ABSTRACT The Arabescato Orobico is a decorative stone and building mate- rial from the Bergamasc Alps, Italy. From the geological standpoint it belongs to the Calcare Rosso, latest Ladinian-Early Carnian in age, which is a peritidal tepee-rich limestone strongly modified by super- imposed early diagenetic processes, outcropping in Lombardy Southern Alps. In the last twenty-five years four commercial varieties have been available on the market, namely Grigio, Grigio-Rosa, Rosa, and Rosso, whose working and abandoned quarries, are located around the extraction districts of Camerata Cornello, and San Gio- vanni Bianco in the median Brembana Valley. Until the 1970s of the last century some different historical types, namely Rosso Antico, Rosso Venato, and Venato Finissimo, where extracted around Arde- sio, in the Seriana Valley, as well. This paper deals with the strati- graphic analysis based on detailed physical correlations of several marker horizons mainly recognized along abandoned and active quarries, and their carbonate facies analysis. Stratigraphic results permit to divide the Calcare Rosso unit in three lithozones (CR1, CR2, and CR3), with a very low angle onlapping geometry at the top of the Esino Limestone. Southward (basinward) the Calcare Rosso gradually passes to dominant grey peritidal carbonates poor in tepee horizons corresponding to the lower Breno Fm.. The petrographic characterization of representative samples from Mecca and Cadei quarries, permits to distinguish peculiar textural and compositional features of the four contemporaneous commercial types. As con- cerns the Grigio we identify almost five different subtypes, respec- tively denominated Grigio Laguna, composed of fossiliferous sub- intertidal grey to dark grey and black wackestone-packstones, Grigio Granulare, composed of inter-supratidal pisolitic grey grainstone- rudstones, Nero Raggiato, very rich in “raggioni”, dark grey to black fibrous-radial early diagenetic calcite, Grigio Laminato composed of poorly to middle deformed antiformal structures, namely embryo to mature tepees, and, finally, Grigio Brecciato, a grey-colored diage- netic-pedogenetic breccia. Remaining types, ascribed to pinkish- grey, Grigio-Rosa, pinkish, Rosa, and reddish, Rosso, colored diage- netic supratidal facies, can be divided into laminated or brecciated subtypes. The former are composed of antiformal syndepositional to early diagenetic structures, i.e. embryo to mature tepees; the brec- ciated subtypes consist of more diagenetically modified senile tepees passing to breccias. These types present different amounts of sedi- ment filling, including internal calcitic and dolomitic sediments, pisolites, terra-rossa paleosols and green/reddish clays, and early cementation, such as fibrous isopachous crust, “raggioni”, sparry cal- cite, of the primary and early diagenetic cavities. The stratigraphic organization, and the facies analysis of this carbonate succession, have been used to evaluate the areal and vertical distribution of the Arabescato Orobico commercial types; in this way the Calcare Rosso depositional model is also suitable for geological prospecting and quarrying activities. KEY WORDS: Calcare Rosso, Arabescato Orobico dimension stone, carbonate petrography, applied stratigraphy, Lombardy Southern Alps. INTRODUCTION The Arabescato Orobico is a very well-known historical- contemporaneous decorative stone and building material from the Bergamasc Alps, with a peak in quarrying output and trading from the 1950s throughout the 1970s of the last century (VOLA, 2003, 2007; VOLA & FIORA, 2008). The extraction activity in the Brembana Valley is firstly docu- mented by the abbot Angelo Mazzoleni in 1767, even if the initial use is probably more ancient (MEDOLAGO & BOFFELLI, 2005). Until the 1970s of the last century almost 15 quarries, were operating in the median Brem- bana Valley, Bergamo. Nowadays the Arabescato Orobico is extracted from three quarries, located close to the Cespedosio village in Camerata Cornello (fig. 1 and tab. 1). Two commercial varieties have been available in the last sixty years, namely Rosso and Grigio, but in the last twenty-five years, also Rosa and Grigio-Rosa are available, and currently represent the most common types on the market (CCIAA, 2002, 2003a, 2003b; PRIMAVORI, 2006; VOLA &PRIMAVORI, 2009a, 2009b). These commercial varieties were codified in the standard UNI EN 12440 (2008) by the Stone Companies Association of Lombardy (ASSOCIAZIONE MARMISTI LOMBARDIA, 2007). Moreover, during the 1970s different historical types, namely Rosso Antico, Rosso Venato, and Venato Finissimo, were extracted around Ardesio in the Seriana Valley, as well (ASSERETO et alii, 1975; SOCIETÀ GEOLOGICA ITALIANA, 1990; CUCINI & RAVAGNANI, 1997; CHIESA & PLEBANI, 2003). The extraction activity in Ardesio is presumed to be older than that in the Brembana Valley, although a pre- cise information is unavailable (PARODI, 1936; PAGANONI, 1987; PAGANONI & CARMELENGHI, 1987; CHIESA et alii, 1994; BIGIOGGERO et alii, 2000). From a geological standpoint the Arabescato Orobico dimension stone pertains to the Calcare Rosso limestone, whose age is still not-well established in detail: previous Authors propose a latemost Ladinian (ASSERETO et alii, 1977; JADOUL et alii, 2012) to Early Carnian (MUTTI, 1992) or fully Early Carnian (BERRA, 2007; BERRA et alii, 2011) age. This stratigraphic unit, recently mapped in dif- ferent geological maps at the scale 1:50,000 (JADOUL & FORCELLA, 2002; JADOUL et alii, 2012; GAETANI et alii, 2012), comprises peritidal strata diagenetically modified into tepees, repeatedly capped by terra-rossa paleosols, and filled by a great variety of fibrous-radial marine cements, and internal sediments. Tepee modification, involving beds for a thickness of 1-3 meters, ranges from simple antiformal structures, or peritidal tepees, to composite breccias floating in synsedimentary fibrous cements, laminated crusts, mega-rays, and internal sedi- (*) Gabriele Vola, Geologist, dimension stone and building materials consultant, via Finazzi 12, 24127, Bergamo, e-mail: gabriele. vola@gmail.com . (**) Flavio Jadoul, Università degli Studi di Milano, Dipartimento di Scienze della Terra “A. Desio”, via Mangiagalli, 34 - 20133, Milano, e-mail: flavio.jadoul@unimi.it. Applied stratigraphy and carbonate petrography of the Arabescato Orobico dimension stone from the Bergamasc Alps (Calcare Rosso, Italy) GABRIELE VOLA (*) & FLAVIO JADOUL (**) Ital. J. Geosci. (Boll. Soc. Geol. It.), Vol. 133, No. 2 (2014), pp. 294-314, 9 figs., 5 tabs. (doi: 10.3301/IJG.2014.11) © Società Geologica Italiana, Roma 2014