Lower Carboniferous brachiopods from Sierra de Almeida, northern Chile

A low-diversity brachiopod assemblage from the upper member of the Zorritas Formation in the Sierra de Almeida, northern Chile, further confirms the p resence of Lower Carboniferous (Tournaisian) strata in that region. Key tax a include Schuchertella? sp., Chilenochonetes anna new genus and species, P aurorhyncha chavelensis (Amos), and Septosyringothyris covacevichi new spec ies. Other elements of the assemblage, including Paraconularia sp., Posidon iella sp., Bellerophon (Bellerophon) sp.. Eocanites sernageominus, and Imit oceras? sp. support this Early Carboniferous age assignment. Local distribu tion of taxa suggests small-scale environmental control. Rhynchonelloid and syringothyroid shells, many articulated, occur in lenticular sandstone bod ies that were deposited in deltaic distributary channels; chonetids, schuch ertellids and mollusc-bearing, iron-rich concretions are found in siltstone s and mudstones that reflect interdistributary quiet-water settings and pos sibly a delta-front setting. Certain elements of this fauna are also presen t in northwestern Argentina and Peru, indicating a regional nearshore elast ic regime, The closest correlation elsewhere is with the Tournaisian faunas of southeastern Australia, although analogous big-shell assemblages are fo und in lower Mississippian elastic strata of the central Appalachians, Ohio , and Indiana.