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Micritization and carbonate-grain binding by endolithic algae

D. R. Kobluk and M. J. Risk
Micritization and carbonate-grain binding by endolithic algae
AAPG Bulletin (July 1977) 61 (7): 1069-1082


Endolithic (boring) algae are the direct or indirect agents of important erosive and early diagenetic processes in carbonate sediments. Algae boring into carbonate grains produce micrite envelopes by repeated boring and infilling of borings by precipitated micrite, as described by Bathurst. However, the algae also produce micrite envelopes outside grains by the calcification (cementation) of exposed dead endolithic filaments, a process which reduces intergranular porosity. Algal filaments grow through the micrite envelopes into intergranular pores, and live within the pores as chasmolithic algae (living in holes not of their own creation); after death these may become calcified to produce an intertwined mesh of calcified filaments on which later micrite and microspar cements precipitate. The calcified intergranular filaments and associated cements further reduce intergranular porosity (and possibly permeability) and serve to bind the grains. Micrite envelopes also may be produced beneath algal-mucous coats through a process of etching and dissolution, resulting in a highly microporous residue micrite. Girvanella and similar Paleozoic and Mesozoic algae may represent calcified algae similar to those described previously, in which cement precipitates on dead algal thalli. Girvanella may be a diagenetic taxon, produced from many algal genera, rather than a discrete biologic form.

ISSN: 0149-1423
EISSN: 1558-9153
Coden: AABUD2
Serial Title: AAPG Bulletin
Serial Volume: 61
Serial Issue: 7
Title: Micritization and carbonate-grain binding by endolithic algae
Pages: 1069-1082
Published: 197707
Text Language: English
Publisher: American Association of Petroleum Geologists, Tulsa, OK, United States
References: 58
Accession Number: 1978-003072
Categories: Sedimentary petrology
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus.
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2019, American Geosciences Institute.
Update Code: 1978
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