The architecture of Middle to early Late Triassic carbonate platforms in the eastern Lombardian Alps is analysed following the accommodation and supply concept. This allows proposing a new sequence stratigraphic scheme. The selected study area can be seen as an earth sciences lab where in a relatively small area distinct synsedimentary tectonics in combination with global sea-level fluctuations caused pronounced differences in basin evolution, leading to repercussions in the carbonate platform development from the Anisian to the Carnian. A base-level fall in the Pelsonian favoured in the area of a long-lasting topographic high and shortly after the Permian-Triassic crisis of carbonate platforms the growth of the first in a cycle of carbonate build-ups, the Camorelli Bank. Slow subsidence combined with high carbonate production caused strong progradation of this carbonate bank. The Calcare di Camorelli is followed later but in the same area by the Pora Platform succession. This underlines that palaeotopography and related subsidence was an important mechanism for platform growth in the area. The well-dated base-level rise at the Pelsonian/Illyrian boundary caused platform flooding and the change to the marly Prezzo Fm (shallow basinal facies) and nodular-cherty Buchenstein Fm (deep basinal facies). In the early Longobardian, base-level fell gradually and the slow subsequent base-level rise triggered the growth of four carbonate platforms in the study area attributed to the Esino Fm: the Pora, Concarena, Pizzo Camino and Presolana platforms. In this paper, the results from detailed sequence stratigraphic studies from the Pora and Concarena area are presented. The cycle of carbonate platforms attributed to the evolution of the Esino Fm led to formation of a much thicker platform and slope succession compared to the preceding Camorelli platform cycle. This development can be best studied at the Concarena area. Initially, an aggradational to weak progradational pattern can be observed, indicating strong subsidence combined with high carbonate production. The lagoonal upper part of the Concarena platform shows much reduced cycle-thicknesses compared with the cycles of the preceding platform stage, combined with strong progradation of the platform slope. At its top, only the Pora Platform shows distinct emersion features, due to a base-level fall and underpinning the position on a local structural high, in contrast to the Concarena, which had somewhat higher subsidence rates and do not show signs of emersion.

The Concarena platform is an outstanding example for the transition from Ladinian to Carnian carbonateplatform development in the Southern Alps. Two major stages of platform evolution are recorded,separated by a marked overturn from slight progradation to pathological progradation sensu Bosellini(1989). Due to the excellent preservation of all facies belts, a static 3D facies model can be constructedallowing for a detailed reconstruction of its geometric evolution. The geomodel is based upon outcropstudies with sampling and mapping campaigns, foto panel interpretation of unaccessible mountainfaces, high resolution satellite imagery (Quickbird data) and digital elevation model (Iconos data). Minmaxscenarios for carbonate production at platform top, reef and slope were established using 2Dstratigraphic forward simulation. The volumetric determination of accumulated sediments allows for thefirst time the quantification and comparison of the carbonate factory at platform top, reef and slopeduring two platform stages originating from different A’/S’ conditions and separated by a turn-aroundpoint in base-level change. Whereas this turn-around point is recorded in other areas of the LombardicAlps by a marked subaerial exposure surface on platform tops, high total subsidence rates at Concarenaprevent the platform from distinct long-term emersion. The comparison of production rates adds furtherevidence to the importance of changing A’/S’ conditions for platform development from aggradation toprogradation and hence to the slope-shedding model sensu Kenter et al. (2005) for high-risingcarbonate platforms. This study furthermore underlines and quantifies the influence of "Tubiphytes" onthe development of Triassic carbonate platforms. Large mounds-up to 4m in diameter and 1.5m inheight-made up exclusively of "Tubiphytes" multisiphonatus are situated in back reef environments anduppermost slope settings. This is the second reported but strongly different occurrence of this"Tubiphytes" species outside the type locality on Hydra (Carnian "Pantokrator Limestone", Greece).

Massive early marine cementation (MEC) is a major diagenetic feature of some carbonate platforms. The comparison of two Triassic buildups of similar size and preservation but contrasting degree of MEC (Latemar, Dolomites, and Concarena, Lombardic Alps) allows for the investigation of differential cementation on carbonate platforms. The assessment of the response of platform cementation to changes in accommodation/sedimentation led to the identification of fundamental boundary conditions for MEC: (1) the time interval available, i.e. a low rate of creation in accommodation space and (2) low carbonate production. Other important factors are: (3) margin topography (e.g. walled reefs) and (4) effective fluid flow (e.g. wave energy, open and connected cavities provided by rigid frameworks). The Latemar–mainly aggrading and locally retrograding–lacks MEC due to a high A′/S′ ratio (i.e. creation/destruction of accommodation in time, A′=dA/dt, vs. changes in sediment supply in time, S′=dS/dt) and a low relief of the reefal margin. In contrast, the Concarena–in the beginning slowly and later rapidly prograding–indicates MEC owing to a low A′/S′ ratio and a distinct topography of the reef. Particular features of the Concarena are cement arrangements of lenticular shape and considerable size in the back-reef domain (up to 3 m in diameter and 2 m in height). These arrangements consist of botryoids and isopachous crusts of radiaxial fibrous calcite cements. They represent one of the main components of the platform margin at Concarena. Cathodoluminescence analyses of cements from both platforms quantifies the influence of shallow and deep burial diagenesis and shows that the majority (60–90%) of all cements are of early marine origin.