Long-Term Evolution of Sediment Routing on an Active Continental Margin Constrained by Detrital Zircon U–Pb Ages and Measured Stratigraphy from Carboniferous–Miocene Strata of NW Argentina, Central Andes

The stratigraphy and provenance of sedimentary rocks in the Andes record how sediment routing patterns evolved over hundreds of millions of years of subduction and diverse extensional, neutral, and contractional deformation regimes. We explore long-term sediment routing using new measured sections, paleocurrent measurements, and detrital zircon U–Pb age data from Carboniferous-Triassic, Cretaceous(?), and Neogene strata of the northern Sierras Pampeanas near Fiambalá, Argentina. Carboniferous–Triassic Paganzo Group strata, which were deposited in an extensional setting and consist of fluvial-lacustrine, alluvial, and eolian clastic sediment, have SSW-directed paleocurrents and contain detrital zircon grains with dominant ages ca. 1.3–0.9 Ga and ca. 660–470 Ma. These ages suggest source areas within the Arequipa and Antofalla massifs (ca. 1.3-0.9 Ga), north of the study area, and Neoproterozoic–Cambrian strata of SW Gondwana (ca. 660–570 Ma), NE of the study area. The overlying El Pedernal Formation contains fluvial conglomerates and sandstones overlain by eolian sandstones. The fluvial interval has similar detrital zircon ages to the Paganzo Group, a ca. 88 Ma zircon maximum depositional age, and SW-directed paleocurrents. The eolian interval has a ca. 15 Ma maximum depositional age. Overlying Miocene conglomerates of the Tambería Formation have E-directed paleocurrents and similar detrital zircon ages to other samples. Together, the samples record the latest Cretaceous or Cenozoic transition from a SW-directed, axial drainage network that persisted for at least ca. 200 Myr to a transverse drainage that eroded the Andes. These findings underscore the potential for long-term persistence and inheritance of sediment routing networks in changing deformation regimes.