(Table 1) Uranium and Thorium concentrations, activity ratios and calcium carbonate content of DSDP Site 54-424

The geochemical behaviour of uranium and thorium in metalliferous sediments and hydrothermal deposits has been widely studied and the main results have been summarised by Boström and Rydell. These isotopes may be used to clarify how the metal-rich solutions are introduced into sediment cover and seawater. Using radiochemistry followed by alpha spectrometry, we have measured uranium concentrations as high as several hundred p.p.m., which must clearly be associated with ocean ridge thermal activity, in sediments interbedded between the basaltic basement and the green hydrothermal mud at DSDP Site 424. These high uranium concentrations indicate the path followed by the hydrothermal fluid which, debouching at the sediment-water interface, formed the green mud.

Mario Casalla: Razón y liberación. Notas para una filosofía latinoamericana. Buenos Aires, Siglo XXI, 1978, 151 p. [Colección mínima N° 54]

Fil: Licata, Rosa.

Empresas de economía social y el rol del Ministerio de Desarrollo Social y Derechos Humanos en función a lo establecido por la ley n° 8.423

Este trabajo trata sobre la definición de las empresas de economía social, forma de comercialización (comercio justo) y cómo se aplican esos conceptos en la provincia de Mendoza, Argentina. Para ello, en primer lugar se analizará cómo está organizado el Ministerio de Desarrollo Social y Derechos Humanos, la Dirección de Economía Social y Asociatividad y un análisis en profundidad de la Ley Provincial Nº 8423. Luego el trabajo se centra en todos los programas que se elaboran para organización, desarrollo y promoción de las empresas de Economía Social de Mendoza, para determinar el alcance y el impacto de dichos programas en la provincia. También se analizan qué tipos de empresas son las que forman parte de este grupo de Empresas de Economía Social, y de esta manera ver cómo se desarrolla este pequeño universo de empresas que en su mayoría son empresas familiares que ofrecen productos artesanales de muy alta calidad y a un muy buen precio.

Radiochemistry at DSDP Leg 54 and 70 Holes

Use of the hydraulic piston corer during DSDP Leg 70 in the Galapagos mounds area allowed recovery of an undisturbed sedimentary sequence down to the basement. It thus became possible to establish the chronology of different events. Several holes on and off the mounds were studied, using uranium series disequilibrium methods of age determination and oxygen isotope stratigraphy. The following sequence was thereby established: 1) From 600,000 to 300,000 years ago there was normal pelagic sedimentation, with an injection of uranium-rich solution, probably of hydrothermal origin, between 400,000 and 300,000 years ago. 2) From 300,000 to 90,000 years ago, nontronitic clay formed, replacing a pre-existing sediment. 3) From 60,000 to 20,000 years ago, manganese oxide deposits formed, probably also replacing pre-existing sediments. 4) About 19,000 years ago there occurred a uranium injection from seawater, attributed to the end of the hydrothermal circulation. In some holes, especially Hole 424, Leg 54, younger manganese oxides have been found, indicating that some mounds may be presently active.