Influence of relative sea level changes on the construction of the Mississippi Fan

A conceptual sea-level-driven depositional model for individual fanlobes (channel-overbank systems) of the Mississippi Fan does not permit direct application of the sequence stratigraphic principles of Vail and colleagues. Deep Sea Drilling Project Leg 96 results suggest that, during initial relative lowering of sea level, the canyon and upper fan channel were formed; excavated fine-grained slope sediments may have formed a debris flow deposit base for the fanlobe. Continued lowering produced constructional channel-levee-overbank deposits. Rising relative sea level inhibited input of coarse clastics, and channel depressions filled with muds. A blanket of (hemi)pelagics represents relative high sea level stand.     

Sea Grant in Latin America?: Adapting the US Sea Grant model of linked applied research,extension, and education to a Latin American Context—Is there a fit?

This paper explores the application of the US Sea Grant model of applied research, extension, and education to two case studies in Latin America: Coastal Ecuador and the Gulf of Fonseca. The analysis is based on a series of meetings and roundtables with in-country partners and leaders of the US Sea Grant program. We conclude that the Sea Grant model provides an institutional structure that Latin America lacks and the model's features would improve governance of marine and coastal resources through more effective linkages between coastal communities, universities, and policy/decision makers at local, national, and international levels.     

Evidence of magmatic CO2-rich fluids in peraluminous graphite-bearing leucogranites from Deep Freeze Range (northern Victoria Land,Antarctica)

Fine-grained peraluminous synkinematic leuco-monzogranites (SKG), of Cambro-Ordovician age, occur as veins and sills (up to 20–30 m thick) in the Deep Freeze Range, within the medium to high-grade metamorphics of the Wilson Terrane. Secondary fibrolite + graphite intergrowths occur in feldspars and subordinately in quartz. Four main solid and fluid inclusion populations are observed: primary mixed CO₂+H₂O inclusions + Al₂SiO₅ ± brines in garnet (type 1); early CO₂-rich inclusions (± brines) in quartz (type 2); early CO₂+CH₄ (up to 4 mol%)±H₂O inclusions + graphite + fibrolite in quartz (type 3); late CH₄+CO₂+N₂ inclusions and H₂O inclusions in quartz (type 4). Densities of type 1 inclusions are consistent with the crystallization conditions of SKG (750°C and 3 kbar). The other types are post-magmatic: densities of type 2 and 3 inclusions suggest isobaric cooling at high temperature (700–550°C). Type 4 inclusions were trapped below 500°C. The SKG crystallized from a magma that was at some stage vapour-saturated; fluids were CO₂-rich, possibly with immiscible brines. CO₂-rich fluids (±brines) characterize the transition from magmatic to post-magmatic stages; progressive isobaric cooling (T<670°C) led to a continuous decrease off _{O 2} can entering in the graphite stability field; at the same time, the feldspars reacted with CO₂-rich fluids to give secondary fibrolite + graphite. Decrease ofT andf _{O 2} can explain the progressive variation in the fluid composition from CO₂-rich to CH₄ and water dominated in a closed system (in situ evolution). The presence of N₂ the late stages indicates interaction with external metamorphic fluids.Contribution within the network Hydrothermal/metamorphic water-rock interactions in crystalline rocks: a multidisciplinary approach on paleofluid analysis. CEC program: Human Capital and Mobility     

Activity in the quiet Sun

Macrospicules have been observed in H and He i D₃, on the disk and above the limb. In 1975, a rate of 1400 (A day)^–1 is inferred, and the ratio of equatorial to polar rates 2. D₃ intensities are a few × 10^–3 of the disk center, and do not decrease in coronal holes. The ratio of H to D₃ intensities is 10. The integral number of macrospicules with D₃ intensity I ₀ is proportional to I ₀ ^–1.     

Are the high-latitude torsional oscillations of the sun real?

A numerical test is made to determine if the high-latitude torsional wave is generated from the low-latitude torsional pattern as a result of our reduction procedures. The results indicate that the high-latitude motions are not an artifact of the analysis, but are true solar features. We demonstrate also that the one-wave-per-hemisphere torsional oscillation does not result from the reduction procedure. These results place the observations in conflict with the predictions of - () models of the solar cycle.Now at Institute for Astronomy, University of Hawaii, Honolulu, Hawaii 96822, U.S.A.     

The Mees CCD imaging spectrograph

The Mees CCD (MCCD) instrument is an imaging spectroscopy device which uses the 25 cm coronagraph telescope and the 3.0 m Coudé spectrograph at Mees Solar Observatory (MSO) on Haleakala, Maui. The instrument works with resolving power up to R 200 000 with significant throughput from 3934 Å (Caii K) to 10 000 Å. A fast guiding active mirror stabilizes the image during observations. A rapidly writing magnetic tape storage system allows observations to be recorded at 256 kbytes s^–1. Currently, the MCCD is used for imaging spectroscopy of solar flares at 6563 Å (H), and velocity measurements of umbral oscillations; future plans include emission line studies of active region coronae, and photospheric studies of solar oscillations.     

Hα observations of the August 12, 1975 type III-RS bursts

We present H filtergram observations of a number of the Type III-RS (reverse slope) bursts that occurred on August 12, 1975. Solar radio emission was peculiar on that date in that a large number, and proportion, of the usually rare reverse slope bursts were observed (Tarnstrom and Zehntner, 1975). We show that the radio bursts coincide in time with a homologous set of H flares located at the limbward edge of spot group Mt. Wilson 19598. We propose a model in which the reverse slope bursts are the downward branches of U bursts, whose upward branches are hidden behind the coronal density enhancement over the spot group.