Paleoenvironment interpretation of a 1760 years B.P. old sediment in a mangrove area of the Bay of Guanabara, using pollen analysis

Abstract

A sediment sample was obtained at 122 cm from the top of a drilling core in the Guapimirim mangrove, Bay of Guanabara, and analyzed using pollen analysis. This muddy core reached a sandy ground at 133 cm. 14 C datation got the age of 1760 ± 50 years B.P. The most frequent pollen grains were mangrove species of Rhizophora mangle, Laguncularia racemosa and Avicennia schaueriana. " Restinga" and tropical rain forest vegetation was recognized behind the mangrove. After the last sea transgression at 2500 years B.P., the water level lowered to its actual size, allowing the installation of this mangrove.

Linked variations in sediment accumulation rates and sea-level in Guanabara Bay, Brazil, over the last 6000years

“…In the second phase, between 4300 and 2000 years ago, the sediment accumulation rate decreases, as best demonstrated in core BG-28. Data from cores T-8 (Barth et al, 2004), T-13 (Baptista Neto et al, 2013) and T-16 (Vilela et al, 2007), do not allow sediment accumulation rates to be estimated in this phase Barth et al (2006) and Vilela et al (2007); T-8, Barth et al (2004); T-13, Baptista Neto et al (2013); T-14 and T-16, Vilela et al (2007Vilela et al ( ). 2001Vilela et al ( 1999Vilela et al ( 1997Vilela et al ( 1993Vilela et al ( 1990Vilela et al ( 1986Vilela et al ( 1983Vilela et al ( 1980Vilela et al ( 1977Vilela et al ( 1973Vilela et al ( 1970Vilela et al ( 1967Vilela et al ( 1963Vilela et al ( 1957Vilela et al ( 1951Vilela et al ( 1946Vilela et al ( 1942Vilela et al ( 1938Vilela et al ( 1934Vilela et al ( 1930Vilela et al ( 1927Vilela et al ( 1922Vilela et al ( 1914Vilela et al ( 1910 because they lack sufficient dates.…”

“…Vilela et al (2006Vilela et al ( , 2007 studied bay evolution during the Holocene based on foraminifera assemblage variations and 14 C dating of cores. Barth et al (2004) and Barth et al (2006) studied bay evolution based on palynology and 14 C dating of cores. Godoy et al (1998aGodoy et al ( , 1998b, based on 210 Pb activity in cores, determined the mean sediment accumulation rate for the bay in the last 100 years.…”

Pollen Grains, Landscapes, and Paleoenvironments

“…Coelho (1999), analyzed sediments from Sepetiba Bay, Rio de Janeiro State, and observed four climate changes: 1) 6,300 to 4,650 BP, a humid phase indicated by elements of dense rainforest; 2) 4,650 to 1,350 BP, a drier period shown by the expansion of open vegetation; 3) 1,350 to 45 BP, a return to characteristics of higher humidity, identified by an increase in forest elements; and 4) from 45 BP to the present, characteristics of a drier environment were attributed to the greenhouse effect (artificial decrease in humidity) and to changes in the vegetation due to deforestation by man. Barth et al (2004) and Barth, São-Thiago & Barros (2006) analyzed sediments from Guanabara Bay, Rio de Janeiro, dated 4,210 and 1.760±50 BP, respectively, the latter study attesting to the existence of mangroves during this period.…”

Palinologia, Paleoflorística e Aspectos Paleoclimáticos de Sedimentos do Pleistoceno Tardio na Bacia Hidrográfica do Rio Guandu, Rio de Janeiro, Brasil

“…Na região das baixadas litorâneas, análises palinológicas foram realizadas por Coelho et al (2008) na Reserva Biológica de Poço das Antas, em Silva Jardim, e por Freitas (2011) na Lagoa da Ferradura, em Búzios. Barreto et al (2006Barreto et al ( e 2007, Barth et al (2004Barth et al ( , 2006Barth et al ( e 2011 Barros (2003), no alto da Serra dos Órgãos (Behling & Saffors, 2010) e na Lagoa de Itaipu em Niterói por Bartholomeu (2010).…”