137 (1987) 61-76
in The Netherlands
Mesozoic and Early Tertiary evolution of the Alpine foreland in Upper Austria and Salzburg, Austria W. NACHTMANN Rohd-Aufsuchungs
and L. WAGNER
W. and Wagner,
Tectonophysics, The Cenozoic extends
Basin of Upper
for a considerable
The area occupied Jurassic
Following the Alpine
in the Alpine
cover. This autochthonous
to subside Early
and by Late
by a major erosional
At the transition
in the area, whereby from the Cretaceous
the Late Cretaceous.
the elastic influx from the Bohemian to the Tertiary,
phase may be related
to the collision
of the North
system. the Palaeocene
and Early Eocene the area subsided
again and became
of the Alpine foreland
is part of the Alpine foredeep.
shales and elastics accumulated
with the Alpine
the Late Senonian.
by an extensive
sional deformation European
Massif and its Mesozoic
to 1000 m of shallow
of the Bohemian
time it was covered
and Early Tertiary
137: 61-76. Molasse
by the crystalline
L., 1987. Mesozoic
In: P.A. Ziegler
margin is formed by the outcropping basement of the Bohemian Massif while its southern margin corresponds to the Alpine thrust front. In this
of Upper Austria and of the Alpine-Carpathian
of the Cenozoic
a few meters
series ranges margin
tends from France through Switzerland, Germany and Austria to Czechoslovakia. In Upper Austria and Salzburg, this basin contains Late Eocene to
over 3000 m along the Alpine deformation front. During the Oligocene and Early Miocene phases of the Alpine orogeny, the southern parts of the
Molasse Basin were overridden and partly scooped out by the advancing Alpine nappe systems.
were deposited series
crystalline basement of the southern extension of the Bohemian Massif (Kollmann, 1977; Kollmann and Malzer, 1980).
Seismic reflection and well data indicate that the autochthonous foreland basement with its Mesozoic and partial Cenozoic cover extends for a considerable distance under the Alpine nappes (Wessely, 1987). This paper deals mainly with the Mesozoic and
The Cenozoic Basin of Upper Austria and Salzburg has the geometry of an asymmetrical, southdipping, 30-55 km wide trough. Its northern 0040.1951/87/$03.50
cl 1987 Elsevier
GEOLOGICAL CROSS SECTION
....... ........ PALINSPASTIC PROFILE
Fig. 1. Situation
map of discussed
wells and sections
. . ...
Early Tertiary Molasse the
Basin and its southward
and Early This
In the concession
It is based
of the substratum
Late Palaeozoic setting The Variscan Bohemian Massif
basement complex of dips southward under
but as Alpine
While a number of wells drilled in Upper have reached the top of the crystalline
230 m of grey to greenish silts and was terminated Only
and red claystones
the base of this series.
1982). However, by the
Austria are fluvial to shalcontaining occasional thin
from zero to 60
erous series occurring along the western margin of the Bohemian Massif (Schroder, 1987) and overly-
ing the Bohemian
Bajocian spores (W. Klaus. pers. commun.. 1978) and they are conformably overlain by Callovian glauconitic
in Lower Austria
wells drilled in Upper low-marine sandstones,
were obtained from these sediments, and these are lithologically comparable to the Permo-Carbonif-
series of Upper
m, and their occurrence is restricted to the southern and southeastern part of the area under re-
at a final total depth
Jurassic basin evolution
continental Late Palaeozoic sediments. The Perwang 1 well (Per 1, Fig. 1) penetrated
3531.50 m without
this hypothesis cannot be substantiated available subsurface data.
Molasse Basin and extends a considerable yet indeterminate distance under the nappes. Austria
1987) and along its
may, in fact. also have come
phase of wrench
of the Permo-
zones which transect
from some 300 wells and a dense grid of reflection lines.
that this major
tain lumachelles, stromal
and, in the eastern
and grade with
echinoids into bio-
parts of the area.
cek, 1977; Matura, 1980). Over 400 m of probably Late Palaeozoic dark grey, fluvial sandstones, silts
also coral reefs (Fig. 3).
