@article{PAR00024218,
  title = {{C}yclic sediment deposition by orbital forcing in the {M}iocene wetland of western {A}mazonia ? {N}ew insights from a multidisciplinary approach},
  author = {{H}oorn, {C}. and {K}ukla, {T}. and {B}ogota-{A}ngel, {G}. and van {S}oelen, {E}. and {G}onzalez-{A}rango, {C}. and {W}esselingh, {F}. {P}. and {V}onhof, {H}. and {V}al, {P}. and {M}orcote-{R}ios, {G}. and {R}oddaz, {M}artin and {D}antas, {E}. {L}. and {S}antos, {R}. {V}. and {D}amste, {J}. {S}. {S}. and {K}im, {J}. {H}. and {M}orley, {R}. {J}.},
  editor = {},
  language = {{ENG}},
  abstract = {{I}n the {M}iocene, a large wetland system extended from the {A}ndean foothills into western {A}mazonia. {T}his system has no modern analogue and the driving mechanisms are not yet fully understood. {D}ynamic topography and {A}ndean uplift are thought to have controlled deposition, with allocyclic base level changes driven by eustasy and orbital forcing also playing a role. {I}n this study we investigate the presumed orbital cyclicity that controlled sediment deposition, while also assessing sediment source and biomes in the {M}iocene wetland. {W}e do this by integrating lithological, palynological, malacological and geochemical data from the {L}os {C}horros site ({A}mazon {R}iver, {C}olombia), and by placing our data in a sequence stratigraphic framework. {I}n this sequence biostratigraphic evaluation, the {L}os {C}horros succession is visualized to be composed of a series of flood-fill packages, with a rapid initial flood, marine-influenced conditions at the time of maximum flood, followed by a longer regressive infill phase. {B}ased on the palynology we could differentiate local vegetation, such as palm swamps, from regional origin such as terra firme vegetation (non-flooded {A}mazonian forest) and {A}ndean montane forest, while from sediment geochemistry we could separate local and regional sediment sources. {A}t the times of flooding, oligotrophic and eutrophic aquatic conditions alternatively characterized the wetland, as is shown by the presence of algae, floating ferns, and mollusc assemblages, while intervening subaquatic debris points to proximal submerged lowlands. {I}n the lower 20 m of the section, marine influences are intermittently evident and shown by short-lived maxima of mangrove pollen, foraminiferal test linings, dinoflagellate cysts, coastal mollusc species, and an episodic decline in terrestrial biomarkers. {T}he upper 5 m of the section is characterized by floodplain forest taxa with a diversity in tropical rain forest taxa and relatively few lacustrine indicators. {T}hese marine, mangrove, and lacustrine indicators suggest that the outcrops at {L}os {C}horros represent predominant marine-influenced lacustrine conditions during periods of sea level highstand. {T}he sequence biostratigraphic evaluation further points to eight 41 kyr obliquity-driven depositional cycles, with rapid phases of transgression. {M}angrove elements would have colonised within the timeframe of each sea level rise. {B}ased on this relative age constraint and comparison to regional records, deposition likely took place prior to the 13.8 {M}yr global sea level fall, and most likely during the period just after 14.5 {M}a, between {M}iddle {M}iocene {C}limatic {O}ptimum ({MMCO}; 17-14 {M}a) and {M}iddle {M}iocene {C}limate {T}ransition ({MMCT}; 14.7-13.8 {M}a). {P}alynological evidence further suggests that to the west, surface elevation ranged from similar to 1000 up to similar to 3500 m and hosted protoparamo vegetation, the oldest yet reported and in agreement with predictions from molecular studies. {I}n contrast, contemporaneous sites to the northeast of the wetland consisted of fluvial and cratonic formations, as shown by their {N}d and {S}r isotopic sediment signature. {I}n summary, our data lead to an improved understanding of how geological and astronomical mechanisms controlled the floral and faunal distribution and controlled sediment deposition in western {A}mazonia during the middle {M}iocene. {A}s {M}iocene conditions strongly contrast with modern western {A}mazonia, our data provide an important context for the deep time history and evolution of the modern western {A}mazon rainforest.},
  keywords = {{A}mazon, palynology ; {S}equence stratigraphy, geochemistry ; {B}iomarkers ; {E}stuarine ; {M}arine incursions ; {COLOMBIE} ; {AMAZONIE} ; {AMAZONE}},
  booktitle = {},
  journal = {{G}lobal and {P}lanetary {C}hange},
  volume = {210},
  numero = {},
  pages = {103717 [26 p.]},
  ISSN = {0921-8181},
  year = {2022},
  DOI = {10.1016/j.gloplacha.2021.103717},
  URL = {https://www.documentation.ird.fr/hor/{PAR}00024218},
}