Highlights: Sources in the Chaco

Foreland basins are the ultimate sink for much of the sediment derived from erosion of fold-and-thrust belts in convergent margins. To better understand the evolution of the Andean cordillera, and convergent-margin syn-orogenic sediments in general, McGlue and others integrate geomorphological observations with analyses of composition, texture, and U-Pb ages of modern detrital sediments of the Río Bermejo megafan in the Chaco foreland basin, northern Argentina. The results document that provenance reflects the lithology of the parent material and the transport distance, with maturity increasing farther from the thrust front and sediment fining towards the forebulge. These data enhance understanding of distributive fluvial systems in overfilled retroarc foreland basins, and may improve interpretation of ancient analogs that have been the source of critical information on the history of convergent orogenic belts. [Editor’s note: other Chacos are interesting as well.]

An integrated sedimentary systems analysis of the Río Bermejo (Argentina): megafan character in the overfilled southern Chaco foreland basin by Michael M. McGlue, Preston H. Smith, Hiran Zani, Aguinaldo Silva, Barbara Carrapa, Andrew S. Cohen, and Martin B. Pepper