Preferred longitudes of sunspot groups and high-speed solar wind streams: Evidence for a ‘solar memory’

Correlation analysis of the mean longitude distribution of sunspot groups (taken from the Greenwich Photoheliographic Results) and high-speed solar wind streams (inferred from the C9 index for geomagnetic disturbances) with the Bartels rotation period P = 27.0 days shows anti-correlation for individual cycles.In particular, the longitudes of post-maximum stable streams of cycle 18 and 19 are well anticorrelated with the preferred longitudes of sunspot groups during the maximum activity periods of these cycles. This is further analyzed using the daily Zürich sunspot number, R, between 1932 and 1980, which reveals a conspicuous similarity of cycle 18 and 19 as well as cycle 20 and 21.We conclude that there is a solar memory for preferred longitudes of activity extending at least over one, probably two cycles (i.e. one magnetic cycle of 22 years). We conjecture that this memory extends over longer intervals of time as a long-term feature of solar activity.     

Zur Altersfrage der Eisenerzlagerstätte Sierra Grande/Rio Negro in Nordpatagonien Aufgrund Neuer Fossilfunde

A small fauna is described in detail from the southern and from the eastern iron ore deposit of Sierra Grande, Prov. Rio Negro, Argentina. The southern deposit could be established to be of Silurian (Wenlockian?) age, whereas the eastern deposit seems to be younger, probably of Lower Devonian age. The rock sequence belongs to the Gondwanide system, known from the southern Sierras of the province of Buenos Aires and from the Falkland Islands (Islas Malvinas). The present study indicates a much larger extension of this system than formerly recognized.     

Petrographisehe Untersuehung der Gleesite des Laacher Seegebietes

In the present publication the hauyn-gleesites (in earlier publications called hauynsanidinites) and the other rocks, which belong genetically to the hauyn-gleesites, as hauynfree gleesites, hornblende-rich alkaligabbros, hornblendites, Laacher hauyntrachytes and hauynlatites, are described. All these different products can only be found in form of fragments in the trachyttuffs around the Laacher See (Germany).The microscopical analysis of the Laacher trachytes and hauynlatites demonstrates, that the magma has been strongly influenced by assimilation. This is characteristically demonstrated by the strong oscillation of the anorthit-content of the plagioclases in each fragment.The primary rocks, which are metamorphosed by the alkalisyenitic respectively alkalitrachytic magma, are the differentiationsproducts of an alkaligabbroic magma, hornblendites, hornblende-rich alkaligabbros and possibly monzonites. The crystallisations sequence of these rocks is: biotite hornblendite augite. The same sequence can be seen in the hauyn-free and the hauyn-bearing gleesites.The relative high content of titanite in the gleesites is remarcably. The source of the TiO₂, which is necessary for the formation of titanite, lies in the magnetites of the alkaligabbroic rocks. In the basic rocks the magnetit contains nearly 17 % Ti0₂. In the magnetite of the hauyn-free gleesites there is only 11 % and in the hauyn-gleesites, which are found in the latest phase of metamorphic transformation, is only 8–9% Ti0₂. The same content of 8–9% TiO₂ is found in the magnetites of the white trachyttuffs around the Laacher See. The glas in all these rock-fragments was formed by the heat during the eruption of the tuffs, possibly under the influence of alkali-rich gases.     

On the r-mode spectrum of relativistic stars

We present a mathematically rigorous proof that the r-mode spectrum of relativistic stars to the rotational lowest order has a continuous part. A rigorous definition of this spectrum is given in terms of the spectrum of a continuous linear operator. This study verifies earlier results by Kojima concerning the nature of the r-mode spectrum.     

Architecture and temporal variations of a terrestrial CO2 degassing site using electric resistivity tomography and self-potential

International Journal of Earth Sciences - The Hartoušov mofette field in NW Bohemia, Czech Republic, is characterized by strong CO2 degassing from the Lithospheric Mantle. In a test survey...     

An experimental study of the Fe oxidation states in garnet and clinopyroxene as a function of temperature in the system CaO–FeO–Fe2O3–MgO–Al2O3–SiO2: implications for garnet–clinopyroxene geothermometry

Samples with eclogitic composition in the system CaO–FeO–Fe₂O₃–MgO–Al₂O₃–SiO₂ were produced from various kinds of starting materials held in graphite-lined Pt capsules at a pressure of 2.5–3.0 GPa and temperatures of 800–1,300 °C using a piston-cylinder or Belt apparatus. Garnets and clinopyroxenes were characterized by analytical transmission electron microscopy and electron probe micro-analysis (EPMA). Fe³⁺/ΣFe ratios determined by electron energy-loss spectroscopy (EELS) decrease in clinopyroxene from 22.2 ± 3.4 % at 800 °C to 13.3 ± 5.4 % at 1,300 °C, while in garnet, they vary between 10.8 ± 1.5 and 15.4 ± 4.7 %, respectively. Temperature estimates according to Krogh (Contrib Mineral Petrol 99:44–48, 1988) reproduce the experimental temperature to ±60 °C without systematic deviations if total iron is used in the calculation. If only the Fe²⁺ content is used, which was obtained by combining EPMA and EELS results, the experimental temperature is underestimated by 33 °C on average at 800–1,200 °C and overestimated by 77 °C on average at 1,300 °C. These systematic deviations can be explained by the temperature-dependent ratio of Fe²⁺/ΣFe in garnet divided by that in clinopyroxene. Since the difference between the calculated and experimental temperature is relatively small, a Fe²⁺-based recalibration of the thermometer appears not to be necessary for the investigated system in the range of pressure, temperature and composition covered by the experiments of this study.     

The origin of salinity and sulphate contamination of groundwater in the Colima State, Mexico, constrained by stable isotopes

Chemical compositions and stable isotope ratios of water and sulphate were used to characterise sources and processes responsible for elevated concentrations of sulphate and other constituents in groundwater from aquifers at Colima State along Mexico’s Pacific Coast. The δ¹⁸O and δ²H values of the groundwater were similar to those of precipitation indicating a meteoric origin, and recharge processes are relatively uniform in large parts of the study area with only slight local evaporation effects. δ³⁴S_sulphate and δ¹⁸O_sulphate analyses indicated that high sulphate concentrations of up to 1,480 mg/l are mainly due to dissolution of evaporites and volcanic exhalations. Chloride is largely related to sources other than seawater. The Marabasco sub basin is affected by anthropogenic contamination through manganese and iron ore mining activities. The obtained knowledge regarding sources and areas of contamination will be essential for the development and design of a water quality monitoring program in the study area.     

Geodynamische Interpretation Ostkretas

The phenomenon of “Stockwerk“-tectonics characterizes Eastern Crete. Autochthonous bedded limestone (“Plattenkalk”) is overlain by the allochthonous units of the “Phyllitic-Series”, the Tripolitza- und Pindos-Series. The “Phyllitic-Series” were recognized as a mélange. The mélange is due to gravity-sliding tectonics under an overburden pressure. Geological evolution and geophysical data across the section Santorin-Crete were interpreted. Instead of a mobile crust hypothesis of moving plates with subduction zones a fixed crust hypothesis of vertical uplift and corresponding subsidence is suggested. The nappe transport by forces of gravity is a secondary effect.