Tracing Lateral Metre-Scale Cycle Variability across the Latemar Platform (Dolomites, Italy) Using Digital Outcrop Modeling
Amour, Frédéric 1; Mutti, Maria 1; Christ,
Nicolas 2; Immenhauser, Adrian 2; Agar, Susan 3;
Yose, Lyndon A.4; Benson, Gregory 3
(1)Institute of
Earth and Environmental Science, Potsdam-Golm, Germany. (2) Institute for
Geology, Mineralogy und Geophysics, Bochum, Germany. (3) ExxonMobil Upstream
Research Company, Houston, TX. (4) ExxonMobil Exploration Company, Houston, TX.
The identification of the auto- or allocyclic factors controlling
the stacking patterns of metre-scale carbonate cycles and their temporal
significance are a key issue in the Latemar controversy. Previous studies have
focused on the vertical facies and stratigraphic changes throughout the 700 m
thick interval of the platform and provided a fundamental contribution towards
the understanding of the mechanisms controlling the carbonate deposition.
However, the lateral facies and cycle changes from the interior platform to the
tepee belt are critical issues to be considered in this discussion.
The study was aimed at characterizing cycle continuity across
critical turning points in the stratigraphic evolution, such as at the
transition between Lower Cyclic Facies (LCF), Middle Tepee Facies (MTF) and
Upper Cyclic Facies (UCF). The lateral facies and cyclic variability in “Cima
de Forcellone“ was documented in sections with spacings as close as 25 m. The
field data were supported by d-GPS and LiDAR survey mapping. The outcrop
morphology allows a 2.5D view, 1 km long and 110 m thick along the depositional
profile of the platform.
The investigation of the lateral variability of the cycles shows
two major scales of change. The first observation reveals an increasing number
of cycles (up to 50% more) along a transect from the lagoon toward the tepee
belt within the MTF unit. The tepees being interpreted as topographic highs,
this observation indicates that autocyclic mechanisms seem to play a more
important role within tepee units than within cyclic units, where increases of
only 25% have been documented. At the second scale, the d-GPS mapping of key
surfaces allows the identification of topographic changes of the tepee belt
from cyclic units and tepee units, indicating changes in the deposition profile
through time. The transition between LCF and MTF, which comes along with an
expansion of the tepee as described previously, is characterized also by a
progressive progradation of a topographic high representing the tepee belt.
Maximum progradation is associated with the flooding surface at the middle of
MTF. The elevation difference between the lagoon and the tepee belt ranges from
1 to 3 m.
The present study reveals that the Latemar platform facies, previously interpreted as highly continuous throughout the platform, actually shows significant lithological, cyclic and topographic lateral changes from the tepee belt to the lagoon and from cyclic to tepee units.
AAPG Search and Discovery Article #90135©2011 AAPG International Conference and Exhibition, Milan, Italy, 23-26 October 2011.