@article{fdi:010053498,
  title = {{R}ecycling of {A}mazon floodplain sediment quantified by cosmogenic {A}l-26 and {B}e-10},
  author = {{W}ittmann, {H}. and von {B}lanckenburg, {F}. and {M}aurice, {L}aurence and {G}uyot, {J}ean-{L}oup and {K}ubik, {P}. {W}.},
  editor = {},
  language = {{ENG}},
  abstract = {{T}he modern {A}mazon trunk stream and tributaries contain substantial amounts of sediments that were formerly stored for 1-3 m.y. in floodplains. {B}y reworking of floodplain deposits, this sediment is being incorporated into {A}mazonian streams. {W}e conclude this from using the ratio of in situ-produced cosmogenic {A}l-26 to {B}e-10 in detrital sediment from rivers draining the sediment-producing {A}ndean, {G}uyana, and {B}razilian shield areas, as well as the largest {A}mazonian lowland rivers. {S}amples from the modern {A}mazon {R}iver yield {A}l-26/{B}e-10 ratios between similar to 3.8 and 5.5, and thus represent mixing between a non-buried sediment end member and a formerly buried sediment end member. {T}he non-buried end member is sourced in the {A}ndes with a ratio of similar to 6.5, reflecting recent erosion of hillslopes exposed to cosmic rays, and the buried end member is potentially represented by deeply stored floodplain sediment as old as {M}iocene age, with a ratio of similar to 3, that was partially shielded from cosmic rays. {T}his simple picture of binary mixing is complicated by grain-size effects. {C}oarser-grained sediment from non-{A}ndean settings (lowlands, cratonic shields) contains slightly more formerly buried material, whereas finer-grained lowland sediment mostly records non-buried {A}l-26/{B}e-10 ratios and nuclide concentrations that are indicative of an {A}ndean source. {O}ur assessment shows an incorporation of formerly buried, old sediment of central {A}mazonian floodplains to the fresh, {A}ndean-derived sediment mainly carried in the {A}mazon trunk stream. {W}e interpret our results to mean that the {A}mazon regularly avulses into these old deposits that crop out in more distal vicinities to the main river and temporarily leaves its current {H}olocene channel.},
  keywords = {},
  booktitle = {},
  journal = {{G}eology},
  volume = {39},
  numero = {5},
  pages = {467--470},
  ISSN = {0091-7613},
  year = {2011},
  DOI = {10.1130/g31829.1},
  URL = {https://www.documentation.ird.fr/hor/fdi:010053498},
}