Tafoflora deógena de depósitos provavelmente correlatos à formação Rio Claro, ocorrente no Município de Jaguariúna, SP

AUTOR(ES)
DATA DE PUBLICAÇÃO

2007

RESUMO

The Jaguariúna taphoflora occurs in Cenozoic sediment probably correlated or included in the Rio Claro Formation, outcropping at the left margin of the km 136,5 of the highway SP-340 (from Campinas to Mogi Mirim direction). This taphoflora is preserved as foliar impressions (parts and counterparts) covered by whitish film, on a massive variegated yellow-orange claystone occurring in two beds of the outcrops; the first one on the base and the other 2, 44 meters above. The phytofossiliferous collection consists of more than 600 foliar specimens, whose preservation allows rarely to observe more than the foliar shape, the primary vein, a diffuse secondary venation and a very unclear tertiary venation. About 312 better preserved specimens were selected for taxonomic analysis. Among them it was possible to recognize the following forms: Filicophyta - dryopteridaceae (Elaphoglossum sp); Magnoliideae Laurales - Lauraceae (Ocotea cf. O. puchelliformis); Monocotyledoneae Poales - Typhaceae (Typha cf. T. tremembensis and Typha fittipaldii sp. n.); Eudicotiledoneae - Caryophyllales- Amaranthaceae (Alternanthera sp.); Malpighiales - Clusiaceae (Garcinia sp), this last identified for the first time in the fossiliferous register of Brazil; Fabales - Fabaceae (Leguminosites sp.) and Gentianales - Apocynaceae (Aspidosperma duartei sp. n.). As results of the morphographic analysis among the others specimens of this population of 312 specimens, it was possible to recognize 02 foliar morpho-genera (Monocotylophyllum and Dicotylophyllum) in 13 distinct forms. The great diversity of forms, the predominance (85%) of entire margin leaves and of acute convex apex are evidences of adaptations to warmer (ca. 5 C higher in the MAT) and wetter climate than nowadays, of low altitudes and latitudes. The predominance of small foliar areas (nanophylls and microphylls) is indicative of probable selection of size during deposition, in area of flooding plain. The Rio Claro Formation sediments have a Neogene age tentatively inferred based in its stratigraphical position and landscapes forms. The warmer and wetter than the modern climate, suggested by the adaptative morphological features of this taphoflora, by its diversity and kaolinic matrix of its sediments, is putatively indicative of a Miocene age, because the global climate became colder and drier since the Pliocene, culminating with the Pleistocene glaciation.

ASSUNTO(S)

paleobotânica neógena tafoflora neogene paleobotany rio claro formation formação rio claro taphoflora jaguariúna municipality (sp) geociencias município de jaguariúna (sp)

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