SOHO ground segment, science operations, and data products

We describe the ground segment, pre-launch operations concepts, and data products supporting the SOHO mission. Our goal is threefold: first, we provide a historical view of the design and development of the systems described here, as a background perspective to those who will use the system and those who may build such systems for future missions. Second, because we hope that many researchers from the solar and space physics communities will visit these facilities during the mission, we provide an overview for the benefit of the end-user. We anticipate that visitors to GSFC may plan observations for one or more of SOHO's complement of instruments, and such researchers may use the facilities to analyze data gathered by the SOHO instruments. Third, we present the working plan for investigators with groundbased or other spacebased instruments to collaborate with SOHO.     

Vaca Muerta mesosiderite strewnfield

Abstract A field investigation is presented of the strewnfield of the mesosiderite Vaca Muerta, originally found in 1861. The area, 11.5 km long, 2.1 km wide, is located about 60 km southeast of Taltal, Chile, in the Atacama Desert. It has yielded 80 meteorites with a total mass exceeding 3782 kg. Most fragments were found in an undisturbed state, but some had been broken by prospectors. The present studies, in connection with historical records, indicate that the original mass of Vaca Muerta exceeded 6 metric tons. One impact feature, somewhat modified by man, consists of a 10.5-m diameter, 1.7-m deep hole, without an uplifted rim. Small masses were scattered up to 85 m from the hole.     

Minor changes in surface-water fertility across the oceanic anoxic event 1d (latest Albian,SE France) evidenced by calcareous nannofossils

The latest Albian sediments deposited in the Vocontian basin in south-eastern France record the oceanic anoxic event (OAE) 1d, locally named the Breistroffer interval. They are represented by argillaceous marls and marls, containing organic matter (total organic carbon varying from 0.8 to 1%). Changes in calcareous nannofossil abundance and assemblage composition as well as macrofauna abundance, ichnofossil assemblage, and bioturbation intensity were analysed in order to evaluate the main palaeoenvironmental factors controlling the deposition of the OAE 1d sediments in this area. The pelagic carbonate production is limited and the carbonate fraction is predominantly of nektonic/benthic, and of allochthonous origin from carbonate platforms. The enrichment in organic carbon within the Breistroffer interval is weak and not associated with high surface-water productivity. The organic matter is mainly terrigenous. Its record is due to (1) a good preservation under dysoxic conditions within the sediments, and (2) a weak input of allochthonous carbonates. Eustatic fluctuations strongly influenced the variations of nannofossil and macrofauna abundances. Distinctive patterns in nannofossil assemblages and macrofauna abundances within the Breistroffer interval are also recognized, reflecting changes from mesotrophic to more oligotrophic conditions which are probably controlled by climate.     

Characteristics and Genesis of Fine-Clastic Rock-Type Au Deposits in the Liaodong Rift

Gold deposits occurring in the Liaodong rift are located in interlayered carbonate rocks and fine-clastic rocks, belonging to the middle and upper parts of the lower Proterozoic. Compared with the Carlin-type Au deposits abroad and gold deposits in Yunnan-Guizhou-Guangxi, Qinling and western Sichuan Province, they are similar in many respects. This paper discusses the geological features of ore-bearing formations and ore-filling structures and metallogenetic characteristics. Through the discussion on the sources of ores, heat and water, it points out that the Au deposits belong to vadose reworked hydrothermal deposits. This conforms to the principle of "mineralization in the neighbouring areas", i.e., the deposits are formed in nearby ore-bearing layers, and the latest hydrothermal event was the main factor in forming the Au deposits.     

Evidence of harmonic microwave radiation during solar flares

First observational evidence of harmonic radiation at microwave frequencies during solar bursts is presented for the event of April 28, 1983. The recordings between 3.1 and 19.6 GHz show a typical continuum with a spectral maximum near 5.2 GHz. Superimposed fine structures with durations in the order of some seconds exhibit a very unusual spectral behaviour. Narrow-banded intensity peaks appeared at 5.2 and 11.8 GHz which were barely visible at 3.1, 8.4 and 19.6 GHz. These structures can be interpreted as harmonic emission. Harmonic radio emission can be generated either by plasma radiation, gyroradiation, electron-cyclotron maser or by nonlinear conversion processes. However, all of those mechanisms require extreme assumptions on the source and the ambient plasma in order to account for the observations.Proceedings of the Second CESRA Workshop on Particle Acceleration and Trapping in Solar Flares, held at Aubigny-sur-Nère (France), 23–26 June, 1986.     

The Late Paleozoic felsic lava-dominated large igneous province in northeast Germany: volcanic facies analysis based on drill cores

In the deep subsurface of the northeast German basin products of extensive volcanism are present that formed during the waning phase of the Variscan orogeny (Permian–Carboniferous boundary). Large volumes (≥48,000 km³) of dominantly felsic magma were emplaced in the northern foreland of the Variscan mountains in a terrestrial semi-arid environment. Most of these units were inferred by previous authors to represent the products of explosive volcanic eruptions such as ignimbrites. However, a detailed analysis of the volcanic texture and lithofacies association shows that most units are best interpreted as coherent lavas emplaced either as extrusive units or as shallow intrusions, with important implications for the reconstruction of the paleo-environment. This study shows that detailed textural examination of drill cores provide important observations, which can be applied as criteria for the interpretation of the mode of volcanic eruptions. Furthermore, phenocryst logging and geochemical fingerprinting based on immobile element ratios can be employed for the classification and discrimination of individual emplacement units.