Kansas Geological Survey, Current Research in Earth Sciences, Bulletin 251, part 1
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Kansas Geological Survey, Current Research in Earth Sciences, Bulletin 251, part 1
Prev Page--Substrates and Sedimentation ||
Next Page--Calcipatera Community
Calcipatera, an erect calcareous alga with a cup-shaped thallus, grew gregariously to form a dense meadow above the substrate. The living thalli probably attached to the substrate by rhizoids (Torres et al., 1992) and grew to a height of about 10 cm. Calcipatera attached to both skeletal-sand and carbonate-mud substrates, and when the rate of sedimentation exceeded the rate of upward algal growth, the community died. The broad thin thalli of Calcipatera and the high percentage of carbonate mud (tables 1 and 2) indicate that Calcipatera probably could not have withstood a high degree of wave or current turbulence. Thus, Calcipatera inhabited a paleo-environment within the photic zone, and below wave base or in protected areas on a shallow epicontinental shelf.
In areas where wave and current turbulence were low, Calcipatera could have probably existed in relatively shallow water. Shallow water and increased light favored maximum algal growth and probably a higher rate of carbonate production (Crowley, 1969). Konishi and Wray (1961, p. 664) interpreted water depths for Eugonophyllum as "probably less than one fathom" and "based on analogy with Recent calcareous Codiaceae" (the family to which Calcipatera was assigned by Torres et al., 1992), "suggest that it did not commonly live at depths greater than 100 feet."
Once Calcipatera was established, it tended to be self-perpetuating-that is, produced abundant bioclastic debris, and baffled, trapped, and stabilized carbonate sediment. The amount of carbonate mud produced by Calcipatera is unknown but could have been substantial if similar to the sediment contributions of such Holocene algae as Penicillus, Rhipocephalus, Udotea, and Acetabularia (Stockman et al., 1967). The baffling and trapping of carbonate mud by Calcipatera can be compared to the role performed by the modern sea grass Thallassia as described by Ginsburg and Lowenstam (1958).
Assuming Calcipatera was attached via a holdfast or similar structure, a stable substrate, although not required, might have been advantageous. Although extant calcareous green algae are known to grow on a variety of substrates, some initial stabilization may have been required for Calcipatera colonization and this could have been provided by nonpreserved microbial activity. Although this in situ occurrence of Calcipatera helped stabilize the substrate and baffled and trapped sediment, it did not produce a mound or moundlike structure at this locality.
Ball et al. (1977, p. 251) described a situation where Archaeolithophyllum occurred "in supposed growth position" at a single exposure of Winchell Limestone (Pennsylvanian) near Ranger, Texas, but evidence of mound buildup growth was lacking. Ball et al. (1977, p. 258) concluded, from this and other occurrences, that "phylloid algae were important sources of building material rather than important builders," rejecting the idea that phylloid algae are important bafflers, trappers, and binders of sediment and creators of bioconstructed mounds. However, it is important to note that what is described here and by Ball et al. (1977) in the Winchell Limestone are phylloid algal shelfal banks. Phylloid algal mounds are more typical of Wolfcampian shelf-margin settings as described by Wahlman (1985, 2002) and by Wahlman in Simo et al. (2000) and Simo et al. (2001) from the subsurface Permian basin and in the Hueco Mountains of West Texas. What Ball et al. (1977) described is what Samankassou and West (2002, 2004) would refer to as an accumulational mode of algal occurrence. In refuting this interpretation by Ball et al. (1977), Cross and Klosterman (1981) pointed out that the stromatolitic-bound phylloid algal mound complex in the Laborcita Formation (Permian): (1) have "demonstrable depositional relief of 2.5 m and probable maximum relief of about 10 m" (p. 46), (2) are dominated by the phylloid algae Eugonophyllum that is "preserved erect in growth habit" (p. 48), (3) are "unrelated to pre-existing topography" (p. 57), and (4) that "mound development was controlled by growth of erect phylloid algae, binding by stromatolites, trapping of carbonate mud, and penecontemporaneous submarine cementation" (p. 57). In that Eugonophyllum is now recognized as a cyathiform alga (Torres, 1997), these Permian algal mounds would be referred to as constructional mounds composed of cup-shaped in situ algal growth forms as described by Samankassou and West (2002) for an occurrence in the Pennsylvanian of Kansas.
As suggested by Cross and Klosterman (1981), there are biologically constructed mounds (constructional occurrences of Samankassou and West, 2002) and parautochthonous occurrences of algal debris (accumulational occurrences of Samankassou and West, 2002). Additionally, there are different types of constructional occurrences (Samankassou and West, 2004). Forsythe (2003) studied the Virgilian and Wolfcampian limestones of the Hueco Mountains in West Texas and New Mexico. His studies indicated that Archaeolithophyllum constructed low-relief structures, i.e. biostromes, but that Eugonophyllum and Archaeolithoporella, along with microbes and marine cements, produced rigid frameworks with the cryptic habitats of an active reef.
At this locality in Greenwood County, Kansas, where Calcipatera occurs in growth position, and at other exposures of the Cottonwood limestone in the area, there is no obvious evidence of mounds or moundlike structures. Indeed, this is the only Cottonwood limestone locality, to our knowledge, where Calcipatera occurs in growth position. The platy algal facies, as reported by Laporte (1960, 1962), herein referred to as packstone, occurs at other localities. However, this occurrence of Calcipatera in life position, the work of Cross and Klosterman (1981), and the Pennsylvanian occurrence described by Samankassou and West (2002) suggests that cyathiform algae such as Eugonophyllum, Calcipatera, and some other types of phylloid algae were capable of mound construction, as documented by Forsythe (2003) for Eugonophyllum. It seems reasonable that the cup-shaped thalli of such algae could have baffled and trapped sediment such that mound-like features were the result. Perhaps the absence of any mound-like structures at the locality of this study is the result of environmental perturbations (e.g., increased sedimentation) that smothered algal growth before any significant topographic relief (mounding) developed. Such environmental perturbations are supported by the fact that more than one colonization event by Calcipatera is preserved at this locality. Lack of vertical accommodation space and/or unlimited lateral growth space could have also precluded mound development.
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