How Young is a 300-Year-Old Wetland? The Case of the Pantanal Marimbus, Chapada Diamantina, Brazil

The Chapada Diamantina, in Northeastern Brazil, is one of the few places where one can find drylands with a backswamp containing hundreds of dead deciduous trees in the floodplain. During the 18th century, the region was globally important due to the exploration of mineral resources. The death of these trees was caused by mining activities that silted the main river, leading to the impoundment of the tributary river, and resulting in a wetland known as Pantanal Marimbus, having as indicators: (i) backswamp morphological feature that remains permanently flooded in the axis of the fluvial course, and (ii) alluvial fans concentrated in one footslope area where mining activities at the Chapada Diamantina were also concentrated. The hydrological and sedimentological behavior was investigated to multi-methods. By analysing four different samples from the bark and core of the same tree, we obtained calibrated radiocarbon dates within the 18th century. For no robust dendrochronology could be performed, a simple sequence model was built, revealing a high probability that the tree lived until approximately 1700 AD. 14 C-AMS measured pioneering possible to evaluate the 300-years-old wetlands juvenile evolutionary state.