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Quartz‐sandy, grazing‐contoured stromatolites from coastal embayments of Mauritania, West Africa
Author(s) -
SCHWARZ HANSULRICH,
EINSELE GERHARD,
HERM DIETRICH
Publication year - 1975
Publication title -
sedimentology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.494
H-Index - 108
eISSN - 1365-3091
pISSN - 0037-0746
DOI - 10.1111/j.1365-3091.1975.tb00245.x
Subject(s) - geology , sabkha , microbial mat , aeolian processes , stromatolite , algal mat , quartz , carbonate , geochemistry , clastic rock , reef , biogeosciences , geomorphology , paleontology , sedimentary rock , oceanography , algae , evaporite , cyanobacteria , ecology , materials science , earth science , bacteria , metallurgy , biology
A new occurrence of Recent stromatolites different from those known up to now has been discovered on tidal flats of the Bay of Saint‐Jean (near Cape Timiris). Their most remarkable features are predominance of quartz sand instead of carbonate, characteristic surface‐contouring by grazing fish, absence of cementation, intensive reworking by crabs, and connection with saline sabkha deposits. Entrapment of sand grains and great resistance of the algal sheaths are most important for stromatolitic growth, although today destruction appears to prevail over accretion. Quartz sand of aeolian dunes and carbonatic pellets of aragonitic ooze feeders are the main constituents of the stromatolitic sediments. According to the tidal range the following zonation of the algal mat exists: (A) knoll and cuspate zone, (B) flat zone, (C) gas‐domed zone, and (D) crinkle zone.