%0 Journal Article
%@holdercode {isadg {BR SPINPE} ibi 8JMKD3MGPCW/3DT298S}
%@nexthigherunit 8JMKD3MGPCW/3ER446E
%@archivingpolicy denypublisher denyfinaldraft24
%3 1-s2.0-S0037073812002758-main.pdf
%@secondarymark A1_ENGENHARIAS_III A2_GEOCIÊNCIAS
%D 2012
%4 dpi.inpe.br/plutao/2012/11.28.16.49.49
%T A Late Pleistocene-Holocene wetland megafan in the Brazilian Amazonia
%@usergroup administrator
%@usergroup lattes
%@usergroup marciana
%V 282
%@affiliation Instituto Nacional de Pesquisas Espaciais (INPE)
%F lattes: 0307721738107549 1 RossettiZanCohCohCre:2012:LaPlWe
%@resumeid 8JMKD3MGP5W/3C9JGTQ
%X Despite the growing interest in megafans, definitions provided for this type of environmental setting have not yet been widely agreed upon. A record of sedimentary facies distribution in both space and time including a larger number of analogs is particularly needed for improving megafan facies models. This work focuses on a large fan-like feature from an Amazonian wetland in northern Brazil. Morphological data based on remote sensing, as well as sedimentary facies and radiocarbon analyses, were integrated to propose that this feature is related to a megafan system active during the Late Pleistocene to Holocene. The megafan displays a divergent drainage network, gently-dipping slope, and concave-up and convex-up longitudinal and transverse profiles, respectively. Near surface deposits correspond to fining and coarsening upward sands related to active channels and overbank sand sheets/terminal fan lobes. Sediments are interbedded with abandoned channel/floodplain and lake/pond muds. Morphostructural analyses and drainage anomalies revealed a geological setting affected by reactivation of pre-existing faults contemporaneous with sediment accumulation. Establishment of a megafan system in this wetland most likely occurred within a slightly tectonically subsiding basin under favorable climatic conditions. During wet seasons, high water discharge would have favored sediment transport from highlands into this depositional site. High summer temperatures and drought under a monsoonal regime kept the water levels low. The described megafan could serve as an analog for contemporary tropical wetland megafans formed under a monsoonal climate regime.
%@versiontype publisher
%@electronicmailaddress rossetti@dsr.inpe.br
%@electronicmailaddress hzani@dsr.inpe.br
%@electronicmailaddress
%@electronicmailaddress edipocremon@yahoo.com.br
%@secondarykey INPE--PRE/
%@area SRE
%@e-mailaddress rossetti@dsr.inpe.br
%K tropical wetland megafan, late Pleistocene–Holocene, facies model, residual morphology, monsoonal climate, tectonic subsidence.
%@documentstage not transferred
%@doi 10.1016/j.sedgeo.2012.09.015
%@group DSR-OBT-INPE-MCTI-GOV-BR
%@issn 0037-0738
%@dissemination WEBSCI; PORTALCAPES; COMPENDEX.
%P 276-293
%A Rossetti, Dilce de Fátima,
%A Zani, Hiran,
%A Cohen, Marcelo,
%A Cremon, Édipo Henrique,
%@secondarytype PRE PI
%2 dpi.inpe.br/plutao/2012/11.28.16.49.50
%B Sedimentary Geology