A palynomorph and graptolite biostratigraphy of the Central Precordillera Silurian Basin, Argentina

RUBINSTEIN, CLAUDIA V.; BRUSSA EDSEL

BOLLETTINO DELLA SOCIETA PALEONTOLOGICA ITALIANA

SOC PALEONTOLOGICA ITALIANA

Lugar: Modena; Año: 1999 vol. 38 p. 257 - 266

0375-7633

This work integrates palynological and graptolite studies of the Silurian La Chilca and Los Espejos formations for correlation purposes within the Central Precordillera Basin. Palynomorphs from these two formations have been grouped into five assemblages. In the Normalograptus persculptus graptolite Zone (Hirnantian), acritarchs  are scarce, poorly preserved, and have no stratigraphic value. This stratigraphic interval is dominated by short-spined acritarchs. The upper Stimulograptus sedgwickii - lower Spirograptus turriculatus Zones (upper Aeronian - lower Telychian) contain acritarchs, prasinophytes and lesse abundant cryptospores.  Tylotopalla caelamenicutis and Tylotopalla digitifera appear to be potentially useful for regional correlations of the middle-upper Llandovery boundary. The lower portion of the Los Espejos Formation yielded a highly diversified and well-preserved assemblage of acritarchs, prasinophytes, cryptospores and miospores, but unfortunately no reliable graptolite data are available.  The upper third of this formation, referred to as the Neodiversograptus nilssoni - Lobograptus scanicus Zones (Gorstian), contains a single diversified palynological assemblage of typical Ludlovian age.