UPPER CAMBRIAN/LOWER ORDOVICIAN CONODONT AND GRAPTOLITE RECORDS IN THE LARI SECTION, SALAR DEL RINCÓN, PUNA OF SALTA, ARGENTINA

M. E. GIULIANO; G. ORTEGA; G. L. ALBANESI; C. R. MONALDI

PUBLICACION ESPECIAL - ASOCIACION PALEONTOLOGICA ARGENTINA

ASOCIACIÓN PALEONTOLÓGICA ARGENTINA

Año: 2013 p. 33 - 37

0328-347X

LARI Creek, also named El Médano Creek, nearby the Salardel Rincón, is located in westernmost Salta Province, northwesternArgentina. It belongs to the Puna geological province,in the southern part of the Central Andean Basin (Moya et al.,1993). In this area, a succession of continental and marine Paleozoicrocks crop out. The lower sequence that bears significantindex fossils is intruded by Ordovician volcanic rocks, and coveredby clastic and pyroclastic deposits of Cenozoic age(Koukharsky, 1988; Moya et al., 1993; Koukharsky et al., 1996;Galli et al., 2010). This stratigraphic interval is particularly interestingbecause the index fossils reveal the transitional levelsbetween the Cambrian and Ordovician systems and, therefore,the discussed position of the inter-systemic boundary in SouthAmerica (Albanesi et al., 2010).An invertebrate fauna composed of trilobites, sponges,graptolites, and microfossils (conodonts and palynomorphs)was recorded in the Las Vicuñas Formation of the upper Furongian/lower Tremadocian (Moya et al., 1993; Carrera, 1998; Raoet al., 2000; Vaccari et al., 2010; Toro et al., 2011).The conodonts and graptolites recorded in the upper partof the Las Vicuñas Formation, suggest a probable late Furongianage for the basal levels, and an early Tremadocian age forthe uppermost levels, although the assignment of a definite ageis still tentative.