Summary
Several Waulsortian-type mud mounds nearly 500 m thick and about 5 km long occur in the Middle Paleozoic carbonate section of the Aktur nappe in the mountains on the right bank of Isfara river. These buildups form a well developed barrier system that stretches along the South Ferganian carbonate platform margin and divides the carbonate complex into a fore-reef and a back-reef part. The time of the mounds' most active growth was from the Late Silurian (Ludlow) to the Middle Devonian (Eifel).
Three main facies types can be recognized in the mud mounds: 1. micritic core facies, 2. sparitic flank facies and 3. loferitic capping facies. The central massive or crudely bedded part of the mounds consists of white or light grey clotted micrite. Macrofossils are rare. The sparitic flank facies in contrast consists of coarse and densely packed crinoidal wackestone-floatstones with some brachiopod shell debris. Solitary rugose corals, tabulate corals, stromato-poroids and fragments of mollusks are also abundant. The tops of the mounds are usually covered with loferitic pelmicrites or oolitic grainstone caps. Stromatactis-like structures are very rare and poorly developed in the South Ferganian mud mounds. However, almostin all such mounds horizons of calcitic breccias can be found.
In order to explain all the features found in the Fergana mounds an ‘atoll-like’ model has been proposed which starts the evolution of the mud mounds with a small nucleus bioherm. The main stage of the evolution corresponds to an atoll-like structure developing on the surface of shallow water platforms. White clotted micrite of the mound core facies is interpreted as a accumulation of fine-grained sediment in an inner lagoon flanked by crinoidal bar deposits. The mound flank facies represents the atoll rim deposits from where the carbonate mud is derived. The capping loferitic facies is considered as tidal flat deposit that developed on top of the buildups during the last stage of its evolution. The knoll shape of the mounds is explained by the retreat of the atoll flanking crinoidal bars back into the inner lagoon during the rise in sea level. Stromatactis-like structures of small cavities filled with sparry calcite owe their existence to burrowing organisms. Calcitic breccias are interpreted as paleokarst collapse breccias. They indicate that the tops of the mud mound became subaerially exposed. Other evidence for a subaerial exposure can be seen in the occurrence of Variscian ‘black and white’ limestone gravel on the tops of some mud mounds. According toWard et al. (1970) these sediments were produced above the sea level at the edge of hypersaline lakes situated on islands.
Similar content being viewed by others
References
Bathurst, R.G.C. (1980): Stromatactis-origin related to submarinecemented crusts in Paleozoic mud mounds.—Geology,8, 131–134, Boulder
— (1982): Genesis of stromatactis cavities between submarine crusts in Paleozoic carbonate mud buildups.—J. Geol. Soc. London,139, 165–181, London
Biske, J.S., Gorianov, V.B. & Rzhonsnitskaya, M.A. (1967): Tien-Shan.—In: The Silurian-Devonian boundary.—Stuttgart IUGS, Ser. A,5, 227–237
Bogli, J. (1980): Karst hydrology and physical speleology.—285 pp. Berlin (Springer)
Bosence, D.W., Rowlands, R.J. &Quiner, M.L. (1985): Sedimentology and budget of Recent carbonate mound, Florida Keys.—Sedimentology, 32, 317–343, Tulsa
Bourque, P.-A. &Gignac, H. (1983): Sponge-constructed stromatactis mud mounds. Silurian of Gaspé, Quebec.—J. Sed. Petrol.,53, 521–532, Tulsa
Bridges, P.H. &Chapman, A.J. (1988): The anatomy of a deep water mud mound complex to the southwest of the Dinantian platform in Derbyshire, U.K..—Sedimentology35, 139–162, Amsterdam.
Cotter, E. (1965): Waulsortian-type carbonate banks in the Mississippian Lodgepole Formation of Central Montana.—J. Geol.,73, 881–888, Chicago
Craig, D.H. (1988): Caves and other features of Permian karst in San Andres dolomite, Yates field reservoir, West Texas.—In:James, N.P. &Choquette, P.W. (eds.): Paleokarst.—32–363, New York (Springer)
Dronov, A.V. (1987a): O paleozoiskikh loferitakh khrebta Yauruntuz (Yuzhnaya Fergana).—Vestnik Leningradskogo Universiteta ser.7/3, 88–93, Leningrad
Dronov, A.V. (1987b): Zametki po tectonicheskoy structure griady Sarytash (Yuzhnaya Fergana).—Materialy 2 Conf. mol. uch. MGRI, Dep. VINITI, 3036-B87, 2–18, Moskva
Dronov, A.V. (1988): Uslovia formirovania i geologicheskaya historia carbonatnyh formatsyi srednego paleozoya Yuzhoi Fergany.— Cand. sci. thesis PML LGU, 17 pp. Leningrad
