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GEOREF RECORD

Turning the Capitan Reef upside down; a new appraisal of the ecology of the Permian Capitan Reef, Guadalupe Mountains, Texas and New Mexico

Rachel Wood, J. A. D. Dickson and Brenda Kirkland-George
Turning the Capitan Reef upside down; a new appraisal of the ecology of the Permian Capitan Reef, Guadalupe Mountains, Texas and New Mexico
Palaios (August 1994) 9 (4): 422-427

Abstract

Study of the primary reefal cavities preserved ubiquitously within the Permian Capitan Limestone leads to a profound reappraisal of the ecology, diagenesis and construction of the Capitan reef. Contrary to established opinion, most calcareous sponges (such as the sphinctozoans Guadalupia spp., Amblysiphonella spp., Cystauletes spp. and Lemonia spp.) did not grow upright in thickets to form a reef framework or bafflestone. Rather they were pendant cryptobionts inhabiting cavities, often in considerable abundance. In addition to this distinctive cryptic community, the framework of the reef was constructed in part by microbially-bound sediment, with the walls and ceilings of the cavities frequently supported by fenestellid and ramose bryozoans. Crypts were strengthened and filled by extensive precipitation of syn-sedimentary cements (botryoids and isopachous fibrous cements) combined with algal encrustation, predominantly Archaeolithoporella. Like modern reefs, the Capitan reef biota was thus strongly differentiated into two communities: open surface and cryptic. Our reinterpretation of the ecology of the reef has far-reaching implications for reef construction, and also for sediment supply and facies geometries of adjacent lithosomes. The presence of abundant fragile and delicate skeletons in the reef does not imply tranquil conditions given their cryptic location. We suggest here that the Capitan reef was a wave resistant and highly porous structure. A shallow-water origin for the reef is also supported by the rapid overall rate of carbonate accumulation calculated for the platform as a whole. As in modern coralgal reefs, much of the overall diversity of the Capitan reef was housed within cryptic niches. Indeed, some fossil reef-dwelling organisms previously interpreted as open surface frame-builders, including Paleozoic sphinctozoans sponges, were in fact more common as cryptobionts. Yet even though crypts are an almost ubiquitous component of both modern and fossil reefs, description of fossil cryptic biotas receives relatively little attention. The presence of a well-developed cryptos in the Permian Capitan reef complex, as well as isolated reports from other Phanerozoic reefs, suggests that an appraisal of the ecology of crypts is vital to an understanding of ancient reef ecology.


ISSN: 0883-1351
Serial Title: Palaios
Serial Volume: 9
Serial Issue: 4
Title: Turning the Capitan Reef upside down; a new appraisal of the ecology of the Permian Capitan Reef, Guadalupe Mountains, Texas and New Mexico
Affiliation: University of Cambridge, Department of Earth Sciences, Cambridge, United Kingdom
Pages: 422-427
Published: 199408
Text Language: English
Publisher: Society of Economic Paleontologists and Mineralogists, Tulsa, OK, United States
References: 30
Accession Number: 1995-036087
Categories: Sedimentary petrology
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. sect.
N31°30'00" - N37°00'00", W109°04'60" - W103°00'00"
N25°45'00" - N36°30'00", W106°30'00" - W93°30'00"
Secondary Affiliation: University of Texas at Austin, USA, United States
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Reference includes data supplied by SEPM (Society for Sedimentary Geology), Tulsa, OK, United States
Update Code: 199514
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