Paleontology, sedimentology and paleoenvironment of a new fossiliferous locality of the Jurassic Cañadón Asfalto Formation, Chubut Province, Argentina

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• 作者：Oscar F. Gallego^a ; ^{ofgallego@live.com.ar} ; Nora G. Cabaleri^b ; ^{cabaleri@ingeis.uba.ar} ; Claudia Armella^b ; ^{armella@ingeis.uba.ar} ; Wolfgang Volkheimer^c ; ^{volkheim@mendoza-conicet.gov.ar} ; Sara C. Ballent^d ; ^{sballent@fcnym.unlp.edu.ar} ; Sergio Martí ; nez^e ; ^{smart@fcien.edu.uy} ; Mateo D. Monferran^a ; ^{monfdm@gmail.com} ; Diego G. Silva Nieto^f ; ^{dsilva@mecon.gov.ar} ; Manuel A. Pá ; ez^g ; ^{paez_manuel@yahoo.com}
• 关键词：Paleontology ; Sedimentology ; Late Jurassic ; Cañ ; adó ; n Asfalto Formation ; Patagonia ; Argentina
• 刊名：Journal of South American Earth Sciences
• 出版年：2011
• 出版时间：February 2011
• 年：2011
• 卷：31
• 期：1
• 页码：54-68
• 全文大小：3976 K

文摘

A new Late Jurassic assemblage of “conchostracans”, ostracods, bivalves and caddisfly cases from the locality “Estancia La Sin Rumbo”, Chubut Province (Patagonia, Argentina) is recorded. The fossils occur in the upper part of an outcropping 45 m thick volcaniclastic lacustrine sequence of yellowish tuffs and tuffites of the Puesto Almada Member, which is the upper member of the Cañadón Asfalto Formation with U/Pb age of 161 ± 3 Ma. The sequence represents one sedimentary cycle composed of a (lower) hemicycle of expansion and a (higher) hemicycle of contraction of the water body. The invertebrates lived in small freshwater bodies during the periods of expansion of the lake. The occurrence of a great number of small spinicaudatans, associated with mud-cracks, is evidence of dry climatic conditions and suggests several local mortality events. The spinicaudatan record of the fushunograptid–orthestheriid (component of the Eosestheriopsis dianzhongensis fauna) and the presence of Congestheriella rauhuti Gallego and Shen, suggest a Late Jurassic (Oxfordian to Tithonian) age. Caddisfly cases are recorded for the first time in the Cañadón Asfalto Basin.