Middle Ordovician (early Dapingian) conodonts in the Central Andean Basin of NW Argentina

Abstract

Carlorosi, J., Heredia, S. & Aceñolaza, G, 2013. Middle Ordovician (early Dapingian) conodonts in the Central Andean Basin of NW Argentina. Alcheringa 37, 1–13. ISSN 0311-5518.

This paper describes and analyzes the significance of a conodont fauna from the Alto del Cóndor Formation, exposed in the Los Colorados region of the Argentine Eastern Cordillera. Identified taxa are Baltoniodus triangularis, Baltoniodus sp. cf. B. triangularis, Drepanodus sp., Drepanoistodus basiovalis, Drepanoistodus sp. B., Erraticodon patu, Gothodus costulatus, Oistodus sp., Trapezognathus diprion, T. quadrangulum, Triangulodus sp. and Triangulodus? sp. The presence of Baltoniodus triangularis indicates the base of the Dapingian stage (Middle Ordovician). In addition, we report the coexistence of T. diprion and T. quadrangulum. The conodont association suggests a faunal affinity with Baltica and South China, both belonging to the Shallow-Sea Realm of the Temperate-Cold Domain.

Josefina Carlorosi [josefinacarlorosi77@gmail]com], INSUGEO—Universidad Nacional de Tucumán—CONICET, Miguel Lillo 205, (4000) Tucumán, Argentina; Guillermo F. Aceñolaza [[email protected]], Universidad Nacional de Tucumán—CONICET, Miguel Lillo 205, (4000) Tucumán, Argentina; Susana Heredia [[email protected]], CONICET–CIGEOBIO and Instituto de Investigaciones Mineras, Facultad de Ingeniería, Universidad Nacional de San Juan, Urquiza y Libertador, (5400) San Juan, Argentina. Received 22.8.2012; revised 18.10.2012; accepted 24.10.12.

阿根廷西北部中安第斯盆地的中奥陶世(Dapingian早期)牙行刺

本文描述并分析了出露于阿根廷Eastern Cordillera的Los Colorados地区的Alto del Cóndor组的牙行刺动物群的意义。所鉴定的分类群是:Baltoniodus triangularis、 Baltoniodus sp. cf. B. triangularis、Drepanodus sp.、Drepanoistodus basiovalis、Drepanoistodus sp. B.、Erraticodon patu、Gothodus costulatus、Oistodus sp.、Rapezognathus diprion、T. quadrangulum、Triangulodus sp. 以及Triangulodus？sp.。Baltoniodus triangularis的存在标示Dapingian阶之底(中奥陶世)。另外,我们报道T. diprion 和T. quadrangulum共存。牙行刺组合表现出波罗的海动物群和华南动物群之间的亲缘关系,两个地区都属温暖-寒冷地域的浅海区。

Key words:

• Dapingian
• conodonts
• Central Andean Basin
• NW Argentina

Acknowledgements

The authors express their thanks to the Argentine Research Council (CONICET) and CONICET’s technician Mercedes González for her laboratory work. Special thanks to the reviewers for improving the original manuscript. This work has benefited from financial support of projects CGL2009-09583 (Ministerio de Ciencia e Innovación, Spain) and CIUNT-26-G401/2 (UNT, Argentina).