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The Upper Cambrian-Tremadocian rocks exposed in the Alfarcito area of Cordillera Oriental, northwest Argentina reveal a series of transgressive-regressive cycles punctuated by incision of fluvio-estuarine valleys. An integrated sedimentologic, biostratigraphic and sequence stratigraphic study permits characterization of the sedimentary facies and stratal stacking patterns, and a revision of the stratigraphic framework of this succession. The Upper Cambrian-Tremadocian succession is included within the existing Santa Rosita Formation, which is formally subdivided here into six units, the Tilcara, Casa Colorada, Pico de Halcón, Alfarcito, Rupasca and Humacha members. This scheme recognizes the internal complexities of the formation, in that the Tilcara and Pico de Halcón members record sedimentation in areally-restricted incised valleys and contain structures indicative of tidal dominance, whereas the Casa Colorada, Alfarcito and Rupasca members typify wave-dominated open-marine environments, where background suspension-fallout was punctuated by oscillatory flows during storms. The Tilcara Member is incised into the underlying Mesón Group. The Casa Colorada Member reflects a basinwide Late Cambrian transgression and subsequent progradation and consists of lower to upper offshore deposits. The Pico de Halcón Member is incised into the Casa Colorada Member. The Alfarcito Member is divided into three distinctly upward-coarsening and-thickening intervals. The sandstone-dominated intervals are composed of lower to middle shoreface deposits with minor amounts of offshore transition and upper shoreface deposits. The heterolithic, fine-grained intervals record more distal deposition, ranging from the lower offshore to the offshore transition. The Rupasca Member is a dominantly fine-grained unit that records a major late early to early late Tremadocian transgression. The lower interval of this member consists of lower offshore to offshore-transition deposits, while the upper part is made up of shelf to lower offshore deposits. The Humacha Member is not exposed in the study area. The importance of integrating biostratigraphy within a sedimentologic and sequence-stratigraphic framework is underscored here, in that it enables us to construct a more accurate stratigraphic framework which permits a clear understanding of the sedimentary dynamics of this system.

The Upper Cambrian-Tremadocian rocks exposed in the Alfarcito area of Cordillera Oriental, northwest Argentina reveal a series of transgressive-regressive cycles punctuated by incision of fluvio-estuarine valleys. An integrated sedimentologic, biostratigraphic and sequence stratigraphic study permits characterization of the sedimentary facies and stratal stacking patterns, and a revision of the stratigraphic framework of this succession. The Upper Cambrian-Tremadocian succession is included within the existing Santa Rosita Formation, which is formally subdivided here into six units, the Tilcara, Casa Colorada, Pico de Halcón, Alfarcito, Rupasca and Humacha members. This scheme recognizes the internal complexities of the formation, in that the Tilcara and Pico de Halcón members record sedimentation in areally-restricted incised valleys and contain structures indicative of tidal dominance, whereas the Casa Colorada, Alfarcito and Rupasca members typify wave-dominated open-marine environments, where background suspension-fallout was punctuated by oscillatory flows during storms. The Tilcara Member is incised into the underlying Mesón Group. The Casa Colorada Member reflects a basinwide Late Cambrian transgression and subsequent progradation and consists of lower to upper offshore deposits. The Pico de Halcón Member is incised into the Casa Colorada Member. The Alfarcito Member is divided into three distinctly upward-coarsening and-thickening intervals. The sandstone-dominated intervals are composed of lower to middle shoreface deposits with minor amounts of offshore transition and upper shoreface deposits. The heterolithic, fine-grained intervals record more distal deposition, ranging from the lower offshore to the offshore transition. The Rupasca Member is a dominantly fine-grained unit that records a major late early to early late Tremadocian transgression. The lower interval of this member consists of lower offshore to offshore-transition deposits, while the upper part is made up of shelf to lower offshore deposits. The Humacha Member is not exposed in the study area. The importance of integrating biostratigraphy within a sedimentologic and sequence-stratigraphic framework is underscored here, in that it enables us to construct a more accurate stratigraphic framework which permits a clear understanding of the sedimentary dynamics of this system.

