Growth mode of Middle Triassic carbonate platforms in the Western Dolomites (Southern Alps, Italy)

The correlation of carbonate platform and slope sediments with biostratigraphically and radiometrically dated basinal successions in the Western Dolomites allows the reconstruction of the growth of a Middle Triassic carbonate platform (Schlern/Rosengarten) over a time interval of approximately five ammonoid zones (Reitzi, Secedensis, Curionii, Gredleri, Archelaus zones). The whole platform evolution had a total duration of <4.7 Ma and the growth mode can be reconstructed for each ammonoid zone (corresponding to time intervals of ~ 1 Ma or less). Aggradation of the platform, with a mean rate of 200 Bubnoffs, took place during the Reitzi, Secedensis and parts of Curionii zoones, whereas rapid progradation (~ 2700 m/Ma) was the main growth feature during the Gredleri and Archelaus zones. From observations of the physical stratigraphy of neighbouring carbonate platforms (Geisler, Latemar, Agnello), the sequence-stratigraphic framework of these buildups can also be established. Variations in subsidence and sediment production are interpreted as the main parameters in controlling the growth mode of these platforms. (C) 2000 Elsevier Science B.V. All rights reserved.