Cavities in the reefs of the Wenlock Limestone (Mid-Silurian) of Shropshire, England

Abstract

ZusammenfassungStudien der Wuchsformen und des inneren Baues yon Organismen der Wenloek-Rifle zeigen, dab Hohlr~iume w~ihrend des Riffwachstums zwischen einzelnen RiffstSeken, zwisehen individuellen Kolonien sowie zwischen dem Geriist und im Inneren der Skelette yon Riffbildnern vorhanden waren. Nur vollkommen abgesehlossene, konstruktive Hohlr~iume sind w~hrend der Sedimentation in den Riffen nicht mit Ablagernngen gefiillt worden. Die Lage und Natur diagenetischer Hohlr~iume werden yon den Wuchsformen der Rifle bestimmt. Hohlr~iume entstehen w~ihrend der Diagenese durcb Verlagernng yon Komponenten im Gefolge von Kompaktion und dutch LSsung des oxganischen Karbonatgeriistes; hier werden besonders Bryozoenskelette aufgel5st, die an bestehende Hohlr~iume angrenzen. AbstractStudies of the growth attitudes and internal structure of organisms in the Wenlock reefs show that cavities existed during reef growth between knobs of reef builders, between individual reef builders, between the branches of reef builders and within skeletons. Only the well sealed growth cavities escaped fill by particulate sediment on burial. The location and nature of diagenetic cavities are governed by the growth fabric of the reefs. Diagenetic cavities were formed by the disloeation of reef components during compaction and by dissolution of organisms, particularly bryozoans, that neigbboured growth cavities. R4sum4Des 6tudes de positions d'accroissement et de structures int6rieures des organismes dans les r6cifs de Wenlock montrent que des cavit6s existaient pendant l'accroissement du rtcif entre les bosses des pinacles coralliens, entre les pinacles coralliens individuels, entre les branches des pinacles coralliens et A l'int6rieur des squelettes. Seules les cavit6s tout A fair ferin6es pendant l'accroissement ne furent pas combl6es de s6diments dttritiques lors de l'ensevelissement. La situation et la nature des cavit6s diag6n6tiques sent gouvern6es par la structure des r6cifs. Des cavit6s diag6n6tiques furent form6es par la dislocation des parties constituentes du r6cif pendant le tassement et par la dissolution des organismes, en particulier des bryozoaines qui bordaient les cavitts form6es pendant l'accroissement.I~paT[coe co~el)~anHe I/I3yqag ~0pMH pocTa H BHyTpeHHee CTpoeHrle opraHg3MOB pmlba Wenlock, yCTaHOBH~H, qT0 H0;]OC2H MeTR~y OT~eZibHbIMI4 pBOOBblMH IUTOHaMg, Me~R~y 0T~IeJH,-HbIMrl HOa0HI~gMg, a Ta~e MerK~y H0CTpOI~RO~ n BHyTpH cKe~eTa prIqbootpaay~omnx opPattH3MOB HMe;IHCb y~e BO BpeMg p0cTa oToro pnqba. --CB0~0~HbIMH OT OTJIOH~e-H14~I ocTaIOTCH B0 BpeMg oca;~HoHaRonaeHHg T0abHO C0BepmeHHo H3OJIgpOBaHHbIe rmaocwu. Pacno~omerme rI nprIpo~a ~i~areHeTrmecKrix noz~ocTefr npe~or~pe~eaneTcu OOpM01~ pocTa pr~dpa. HoaocTr~ BO3rlrII~a~oT BO BpeMn ;mareaeaa ~ peay~r~TaTe he-

Biosedimentology of a Silurian Thrombolite Reef with Meter-Scale Growth Framework Cavities

“…The downward-pointing growth direction of pendant bushy mesoclots in the thrombolite reef (Fig. 4 B, C) indicates that at one time sea water flowed beneath the mesoclots (Scoffin 1972;James and Gravestock 1990). It is concluded that hypothesis 1 (13A, B) accounts best for the formation of the large reef cavities (Fig.…”

“…In both hypotheses, creation of large cavities involves the abilities of Angulocellularia and renalcid microorganisms to calcify rapidly (Kobluk and James 1979;Turner et al 2000), and to grow in all possible directions including upwards and laterally (Kobluk and James 1979;Pratt and James 1982;Pratt 1984;Riding 1991aRiding , 1991b) (Figs. 4B, C, 5 D, F), making it possible for the mesoclots to create elevated prominences (Scoffin 1972;James 1983) with lateral extensions that could merge to roof-over spaces that were centimeters to meters deep and/or wide to create growth framework cavities (Figs. 3, 13).…”

Interaction of genetic processes in holocene reefs off North Eleuthera Island, Bahamas

“…Similarly, the ceilings and overhangs near the MLW level are interpreted to result from lateral growth which became dominant when vertical growth was curbed by sea-level. SCOFFIN (1972) ascribed the formation of overhangs and cavities in Recent Bermuda reefs and Silurian reefs of Shropshire (England) to. frame growth, thus providing additional examples for the growth pattern suggested e).…”

Upper Ordovician (Richmondian) cavity-dwelling (coelobiontic) organisms from southern Ontario

“…Coelobiontic bryozoans are not common; they occur in less than 20% of the cavities, and appear to be less important than in some other described lower and middle Paleozoic reef cavities (e.g., Scoffin 1972;Spjeldnaes 1974;Kobluk 1980).…”

“…Among them are reports of Cambrian coelobionts by Kobluk and James (1979), Kobluk (1979), Brasier (1976, Ordovician coelobionts by Brett and Liddell (1978), Kobluk and Karolyi (1978), and Kobluk (1980), and Silurian coelobionts by Scoffin (1972) and Spjeldnaes (1974). Later Paleozoic coelobionts are reported by Newell et al (1953), Bonem (1977), and Flugel (1977).…”