TREMADOCIAN TRILOBITES FROM DARK SHALE FACIES OF THE ALFARCITO MEMBER (SANTA ROSITA FORMATION), QUEBRADA DE MOYA, JUJUY, ARGENTINA. The Quebrada de Moya constitutes a distinctive locality of the Santa Rosita Formation (uppermost Furongian—lowermost Ordovician) in the Quebrada de Humahuaca (Sierra de Tilcara, Cordillera Oriental of Jujuy, Argentina). The trilobites Leptoplastides marianus (Hoek), Parabolinella sp., Hapalopleura acantha Malanca and Brandán, and Asaphellus sp. are described from the dark shale facies of the upper part of the Alfarcito Member. A grainstone interstratified in the mudstones contains a low-diversity conodont assemblage of the Cordylodus angulatus Zone (lower Tremadocian). The Ordovician age of the section is confirmed, in addition, by the record of the graptolite Rhabdinopora flabelliformis ssp. in a sandstone underlying the studied levels. The dark shales accumulated by suspension fall-out during periods of maximum flooding, in a reducing, distal offshore marine environment. The trilobite fauna is largely dominated by L. marianus. The upper part of the Alfarcito Member does not show dark facies in other sectors of the Sierra de Tilcara. The sedimentologic characters of the section described, the low diversity of the conodont assemblage, and the scarcity of agnostoid trilobites may be indicative of a partial isolation of the basin.
You have requested a machine translation of selected content from our databases. This functionality is provided solely for your convenience and is in no way intended to replace human translation. Neither BioOne nor the owners and publishers of the content make, and they explicitly disclaim, any express or implied representations or warranties of any kind, including, without limitation, representations and warranties as to the functionality of the translation feature or the accuracy or completeness of the translations.
Translations are not retained in our system. Your use of this feature and the translations is subject to all use restrictions contained in the Terms and Conditions of Use of the BioOne website.