Abstract Detail



Paleobotany

Martinez Aguillon, Camila [1], Crepet, William [2], Jaramillo, Carlos [3], Aliaga, Angélica [4], Moreno, Federico [5].

Paleobotanical record from the Descanso­-Yauri Basin, Peru: insights into the Neogene paleoclimate and elevation history of the Central Andean Plateau.

With an average elevation of 4000 m, the Central Andean Plateau exert huge influence in the regional climate and biogeography of tropical South America. The study of the changes in the paleoecology of the region associated to the elevation history of the mountain belt provides insights into the roll that the orogen plays today shaping climate and life. Here, we study the paleoflora of the Descanso-­Yauri Basin, an intermontane basin located in the northern part of the Central Andean Plateau, which holds the Neogene sedimentary record of the Central Andes. Fossil wood, leaves and pollen from Miocene and Pliocene localities from the Descanso­-Yauri Basin were morphologically and anatomically described, and when possible identified. We used stratigraphic field observations, U/Pb radiometric dating in igneous zircons and previous stratigraphic studies of the region to constrain the age of the localities studied.
From late Miocene localities thirteen permineralized wood specimens were found, together with one palm leaf morphotype, and abundant Podocarpaceae and Cyatheaceae pollen. Wood anatomical characters were indicative of typical tropical lowland canopy trees. Six wood samples were identified to the legume family (Fabaceae). Tree­height estimations for one of the legume specimens suggest a height of approximately 32 m.
From the Pliocene localities, abundant leaf material was studied and found associated with extant genera of Equisetum, Polystichum, Berberis, Polylepis and Ribes, and the palynological record was mostly dominated by grasses and herbs. A maximum likelihood estimation of climate was performed based on the coexistence of the identified fossil taxa for the Miocene and Pliocene localities. The analyses suggest that by the late Miocene (~18–9 Ma) the Descanso­-Yauri basin was dominated by a low to mid elevation tropical forest of no more than 2500 m, with high precipitation. In contrast, the paleobotanical record of the early Pliocene (~5 Ma) suggests that highland conditions, and a vegetation similar to today’s ecosystem was present in the basin, indicating the possible beginning of the puna ecosystem in this region. Our results are in line with the hypothesis of a rapid regional surface uplift of the northern Central Andean Plateau between ca. 9 and 5 Ma.


1 - Cornell University, 412 Mann Library Building, 412 Mann Library Building, Ithaca, NY, 14853, United States
2 - Section Of Plant Biology, 413 Mann Library, Cornell University, Ithaca, NY, 14853, United States
3 - Smithsonian Tropical Research Institute, Center for Tropical Paleoecology and Archaeology, Ancon, Panama, Panama
4 - Museo de Historia Natural Lima­ UNMSM, Departamento de Paleontología de Vertebrados, Av. Arenales 1256, Jesús María, Lima, Peru
5 - University of Rochester, Earth & Environmental Sciences, 227 Hutchison Hall, University of Rochester, Rochester, New York, 14627, United States

Keywords:
none specified

Presentation Type: Oral Paper
Number:
Abstract ID:651
Candidate for Awards:Isabel Cookson Award,Maynard F. Moseley Award


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