ALBERT

Description: Strontium isotopic ratios of gypsums recovered from upper Miocene (Messinian) evaporites at ODP Leg 107 Holes 652A, 653B, and 654A (Tyrrhenian Sea) are lower than expected. The values for the Messinian balatino-like gypsum, single gypsum crystals, and anhydrites range from 0.70861 to 0.70886 and are approximately 25 * 10**-5 less than would be expected for evaporites precipitated from Messinian seawater (0.70891-0.70902). Pre-evaporitic planktonic foraminifers from Hole 654A show variable degrees of dolomitization and 87Sr/86Sr values that irregularly decrease upward from normal marine values approximately 81m below the lowest evaporite occurrence. This suggests diagenetic alteration by advecting interstitial water with a low 87Sr/86Sr ratio or that the lower Sr isotopic ratios for the Messinian evaporites could have resulted from a greater influence of fresh water on the Sr isotopic composition of the desiccating Tyrrhenian Sea. Fluctuations of the 87Sr/86Sr-ratio for evaporites in the sedimentary cycles recognized for Holes 653B and 654A, the generally low Sr isotopic ratio of river water entering the Mediterranean Sea, and the presence of dwarf marine microfossils suggest that the 87Sr/86Sr ratio of the evaporites responded to hydrologic variations in a very restricted basin with variable rates of marine and fresh water input. The strontium isotopic ratios of the Messinian anhydrites from the proposed lacustrine sequence at Hole 652A fall in the same range as the marine evaporites from Holes 654A and 653B. This suggests a common or similar origin of the brines at the three locations. The complex depositional and hydrologic conditions in the Mediterranean during the Messinian salinity crisis preclude the use of Sr isotopic values from the evaporites for stratigraphic correlation and dating. They are, however, very useful in the interpretation of the depositional history of the basin. General calculations assuming a closed system suggest that the 87Sr/86Sr ratio of Messinian seawater (-0.7090) could be reduced to that of the evaporites (-0.7087) by mixing with fresh water (e.g., Nile River) in times of 10**4 to 10**5 yr.

Description: Abstract

Description: Es werden 5 Niederschlagsdatensätze bereitgestellt, die für die Validierung der stochastischen Niederschlagsmodelle genutzt wurden. Jeder Datensatz besteht aus Zeitreihen für 45 ausgewählte Messstellen in Deutschland. Die Lage der Messstellen ist in der Abbildung 5 der zugehörigen Publikation dargestellt. Die Messstellennummern und Koordinaten (UTM ETRS 89; EPSG: 25832) der Stationen können der beiliegenden Exceltabelle entnommen werden. Die Datensätze sind wie folgt kurz beschrieben: 1. "REF" -〉 Referenz: beobachteter langjähriger Niederschlag am Ort (Zeitreihenlänge: 20 a) 2. "WAWI" -〉 Synthetischer Niederschlag vom Modell der Leibniz Uni Hannover (Zeitreihenlänge: 300 a), 3. "LHG" -〉 Synthetischer Niederschlag vom Modell der Uni Stuttgart (Zeitreihenlänge: 300 a), 4. "MIXED" -〉 Synthetischer Niederschlag alternierend gemischt von beiden Modellen WAWI & LHG (Zeitreihenlänge: 300 a, 150 a Jahre von jedem Modell), 5. "PRA" -〉 Praxis: beobachteter Niederschlag von der nächstgelegenen Beobachtungsstation des DWD (Zeitreihenlänge: 10 bis 20 a). Die Daten sind in Unterordnern mit der Messstellennummer jahresweise im MD-Format abgespeichert. Eine Formatbeschreibung ist beigelegt. Five precipitation data sets are provided, which have been used for validation of the precipitation models. Each data set contains time series for 45 selected stations in Germany. The location of the stations is shown in Fig. 5 of the associated paper. Station id's and coordinates are listed in the associated Excel table. The data sets are briefly described as follows: 1. "REF" -〉 Reference: observed precipitation with long records (time series length 20yr), 2. "WAWI" -〉 synthetic rainfall from the precipitation model of the Leibniz University Hannover (time series length 300 yr), 3. "LHG" -〉 synthetic rainfall from the precipitation model of the University Stuttgart (time series length 300yr), 4. "MIXED" -〉 synthetic rainfall alternating mixed from both precipitation models WAWI & LHG (time series length 300yr, 150yr from each model), 5. "PRA" -〉 Practice: observed rainfall from the closest to the reference station located DWD station (time series length 10 to 20 yr). The data are stored in folders with station id's which contain for each year in one file in MD format. A format description is attached.

Description: Abstract

Description: The melting relations of the CaCO3 MgCO3 system are investigated and trace element partition coefficient of Li, Na, K, Mn, Fe, Sr, Ba, Pb, Nb, Y and rare earth elements (REEs) between carbonates (Mg-calcite, Ca-magnesite) and dolomitic melt are established from high pressure (6 and 9 GPa) and temperature (1300 1800 ℃) experiments utilizing a rocking multi anvil press. We show that Ca Mg carbonates are stable within the subducting slab beyond ~300 km (9 GPa) but will (partial) melt beneath mid ocean ridges and in upwelling plumes. In contrast to previous studies, we report incongruent melting of carbonates producing a carbonate melt and periclase between 4 and 9 GPa. Partial melting of carbonates produces dolomitic melts whereby the trace element signature largely depends on the Ca/Mg-ratio of the bulk system. For instance, REE will be fractionated by two orders or magnitude between Ca magnesite and dolomitic melt. In contrast, melting of Ca rich carbonates will not lead to a significant REE fractionation. The here published data set includes all chemical analysis (major and trace elment composition) of run products and starting materials. From this data set we obtained the melting relations and partition coefficients reported in Sieber et al. (2020); Sieber et al. (under review).