and clays were penetrated (Hohg 1. Fig. 1) near
Jurassic corresponds approximately to a glauconitic limestone bed which is a few metres thick,
border. These Carboniferous
in the Hochburg area the Austrian-Bavarian
an association of Permo(Stephanian-Lower Per-
mian; I. Draxler, pers.commun., 1981). It is, however, uncertain whether these spores are in-situ or were reworked. The area1 distribution
Late Palaeozoic sediments is difficult to determine on the basis of the available well and seismic data. They appear to be limited to the southwestern margin of the Central Swell Zone which forms the southeastern extension of the Landshut-Neuoetting High of Bavaria (Fig. 2). In view of this, it is
with a similar
outcrops on the Franconian Platform of Bavaria (Meyer and Schmidt-Kaler. 1984). The late Jurassic series forms an extensive
During the Callovian and Late Bajocian-Bathonian basin margins
platform. Jurassic, the became pro-
gressively overstepped. In the northern and northwestern parts of the area. the Late Jurassic platform carbonates transgress directly over the crystalline basement. In the west, Oxfordian and Kimmeridgian algal and sponge banks, some 200 m thick. are capped
FLAT+ LAGOON BRECCIA HORIZONS
Fig. 3. Distribution
facies types in the subcrop
by coral reefs. To the east these grade into oolitic grainstone which are interspersed with sponge biostromes
and to establish
Early Cretaceous erosional phase During
lagoonal, semi-restricted banks (Fig. 3). The latter are characterised by “bird’s eye” and “black pebble”
of the Molasse
the Early Cretaceous
the area of Upper
graphically deeper levels in the east than in the west, indicating a progressive westward shallowing
tectonic activity along NW-SE striking fault systems to the southwest of the Bohemian Massif and
of the basin.
the Central Swell Zone. Subsurface data indicate
close this depositional ded fine crystalline breccias
cycle, consist dolomites,
(Figs. 4 and
of the Central
Characea indicates that fresh water conditions were repeatedly established on these extensive tidal
Over the crest of this NW-SE
Late Jurassic carbonates are frequently dolomitised and characterised by secondary porosity. Moreover, in most wells, there is evidence for deep
Jurassic series became deeply truncated during the Early Cretaceous. This is evident from the unconformable relationship between Jurassic carbonates and the overlaying Late Cretaceous strata, particu-
karstification and fracturing. The top of the Jurassic and Purbeckian series corresponds to a regional unconformity. Prior to their regional truncation, Jurassic sediments probably attained a maximum thickness of some 750 m in the western parts of the area. Because of their complete erosion towards the Bohemian Massif, it is difficult to assess their depositional limit to the
by the reactivation
fault systems. trending
larly along the northern flank of the Central Swell Zone near the Austrian-Bavarian border where the thickness of these carbonates varies between 35 m in Munderfing 1 (Mu I ) and 398 m in Maria Schmolln 1 (MS 1). To judge by the thickness of Jurassic series preserved in areas adjacent to the Central Swell Zone, its Early Cretaceous uplift
filled the karst relief of the top Jurassic
must have been of the order of 600 m. At the same time the northeastern area became mark
the southwestern the Early
by the age of the overlying 1, Fig. 1)
sandstones, shales, marly and calcareous which unconformably overlie Jurassic
by Late Eocene
part of the Molasse
and Jurassic series
In the adjacent
marls which grade upwards glauconitic marine
pulse. with a second pulse during the Aptian. These deformations correlate with rift and wrench tectonic
phases which affected
much of northwest-
ern Europe, and which can be related to crustal extensions in the North Atlantic and NorwegianGreenland Sea areas (Ziegler, 1982, 1987).
In areas to the southwest
of the Central
The bulk of the Cenomanian
mudstones Campanian derived Central
Campanian mudstones conditions.
of the Central
sediwhich In areas
are overlain by some 300 m of Late shallow-marine sandstones which were
from the Bohemian Massif. Across the Swell Zone these sands shale out and give
way to mudstones. No Maastrichtian been
up to 75 m, are conformably
in the imbricated Alpine
in the autochthonous Cretaceous
series of However,
zone along the northern Campanian
Maastrichtian shallow-marine clays are preserved under the base-Tertiary unconformity. On the Swell
in the allochthonous
Zone, the essentially Late Cretaceous sedimentary cycle had already commenced with the accumula-
outcropping in the record is continuous
tion of Apto-Albian
storm-dominated, shallow-marine, glauconitic sandstones which were deposited on a broad shelf.
of the Late Cretaceous basin evolution
Massif (Fig. 4).
to the northwest nature and tectonic
that the Early Cretaceous
of the Upper
in a narrow
limit of the Jurassic
and west towards
bian and younger sediments (Lange 1971; Bachmann et al., 1987). This indicates
Late Turonian to basal Late ments consist of shallow-marine
mations were probably of a polyphase involved a first Berriasian-Hauterivien
Barremian marine sands overlie Jurassic strata and are, in turn, unconformably overlain by Aland Paulus,
yielded Berriasian-Hauterivian microfossils. Elsewhere,
and thus initiated
1 well (Mlbg
carbonates, Cenomanian strata
Massif in Bavaria.
