12 Basin Evolution and Sediments
Mega-Rifting in Europe and
Intracontinental Sag Basins
(12.3 and 12.4)
12.3 Mega-Rifting and Mesozoic Sediments
in Europe (Overview)
12.3.1 Intracontinenta1 Basin Evolution
(Mega-Rifting)
12.3.2 Mesozoic Sediments
12.3.3 Summary (Mega-Rifting in Europe)
12.4 Intracontinenta1 Sag Basins
12.4.1 Occurrence and General Characteristics
12.4.2 Tectonic Evolution and
Subsidence History
12.4.3 Sediments
12.4.4 Summary (Intracontinental Sag Basins)
12.3 Mega-Rifting and Mesozoic
Sediments in Europe (Overview)
12.3.1 Intracontinental Basin Evolution
(Mega-Rifting)
This section is thematically related to the previous
and following sections (Sects. 12.2 and 12.4). It is
intended to give abrief overview of the Mesozoic
extra-Alpine sedimentary history of wide areas in
Europe. Some knowledge about a classical region
mayaiso be useful for the interpretation of the geological history of areas outside of Europe.
During the late Permian and Triassic, the Pangean
supercontinent became increasingly unstable due to
the reactivation of peripheral rift zones and the development of new interior rift systems. From the Triassic to the rniddle Jurassie, two principal, multi-directional rift systems transected the former Variscan
fold belt and its fore land: from the north, the
Norwegian-Greenland Sea rift prograded southward,
and the Tethys rift system prograded from Asia westward. In the central and north Atlantic, these two
mega-rift systems interfered with each other, but the
neighboring areas, including western and central Europe, were also strongly affected by this plate reorganization or "mega-rifting". Pre-existing Permo-Carboniferous fracture systems were reactivated, and
wide areas around the future continental rnargins underwent extensional stresses. These caused differential subsidence and thus basin fills of varying thicknesses between zones of higher elevation and moderate uplift.
The depositional environments and histories of
these basins were affected by many local factors and
therefore vary from basin to basin. Nevertheless,
some general trends can be recognized which rnay
also characterize other basins of sirnilar origin. This
is exemplified by the evolution of the European Mesozoic basin association between the growing Tethys
Ocean in the south and the N orth Sea in the north.
The effects of short-term sea-Ievel changes and minor clirnatic cycles are not discussed here (cf. Chap.
7).
Central and western Europe, including its continental she1f
and the North Sea, are characterized by a considerab1e
number of sedimentary basins which developed since the
Permo-Triassie and persisted through the Mesozoic or Cenozoic time. These basins represent well-known examples
of intracontinental basins, the evolution of which was initiated by rifting and complicated by block faulting and
wrench tectonics (Ziegler 1982, 1988). In all these cases,
rifting did not lead to the formation of new oceanic crust
(failed rifts). However, during and subsequent to rifting,
these basins experienced long-lasting thermal subsidence
simi1ar to passive continental margins. Some of these basins may be regarded as continenta1 sag basins (Sect. 12.4),
although their development spans less time than that of
typical sag basins.
12.3.2 Mesozoic Sediments
Triassie. As a result of the northward drift of
Pangea, Europe moved out of an equatorial position
held during the late Carboniferous, reached the
northern trade-wind belt, and reached a zone of dry,
hot climate.
Western Tethys, Alps. During the Triassic, the large
shelf areas in the western Tethys Ocean were characterized by extensive carbonate platforms, some
evaporite basins, and intervening troughs accumulating deep water carbonates and shales (Fig. 12.l6a;
e.g., Bechstädt et al. 1978; Brandner 1985; Ziegler
1988; Elmi 1990). The extensive, thick carbonate
buildups of the eastern and southern Alps and other
Alpine regions in southern Europe document subtropical clirnate and the efficiency of shallow-water
Mega-Rifting in Europe and
Intracontinental Sag Basins
(12.3 and 12.4)
12.3 Mega-Rifting and Mesozoic Sediments
in Europe (Overview)
12.3.1 Intracontinenta1 Basin Evolution
(Mega-Rifting)
12.3.2 Mesozoic Sediments
12.3.3 Summary (Mega-Rifting in Europe)
12.4 Intracontinenta1 Sag Basins
12.4.1 Occurrence and General Characteristics
12.4.2 Tectonic Evolution and
Subsidence History
12.4.3 Sediments
12.4.4 Summary (Intracontinental Sag Basins)
12.3 Mega-Rifting and Mesozoic
Sediments in Europe (Overview)
12.3.1 Intracontinental Basin Evolution
(Mega-Rifting)
This section is thematically related to the previous
and following sections (Sects. 12.2 and 12.4). It is
intended to give abrief overview of the Mesozoic
extra-Alpine sedimentary history of wide areas in
Europe. Some knowledge about a classical region
mayaiso be useful for the interpretation of the geological history of areas outside of Europe.
During the late Permian and Triassic, the Pangean
supercontinent became increasingly unstable due to
the reactivation of peripheral rift zones and the development of new interior rift systems. From the Triassic to the rniddle Jurassie, two principal, multi-directional rift systems transected the former Variscan
fold belt and its fore land: from the north, the
Norwegian-Greenland Sea rift prograded southward,
and the Tethys rift system prograded from Asia westward. In the central and north Atlantic, these two
mega-rift systems interfered with each other, but the
neighboring areas, including western and central Europe, were also strongly affected by this plate reorganization or "mega-rifting". Pre-existing Permo-Carboniferous fracture systems were reactivated, and
wide areas around the future continental rnargins underwent extensional stresses. These caused differential subsidence and thus basin fills of varying thicknesses between zones of higher elevation and moderate uplift.
The depositional environments and histories of
these basins were affected by many local factors and
therefore vary from basin to basin. Nevertheless,
some general trends can be recognized which rnay
also characterize other basins of sirnilar origin. This
is exemplified by the evolution of the European Mesozoic basin association between the growing Tethys
Ocean in the south and the N orth Sea in the north.
The effects of short-term sea-Ievel changes and minor clirnatic cycles are not discussed here (cf. Chap.
7).
Central and western Europe, including its continental she1f
and the North Sea, are characterized by a considerab1e
number of sedimentary basins which developed since the
Permo-Triassie and persisted through the Mesozoic or Cenozoic time. These basins represent well-known examples
of intracontinental basins, the evolution of which was initiated by rifting and complicated by block faulting and
wrench tectonics (Ziegler 1982, 1988). In all these cases,
rifting did not lead to the formation of new oceanic crust
(failed rifts). However, during and subsequent to rifting,
these basins experienced long-lasting thermal subsidence
simi1ar to passive continental margins. Some of these basins may be regarded as continenta1 sag basins (Sect. 12.4),
although their development spans less time than that of
typical sag basins.
12.3.2 Mesozoic Sediments
Triassie. As a result of the northward drift of
Pangea, Europe moved out of an equatorial position
held during the late Carboniferous, reached the
northern trade-wind belt, and reached a zone of dry,
hot climate.
Western Tethys, Alps. During the Triassic, the large
shelf areas in the western Tethys Ocean were characterized by extensive carbonate platforms, some
evaporite basins, and intervening troughs accumulating deep water carbonates and shales (Fig. 12.l6a;
e.g., Bechstädt et al. 1978; Brandner 1985; Ziegler
1988; Elmi 1990). The extensive, thick carbonate
buildups of the eastern and southern Alps and other
Alpine regions in southern Europe document subtropical clirnate and the efficiency of shallow-water