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

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

Mendoza

Congreso; 3th International Conodont Symposium; 2013

Pander Society

LARI Creek, also named El Médano Creek, nearby the Salar del Rincón, is located in westernmost Salta Province, northwestern Argentina. 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 Paleozoic rocks crop out. The lower sequence that bears significant index fossils is intruded by Ordovician volcanic rocks, and covered by 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 interesting because the index fossils reveal the transitional levels between the Cambrian and Ordovician systems and, therefore, the discussed position of the inter-systemic boundary in South America (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; Rao et al., 2000; Vaccari et al., 2010; Toro et al., 2011). The conodonts and graptolites recorded in the upper part of the Las Vicuñas Formation, suggest a probable late Furongian age for the basal levels, and an early Tremadocian age for the uppermost levels, although the assignment of a definite age is still tentative.