Only in the Mtihlberg marine sands,
(1987) from the southwest-
of the Bohemian
of the Bohemian
along the fault systems
Massif (Fig. 5). This deformation with
To the northeast of this long-standing tectonic lineament, the oldest Cretaceous deposits are locally developed, non-fossiliferous, fluvial, lightgrey to white, often coarse-grained sandstones which sometimes infill the Jurassic karst to depths of 100 m below the Jurassic surface. Where these so-called “Schutzfels Beds”, which are probably of Late Aptian to Albian age, have not totally in-
same area, the sedimentary from the Senonian to the
In the easternmost part of the Upper Austrian Cretaceous Basin, Late Cretaceous series were deposited directly on the crystalline basement. Here the sequence begins with fluvial granite-wash, occasionally overlain by marsh deposits. The Late Cenomanian to earliest Turonian transgressive marine sediments consist of inner-shelf storm deposits and outer-shelf mudstones. These are over-
FM. _ ~~ ~. ---
Fig. 5. C;eohgical CKF.~sections A and B through
subcrep of the Molaase
Obg I Win 2
see Fig. 1; for colour
Egdg W I
see Fig. 2
y$l -I %
EASTERNMOUSSE 8. EASTERNMOLASSE 8. tM8R’CATED Z0NE K3ALLEURG,U.-BUSTR iA>
(UPPER AUSTRIA1 SWELL MNh
CONTINENTAL. LACUSTRM SANCISTOM?. CONSLOMERATE
DEEPER-MARS& [email protected]
~lflC SAHDSTONE, [email protected]
FOLDING. THRUSTHG HIOHAFGLE BOOTY,
Fig. 6. Chronology and lithostratigraphic
lain by ~~~~d~~c
columns of the Molasse Basin and its Mesozoic subcrop in Upper Austria and Salzburg.
Later Turonkin to Senonian elastic fan deposits, which advanced in a southwestern direction from the Bohemian Massif (Wessely et al., 1981; Wessely, 1987). Throughout the Upper Austrian Basin, the top of the Cretaceous correponds to a regional unconformity. Depositional thicknesses of the Late Cretaceous series ranged between 750 and 1000 m. Due to their profound truncation by the base-
Eocene ~~nfo~ty, it is almost abbe to reconstruct the original geometry and outlines of the Upper Austrian Cretaceous Basin. Yet, judging from the thickness and facies development of the Cretaceous strata at their partly fat&-bounded erosional Emit towards the Bohemian h4assf (Fig 5), it must be assumed that the latter was formerly covered to a considerable extent by Late Cretaceous sediments.
Latest Cretaceous to Palaeocene basin inversion
1000 m (Figs. that
zoic series the Upper
map it is evident affected earliest
that major tectonic
this area in the latest
the Central into evidence
to the east, with the result that the
series are generally
Swell Zone, during
which had already
its Cretaceous its remnant
the Early Cretaceous,
cally even through
had developed became
1987) it is likely
with the southwest
were of a dextral
At the same time, individual tilted uniformly
these deformations, the area under conbecame uplifted and transsected by a
system of NW-SE
pressional that during
map of the Meso-
at the base-Eocene
5 and 7). Fault
the basement. This major structural element extends northwestwards into the Landshut-Neuoet-
served in their eastern parts. The structural relief generated by these deformations is in the order of
END OF CRETACEOUS
END OF JURASSIC
Fig. 7. Palinspastic Eocene.
of the Mesozoic
at the end of the Jurassic.
of the Cenomanian
Fig. 9. Tectonic
map of the haae of Tertia?.
faults only and oil dnd gas fields contained
in Eocene s&es
High of Bavaria
from the remnant
sive Cretaceous of Upper
to its exten-
by the development
Oligocene tensional weight
of a dense
systems (Kittler last phase
This phase crust
and Laramide reactivated
tectonic instability of the area which preculminated during the Middle to Late
the Oligocene and Miocene a gradual migration of the axis of the Upper
Upper Austrian Basin during Campanian probably reflects
in the main
inversion (Fig. 7).
which were shed into this foredeep
by the accumulation of thick, often turbidites in the Puchkirchen series.
the area of Upper Austria a distinction between these two phases cannot be made, partly in view
and Early Miocene
of the lack of a Maastrichtian graphic record.
of the Molasse
Late Eocene and Oligocene Molasse Basin
Basin can be observed.
