CHARACTERIZING THE AEOLIAN SEDIMENTS OF THE SELVA QUARRY, ARGENTINA USING DETRITAL ZIRCON U-PB GEOCHRONOLOGY

The Chaco and the Pampean plains of Argentina contain some of the largest aeolian deposits in the world, understanding the boundary between these environs and inherently the associated aeolian systems will help constrain climate variations in the Quaternary. The Chaco-Pampean plain is located in the retro-arc foreland basin east of the Andes orogeny. The plain is presently characterized by a semi-arid to subtropical climate in the north (Chaco) varying to temperate in the south (Pampas). Geomorphology is controlled by intercalated fluvial and aeolian processes. The Selva quarry rests east of a neotectonic high angle fault, allowing for easy access to the underlying stratigraphy. This scarp exposes a section covering the late Pleistocene – Holocene consisting of an upper loess/paleosol sequence and lower lacustrine deposits. Samples were collected for detrital zircon U-Pb dating and optically stimulated luminescence to characterize both the provenance and depositional ages.. Three samples were taken from the upper aeolian sequence, one from the San Guillermo formation, and two from the Tezanos Pinto formation.. The most abundant age populations are ≤2 Ma, indicating a large contribution of detritus from a Quaternary source. A subsidiary population is present of Neogene ages. Two Mesozoic ages are present. There is a minor population of analyses of Neoproterozoic – early Paleozoic. . The predominance of Quaternary ages, indicates quick deflation of relatively young volcanic (?) materials, likely from or related to the Antofalla volcanic complex located on the southern Puna plateau. The source rocks being to the northwest indicate a westerly wind that transported the sediments.