The late Jurassic records one of the largest reefal expansions of the Phanerozoic, with a greater diffusion and differentiationin the Tethys realm. SEveral depositional models about Upper Jurassic reef types have been pubblished but little knowledge is available about the Eastern Sardinian reef. This study focuses on the detailed composition and sedimentological charcterization of the Upper Tithonian reef complex of Eastern Sardinia, which is presently exposed in the area of Calagonone (Orosei Gulf). This reef complex characterises the lower part of the Bardia Fm. which represents the upper lithostratigraphic unit of the tripartite Jurassic succession of eastern Sardinia. This formation developed after thr Early Tithonian regressive trend, locally marked by subaereal carbonate breccias. The Bardia Fm. reef complex represents an inferred off lap break\ramp margin succesison that was initially aggradational and then was followed by progradation of carbonate sigmidal clinoforms (3-15°).Compositional and sedimentological analysisi of the Bardia reef complex has been caried out though thr combination of "macroscopic (outcrop scale) and "microscopic" (microfacies-scale) observation on exceptional exposed saw-cut quarry facies, over a surface of a few hundred squared meters in three different locations. Reef components were grouped into three broad categories: 1) macroscopically detectable organisms, mainly represented by corals, sponges bivalves, gastropods, echinoderms, 2) microscopically detectable components corresponding to microencrusters and microbialites, 3) fine to coarse bioclastic debris and mud-supported facies. These components combine in various proportion forming peculiar facies associations. Their distribution and frequency vary among the quarries and highlight a mosaic of biocontructed structures throughout the reef complex.Hight biotic diversty, multivarious interaction among the main reef builders, such as corals, calcareous and siliceous sponges, microencrusters and microbialites, the great variety of coral forms, the strong coral zonation, and the adrupt lateral and vertical facies chnges, are some of the most prominent features of this reef complex. These structures illustrate the depositional, paleoecological and stratigraphic evolution of this reef complex, and provide a solid base for comparison with other Upper Jurassic Tethyan reef complexes.
Coral sponge-microincruster-microbialite associations in the uppermost Jurassic reef complex of Eastern Sardinia (Italy) / C. Ricci, F. Jadoul, A. Lanfranchi, G. Rusciadelli, G. Della Porta, B. Lathullier, F. Berra. ((Intervento presentato al 29°. convegno IAS Meeting of Sedimentology tenutosi a Schladming (Austria) nel 2012.
|Titolo:||Coral sponge-microincruster-microbialite associations in the uppermost Jurassic reef complex of Eastern Sardinia (Italy)|
JADOUL, FLAVIO (Secondo)
BERRA, FABRIZIO (Ultimo)
|Data di pubblicazione:||13-set-2012|
|Settore Scientifico Disciplinare:||Settore GEO/02 - Geologia Stratigrafica e Sedimentologica|
|Enti collegati al convegno:||International association of Sedimentology|
|Citazione:||Coral sponge-microincruster-microbialite associations in the uppermost Jurassic reef complex of Eastern Sardinia (Italy) / C. Ricci, F. Jadoul, A. Lanfranchi, G. Rusciadelli, G. Della Porta, B. Lathullier, F. Berra. ((Intervento presentato al 29°. convegno IAS Meeting of Sedimentology tenutosi a Schladming (Austria) nel 2012.|
|Appare nelle tipologie:||14 - Intervento a convegno non pubblicato|