@article{fdi:010085191,
  title = {{L}ate quaternary hydrological changes in the {S}outheastern {A}mazon basin from n-alkane molecular and isotopic records in sediments of {S}aci lake, {P}ara state ({B}razil)},
  author = {{M}artins, {G}. {S}. and {C}ordeiro, {R}. {C}. and {T}urcq, {B}runo and {M}eyers, {P}. {A}. and {M}endez-{M}illan, {M}ercedes and {M}oreira, {L}. {S}. and {F}ontes, {D}. and {R}odrigues, {R}. {A}. and {S}ifeddine, {A}bdelfettah and {B}ehling, {H}. and {B}ouloubassi, {I}. {D}.},
  editor = {},
  language = {{ENG}},
  abstract = {{T}he molecular distributions and isotopic ratios (delta {C}-13 and 8{D}) of n-alkanes in sediments deposited during the last 35 cal kyr {BP} in {S}aci {L}ake, southeastern {A}mazonia, have been measured and interpreted for their paleoclimate information. {A} terrestrial origin for the odd carbon-numbered long-chain (> {C}27) n-alkanes has been inferred from molecular distributions. {A} shift in the n-alkane delta {C}-13 values across the {P}leistocene-{H}olocene boundary coincides with a climate-induced floral change previously deduced from palynological analyses. {D}ry conditions during the late {P}leistocene and mid-{H}olocene were confirmed by several n-alkane indices used to estimate the availability of moisture and by larger 8{D} values. {H}igh {ACL} values indicate relatively dry conditions from 29 to 18.2 cal kyr {BP} and again from 8.0 and 5.0 cal kyr {BP} with a decrease in precipitation and an increase of grasses. {C}hanges in the n-alkane {C}-29 isotopic compositions (delta {D} and delta {C}-13) were observed during the {P}leistocene{H}olocene transition, coinciding with a floristic change induced by climatic conditions that is also observed in palynological results from the same lake. {T}he n-alkane {C}-29 delta {C}-13 values remain between -33.2%o and - 35.7%o, which is representative for n-alkanes derived from {C}-3 vegetation. {T}hese lines of evidence suggest a continuous gallery forest cover in the {S}aci {L}ake catchment for the last ~35 cal kyr {BP} in contrasted with the observed palynological changes which represent the dynamics of the vegetation on the upland areas. {T}he n-alkane {C}-29 delta {D} values are less negative in the {P}leistocene and more negative during the {H}olocene in the lake record. {T}hese characteristics suggest more humid conditions during the {H}olocene than in the {P}leistocene, probably associated with the {S}outh {A}merican {M}onsoon {S}ystem ({SAMS}). {H}owever, an increase of approximately 10%o occurs during the late {H}olocene, which coincides with the forest expansion around 5 cal kyr {BP} that is recorded in palynological data of {S}aci {L}ake and other records of the {A}mazon {F}orest. {T}his change suggests that the {D}/{H} ratio is also influenced by the increase of the plant biomass, which would provide an enrichment of {D} in the isotopic signal as a function of regional moisture recycling caused by evapotranspiration.},
  keywords = {{S}outheastern {A}mazon basin ; {V}egetation ; {P}aleoclimate, n-{A}lkane ; {C}ompound specific isotope composition ; {BRESIL} ; {PARA} {ETAT} ; {AMAZONE} {BASSIN} ; {SACI} {LAC}},
  booktitle = {},
  journal = {{G}lobal and {P}lanetary {C}hange},
  volume = {213},
  numero = {},
  pages = {103833 [15 p.]},
  ISSN = {0921-8181},
  year = {2022},
  DOI = {10.1016/j.gloplacha.2022.103833},
  URL = {https://www.documentation.ird.fr/hor/fdi:010085191},
}