Programa de Pós-Graduação em Geologia e Geoquímica - PPGG/IG

URI Permanente desta comunidadehttps://repositorio.ufpa.br/handle/2011/2603

O Programa de Pós-Graduação em Geologia e Geoquímica (PPGG) do Instituto de Geociências (IG) da Universidade Federal do Pará (UFPA) surgiu em 1976 como uma necessidade de desmembramento do então já em pleno desenvolvimento Curso de Pós-Graduação em Ciências Geofísicas e Geológicas (CPGG), instalado ainda em 1973 nesta mesma Universidade. Foi o primeiro programa stricto sensu de Pós-Graduação (mestrado e doutorado) em Geociências em toda Amazônia Legal. Ao longo de sua existência, o PPGG tem pautado sua atuação na formação na qualificação de profissionais nos níveis de Mestrado e Doutorado, a base para formação de pesquisadores e profissionais de alto nível. Neste seu curto período de existência promoveu a formação de 499 mestres e 124 doutores, no total de 623 dissertações e teses.

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Acesso aberto (Open Access)
Os efeitos da subida do nível do mar sobre os manguezais do litoral sul da Bahia durante o Holoceno
(Universidade Federal do Pará, 2015-03-25) FONTES, Neuza Araújo; COHEN, Marcelo Cancela Lisboa; http://lattes.cnpq.br/8809787145146228
This work integrates the palinological, sedimentological and geomorphological data with radiocarbon dating, as well as δ13C and C/N from the sedimentary organic matter to identify the impact of changes in sea level and climate during the Holocene in Jucuruçu River’s mangroves, near the city of Prado, South Bahia. A sediment core with 4.5 m depth was sampled from a fluvial valley, 23 km away from the modern coastline. The base of sediment core presents age of 7450 cal yrs BP. The data reveal two important phases characterized by 1) an estuarine system with tidal flats colonized by mangroves. Its sedimentary organic matter is mainly sourced from estuarine algae during the early and middle Holocene; and 2) in the second phase, the mangroves shrank and herbaceous vegetation expanded. The δ13C and C/N values show an increase in contribution of terrestrial C3 plants. These phases identified in this study are in agreement with the relative sea-level (RSL) rise during the early and middle Holocene, and its subsequent fall during the late Holocene. In addition, the influence of weather patterns proposed for Holocene may be identified throughout the studied sediment core. Probably, changes in depositional environment and dominant vegetation at the study site were caused by the combined action of changes in RSL and fluvial discharge. According to the model proposed in this work, during the early and middle Holocene occurred a RSL rise that caused a marine incursion along the studied fluvial valley. The dry period occurred during the early and middle Holocene produced a decrease in the fluvial discharge and contributed to this marine transgression. However, during the late Holocene occurred a RSL fall and a wet period. It favored the marine regression and consequently, the mangroves migrated to tidal flats attached to the edge of lagoons near the modern coastline. The geomorphologic and vegetation evolution is in agreement with the mid-Holocene RSL maximum above present RSL and subsequent fall to the present time. Keywords: climate; Holocene; relative sea-level; South of Bahia; vegetation.
Acesso aberto (Open Access)
Palinologia da Formação Pirabas, nos municípios de Primavera e Salinópolis, nordeste do estado do Pará, Brasil
(Universidade Federal do Pará, 2016-04-30) SILVA, Carla Batista da; GUIMARÃES, José Tasso Felix; http://lattes.cnpq.br/9602707802326509
During the Paleogene - Neogene transition, the Amazon coast (Brazil) presented very low rates of sedimentation and influx of siliciclastic sediments supplied by an ancient river basin, which allowed the formation of extensive and thick carbonate deposit. According to the development of Amazon fan in the upper Miocene, these deposits may have represented the last stage of carbonate sedimentation in transitional environments of the Amazon coast. The integration of facies and pollen analysis of a drill hole from Primavera/PA (FPR-160 core) and reassessment of pollen systematic of Cunha (2013) from an outcrop in Salinopólis/PA, allowed the identification of a lagoon connected to a shallow marine platform formed between the upper Oligocene and lower Miocene. The occurrence of Retibrevitricolporites grandis in FPR-160 core in the basal portion of the core, which is just above the crystalline basement rocks, provided a maximum age restricted to the upper Oligocene for the base of the formation Pirabas. The presence of Retitrescolpites irregularis, Psilatricolporites crassoexinatus and Retibrevitricolporites grandis together with the absence of Zonocostites ramonae and Deltoidospora adriennis may indicate that there was considerable continental influence on the deposits or occurrence of a marine environment with restricted mangrove areas. The occurrence of Mauritiidites franciscoi, P. crassoexinatus, R. irregularis, Malvacipolloides maristellae and Zonocostites ramonae in the outcrop in Salinopólis/PA, suggests lower Miocene age to the top of this unit, interpreted as a lagoon bordered palaeoenvironment by mangrove vegetation.
