A microbial origin has been proposed for matrix-supported, low-diversity buildups reported from different palaeocontinents during the onset of the Mulde positive carbon isotope excursion. We have investigated a small aphanitic buildup from the Lower Quarried Limestone Member of the Much Wenlock Limestone Formation, exposed at Whitman’s Hill (Herefordshire), corresponding to the central part of the Midland Platform (UK). Up to 50% of the rock volume in this buildup consists of mottled micrite. The SEM studies revealed that the micrite is largely detrital and does not show features characteristic of calcareous cyanobacteria or leiolites. The aphanitic character of the buildup is suggested to be controlled by the depositional rate, and the widespread occurrence of matrix-supported reefs in this interval to be driven by a mid-Homerian rapid eustatic transgression.
Archer, A. W. & Feldman, H. R. 1986. Microbioherms of the Waldron Shale (Silurian, Indiana): implications for organic framework in Silurian Reefs of the Great Lakes area. PALAIOS, 1, 133–140.
http://dx.doi.org/10.2307/3514506
Brett, C. E., McLaughlin, P. I., Schramm, T. J., Sullivan, N. B. & Thomka, J. R. 2012. Middle Paleozoic Sequence Stratigraphy and Paleontology of the Cincinnati Arch: Part 1. Central Kentucky and Southern Ohio. University of Cincinnati, Cincinnati, 143 pp.
Brunton, F. R. & Dixon, O. A. 1994. Siliceous sponge-microbe biotic associations and their recurrence through the phanerozoic as reef mound constructors. PALAIOS, 9, 370–387.
http://dx.doi.org/10.2307/3515056
Buczynski, C. & Chafetz, H. S. 1993. Habit of bacterially induced precipitates of calcium carbonate: examples from laboratory experiments and recent sediments. In Carbonate Microfabrics (Rezak, R. & Lavoie, D. L., eds), Frontiers in Sedimentary Geology, 19, 105–116. Springer, New York.
Calner, M. 2005. Silurian carbonate platforms and extinction events – ecosystem changes exemplified from Gotland, Sweden. Facies, 51, 584–591.
http://dx.doi.org/10.1007/s10347-005-0050-0
Calner, M. & Jeppsson, L. 2003. Carbonate platform evolution and conodont stratigraphy during the middle Silurian Mulde Event, Gotland, Sweden. Geological Magazine, 140, 173–203.
http://dx.doi.org/10.1017/S0016756802007070
Calner, M. & Säll, E. 1999. Transgressive oolites onlapping a Silurian rocky shoreline unconformity, Gotland, Sweden. GFF, 121, 91–100.
http://dx.doi.org/10.1080/11035899901212091
Calner, M., Sandström, O. & Mõtus, M.-A. 2000. Significance of a halysitid-heliolitid mud-facies autobiostrome from the Middle Silurian of Gotland, Sweden. PALAIOS, 15, 511–523.
http://dx.doi.org/10.1669/0883-1351(2000)015<0511:SOAHHM>2.0.CO;2
Calner, M., Kozłowska, A., Masiak, M. & Schmitz, B. 2006. A shoreline to deep basin correlation chart for the middle Silurian coupled extinction–stable isotopic event. GFF, 128, 79–84.
http://dx.doi.org/10.1080/11035890601282079
Corfield, R. M., Siveter, D. J., Cartlidge, J. E. & McKerrow W. S. 1992. Carbon isotope excursion near the Wenlock–Ludlow, (Silurian) boundary in the Anglo-Welsh area. Geology, 20, 371–374.
http://dx.doi.org/10.1130/0091-7613(1992)020<0371:CIENTW>2.3.CO;2
Cramer, B. D., Condon, D. J., Söderlund, U., Marshall, C., Worton, G. J., Thomas, A. T., Calner, M., Ray, D. C., Perrier, V., Boomer, I., Patchett, P. J. & Jeppsson, L. 2012. U–Pb (zircon) age constraints on the timing and duration of Wenlock (Silurian) paleocommunity collapse and recovery during the “Big Crisis”. Geological Society of America Bulletin, 124, 1841–1857.
http://dx.doi.org/10.1130/B30642.1
Guido, A., Papazzoni, C. A., Mastandrea, A., Morsilli, M., La Russa, M. F., Tosti, F. & Russo, F. 2011. Automicrite in a ‘nummulite bank’ from the Monte Saraceno (Southern Italy): evidence for synsedimentary cementation. Sedimentology, 58, 878–889.
http://dx.doi.org/10.1111/j.1365-3091.2010.01187.x
Jaeger, H. 1991. Neue Standard-Graptolithenzonenfolge nach der ‘Großen Krise’ an der Wenlock/Ludlow-Grenze (Silur). Neues Jahrbuch für Geologie und Paläontologie – Abhandlungen, 182, 303–354.
