Palynomorphs from the Upper Jurassic Vaca Muerta Formation at Quebrada del Sapo in the Neuquén Basin of Patagonia, Argentina

A new palynological assemblage is documented from the Vaca Muerta Formation in the Quebrada del Sapo area of the Neuquén Basin in Argentina. One hundred and three palynomorph species are recognized. Systematic treatments are provided for sporomorphs (Cyathidites, Cyclusphaera, Nevesisporites, Shanbeipollenites), algae (Cymatiosphaera and Tetrastrum), acritarchs (Leiosphaeridia) and dinoflagellate cysts (Cribroperidinium, Dingodinium, ?Lithodinia, cf. Sirmiodinium). Tetrastrum multifilorum is identified for the first time from Argentina, while Cyathidites asper and Dingodinium tuberosum represent new occurrences from the Neuquén Basin; Cribroperidinium granulatum var. 1 is recorded for the second time globally. The dinoflagellate cyst composition indicates that the lower part of the Vaca Muerta Formation cannot be younger than early-late Tithonian; upper Tithonian deposits likely extend to near the top of the unit. The top of the Vaca Muerta Formation may lie within the lower part of the upper Tithonian. Our new evidence suggests that the basal range of Cyclusphaera radiata in Argentina extends into at least the ?lower Berriasian. Shanbeipollenites proxireticulatus extends into the upper Tithonian, and reveals its first Upper Jurassic occurrence outside of Tanzania. Scenedesmus ranges into the upper Tithonian and is thus the first Jurassic example in Argentina and the second oldest globally. Palaeobiogeographically, the Vaca Muerta Formation assemblage is comparable to those from the Upper Jurassic of southeast Africa, and could reflect a marine connection between the Neuquén Basin and the Mandawa and Lamu basins via the Mozambique Corridor.Luis S Agüero* [luisaguero@ingeosur-conicet.gob.ar], Instituto Geológico del Sur (INGEOSUR), Universidad Nacional del Sur- Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Av. Alem 1253, cuerpo B′, 1° Piso, B8000CPB Bahía Blanca, Buenos Aires, Argentina; Departamento de Geología, Universidad Nacional del Sur (UNS), Av. Alem 1253, cuerpo B’, 2.° Piso, B8000CPB Bahía Blanca, Buenos Aires, Argentina; Marcelo A. Martínez [martinez@criba.edu.ar], Instituto Geológico del Sur (INGEOSUR), Universidad Nacional del Sur- Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Av. Alem 1253, Cuerpo B′, B8000CPB Bahía Blanca, Buenos Aires, Argentina; Departamento de Geología, Universidad Nacional del Sur (UNS), Av. Alem 1253, cuerpo B’, 2.° Piso, B8000CPB Bahía Blanca, Buenos Aires, Argentina; Daniela E. Olivera [daniela.olivera@uns.edu.ar], Shandong Provincial Key Laboratory of Depositional Mineralization and Sedimentary Minerals, Shandong University of Science and Technology. Qianwangang Road 579, 266590 Qingdao, Shandong Province, PR China.