— (1990): Beskarkasnye organogennye postroiki srednepaleozoiskogo carbonatnogo shelfa Turkestano-Alaya.—Vestnik Leningradskogo Universiteta ser.7/1, 11–28, Leningrad
Esteban, M.C. & Klappa, C.F. (1983): Subaerial exposure.—In:Scholle, P.A., Bebout, D.G. & Moore, C.H. (eds.): Carbonate depositional environments.—Amer. Ass. Petrol. Geol. Mem.33, 1–54, Tulsa
Fischer, A.G. (1964): The Lofer Cyclothems of the Alpine Triassic. —Kansas Geol. Surv. Bull.169, 107–149, Kansas
Folk, R.G. (1959): Practical petrographic classification of limestones.—Amer. Ass. Petrol. Geol. Bull.,43, 1–38, Tulsa
Ford, D. (1988): Characteristics of dissolutional cave systems in carbonate rocks.—In:James, N.P. &Choquette, P.W. (eds.): Paleokarst—25–57, Berlin (Springer)
Hanshaw, B.B. &Back, W. (1980): Chemical mass-wasting of the northern Yucatan Peninsula by groundwater dissolution.— Geology,8, 222–224, Boulder
James, N.P. &Choquette, P.W. (1984): Limestones—the meteoric diagenetic environment—Geoscience Canada,11, 61–194,
Koren, T.N. &Klishevich, V.L. (1982): Biostratigraficheskoe raschlenenie opornikh razrezov Devona Sredney Asii po graptolitam i dacrioconararidam.—In: Biostratigrafiya pogranichnykh otlozheniy nizhnego i Srednego Devona.—13–97, Leningrad (Nauka)
London, L.R. &Bowsher, A.L. (1941): Mississippian formations of Sacramento Mountains, New Mexico.—Amer. Ass. Petrol. Geol., Bull.,25, 2107–2160, Tulsa
Lees, J.A. (1961): The Waulsortian ‘reefs’ of Eire: a carbonate mudbank complex of Lower Carboniferous age.—J. Geol.69, 101–109, Boulder
— (1963): The structure and origin of the Waulsortian (Lower Carboniferous) ‘reefs’ of west-central Eire.—Phil. Trans. R. Soc. London,247, 483–531, London
Mathur, A.C. (1975): A deep water mud mound facies in the Alps. —J. Sed. Petrol.,45, 787–531, Tulsa
Mohr, C.G. &Van der Meer, X. (1969) The stratigraphy of Cambrian Laucara Formation between the Luna River and the Esla River in the Cantabrian Mountains, Spain.—Leidse Geol. Med.,43, 233–316, Leiden
Monty, C.L.V. (1976): The origin and development of cryptalgal fabrics.—In:Walter, M.R. (ed.): Stromatolites.—Dev. Sediment.,20, 193–249, Amsterdam (Elsevier)
Neumann, A.C., Koefoed, J.W. &Keller, G.H. (1977): Lithoherms in the Straits of Florida.—Geology,5, 4–10, Boulder
Parkinson, D. (1957): Lower Carboniferous reefs of northern England.—Amer. Ass. Petrol. Geol. Bull.,41, 511–537, Tulsa
Philcox, M.E. (1963): Bounded calcite mudstone in the Lower Carboniferous “reef” knolls of the Dublin Basin, Ireland.—J. Sed. Petrol.,33, 904–913, Tulsa
Porshniakov, G.S. (1973): Hercinidy Alaia i smeznikh raionov Yuzhnogo Tien-Shana.—216 pp. Leningrad (Izdat. LGU)
— (1983): Atapy formirovanya tektonicheskikh struktur razlichnikh segmentov hercynid Yuzhnogo Tien-Shana i Pamira. —66–73, Moskya (Nauka)
Pratt, B.R. (1982): Stromatolitic framework of carbonate mud mounds.—J. Sed. Petrol.,52, 1203–1228, Tulsa
Prey, L.C. (1958): Fenestrate bryozoan core facies, Mississippian bioherms, southwestern United States.—J. Sed. Petrol.,28, 261–273, Tulsa
Schwarzacher, W. (1961): Petrology and structure of some Lower Carboniferous reefs in Northwestern Ireland.—Amer. Ass. Petrol. Geol. Bull.,45, 1481–1503, Tulsa
Shinn, E.A. (1963): Practical significance of birdseye structure in carbonate rocks.—J. Sed. Petrol.,38, 215–223, Tulsa
— (1968) Burrowing in recent lime sediments of Florida and the Bahamas.—J. Paleont.42, 879–894
— (1983) Birdseyes, fenestrae, shrinkage pores, and loferites: A reevaluation.—J. Sed. Petrol.53, 619–628, Tulsa
Tsien, H.H. (1985a): Algal-bacterial origin of micrites in mudmounds.—In:Toomey, D.F. &Nitecki, M.H. (eds.): Paleoalgology.—290–296, Berlin (Springer)
— (1985b) Origin of stromatactis—a replacement of colonial microbial accretions.—In:Toomey, D.F. &Nitecki, M.H. (eds.): Paleoalgology.—274–289, Berlin (Springer)
Ward, W.C., Folk, R.L. &Wilson, J.L. (1970): Blackening of eolianite and caliche adjacent to Saline Lakes, Isla Mujeres, Quintana Roo, Mexico.—J. Sed. Petrol.,40, 548–555, Tulsa
Wilson, J.L. (1975): Carbonate facies in geologic history.—471 pp., Berlin (Springer)
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Dronov, A.V. Middle paleozoic waulsortian-type mud mounds in Southern Fergana (Southern Tien-Shan, commonwealth of independent states): The shallow-water atoll model. Facies 28, 169–180 (1993). https://doi.org/10.1007/BF02539735
Received:
Accepted:
Issue Date:
DOI: https://doi.org/10.1007/BF02539735