314
K. Leyrer· C. Strohmenger . K. Rockenbauch . T. Bechstaedt
The subsidence of both the Northern and Southern Permian Basin was mainly a
consequence of the decay of Stephanian-Autunian induced thermal anomalies
and began during the Saxonian (Ziegler 1990). Subsidence in main parts of the
basins resulted from thermal contraction of the lithosphere and the loading of
the basins by water and sediments (Ziegler 1988). The occurrence of minor synZechstein faulting is restricted to a few areas along the southern margin of the
Southern Permian Basin. Ca2 sedimentation in the investigated areas indicates
no synsedimentary faulting and therefore, as a first approach, tectonic subsidence during Ca2 time was assumed to be linear.
Tectonic subsidence rates within PHIL 5.1 are specified at hingepoints along
the model profile (Marco Polo Software 1994) and are linearly interpolated between these points. The hingepoints may be user-defined and PHIL 5.1 allows at
any time to vary both the temporal and spatial distribution of subsidence rates.
In addition, PHIL's algorithms allow specification of the lithosphere's flexural
loading (e.g. flexural parameter and mantle density) and compaction (defined
by initial porosity and compaction rate) for up to 24 different lithologies.
A common way of calculating subsidence rates is by backstripping overlying
geological formations. As many case studies show, this generally works well in
younger sediments, but with increasing sediment age the calculation error
grows rapidly. Backstripping of the Ca2 sediments in northern Central Europe
faces many problems and therefore the results of such calculations should be
used only as a general guide. Recently performed backstripping of Ca2 sediments in parts of Northwest Germany showed subsidence rates of about 1.5 cm/
ka up to 3 cm/ka for sediments in Ca2 platform position and 7-11 cm/ka for
those in basin positions. This fits well to earlier calculations of Fiichtbauer
(1964), who suggested a subsidence rate of 2 cm/ka for Ca2 platform sediments
in Northwest Germany. Simulations performed using these subsidence rates
show reasonable results. Major and sudden changes in subsidence are not indicated. Varying subsidence rates during numerous simulation runs showed the
sensitivity of the Ca2 sediments to subsidence rate changes and made a quantification of subsidence possible. Simulated linear subsidence rates of 1 cm/ka to
2.5 cm/ka in the platform realm, 4 cm/ka to 8 cm/ka in slope position and
10cm/ky to 12 cm/ky in basinal areas are within a reasonable range and result in
the best fit between model results and core data. In addition to the amount of
subsidence for each area the difference in rate between platform and slope are
important. In eastern Germany, difference in subsidence rates is one of the factors ruling the development of the topographic setting, since it is fundamentally
important for the development of off-platform highs. In comparison to the
northwest German Ca2 platform, these islands, which are thought to have established themselves on older (pre-Zechstein) horst-positions (Van der Baan
1990; Strohmenger et al. 1993a, 1996b) or on volcanic highs of Carboniferous/Lower Permian age, show increased subsidence rates in slope and basinal
areas. This increase is fundamentally important for the islands to maintain
their isolated character and results in a characteristic facies distribution in the
early Ca2 time.
K. Leyrer· C. Strohmenger . K. Rockenbauch . T. Bechstaedt
The subsidence of both the Northern and Southern Permian Basin was mainly a
consequence of the decay of Stephanian-Autunian induced thermal anomalies
and began during the Saxonian (Ziegler 1990). Subsidence in main parts of the
basins resulted from thermal contraction of the lithosphere and the loading of
the basins by water and sediments (Ziegler 1988). The occurrence of minor synZechstein faulting is restricted to a few areas along the southern margin of the
Southern Permian Basin. Ca2 sedimentation in the investigated areas indicates
no synsedimentary faulting and therefore, as a first approach, tectonic subsidence during Ca2 time was assumed to be linear.
Tectonic subsidence rates within PHIL 5.1 are specified at hingepoints along
the model profile (Marco Polo Software 1994) and are linearly interpolated between these points. The hingepoints may be user-defined and PHIL 5.1 allows at
any time to vary both the temporal and spatial distribution of subsidence rates.
In addition, PHIL's algorithms allow specification of the lithosphere's flexural
loading (e.g. flexural parameter and mantle density) and compaction (defined
by initial porosity and compaction rate) for up to 24 different lithologies.
A common way of calculating subsidence rates is by backstripping overlying
geological formations. As many case studies show, this generally works well in
younger sediments, but with increasing sediment age the calculation error
grows rapidly. Backstripping of the Ca2 sediments in northern Central Europe
faces many problems and therefore the results of such calculations should be
used only as a general guide. Recently performed backstripping of Ca2 sediments in parts of Northwest Germany showed subsidence rates of about 1.5 cm/
ka up to 3 cm/ka for sediments in Ca2 platform position and 7-11 cm/ka for
those in basin positions. This fits well to earlier calculations of Fiichtbauer
(1964), who suggested a subsidence rate of 2 cm/ka for Ca2 platform sediments
in Northwest Germany. Simulations performed using these subsidence rates
show reasonable results. Major and sudden changes in subsidence are not indicated. Varying subsidence rates during numerous simulation runs showed the
sensitivity of the Ca2 sediments to subsidence rate changes and made a quantification of subsidence possible. Simulated linear subsidence rates of 1 cm/ka to
2.5 cm/ka in the platform realm, 4 cm/ka to 8 cm/ka in slope position and
10cm/ky to 12 cm/ky in basinal areas are within a reasonable range and result in
the best fit between model results and core data. In addition to the amount of
subsidence for each area the difference in rate between platform and slope are
important. In eastern Germany, difference in subsidence rates is one of the factors ruling the development of the topographic setting, since it is fundamentally
important for the development of off-platform highs. In comparison to the
northwest German Ca2 platform, these islands, which are thought to have established themselves on older (pre-Zechstein) horst-positions (Van der Baan
1990; Strohmenger et al. 1993a, 1996b) or on volcanic highs of Carboniferous/Lower Permian age, show increased subsidence rates in slope and basinal
areas. This increase is fundamentally important for the islands to maintain
their isolated character and results in a characteristic facies distribution in the
early Ca2 time.