New conodont taxa and biozones from the Lower Ordovician of the Cordillera Oriental, NW Argentina

ALBANESI, GUILLERMO; ORTEGA, GLADYS; MONALDI, CESAR RUBEN; VOLDMAN, GUSTAVO; GIULIANO, MARIA EUGENIA; ORTEGA, GLADYS; VOLDMAN, GUSTAVO; GIULIANO, MARIA EUGENIA; ALBANESI, GUILLERMO; MONALDI, CESAR RUBEN

GEOLOGICAL JOURNAL (CHICHESTER)

JOHN WILEY & SONS LTD

Lugar: LOndres; Año: 2016

0072-1050

 Theupper strata of the Santa Rosita and the Acoite formations (Lower Ordovician)exposed at Chulpíos Creek in the Santa Victoria study area of the CordilleraOriental, NW Argentina, are analysed by means of conodont  biostratigraphy. Four conodont  zones are analysed  for the referred  formations, i.e. the Acodus apex, Acodustriangularis, Gothodus vetus and Gothodus andinus zones, on the basis of acollection with ca. 2800  conodont  specimens that  includes new conodont  taxa. Acodus apex Albanesi and Zeballo, Acodustriangularis (Ding), Acodus  zeballus n.sp., Gothodus andinus (Rao et al.), Gothodus vetus n. sp., and Paltodus cf.inaequalis  (Pander) are described  herein. The conodont  genus Zentagnathus  is diagnosed including  two previously  known species: Zentagnathus argentinensis (Raoet al.) and Zentagnathus primitivus (Voldman et al.). The Tetragraptusakzharensis and  Baltograptus cf.deflexus graptolite zones were identified as well in the 1800-m-thick  stratigraphic  section. The incertae sedis  Phosphannulus  universalis Müller et al. is discussed  for the Cordillera Oriental for the firsttime. The lower part of the Chulpíos section that involves the contact  between the Santa Rosita and the Acoite  formations is not  able to be dated with precision either asupper Tremadocian or lower  Floian  because the ranges of the index  taxa  recorded  in that  interval of  the study  sectionspan the stage boundary