Characterization and genesis of waterfalls of the Presidente Figueiredo region, northeast State of Amazonas, Brazil

Citation
Acr. Nogueira et Rr. Sarges, Characterization and genesis of waterfalls of the Presidente Figueiredo region, northeast State of Amazonas, Brazil, AN AC BRASI, 73(2), 2001, pp. 287-301
Citations number
42
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Multidisciplinary
Journal title
ANAIS DA ACADEMIA BRASILEIRA DE CIENCIAS
ISSN journal
0001-3765 → ACNP
Volume
73
Issue
2
Year of publication
2001
Pages
287 - 301
Database
ISI
SICI code
0001-3765(200106)73:2<287:CAGOWO>2.0.ZU;2-3
Abstract
The waterfalls of the Presidente Figueiredo municipality represent a fascin ating natural scenery of northeast state of Amazonas, northern Brazil. The falls, generally less than 10m high, are: developed on siliciclastic rocks of the Nhamunda (Lower Silurian), and Manacapuru (Upper Silurian - Lower De vonian) formations. Morphological and structural analysts of these features indicate that most of them originated through Quaternary neotectonics and are installed in NE-trending normal fault escarpments. Waterfalls also deve loped within pseudokarstic features, but an less frequent. The origin of the Presidente Figueiredo waterfalls probably goes back to th e Neogene, when the region was submitted to laterization processes associat ed with a humid climate and a dense rainforest. These conditions favored th e development of caves in quartzarenites of the Nhamunda Formation. During the Quaternary, the region was subjected to NE-trending normal faulting whi ch displaced laterite layers, rivers and streams giving rise to waterfalls. These climatic and tectonic phenomena promoted intense relief dissection, as indicated by fault escarpment retreat and cave dismantlement, responsibl e for the present-day morphologic configuration.