Navegando por Assunto "Senador José Porfírio - PA"

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Acesso aberto (Open Access)
Oscilações climáticas Plio-Pleistocênicas e sua influência na prospecção de ouro na área do garimpo do Manelão (PA)
(2001-07) SOUZA, Valmir da Silva; KOTSCHOUBEY, Basile
In the Manelão deposit the gold is associated with quartz veins hosted in the São Manoel metavolcano-sedimentary sequence. At period Plio- Pleistocene, under a humid climate, an autochthonous and immature lateritic cover was developed on the São Manoel sequence. This lateritic cover contains gold particules of high purity suggesting lixiviation or remobilization and redeposition processes of Au-Ag in a lateritic enviroment. During Pleistocene the climate changed to arid or semi-arid favouring the erosion of the lateritic profile through colluvial processes associated with periodical floods. This colluvial deposit cover lateritic profile destroying a possible geochemical disperson of pattern of the supergenic gold and harming the geochemical exploration surface. At the end of Pleistocene and beginning of Holocene the humid climate condition returned and associated with the intemperic processes form stone line and latosols. The lateritic and colluvial cover were the source area for the current alluvial material of the São Manoel river, in which the gold occurs free in the lower sedimentary strata and forms concentrations around 10 g/ton.
Acesso aberto (Open Access)
O programa PROAMBIENTE na Transamazônica: lições aprendidas
(2013-06) ALMEIDA, Everaldo Nascimento de; XIMENES, Tereza Ferreira; JORGE, Yared; BRIENZA JÚNIOR, Silvio; POÇA, Raquel Rodrigues da
The study aimed at formulating lessons from the Brazil's Programme for the Socio-Environmental Development of Rural Family Production (PROAMBIENTE) in the Transamazon Highway pole in the Xingu region, Para State. The methodology included interviews to small farmers as well as institutional actors that participated in the Programme. From the analysis of the Programme interventions some important lessons could be formulated, among them the need to: i) involve farmers with a real interest an capacity to assume risks; ü) avoid paternalistic behaviors (based on donations); üi) ensure continuity of key activities such as the scheme for payment for environmental services; iv) use an integrated approach of the production system; v) shift the way technical assistance and rural extension are conceived and practiced; vi) strengthen the local rural organization; vü) generate value-add to production thru processing and commercialization of products of economic importance; and vüi) avoid the creation of false expectations among farmers.