Submarine groundwater discharge: A large, previously unrecognized source of dissolved iron to the South Atlantic Ocean

This paper reports the initial results of a study of groundwater and coastal waters of southern Brazil adjacent to a 240 km barrier spit separating the Patos Lagoon, the largest coastal lagoon in South America, from the South Atlantic Ocean. The objective of this research is to assess the chemical alteration of freshwater and freshwater–seawater mixtures advecting through coastal permeable sands, and the influence of the submarine discharge of these fluids (SGD) on the chemistry of coastal waters. Here we focus on dissolved iron in this system and use radium isotopic tracers to quantify SGD and cross-shelf fluxes. Iron concentrations in groundwaters vary between 0.6 and 180 μM. The influence of the submarine discharge of these fluids into the surf zone produces dissolved Fe concentrations as high as several micromolar in coastal surface waters. The offshore gradient of dissolved Fe, coupled with results for Ra isotopes, is used to quantify the SGD flux of dissolved Fe from this coastline. We estimate the SGD flux to be 2 × 10⁶ mol day^− 1 and the cross-shelf flux to be 3.2 × 10⁵ mol day^− 1. This latter flux is equal to about 10% of the soluble atmospheric Fe flux to the entire South Atlantic Ocean. We speculate on the importance of this previously unrecognized iron input to regional ocean production and on the potential significance of this source to understanding variations in glacial–interglacial ocean production.     

Die Spuren eiszeitlicher Vergletscherung in Anatolien

Ohne Zusammenfassung     

I. Erdöl Ergebnisse der erdölgeologischen Erforschung Nordwestdeutschlands 1932–1947, ein Überblick

Ohne Zusammenfassung     

Martian canyons and African rifts: Structural comparisons and implications

The resistant parts of the canyon walls of the Martian rift complex Valles Marineris have been used to infer an earlier, less eroded reconstruction of the major troughs. The individual canyons were then compared with individual rifts of East Africa. When measured in units of planetary radius, Martian canyons show a distribution of lengths nearly identical to those in Africa, both for individual rifts and for compound rift systems. A common mechanism which scales with planetary radius is suggested. Martian canyons are significantly wider than African rifts. This is consistent with the long-standing idea that rift width is related to crustal thickness: most evidence favors a crust on Mars at least 50% thicker than that of Africa. The overall pattern of the rift systems of Africa and Mars are quite different in that the African systems are composed of numerous small faults with highly variable trend. On Mars the trends are less variable; individual scarps are straighter for longer than on Earth. This is probably due to the difference in tectonic histories of the two planets: the complex history of the Earth and the resulting complicated basement structures influence the development of new rifts. The basement and lithosphere of Mars are inferred to be simple, reflecting a relatively inactive tectonic history prior to the formation of the canyonlands.     

Swimming speeds of oyster larvaeCrassostrea virginica in different salinities and temperatures

Swimming speeds of oyster larvaeCrassostrea virginica were determined in constant and increasing salinities to learn more about the oyster larval “salinity response”. “Normal” non-directed swimming speeds ranged from less than 1 cm/min for early veligers to 5 cm/min for “eyed” veligers with temperature an important variable. When subjected to hourly salinity increases of 0.5‰, most larvae swam upward or downward at approximately 3 times the above speeds. Larvae with values closed in response to traces of formalin sank at speeds of 5 to 50 cm/min depending on larval stage. The results may explain the differential vertical position of larval stages in estuaries and suggest the presence of a taxic component to the salinity response.     

Die Gastiain-Struktur (Nordspanien)

Zusammenfassung Die Exploration nach Kohlenwasserstoffen in Nordspanien wird am Beispiel der Antiklinalstruktur Gastiain geschildert. Aufgrund geologischer Feldaufnahmen und seismischer Untersuchungen wurden 4 Tiefbohrungen niedergebracht, die jedoch keine wirtschaftlich verwertbaren Mengen von Kohlenwasserstoffen antrafen.Die Strukturgeschichte des Raumes Gastiain und die Gründe für das negative Ergebnis der Exploration werden diskutiert.

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The anticlinal structure of Gastiain is shown as an example of the exploration for hydrocarbons in Northern Spain. After geological surveys and seismic measurements, four wells were drilled, however with negative or at least not economic results.The structural history of the Gastiain region and the reasons for the negative result of the exploration are discussed.

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Résumé L'exploration d'hydrocarbure dans le Nord de l'Espagne est décrite par l'exemple de l'anticline de Gastiain. A l'aide de recherches géologiques et sismiques, quatre forages ont été forés, cependant sans trouver des quantités économiquement utilisables d'hydrocarbure.L'histoire de la structure de la région Gastiain et les raisons pour le résultat négatif de l'exploration sont discutées.

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Gastiain . 4 , . — .

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Herrn Professor Dr.Roland Brinkmann zum 70. Geburtstag gewidmet.     

Calculated geochronology and stress field orientations along the Hawaiian chain

A new method has been discovered for calculating ages of the main shield building stages of volcanoes along the Hawaiian chain from Kilauea to the Hawaiian-Emperor bend. The method is based on a graphical technique for hypothetical subtraction of distance intervals that theoretically represent regions of simultaneous volcanism along adjacent or nearly en-echelon loci of volcanism. Distances along the chain, measured from Kilauea, when progressively foreshortened by the distances of hypothetical “collapse” and plotted versus existing age data are found to give linear age-distance relationships. A calibration graph is presented that agrees closely with the measured ages in 17 of the 20 existing dated volcanoes. The criterion for simultaneous activity on different loci is based on the concept of equal azimuths of synchronous volcanic propagation within coeval segments of the chain. This is the predicted relationship when magmatic fluids inject the lithosphere along directions normal to a nearly horizontal least principal stress. It appears that the Pacific plate has been subjected to oscillatory, but principally clockwise, rotations of horizontal stress components during the last 40 m.y.