Lagoon Deposits

Lagoon Deposits

 

the sediments of lagoons. The sediments of lagoons with low salinity contain chiefly sandy, clayey, and sometimes clayey-carbonaceous silts enriched by organic matter. In the mineral state the silts are associated with sandy-clayey deposits containing narrow interlayers of marls and limestones and often also interlayers and lenses of coal. In lagoons with unusually high salinity a black silt with a pungent smell of hydrogen sulfide is deposited, composed chiefly of microcrystals of assorted chemogenic formations. Mineral salt-bearing lagoon deposits include strata of sulfate and chlorous sodium salts, gypsum, anhydrite, and, of the carbonaceous rocks, dolomite limestones, dolomites, and sometimes magnesite. Both types of lagoon deposits are characterized by either an absence of fossil fauna or by stunted and specialized forms with rich development of a few species.

Lagoon deposits are distinguished by rapid changes in the rocks and facies both horizontally and vertically, which indicates the transitional conditions (from marine to continental) of their formation. The most frequently encountered mineral products in lagoon deposits are salts, gypsum, anhydrite, and coals. The deposits of lagoons lying in circular coral atolls contain carbonaceous sediments cemented with lime.

References in periodicals archive ?
The major portion of middle part is characterized by lagoon deposits. As a whole both sections represent inner ramp settings.
At the bottom, late-Pleistocene marine deposits are found above the Holocenic lagoon deposits. Both of them consist of silty-sandy-clay soils with low consistency and high vertical and lateral variability.
These sedimentary environments include alluvial fans, meandering river deposits, lake deposits, eolian (desert) deposits, deltaic deposits, lagoon deposits, glacial deposits, peritidal deposits, clastic shelf deposits, continental rise deposits, and pelagic sediments of the deep sea.