Palynological analysis of a late Holocene core from Santo Antônio da Patrulha, Rio Grande do Sul, Southern Brazil

Anais da Academia Brasileira de Ciências

Renato B. Macedo²  Paulo A. Souza²  Soraia G. Bauermann¹  Sérgio A.l. Bordignon¹ 

[1] ,Universidade Federal do Rio Grande do Sul Instituto de Geociências Departamento de Paleontologia e EstratigrafiaPorto Alegre RS ,Brasil

关键词: Palynology;    Paleoecology;    Paleoclimatology;    Atlantic rainforest;    late Holocene;    Rio Grande do Sul State;    Palinologia;    Paleoecologia;    Paleoclimatologia;    Floresta Atlântica;    Holoceno tardio;    Rio Grande do Sul;   

DOI  :  10.1590/S0001-37652010000300020

来源: SciELO

【 摘 要 】

A sedimentar core collected at Santo Antônio da Patrulha, Rio Grande do Sul State, southmost Brazil, was submitted to pollen analysis to provide the vegetational history of this region, and the paleoecological and paleoclimatic changes. A total of 98 taxa of palynomorphs was identified from 35 subsamples. Three radiocarbonic datings were obtained along a section of 115 cm depth, including the basal age of 4730 ± 50 yr BP. Pollen diagrams and cluster analysis were performed based on palynomorphs frequencies, demonstrating five distinct phases (SAP-I to SAP-V), which reflected different paleoecological conditions. The predominance of plants associated with grasslands in the phase SAP-I suggests warm and dry climate conditions. A gradual increasing of humidity conditions was observed mainly from the beginning of the phase SAP-III, when the vegetation set a mosaic of grasslands and Atlantic rainforest. Furthermore, the presence of some forest taxa ( Acacia-type, Daphnopsis racemosa, Erythrina-type and Parapiptadenia rigida-type), from the phase SAP-IV, is interpreted as an influence of the seasonal semideciduous forest in the study region. From the phase SAP-V (ca. 4000 yrs BP), the vegetation became similar to the modern one (extant Atlantic rainforest Biome), especially after 2000 yrs BP (calibrated age).

【 授权许可】

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