Lithology and geochemistry of ODP Leg 198 sites, Shatsky Rise

Samples of chert, porcellanite, and chalk/limestone from Cretaceous chert-bearing sections recovered during Leg 198 were studied to elucidate the nature and origin of chert color zonations with depth/age. Sedimentary structures, trace fossils, compactional features, sediment composition, texture, geochemistry, and diagenetic history were compared among lithologies. Trends in major and minor element composition were determined. Whereas geochemical analyses demonstrate systematic elemental differences among the different lithologies, there are less distinct patterns in composition for the colored cherts. The color of the chert appears to be related primarily to the amount of silica and secondarily to the proportion of other components. Red cherts are almost pure silica with only minor impurities. This may allow pigmentation from fine Fe oxides to dominate the color. These red cherts are from places where geophysical logs indicate that chert is the dominant rock type of the section. These red chert intervals cannot be unequivocally distinguished from surrounding chert-bearing lithologies in terms of sedimentary structures.

Stable carbon and oxygen isotope compositions of benthic foraminifera N. truempyi samples and coarse fraction analyses from ODP Site 198-1209

We have compiled the first stratigraphically continuous high-resolution benthic foraminiferal stable isotope record for the Paleocene from a single site utilizing cores recovered at Pacific ODP Site 1209. The long-term trend in the benthic isotope record suggests a close coupling of volcanic CO2 input and deep sea warming. Over the short-term the record is characterized by slow excursions with a pronounced periodic beat related to the short (100-kyr) and long (405-kyr) eccentricity cycle. The phase relationship between the benthic isotope record and eccentricity is similar to patterns documented for the Oligocene and Miocene confirming the role of orbital forcing as the pace maker for paleoclimatic variability on Milankovitch time scales. In addition, the record documents an unusual transient warming of 2°C coeval with a 0.6 per mil carbon isotope excursion and a decrease in carbonate content at 61.75 Ma. This event, which bears some resemblance to Eocene hyperthermals, marks the onset of a long-term decline in d13C. The timing indicates it might be related to the initiation of volcanism along Greenland margin.

Anthony Giddens. La tercera vía. La renovación de la socialdemocracia. Taurus, Madrid, 1999, 198 páginas. (edición original en inglés de 1998)

Fil: Prati, Marcelo. Universidad Nacional de La Plata. Facultad de Humanidades y Ciencias de la Educación; Argentina.

Dupuy, Andrea. 2004. El fin de una sociedad de frontera en la primera mitad del siglo XIX. Hacendados y estancieros en Pergamino. Mar del Plata: Universidad Nacional de Mar del Plata. 198 p.

Fil: Huarte, Germán A.. Universidad Nacional de La Plata. Facultad de Humanidades y Ciencias de la Educación; Argentina.

Anthony Giddens. La tercera vía. La renovación de la socialdemocracia. Taurus, Madrid, 1999, 198 páginas. (edición original en inglés de 1998)

Fil: Prati, Marcelo. Universidad Nacional de La Plata. Facultad de Humanidades y Ciencias de la Educación; Argentina.