Acesso aberto (Open Access)
Processos autocíclicos e alocíclicos afetando os registros da paleoflora da foz do rio Jucuruçu, litoral sul da Bahia, durante os últimos 1000 anos
(Universidade Federal do Pará, 2016-06-07) MORAES, Caio Alves de; COHEN, Marcelo Cancela Lisboa; http://lattes.cnpq.br/8809787145146228
The vegetation holocenic history along the southern Bahia littoral is characterized by establishment, expansion and contraction phases of mangroves. This vegetation dynamics is mainly associated to climate change and to relative sea level oscillations. However, punctually and in a smaller time scales, for example, during the last 1000 years, other processes inherent to the sedimentary dynamics of depositional environment, termed autocyclic processes, are controlling the pollen assembly along stratigraphic profiles formed by active channels followed by its abandonment. Based on sedimentary features, pollen grains, isotopes (δ13C, δ15N C/N) and radiocarbon dating of sedimentary organic matter from two cores (PR-11 and PR-12) sampled from an abandoned meander and a tidal flat in the mouth of the Jucuruçu river, is proposed a model for evolution of a tidal channel surrounded by wetlands. The core PR-11, with 1.48 meters depth, was sampled from a mangrove zone, with a maximum age of 678 cal yr BP. The PR-12 was collected from a várzea vegetation, approximately 2.7 km from the current shoreline with 1.92 meters depth and, maximum age of 680 cal yr BP. The data present two facies associations: (A) Tidal channel, represented by massive sand deposits (facies Sm); cross-stratified sand (Scs) and facies flaser heterolithic bedding (Hf) and (B) Tidal plain, represented by facies wavy heterolithic bedding (Hw), lenticular heterolithic bedding (Hl), massive mud (Mm) and massive sand (Sm). The pollen data reveals that the facies association (A) presents absence of pollen grains of mangroves. It may have been caused be an intense activity of sediments reworking of channel margins and sediment deposition with pollen grains sourced from vegetation units not necessarily from the study site. In the top of the studied succession, in association facies (B), is possible to identify the establishment and expansion of mangroves in the newly formed tidal flat (PR-11) or lake (PR-12). Regarding the core PR-12, it is marked by channel abandonment. The reduced interaction between fluvial discharge and tidal waves have caused the infilling of mud sediments, and a highest potential for organic matter preservation. It provided conditions for the mangrove development and pollen preservation. In the case of PR-11, the tidal channel migration have caused the development of a tidal flat, which have favored the mangrove expansion. These depositional environments, favorable to the formation of mangroves, can be partially or completely modified by the natural dynamics of tidal channels and estuarine channels, which are under the influence of changes of sedimentary fluvial contribution on the shore and littoral drift processes along the coast associated with tides, waves and currents. These results were compared with some data from one core sampled 23 km upstream of Jucuruçu River that also indicated the presence of mangroves on tidal flat with estuarine organic matter during the early and middle Holocene, followed by herbaceous vegetation on a fluvial plain with organic matter sourced from freshwater during the late Holocene (Fontes, 2015). In this case, the sea level fluctuations and climate change were the main driving forces controlling the wetlands dynamics at the mouth of this river during the Holocene, characterizing an allocyclic process. However, considering the stratigraphic sequences of the analyzed cores in this master's work (PR-11 and PR-12), such sedimentary sequences associated with changes in vegetation and sources of organic matter are related to the infilling processes of coastal depressions, mainly marked by active channels, abandoned channels and tidal flats. Therefore, in a small time scale of coastal vegetation changes are not necessarily directly associated with sea-level and climate change (allocyclic processes). On the other hand, processes associated to the sedimentary dynamics of the depositional environment (autocyclic processes) must have controlled pollen assembly along the studied stratigraphic profiles.

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Navegando Programa de Pós-Graduação em Geologia e Geoquímica - PPGG/IG por CNPq "CNPQ::CIENCIAS BIOLOGICAS::BOTANICA::MORFOLOGIA VEGETAL::PALINOLOGIA"