High-Resolution Forward Stratigraphic Modeling of Ca2Carbonate Platforms and Off-Platform Highs (Upper
Permian, Northern Germany)
K. Leyrer, C. Strohm enger, K. Rockenbauch and T. Bechstaedt
1
Introduction
The Zechstein 2 Carbonate, also called Ca2 or Stassfurt -Carbonate, is Germany's
most prolific carbonate gas play. An important target for exploration in Germany for more than half a century, the Ca2 has been penetrated by several hundreds
of wells.
Throughout the Southern Zechstein Basin the Ca2 is sandwiched between the
anhydrites of the first Zechstein cycle (Werra Anhydrite, or A1) and the anhydrites of the second Zechstein cycle (Basal Anhydrite, or A2). The depth of the
Ca2 reservoir varies between 2000 and 4500 m in the western parts of Germany
and 1500 and 3000 m in eastern Germany. The Ca2 depositional patterns were
strongly controlled by the preexisting morphology, which mainly evolved during the formation of the Al (Strohmenger et al.1993c, 1996b). The thickness of
the Ca2 ranges from 20 to 80 m in a platform position and reaches a maximum
thickness of more than 250 m in a slope position several hundreds of meters basinward of the AI-platform margin (Fig. 4). In basinal environments, the Ca2
thickness decreases rapidly and generally does not exceed 10 m.
Detailed investigations on the basement of the Ca2 in Northwest Germany
show that the Zechstein Conglomerate (ZlC), which either overlies the Early
Permian Rotliegendes or Late Carboniferous strata (Fig. 1), reaches a maximum
thickness of only about 0.5 m and therefore is not able to create a distinct morphology above the more or less plain topography which characterizes the landscape in Northwest Germany after Rotliegend time. The following intervals,
which are called Mutterfloz Carbonate (TlCa) and Copper Shale (Tl), together
reach a maximum thickness of several meters and are also without any influence
on the overlying strata. The Zechstein Limestone (Cal) is the first formation in
Late Permian time which reaches thicknesses of some tens of meters. The controlling factors of these unequal sediment distributions mostly remain unclear,
but the chemical composition of the water enabled several organisms like algae
and brachiopods to build up reef-like communities, e.g. in the Thuringian (Peryt
1986) and Emsland areas. However, the morphological highs of the Cal are not
reflected by the thickness patterns of the Werra Anhydrite (Al), which overlies
the Cal.
Permian, Northern Germany)
K. Leyrer, C. Strohm enger, K. Rockenbauch and T. Bechstaedt
1
Introduction
The Zechstein 2 Carbonate, also called Ca2 or Stassfurt -Carbonate, is Germany's
most prolific carbonate gas play. An important target for exploration in Germany for more than half a century, the Ca2 has been penetrated by several hundreds
of wells.
Throughout the Southern Zechstein Basin the Ca2 is sandwiched between the
anhydrites of the first Zechstein cycle (Werra Anhydrite, or A1) and the anhydrites of the second Zechstein cycle (Basal Anhydrite, or A2). The depth of the
Ca2 reservoir varies between 2000 and 4500 m in the western parts of Germany
and 1500 and 3000 m in eastern Germany. The Ca2 depositional patterns were
strongly controlled by the preexisting morphology, which mainly evolved during the formation of the Al (Strohmenger et al.1993c, 1996b). The thickness of
the Ca2 ranges from 20 to 80 m in a platform position and reaches a maximum
thickness of more than 250 m in a slope position several hundreds of meters basinward of the AI-platform margin (Fig. 4). In basinal environments, the Ca2
thickness decreases rapidly and generally does not exceed 10 m.
Detailed investigations on the basement of the Ca2 in Northwest Germany
show that the Zechstein Conglomerate (ZlC), which either overlies the Early
Permian Rotliegendes or Late Carboniferous strata (Fig. 1), reaches a maximum
thickness of only about 0.5 m and therefore is not able to create a distinct morphology above the more or less plain topography which characterizes the landscape in Northwest Germany after Rotliegend time. The following intervals,
which are called Mutterfloz Carbonate (TlCa) and Copper Shale (Tl), together
reach a maximum thickness of several meters and are also without any influence
on the overlying strata. The Zechstein Limestone (Cal) is the first formation in
Late Permian time which reaches thicknesses of some tens of meters. The controlling factors of these unequal sediment distributions mostly remain unclear,
but the chemical composition of the water enabled several organisms like algae
and brachiopods to build up reef-like communities, e.g. in the Thuringian (Peryt
1986) and Emsland areas. However, the morphological highs of the Cal are not
reflected by the thickness patterns of the Werra Anhydrite (Al), which overlies
the Cal.