Jarochowska, E., Munnecke, A. & Kozłowski, W. 2014a. An unusual microbial-rostroconch assemblage from the Mulde Event (Homerian, middle Silurian) in Podolia, Western Ukraine. GFF, 136, 120–124.
http://dx.doi.org/10.1080/11035897.2013.873988
Jarochowska, E., Ray, D. C., Päßler, J.-F., Worton, G. J. & Munnecke, A. 2014b. The Mulde (Homerian, middle Silurian) positive δ13C excursion at Whitman’s Hill, Herefordshire, UK. In 4th Annual Meeting of IGCP 591, Estonia, 10–19 June 2014, Tartu (Bauert, H., Hints, O., Meidla, T. & Männik, P., eds), p. 47. University of Tartu.
Jeppsson, L. 1993. Silurian events: the theory and the conodonts. Proceedings of the Estonian Academy of Sciences, Geology, 42, 23–27.
Kaljo, D., Boucot, A. J., Corfield, R. M., Le Hérissé, A., Koren, T. N., Křiž, J., Männik, P., Märss, T., Nestor, V., Shaver, R. H., Siveter, D. J. & Viira, V. 1995. Silurian bio-events. In Global Events and Event Stratigraphy in the Phanerozoic (Walliser, O. H., ed.), pp. 173–224. Springer, Berlin.
Kershaw, S. & Da Silva, A.-C. 2013. Stromatoporoid diversity and growth in late Wenlock reefs and associated facies (Silurian) at Wenlock Edge, UK In 3rd IGCP 591 Annual Meeting, Lund, Sweden (Lindskog, A. & Mehlqvist, K., eds), pp. 157–158. Lund University.
Kershaw, S., Li, Y. & Guo, L. 2007. Micritic fabrics define sharp margins of Wenlock patch reefs (middle Silurian) in Gotland and England. Geological Society, London, Special Publications, 275, 87–94.
http://dx.doi.org/10.1144/GSL.SP.2007.275.01.06
Klaamann, E. & Einasto, R. 1977. Coral reefs of Baltic Silurian (structure, facies relations). In Ecostratigraphy of the East Baltic (Kaljo, D. & Einasto, R., eds), pp. 35–41. Institute of Geology, Estonian Academy of Sciences, Tallinn.
Kõrts, A. 1991. Distribution of calcareous algae, oncolites and stromatolites in the Wenlock–Ludlow boundary beds in Estonia. Proceedings of the Estonian Academy of Sciences, Geology, 40, 43–49.
Marshall, C., Thomas, A. T., Boomer, I. & Ray, D. C. 2012. High resolution δ13Ccarb stratigraphy of the Homerian (Wenlock) of the English Midlands and Wenlock Edge. Bulletin of Geosciences, 87, 669–679.
http://dx.doi.org/10.3140/bull.geosci.1306
Munnecke, A., Calner, M., Harper, D. A. T. & Servais, T. 2010. Ordovician and Silurian sea-water chemistry, sea level, and climate: A synopsis. Palaeogeography, Palaeoclimatology, Palaeoecology, 296, 389–413.
http://dx.doi.org/10.1016/j.palaeo.2010.08.001
Penn, J. S. W. 1971. Bioherms in the Wenlock Limestone of the Malvern area (Herefordshire, England). Mémoires du Bureau de Recherches Géologiques et Minières, 73, 129–137.
Ratcliffe, K. T. 1988. Oncoids as environmental indicators in the Much Wenlock Limestone Formation of the English Midlands. Journal of the Geological Society, 145, 117–124.
http://dx.doi.org/10.1144/gsjgs.145.1.0117
Ratcliffe, K. T. & Thomas, A. T. 1999. Carbonate depositional environments in the late Wenlock of England and Wales. Geological Magazine, 136, 189–204.
http://dx.doi.org/10.1017/S0016756899002538
Ray, D. C., Brett, C. E., Thomas, A. T. & Collings, A. V. J. 2010. Late Wenlock sequence stratigraphy in central England. Geological Magazine, 147, 123–144.
http://dx.doi.org/10.1017/S0016756809990197
Ray, D. C., Richards, T. D., Brett, C. E., Morton, A. & Brown, A. M. 2013. Late Wenlock sequence and bentonite stratigraphy in the Malvern, Suckley and Abberley Hills, England. Palaeogeography, Palaeoclimatology, Palaeoecology, 389, 115–127.
http://dx.doi.org/10.1016/j.palaeo.2013.03.024
Riding, R. 2002. Structure and composition of organic reefs and carbonate mud mounds: concepts and categories. Earth-Science Reviews, 58, 163–231.
http://dx.doi.org/10.1016/S0012-8252(01)00089-7
Schmid, D. U. 1996. Marine Mikrobolithe und Mikroinkrustierer aus dem Oberjura. Profil, 9, 101–251.
Thomka, J. R. & Brett, C. E. 2014. Palaeontological and sedimentological effects of micro-bioherms in the Middle Silurian Massie Formation of southeastern Indiana, USA. Lethaia
http://dx.doi.org/10.1111/let.12097
http://dx.doi.org/10.1007/s10347-009-0207-3
