320
K. Leyrer· C. Strohmenger . K. Rockenbauch . T. Bechstaedt
4
Basin Modeling
The main goals of high-resolution forward stratigraphic modeling of the Ca2
with PHIL 5.1 were to:
1. explain the observed facies distribution,
2. quantify the sedimentation-governing parameters and, as a consequence,
3. improve the prediction of reservoir facies distribution.
Although the modeled areas are quite different in terms of topographic setting,
they show striking similarities in their sequence stratigraphic evolution. Both
areas were modeled in equal time steps of 10 ka resulting in 150 time slices. In
order to give a sufficient overview, the simulated development of the Ca2 sedimentary succession is described at each parasequence boundary. The simulation results are partly shown in Figs. 12-27. As already mentioned, the basement
(Werra Anhydrite, or AI) topography was provided as input (Figs. 12,20) because inadequate modeling options exist for simulating the development of pure
evaporite formations.
4.1
Parasequences 1-3 (lST of Zechstein sequence Z53)
Parasequences 1-3 comprise the TST of Zechstein sequence ZS3, and, according
to simulation results, are established during a time span of approximately 400 ka.
Due to the fact that sea level remains in slope position during this part of Ca2
time, sedimentation occurs only on the slope. As a consequence, no aggradational and only slight progradational patterns are developed during the TST.
Parasequence 1 (PSI; Figs. 13, 21)
Core investigations and simulation results suggest a substantial drop in sea-level
in both the south Oldenburg area and the southeast Brandenburg area at the end
of Al time (AI-HST of Zechstein sequence ZS2). During most of the LST of
Zechstein sequence ZS3 sea level stayed in positions near the middle and upper
parts of the Al slope and was characterized by only small-scale fluctuations.
The modeling of the Ca2 starts within the last few 10000 years of parasequence 1 (PSI, or lower part of Ca2 cycle Ia). Simulation shows a slow sea-level
rise occurring during PSI, which is interpreted as belonging to the early TST of
Zechstein sequence ZS3. Due to the steep inclination of the Al slope, the sediments generated in this stage are deposited in a very unstable position and are
subjected to erosional processes mainly governed by water energy. Because this
energy regime has its greatest influence in the upper parts of the water body, the
sediments affected are mainly high-energy shallow-subtidal carbonates. In
Northwest Germany this leads to a nearly complete in-situ reworking and resedimentation in basinward positions of the sediments generated during the late
parts of the first parasequence. In contrast, most of the carbonate sediments of
K. Leyrer· C. Strohmenger . K. Rockenbauch . T. Bechstaedt
4
Basin Modeling
The main goals of high-resolution forward stratigraphic modeling of the Ca2
with PHIL 5.1 were to:
1. explain the observed facies distribution,
2. quantify the sedimentation-governing parameters and, as a consequence,
3. improve the prediction of reservoir facies distribution.
Although the modeled areas are quite different in terms of topographic setting,
they show striking similarities in their sequence stratigraphic evolution. Both
areas were modeled in equal time steps of 10 ka resulting in 150 time slices. In
order to give a sufficient overview, the simulated development of the Ca2 sedimentary succession is described at each parasequence boundary. The simulation results are partly shown in Figs. 12-27. As already mentioned, the basement
(Werra Anhydrite, or AI) topography was provided as input (Figs. 12,20) because inadequate modeling options exist for simulating the development of pure
evaporite formations.
4.1
Parasequences 1-3 (lST of Zechstein sequence Z53)
Parasequences 1-3 comprise the TST of Zechstein sequence ZS3, and, according
to simulation results, are established during a time span of approximately 400 ka.
Due to the fact that sea level remains in slope position during this part of Ca2
time, sedimentation occurs only on the slope. As a consequence, no aggradational and only slight progradational patterns are developed during the TST.
Parasequence 1 (PSI; Figs. 13, 21)
Core investigations and simulation results suggest a substantial drop in sea-level
in both the south Oldenburg area and the southeast Brandenburg area at the end
of Al time (AI-HST of Zechstein sequence ZS2). During most of the LST of
Zechstein sequence ZS3 sea level stayed in positions near the middle and upper
parts of the Al slope and was characterized by only small-scale fluctuations.
The modeling of the Ca2 starts within the last few 10000 years of parasequence 1 (PSI, or lower part of Ca2 cycle Ia). Simulation shows a slow sea-level
rise occurring during PSI, which is interpreted as belonging to the early TST of
Zechstein sequence ZS3. Due to the steep inclination of the Al slope, the sediments generated in this stage are deposited in a very unstable position and are
subjected to erosional processes mainly governed by water energy. Because this
energy regime has its greatest influence in the upper parts of the water body, the
sediments affected are mainly high-energy shallow-subtidal carbonates. In
Northwest Germany this leads to a nearly complete in-situ reworking and resedimentation in basinward positions of the sediments generated during the late
parts of the first parasequence. In contrast, most of the carbonate sediments of