This paper conducted a review and update about the current distribution of Sotalia dolphins that inhabit freshwater in Colombia, Ecuador and Peru, as well as freshwater and estuarine areas in Venezuela and Suriname. This review and update is based on previous research and on information from recent surveys conducted in selected rivers across the Amazon and Orinoco River basins, and in estuarine areas of Suriname. This paper is part of an initiative to establish a network of Freshwater Protected Areas (FWPAs), specifically involving researchers, governments and local communities into the South American River Dolphin Protected Area Network (SARDPAN), whose goal is to investigate the ecological integrity of freshwaters for the conservation of river dolphins in the Amazon and Orinoco River basins in South America.

In this study, I present emplacement ages, petrography and the geochemical composition of doleritic dykes and one sill from the eastern and south-eastern area of the Kaapvaal Craton. These results refine the previous 2253 ± 45 and 2202 ± 74 Ma ages of the Mashining event to ca. 2168 Ma, and shows that this swarm is intermixed with the younger 1875-1835 Ma Black Hills dyke swarm. Geochemical data of the Mashining swarm suggest these dykes may acted as feeders of ca. 2.2 Ma Hekpoort magmatism within the Pretoria Group. A Southern extension of Mashining magmatism in the Kaapvaal Craton is represented by the ENED-03 dyke, herein dated to 2168 ± 7 Ma. However, despite this age match, there are considerable geochemical differences. The trend of the Black Hills dyke parallels the older ca. 2168 Ma Mashining dykes within the Transvaal sub-basin. Further north, in the area of the Archean basement, it extents close to the ca. 1.85 Ga Soutpansberg Group basin, suggesting a possible connection and a common magmatic event. The northerly trend of Black Hills dykes just northeast of the Transvaal sub-basin seems to be locally deflected by older NE-trending fracture zones and dykes that belong to a major ca. 2.70-2.66 Ga NE-trending swarm. Echelon and dyke patterns, thus suggest that the trend of Black Hills dykes in that area was controlled by former regional paleo-stresses and fracture zones. The definition of the ca. 2168 Ma age for the Mashining magmatic event on the Kaapvaal Craton indicates possible connection to coeval magmatic events in the Wyoming, Dharwar and Superior Cratons. Resumen En este estudio se presentan edades, petrografía y datos geoquímicos de diques doleríticos y un silo ubicados al este y sudeste del Cratón de Kaapvaal. Estos resultados refinan edades previas de 2253 ± 45 y 2202 ± 74 Ma para el evento de Mashining a ca. 2168 Ma, adicionalmente indica que estos diques se encuentran intercalados con un enjambre más joven, el enjambre Black Hills de 1875-1835 Ma. Datos geoquímicos del enjambre de diques Mashining sugieren que estos pudieron actuar como fuente alimentando el volcanismo del evento Hekpoort datado a ca. 2.2 Ma y que está presente dentro del Grupo Pretoria. Una extensión más al sur del magmatismo del evento Mashining en el Cratón Kaapvaal está representada por el dique ENED-03, aquí datado a 2168 ± 7 Ma. Sin embargo, a pesar de esta edad se encuentran presentes marcadas diferencias geoquímicas entre dicho dique y el evento Mashining. El rumbo de los diques de Black Hills es paralelo a los diques de Mashining dentro de la sub-cuenca Transvaal. Hacía el norte, en el área del basamento Arqueano, los diques de Black Hills se extienden cerca de la Cuenca Soutpansberg datada a ca. 1.85 Ga, indicando una posible conexión entre estos eventos. El rumbo norte de los diques de Black Hills al noreste de la sub-cuenca Transvaal parece estar deflectado por diques de edad ca. 2.70-2.66 Ba y zonas con rumbo NE más antiguas. El rumbo de los diques y patrones en echelon indican que el rumbo de los diques de Black Hills en el área está controlado por paleo-esfuerzos y zonas de fractura anteriores a los diques. La nueva edad de ca. 2168 Ma para el evento magmático de Mashining en el Cratón de Kaapvaal indica una posible conexión con eventos magmáticos coetáneos en los Cratones de Wyoming, Dharwar y el Superior.