Fabric transitions from shell accumulations to reefs: an introduction with Palaeozoic examples

Álvaro JJ, Aretz M, Boulvain F, Munnecke A, Vachard D, Vennin E (2007)

Publication Language: English

Publication Type: Book chapter / Article in edited volumes

Publication year: 2007

Edited Volumes: Geological Society, London, Special Publication

Series: Palaeozoic Reefs and Bioaccumulations: Climatic and Evolutionary Controls

City/Town: London

Book Volume: 275

Pages Range: 1-16

ISBN: 9781862392212

URI: http://sp.lyellcollection.org/content/275/1/1

DOI: 10.1144/GSL.SP.2007.275.01.01

Open Access Link: http://sp.lyellcollection.org/content/275/1/1.full-text.pdf


One unresolved conceptual problem in some Palaeozoic sedimentary strata is the boundary between the concepts of ‘shell concentration’ and ‘reef’. In fact, numerous bioclastic strata are transitional coquina-reef deposits, because either distinct frame-building skeletons are not commonly preserved in growth position, or skeletal remains are episodically encrusted by ‘stabilizer’ (reef-like) organisms, such as calcareous and problematic algae, encrusting microbes, bryozoans, foraminifers and sponges. The term ‘parabiostrome’, coined by Kershaw, can be used to describe some stratiform bioclastic deposits formed through the growth and destruction, by fair-weather wave and storm wave action, of meadows and carpets bearing frame-building (archaeocyaths, bryozoans, corals, stromatoporoids, etc.) and/or epibenthic, non-frame-building (e.g. pelmatozoan echinoderms, spiculate sponges and many brachiopods) organisms.

This paper documents six Palaeozoic examples of stabilized coquinas leading to (pseudo)reef frameworks. Some of them formed by storm processes (generating reef soles, aborted reefs or being part of mounds) on ramps and shelves and were consolidated by either encrusting organisms or early diagenesic processes, whereas others, bioclastic-dominated shoals in barrier shelves, were episodically stabilized by encrusting organisms, indicating distinct episodes in which shoals ceased their lateral migration.

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Álvaro, J.-J., Aretz, M., Boulvain, F., Munnecke, A., Vachard, D., & Vennin, E. (2007). Fabric transitions from shell accumulations to reefs: an introduction with Palaeozoic examples. In Geological Society London (Eds.), Geological Society, London, Special Publication. (pp. 1-16). London.


Álvaro, José-Javier, et al. "Fabric transitions from shell accumulations to reefs: an introduction with Palaeozoic examples." Geological Society, London, Special Publication. Ed. Geological Society London, London, 2007. 1-16.

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