most commonly reference material used in LA-ICPMS, heterogeneities have been reported for some sample charges [4,5]. In addition, geological relevant elements such as Ti, Fe and Mg are present in very low concentrations only and thus not well suited for calibration.…”

“…The deviation of the actual evaporation rate from the ideal evaporation rate, which is given by an equilibrium vapor pressure and the kinetic theory of gases, is expressed as an evaporation coefficient (=Actual rate/Ideal rate) ranging from 0 to 1 (a measure of kinetic hindrance for evaporation). The evaporation coefficient is 0.1-0.01 for evaporation of forsterite in vacuum and in hydrogen gas depending on temperature and crystallographic orientation of the evaporating surface [e.g., [1][2][3][4]. Besides the free-evaporation dominated regime [FED] (evaporation in vacuum) and the hydrogen-reaction dominated regime [HRD] (evaporation in hydrogen gas), Tsuchiyama et al [5] proposed another evaporation regime called H 2 O/H 2 buffer-dominated regime [HBD] as a dominant evaporation regime for forsterite in protoplanetary disks at temperatures of <1400 K and under H 2 O-rich conditions.…”

“…Forsterite (Mg 2 SiO 4 ) is one of the most abundant crystalline silicates in extraterrestrial materials and in circumstellar environments, and its evaporation behavior has been intensively studied in vacuum and in the presence of low-pressure hydrogen gas [e.g., [1][2][3][4]. It has been known that the evaporation rate of forsterite is controlled by a thermodynamic driving force (i.e., equilibrium vapor pressure), and the evaporation rate increases linearly with pH 2 1/2 in the presence of hydrogen gas due to the increase of the equilibrium vapor pressure.…”