Abstract

ALBANESI, Guillermo L.; ORTEGA, Gladys  and  HUNICKEN, Mario A.. Conodont-graptolite biostratigraphy of the silurian at Talacasto Range, San Juan Precordillera, Argentina. Ameghiniana [online]. 2006, vol.43, n.1, pp.93-112. ISSN 1851-8044.

Present contribution aims to taxonomic, biostratigraphic, and paleoenvironmental studies of new conodont and graptolite collections from the Silurian La Chilca and Los Espejos formations, which crop out in the Ancha Creek, at Talacasto Range, Central Precordillera of San Juan Province. Graptolite species recovered from the upper part of the La Chilca Formation represent the upper Llandovery Series (Telychian Stage). Conodonts from carbonate coquinas with Saetograptus argentinus (Cuerda), of the middle-upper Los Espejos Formation, allow us to determine the Kockelella variabilis variabilis Zone from the lower Ludlow (Gorstian). The Silurian sequence paraconformably overlies the San Juan Formation, whose upper limestones yielded conodonts from the Lenodus variabilis Zone (uppermost Arenig - lowermost Llanvirn, Middle Ordovician). The studied section develops up to the Lower Devonian shales that paraconformably overlies the Silurian sequence. The conodont association recorded in the Los Espejos Formation suggests a correspondence with the Linde Event, which occurred between two consecutive stable episodes. Isolated conodonts from this unit show a CAI 3, which indicates overburden paleotemperatures of 110-200° C.

Keywords : Conodonts; Graptolites; Systematics; Biostratigraphy; Events; Silurian; Precordillera; Argentina.