@article{fdi:010083585,
  title = {{B}iological origin of rhythmites in muddy sediments of {F}rench {G}uiana},
  author = {{D}ebenay, {J}.{P}. and {J}ouanneau, {J}. {M}. and {S}ylvestre, {F}lorence and {W}eber, {O}. and {G}uiral, {D}aniel},
  editor = {},
  language = {{ENG}},
  abstract = {{S}ediment deposition along the coasts of {F}rench {G}uiana depends on three different processes: mass deposition when a mudbank reaches the area, seasonal exchange between the mudbank and the shoreline, and the effect of tide cycles. {T}he objectives of this work were to determine whether the three different processes are recorded in the sediments, and if rhythmites are discernible, preserved, and usable for paleoenvironmental studies. {T}he study area was in the {K}aw estuary, southeast of {C}ayenne ({F}rench {G}uiana) at a latitude of about 4 degrees 55' {N} and longitude about 5 degrees 10' {W}. {F}our stations were selected for the collection of push cores, which were then split and described. {R}edox and water content were measured; grain-size analyses, radioisotopic measurements ({P}b-210 geochronology), and {X}-ray image-analyses were carried out. {T}he {SCOPIX} {X}-ray image-processing tool was used for establishing gray-scale profiles. {A}fter mass deposition, sediment processes are dominated by reworking of the muddy sediment with a predominance of tidal effects. {E}rosion and deposition processes are governed by tide cycles and depend on threshold speeds of tidal currents. {M}icrophytobenthos, mainly diatoms, play a major bole in binding the sediment by secretion of extracellular polymeric substances ({EPS}). {T}hey induce the formation of alternating dark and clear laminae. {E}ven if erosion, irregular seasonal sediment supply, and bioturbation do not allow continuous recording of sediment laminae, the cyclic sediment deposits may result in tidal rhythmites, even in the highly size-sorted sediments of {F}rench {G}uiana. {W}hen preserved, the rhythmites provide valuable information on fortnightly cycles.},
  keywords = {tidal rhythmites ; laminations ; microphytobenthos ; {A}mazonian muds ; {S}outh {A}merica},
  booktitle = {},
  journal = {{J}ournal of {C}oastal {R}esearch},
  volume = {23},
  numero = {6},
  pages = {1431--1442},
  ISSN = {0749-0208},
  year = {2007},
  DOI = {10.2112/04-0299.1},
  URL = {https://www.documentation.ird.fr/hor/fdi:010083585},
}