The Upper Cambrian-Tremadocian rocks exposed in the Alfarcito area of Cordillera Oriental, northwest Argentina reveal a series of transgressive-regressive cycles punctuated by incision of fluvio-estuarine valleys. An integrated sedimentologic, biostratigraphic and sequence stratigraphic study permits characterization of the sedimentary facies and stratal stacking patterns, and a revision of the stratigraphic framework of this succession. The Upper Cambrian-Tremadocian succession is included within the existing Santa Rosita Formation, which is formally subdivided here into six units, the Tilcara, Casa Colorada, Pico de Halcón, Alfarcito, Rupasca and Humacha members. This scheme recognizes the internal complexities of the formation, in that the Tilcara and Pico de Halcón members record sedimentation in areally-restricted incised valleys and contain structures indicative of tidal dominance, whereas the Casa Colorada, Alfarcito and Rupasca members typify wave-dominated open-marine environments, where background suspension-fallout was punctuated by oscillatory flows during storms. The Tilcara Member is incised into the underlying Mesón Group. The Casa Colorada Member reflects a basinwide Late Cambrian transgression and subsequent progradation and consists of lower to upper offshore deposits. The Pico de Halcón Member is incised into the Casa Colorada Member. The Alfarcito Member is divided into three distinctly upward-coarsening and-thickening intervals. The sandstone-dominated intervals are composed of lower to middle shoreface deposits with minor amounts of offshore transition and upper shoreface deposits. The heterolithic, fine-grained intervals record more distal deposition, ranging from the lower offshore to the offshore transition. The Rupasca Member is a dominantly fine-grained unit that records a major late early to early late Tremadocian transgression. The lower interval of this member consists of lower offshore to offshore-transition deposits, while the upper part is made up of shelf to lower offshore deposits. The Humacha Member is not exposed in the study area. The importance of integrating biostratigraphy within a sedimentologic and sequence-stratigraphic framework is underscored here, in that it enables us to construct a more accurate stratigraphic framework which permits a clear understanding of the sedimentary dynamics of this system.El análisis de las rocas del Cámbrico Superior-Tremadociano aflorantes en el área de Alfarcito, Cordillera Oriental, noroeste de Argentina, revela una serie de ciclos transgresivos-regresivos e incisiones de valles fluvio-estuarinos. Un estudio sedimentológico, bioestratigráfico y estratigráfico-secuencial integrado proporciona información para caracterizar las facies sedimentarias, analizar los patrones de apilamiento estratal y revisar el marco estratigráfico de estas sucesiones. La sucesión cámbrica-tremadociana es incluida en la Formación Santa Rosita, la cual es formalmente subdividida en seis miembros, Tilcara, Casa Colorada, Pico de Halcón, Alfarcito, Rupasca y Humacha. De este modo, este esquema retiene para el área de Alfarcito una unidad estratigráfica ampliamente aceptada como la Formación Santa Rosita y al mismo tiempo reconoce las complejidades internas de la misma, subdividiéndola en miembros. Los miembros Tilcara y Pico de Halcón registran depositación en valles incisos restringidos arealmente y contienen estructuras indicadoras de dominio mareal. Por el contrario, los miembros Casa Colorada, Alfarcito y Rupasca tipifican sedimentación en ambientes marinos abiertos dominados por el oleaje, donde la sedimentación por decantación alternó con flujos oscilatorios generados durante tormentas. El Miembro Tilcara está inciso en el subyacente Grupo Mesón. El Miembro Casa Colorada refleja una transgresión cámbrica tardía a escala de cuenca y la subsecuente progradación. En el área de estudio, esta unidad está representada por depósitos de offshore inferior a transición a offshore. El Miembro Pico de Halcón está inciso sobre el Miembro Casa Colorada. El Miembro Alfarcito está dividido en tres intervalos muy distintivos grano y estratocrecientes. Los intervalos arenosos están dominados por depósitos de shoreface inferior a medio con proporciones menores de depósitos de transición a offshore y shoreface superior. Los depósitos de los intervalos heterolíticos de grano fino registran depositación en un ambiente más distal, desde el offshore inferior a la transición al offshore. El Miembro Rupasca es una unidad dominantemente de grano fino, que registra una transgresión mayor de edad tremadociana temprana tardía a tardía temprana. El intervalo inferior del Miembro Rupasca consiste en depósitos de offshore inferior a transición a offshore, mientras que el intervalo superior consiste en depósitos de plataforma a offshore inferior. El Miembro Humacha no se encuentra expuesto en el área. La importancia de integrar estudios bioestratigráficos dentro de un marco sedimentológico y estratigráfico-secuencial es resaltada en este estudio. Este enfoque es esencial para construir un marco estratigráfico y correlaciones más precisas que ayuden a clarificar la nomenclatura estratigráfica de la cuenca.

The Upper Cambrian-Tremadocian rocks exposed in the Alfarcito area of Cordillera Oriental, northwest Argentina reveal a series of transgressive-regressive cycles punctuated by incision of fluvio-estuarine valleys. An integrated sedimentologic, biostratigraphic and sequence stratigraphic study permits characterization of the sedimentary facies and stratal stacking patterns, and a revision of the stratigraphic framework of this succession. The Upper Cambrian-Tremadocian succession is included within the existing Santa Rosita Formation, which is formally subdivided here into six units, the Tilcara, Casa Colorada, Pico de Halcón, Alfarcito, Rupasca and Humacha members. This scheme recognizes the internal complexities of the formation, in that the Tilcara and Pico de Halcón members record sedimentation in areally-restricted incised valleys and contain structures indicative of tidal dominance, whereas the Casa Colorada, Alfarcito and Rupasca members typify wave-dominated open-marine environments, where background suspension-fallout was punctuated by oscillatory flows during storms. The Tilcara Member is incised into the underlying Mesón Group. The Casa Colorada Member reflects a basinwide Late Cambrian transgression and subsequent progradation and consists of lower to upper offshore deposits. The Pico de Halcón Member is incised into the Casa Colorada Member. The Alfarcito Member is divided into three distinctly upward-coarsening and-thickening intervals. The sandstone-dominated intervals are composed of lower to middle shoreface deposits with minor amounts of offshore transition and upper shoreface deposits. The heterolithic, fine-grained intervals record more distal deposition, ranging from the lower offshore to the offshore transition. The Rupasca Member is a dominantly fine-grained unit that records a major late early to early late Tremadocian transgression. The lower interval of this member consists of lower offshore to offshore-transition deposits, while the upper part is made up of shelf to lower offshore deposits. The Humacha Member is not exposed in the study area. The importance of integrating biostratigraphy within a sedimentologic and sequence-stratigraphic framework is underscored here, in that it enables us to construct a more accurate stratigraphic framework which permits a clear understanding of the sedimentary dynamics of this system.