Growth analysis of a Middle Triadic carbonate platform in the Western Dolomites (Southern Alps)

Authors
Citation
F. Maurer, Growth analysis of a Middle Triadic carbonate platform in the Western Dolomites (Southern Alps), ECLOG GEOL, 92(3), 1999, pp. 361-NIL_10
Citations number
48
Categorie Soggetti
Earth Sciences
Journal title
ECLOGAE GEOLOGICAE HELVETIAE
ISSN journal
00129402 → ACNP
Volume
92
Issue
3
Year of publication
1999
Pages
361 - NIL_10
Database
ISI
SICI code
0012-9402(1999)92:3<361:GAOAMT>2.0.ZU;2-V
Abstract
The combination of geological mapping and correlation of platform-to-basin successions on seismic-scale outcrops in the Western Dolomites (Schfern/ Ro sengarten area) allows a detailed reconstruction of the growth of a Middle Triassic carbonate platform over a time interval of five ammonoid zones (Re itzi, Secedensis, Curionii, Gredleri and Archelaus zone). Tuff layers (the so-called "pietra verde"), which can be traced throughout the basinal succession (Buchenstein Fm.) and also in parts of the slope sed iments (Schlern Dolomite Fm.) were used as main correlation tool. In additi on they indicate a duration of < 5 Ma for the whole platform evolution (Mun dil et al. 1996). The platform shows a strong aggradation of 600-700 m in the Reitzi and Sece densis zone, a transition to progradation in the Curionii zone and a rapid progradation of more than 3 km in the Gredleri and Archelaus zone. When it stopped growing, due to Late Ladinian igneous activity; the platform reache d a thickness of 850 m and a total progradation of approximately 5.5 km. Sedimentation rates on platform top during aggradation reach values of 200 Bubnoffs (m/Ma); progradation during the Gredleri and Archelaus zone took p lace with an average rate of 2700 m/Ma. Volume-based calculations on platfo rm sedimentation suggest a continuous increase in carbonate production duri ng platform evolution. During the progradation the production within one am monoid zone was six times higher than during the whole aggradation phase. The impact of relative sea-level changes and episodic fallouts of acidic vo lcaniclastics (pietra verde) on the platform development is discussed.