328
K. Leyrer· C. Strohmenger . K. Rockenbauch . T. Bechstaedt
In the northwest German platform setting, the general sedimentation patterns are similiar to those of eastern Germany, given that the sequence stratigraphie framework and the reconstructed sea level have the same characteristics. However, due to lower water energy, lower subsidence rates and higher
sediment production rates, depositional results vary to some extent. Progradation and aggradation rates are much higher in NW Germany than in eastern
Germany and sedimentation nearly always keeps pace with sea-level during
the HST of Zechstein sequence ZS3. Consequently, the four shallowing-upward trends (PS4 to PS7) caused by fifth-order sea-level fluctuations during
the highstand systems tract of Zechstein sequence ZS3 are clearly visible in
Ca2 platform sediments of Northwest Germany, and both vertical and lateral
facies successions show intensive interfingering (Fig. 5). The sea level lowstand
at parasequence boundary PSB5 affects Ca2 platform sediments for only a
short time. The subsequent rise of sea level at the initial stage of PS6 is not as
impressive as in eastern Germany. Simulation results in both study areas indicate that the end of Zechstein sequence ZS3 is reached after about 900 ka of
sedimentation.
4.3
Parasequences Ca2/A2-1 and Ca2/A2-2 (Figs. 18,26)
The first cycle of Zechstein sequence ZS4 (Ca21 A2-cycle I) contains the two parasequences Ca2/A2-1 and -2 and builds up the main parts of the LST of Zechstein sequence ZS4. Being superimposed on the regressive part of the simulated
third-order cycle, both parasequences are generally characterized by a major
and rapid drop in sea level. Only the intercalated marine flooding surface, which
marks the start of parasequence Ca21 A2-2, indicates a short-term sea level rise.
However, due to its position on the Ca2 slope and the following slow transgression phase, this surface is not preserved in the sedimentary record.
The East German high-relief off-platform highs are affected by this major
drop in relative sea level (about 30-50 m) during the LST of Zechstein sequence
ZS4, resulting in erosional processes mainly in the realm of the Ca2 platform. In
addition, minor erosion and reworking takes place in upper slope sediments.
The products of these processes are resedimented at the base of slope and build
up, together with in-situ carbonates, a lowstand wedge several meters thick.
In contrast to this, the drop in relative sea level at the initial stage of Zechstein
sequence ZS4 has a more dramatic impact in the northwest German setting. Due
to lower subsidence rates, sea level drops about 50-70 m in this area. Besides
this, the sea -level rise at the beginning of parasequence Ca21 A2-2 leads to intensive reworking and nearly in-situ resedimentation of the highstand systems
tract of Zechstein sequence ZS4. Being superimposed on a third-order sea level
rise, the transgression continues throughout the second parasequence, resulting
in continued reworking (and in-situ resedimentation) of most of the prograded
Ca2-platform sediments. At the base of the LSW, this leads to a distinct facies
contact of upper slope mudstones and high -energy shoal and bar sediments con-
K. Leyrer· C. Strohmenger . K. Rockenbauch . T. Bechstaedt
In the northwest German platform setting, the general sedimentation patterns are similiar to those of eastern Germany, given that the sequence stratigraphie framework and the reconstructed sea level have the same characteristics. However, due to lower water energy, lower subsidence rates and higher
sediment production rates, depositional results vary to some extent. Progradation and aggradation rates are much higher in NW Germany than in eastern
Germany and sedimentation nearly always keeps pace with sea-level during
the HST of Zechstein sequence ZS3. Consequently, the four shallowing-upward trends (PS4 to PS7) caused by fifth-order sea-level fluctuations during
the highstand systems tract of Zechstein sequence ZS3 are clearly visible in
Ca2 platform sediments of Northwest Germany, and both vertical and lateral
facies successions show intensive interfingering (Fig. 5). The sea level lowstand
at parasequence boundary PSB5 affects Ca2 platform sediments for only a
short time. The subsequent rise of sea level at the initial stage of PS6 is not as
impressive as in eastern Germany. Simulation results in both study areas indicate that the end of Zechstein sequence ZS3 is reached after about 900 ka of
sedimentation.
4.3
Parasequences Ca2/A2-1 and Ca2/A2-2 (Figs. 18,26)
The first cycle of Zechstein sequence ZS4 (Ca21 A2-cycle I) contains the two parasequences Ca2/A2-1 and -2 and builds up the main parts of the LST of Zechstein sequence ZS4. Being superimposed on the regressive part of the simulated
third-order cycle, both parasequences are generally characterized by a major
and rapid drop in sea level. Only the intercalated marine flooding surface, which
marks the start of parasequence Ca21 A2-2, indicates a short-term sea level rise.
However, due to its position on the Ca2 slope and the following slow transgression phase, this surface is not preserved in the sedimentary record.
The East German high-relief off-platform highs are affected by this major
drop in relative sea level (about 30-50 m) during the LST of Zechstein sequence
ZS4, resulting in erosional processes mainly in the realm of the Ca2 platform. In
addition, minor erosion and reworking takes place in upper slope sediments.
The products of these processes are resedimented at the base of slope and build
up, together with in-situ carbonates, a lowstand wedge several meters thick.
In contrast to this, the drop in relative sea level at the initial stage of Zechstein
sequence ZS4 has a more dramatic impact in the northwest German setting. Due
to lower subsidence rates, sea level drops about 50-70 m in this area. Besides
this, the sea -level rise at the beginning of parasequence Ca21 A2-2 leads to intensive reworking and nearly in-situ resedimentation of the highstand systems
tract of Zechstein sequence ZS4. Being superimposed on a third-order sea level
rise, the transgression continues throughout the second parasequence, resulting
in continued reworking (and in-situ resedimentation) of most of the prograded
Ca2-platform sediments. At the base of the LSW, this leads to a distinct facies
contact of upper slope mudstones and high -energy shoal and bar sediments con-