caa a22 4500 467934037 CHVBK 20180406152951.0 cr unu---uuuuu 170328e20060801xx s 000 0 eng 10.1007/s10347-006-0078-9 doi (NATIONALLICENCE)springer-10.1007/s10347-006-0078-9 Patch reef development in the florigemma -Bank Member (Oxfordian) from the Deister Mts (NW Germany): a type example for Late Jurassic coral thrombolite thickets [Elektronische Daten] [Carsten Helm, Immo Schülke] Small reefal bioconstructions that developed in lagoonal settings are widespread in a few horizons of the Late Jurassic (Oxfordian) succession of the Korallenoolith Formation, exposed southwest of Hannover, Northwest Germany. Especially the florigemma-Bank Member, "sandwiched” between oolite shoal deposits, exposes a high variety of build-ups, ranging from coral thrombolite patch reefs, to biostromes and to coral meadows. The reefs show a distribution with gradual facies variations along an outcrop belt that extends about 30km from the Wesergebirge in the NW to the Osterwald Mts in the SE. The patch reefs from the Deister Mts locality at the "Speckhals” are developed as coral-chaetetid-solenoporid-microbialite reefs and represent a reef type that was hitherto unknown so far north of its Tethyan counterparts. They are mainly built up by coral thickets that are preserved in situ up to 1.5m in height and a few metres in diameter. They contain up to 20 coral species of different morphotypes but are chiefly composed of phaceloid Stylosmilia corallina and Goniocora socialis subordinately. The tightly branched Stylosmilia colonies are stabilized by their anastomosing growth. The coral branches are coated with microbial crusts and micro-encrusters reinforcing the coral framework. Encrusters and other biota within the thicket show a typical community replacement sequence: Lithocodium aggregatum, Koskinobullina socialis and Iberopora bodeuri are pioneer organisms, whereas the occurrence of non-rigid sponges represents the terminal growth stage. The latter are preserved in situ and seem to be characteristic so far poorly known constituents of the Late Jurassic cryptobiont reef dweller community. The distance and overall arrangement of branches seems to be the crucial factor for the manifestation of a (cryptic) habitat promoting such community replacement sequences. Widely spaced branches often lack any encrusting and/or other reef dwelling organisms, whereas tightly branched corals, as is St. corallina, stimulate such biota. Hence, such reefs are well suited for research on coelobites and community sequences of encrusting and cavity dwelling organisms. Springer-Verlag, 2006 Corals nationallicence Reef nationallicence Growth fabric nationallicence Palaeoecology nationallicence Coelobites/cryptobionts nationallicence Community replacement sequence nationallicence Oxfordian nationallicence Germany nationallicence Lower Saxony Basin nationallicence Helm Carsten Institut für Geologie und Paläontologie, Universität Hannover, Callinstraße 30, 30167, Hannover, Germany aut Schülke Immo Institut für Geologie und Paläontologie, Universität Hannover, Callinstraße 30, 30167, Hannover, Germany aut Facies Springer-Verlag 52/3(2006-08-01), 441-467 0172-9179 52:3<441 2006 52 10347 https://doi.org/10.1007/s10347-006-0078-9 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/s10347-006-0078-9 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Helm Carsten Institut für Geologie und Paläontologie, Universität Hannover, Callinstraße 30, 30167, Hannover, Germany aut NATIONALLICENCE 700 1- Schülke Immo Institut für Geologie und Paläontologie, Universität Hannover, Callinstraße 30, 30167, Hannover, Germany aut NATIONALLICENCE 773 0- Facies Springer-Verlag 52/3(2006-08-01), 441-467 0172-9179 52:3<441 2006 52 10347 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer