Paleopalynological evidence for the Middle Miocene vegetation in the Tehuacán Formation, Puebla, Mexico.

RAMIREZ-ARRIAGA, E.; PRAMPARO, MERCEDES B; NIETO-SAMANIEGO, A.F.; MARTINEZ -HERNANDEZ, E.; VALIENTE -BAUNET, A.; MACIAS-ROMO, C.; DAVALOS-ALVAREZ, O.G.

PALYNOLOGY

AMER ASSOC STRATIGRAPHIC PALYNOLOGISTS FOUNDATION

Lugar: Oxon; Año: 2014 vol. 38 p. 1 - 27

0191-6122

Palynological assemblages recovered from the Tehuacan Formation (TF), geochronologically dated as Middle Miocene (15.6 - 0.4 Ma), give evidence of a highly diverse flora that at the generic level is quite similar to the extant flora in the Tehuacan Valley. We propose that during Miocene time, plant communities may have been formed of similar botanical elements to those seen today in the region, with some taxa adapted to semiarid conditions. While major temperate floristic elements of Pinus, Quercus, Juniperus, cloud forest and mexical vegetation can be recognized, major components of the tropical deciduous forests, such as Burseraceae, Leguminosae and Cactaceae, are also present, indicating semiarid conditions. Semiarid local conditions also are inferred from the geologic record, consisting of lacustrine and alluvial fan deposits, which contain abundant beds of evaporites. This lithology was formed under high evaporation and moderate precipitation conditions, as usually occurs in small basins fed by a seasonal input of water in semiarid environments. Important differences in the vegetation from the TF palynoflora as compared to older fossil associations from south-central Mexico can be inferred, such as an increase in diversification of semiarid taxa, belonging to Leguminosae and Burseraceae, and the first abundance of the Cactaceae in a fossil palynological association.