Discussion: “Facies analysis and palaeoenvironmental interpretation of the Late Oligocene Attard Member (Lower Coralline Limestone Formation), Malta” by Brandano et al. (2009), Sedimentology, 56, 1138-1158

Abstract

PETER A. GATTDepartment of Earth Sciences, University of Durham, South Road, Durham DH1 3LE, UK (E-mail:p.a.gatt@durham.ac.uk)INTRODUCTIONThis Discussion of the paper by Brandano et al.(2009) evaluates the 40 km wide and 60 m in the Maltese Islands (Gattet al.,2009)andnot10to15 masindicatedintheirfig. 1C.In their fig. 2A, the authors present logs of theirmeasured sections of the Attard Member. How-ever, the lowermost 3AE5 m thick coral-bioclasticwackestone/floatstone facies in their section II,described as having a matrix with a high percent-age of micrite (40%), actually forms the top part ofthe Maghlaq Member which was deposited in aprotected lagoonal environment 20 m thick Maghlaq Member that cropsout at the Mosta Quarry [Grid reference 489 757]located ca 1AE5 km to the north-east of the siteshown in their fig. 2. The Maghlaq Member isdominated by miliolids in a micritic matrix,whereas micrite in the overlying Attard Memberis only abundant in intermittent <1 m thick bedsrecorded by Brandano et al. (2009) in some oftheir measured sections: the topmost section IIIand ca 3 m below the top of section IV.Parasequences in the logged sections by Brand-ano et al. (2009) are described as ‘‘basal trans-gressive porcelaneous foraminiferal grainstonespassing upward to the rhodolith floatstone/rud-stone facies (i.e. a deepening-upward sequence)’’.However, the ca 3 m thick parasequence sets seenin the nearby Mosta Quarry and other localitiesare distinctly shallowing-upward. These succes-sive parasequences begin with subtidal rhodolithand coral facies and terminate with a <20 cmthick laminar micritic bed of microbial origin thatwas deposited in a peritidal environment. Theparasequences are capped by a flooding surfacewhich consists of a thin bed of sub-tidal micritethat thickens towards the east which wasburrowed intensely by the bivalve Kuphus.In their fig. 2D, Brandano et al. (2009) make anattempt at dating their sections using biostratig-raphy. They correlate their logged sections infig. 2 with the large benthic foraminiferal bio-zones of Cahuzac & Poignant (1997) and with theglobal sea-level curve of Haq et al. (1987), andidentify the sequence boundary Ch2 of Hardenbolet al. (1998). This sequence boundary is markedin their fig. 2D but not indicated in their logs ofmeasured sections in fig. 2A and, consequently,is dismissed as being of minor importance. How-ever, a sequence boundary extending to the MostaSedimentology (2010) 57, 1152–1154