Orogene und kratogene Metallogenese

The typical features of metallogenic provinces in the orogenic belts are described and explained in the sense of the modern plate tectonics. Some phenomena, however, are not in agreement with the scheme of “consuming margins” — particulary the timing of the magmatic-tectonic cycles and the assembly of ore metals in mountain chains. Therefore the older assumption of a synorogenic anatexis of the continental crust has to be maintained. The metals of the continental crust got combined with the volatiles and with the metals of the basaltic magma to form ore deposits. The Alpine-Mediterranean metallogenesis seems to be the result of repeated and interfering subduction (producing deposits of Cu, Fe, Cr) and palingenesis (producing deposits of Pb-Zn, Au, Ag etc.) in Cretaceous and in Tertiary time. In the cratonic areas, three types of metallogenic provinces can be distinguished: Huge lakkolithes of liquid basic mantle magma with Cr, Ni, Cu, Pt — areas of granitization with a haphazard distribution of different ores — and the simple stratiform deposits in the stable platform cover; the latter as well as the small deposits along rifts and separating margins can best be explained as mobilisates created by heat flow and some mantle volatiles.     

Die Paläogeographische Auswertung der Altvulkanischen Bildungen zur Rekonstruktion der Korrelaten Sedimentationsräume im Bereich Späterer Abtragung

Ohne ZusammenfassungVortrag, gehalten am 14. März 1955 auf der Hauptversammlung der Geologischen Vereinigung in Mainz.     

Determination of the bulk temperature from NOAA/AVHRR satellite data in a midlatitude lake

The spatial and temporal variability of the bulk temperature gives important insights into biological and hydrodynamic processes. However, standard algorithms for satellite data only provide information of the surface temperature. The comparison of current and new split-window coefficients applied on NOAA-14/AVHRR brightness temperatures of Lake Constance showed that a regional adaption was most promising. To derive the bulk temperature information, a priori progression from a weather station was included into the AVHRR analysis. Among the weather is data, the mean temperature of the three preceding days and the day of the year were the most relevant additional information. By a multiple regression approach the bulk temperature in the upper 4 m of Lake Constance could be determined with an accuracy of ±1.20 °C. The training of a neural network improved the determination of the bulk temperature to ±1.04 °C.An extended field campaign demonstrated that the algorithm is also applicable to other sensors with the same spectral band settings (in this case NOAA-16/AVHRR) with an acceptable error and that it is equally accurate over the entire lake.     

Evaluation of the Salicylic Acid—Liquid Phase Scrubbing Technique to Monitor Atmospheric Hydroxyl Radicals

A novel method has been examined for monitoring tropospheric hydroxyl radicals (OH), the most important oxidant in tropospheric chemistry. Aqueous phase salicylic acid reacts with atmospheric OH to produce 2,5-dihydroxy benzoic acid (2,5-DHBA) and other products. High Performance Liquid Chromatography (HPLC) is used to separate the post-reaction solution and the products are quantified using fluorescence detection. Unlike other methods, it has been reported to be inexpensive, portable and relatively simple. Although the sensitivity was sufficient to measure typical daytime OH concentrations of 0.04–0.4 ppt., the method was hindered by numerous interferences. Successive identification and elimination of these still resulted in a signal that was much larger than expected. Tests showed that this was not likely to be due to ozone, HO₂, NOx, H₂O₂, aerosols, light or bacteria. Experimental and numerical studies suggest that the interference could be due to methyl peroxy radicals. The effect of many other components in the atmosphere, both individual and combined, must also be tested before the method can be used reliably in the field. The validity of previous reports of ambient hydroxyl measurements using this technique is therefore brought into question.     

Calcite solubility and speciation in supercritical NaCl-HCl aqueous fluids

The solubility of calcite in NaCl-H₂O and in HCl-H₂O fluids was measured using an extraction-quench hydrothermal apparatus. Experiments were conducted at 2 kbar, between 400° C and 600° C. Measurements in NaCl-H₂O were conducted in two ways: 1) at constant pressure and NaCl concentration, as a function of temperature; and 2) at constant pressure and temperature, as a function of NaCl concentration. In both the NaCl-H₂O and the HCl-H₂O systems, the solubility of calcite increases with increasing chlorine concentrations. For example, the log calcium molality in equilibrium with calcite increases from –3.75 at 2 kbar and 500° C, in pure H₂O to –3.10 at 2 kbar and 500° C at log NaCl molality=–1.67. At fixed pressure and NaCl molality, the solubility of calcite is almost constant from 400° C to 550° C, but increases somewhat at higher temperatures. The results can be used to determine the dominant calcium species in the experimental solutions as a function of NaCl concentration and to obtain values for the second dissociation constant of CaCl_2(aq). At 2 kbar, 400° C, 500° C, and 600° C, we calculate values for the log of the dissociation constant of CaCl⁺ of –2.1, –3.2, and –4.3, respectively. The 400° C and 500° C values are consistent with those obtained by Frantz and Marshall (1982) using electrical conductance techniques. However, our 600° C value is 0.8 log units higher than that reported by Frantz and Marshall. The calcite solubilities in the NaCl-H₂O and HCl-H₂O systems are inconsistent with the solubilities of calcite in pure H₂O reported by Walther and Long (1986). They are, however, consistent with the measurements of calcite solubilities in pure H₂O presented in this study. These results allow for the calculation of the solubilities of calcium silicates and carbonates in fluids that contain CO₂ and NaCl.