Such a timing is compatible with the subHercynian and Laramide foreland deformations in northwestern
the Coniacian the gradually
to the flexural
in the overlaying
can be related
Basin of rapidly
of which die out upwards
by the present and
faults (Figs. 2 and 8)
In the area
of these deformations
The timing by
of the formerly
cover to its northeast.
the area occupied
fold belt. During parts
the Late Oligocene
of the Alpine
overridden and partly scooped out by the AustroAlpine, Flysch and Helvetic nappes. The Middle of the
and Later Miocene Hall and Innviertel shales acd sandstones were deposited under upward-shallowing conditions
Rapid erosion of the structural relief induced by the latest Cretaceous to Paleocene inversion
and post-Miocene reactivations of the Upper Austrian Alpine deformation front were of minor
movements left an undulating peneplain onto which the Tethys Sea progressively encroached
crust by the advancing
systems caused the asymmetric subsidence Alpine foredeep, of which the area of Austria formed the northern Late Eocene and Oligocene.
to the tectonic
nappe of the Upper
and contributed of the molasse.
In Upper Austria and Salzburg the basal Late Eocene series is formed by fluvial and shallowmarine transgressive sandstones. These grade upward into Lithothamnium carbonates. Their lateral equivalents in the southern parts of Salzburg are open-marine Nummulite-bearing limestones and Discocyclina marls (Kollmann and Malzer, 1980; Wagner, 1980). During the latest Eocene and Early Oligocene
Conclusions In the area of Upper Austria and Salzburg. Middle and Late Jurassic series ranging in thickness from 600 to 700 m were deposited on a tectonically quiescent shelf which was open to the south towards the Tethys Sea. Early Cretaceous deformations,
and related to major tectonic activity elsewhere in northwestern Europe. resulted in the partial disruption of the Late Jurassic carbonate shelves. Following a major hiatus that spanned much of the Early Cretaceous, the area under consideration began to subside again during the Cenomanian.
of 750 to 1000 m. Severe
is probably erogenic
of the North During
to the collision
with the southern (Ziegler.
to Early Oligocene
phase of the Molasse of the crust under
and Early defor-
the Late Eocene to Miocene,
1987). of the
Basin, flexural downbending the load of the advancing
Alpine nappes induced the development of a dense network of essentially basin-parallel synthetic and antithetic normal faults (Fig. 9). having throws of up to several hundred metres. The resulting structures
Miiller. M. and Weggen.
of the Molasse physics. Kittler.
137 (this volume):
G. and Neumayer
In: A.W. Styles,
R., 1983. Austrian
during the Laramide reactivated during
inversion phase, the Oligocene
were partly and Early
Miocene phases of the Alpine orogeny. Their vertical throw is usually only in the order of some tens of metres. These young fault planes follow the strike of the original
faults but they sometimes
dip into opposite directions. However, the reactivated of minor tensional
to the Ohgocene
The authors wish to thank the management of Roh~l-Aufsuchungs GmbH for authorising this publication, and the personnel of RAG’s geological drafting department for their technical assistance.
Molassezone (Editor). Museum.
(this volume): 0..
2.. 87: 150-162. and Tertiary
hasins of the
Erdiil- und Erdgastrkger 2. Die Konglomerate Erdgas
und Fazies des
Senke im Bayrischen
Massif and their evolution.
Z., 97: 20-28.
A., 1980. Das Perm van Ziibing. &terreichs.
New York. N.Y.. pp. 137-138.
In: Der geoiogische
H., 1984. Erdgeschichte
2nd ed., 260
B.. 1987. Inversion
of the Bohemian
along the western margin
137 (this volume):
W., 1977. Perm
Geologischen logische Wagner.
Erdiil- und Erdgastrgger 1. Die Sandsteine
L., 1980. GeoloBische
338-346. G., 1987.
137 (this volume):
Geol. Bundesanst. Ziegler,
P.A., 1982. Geological
im ostlichen (Austria),
of the Tectono-
R.. 1981. Lithofazies und Oberkreide des Oberosterreich.
175-281. of Western
130 pp. and encl.
P.A., 1987. Late Cretaceous
Wessely. G., Schreiber. OS. and Fuchs. und Mikrostratigraphie der MittelMolasseuntergrundes
faults are, in general,
M., 1987. The Mesozoic
In: F. Bachmayer
into deltaic and continental elastics. The pre-Eocene fault systems, which developed
B., 1971. Stratigraphic
Gault und Cenoman
and F. Berger Horn, pp. 179-201.
H. and Paulus,
Meyer, R. and Schmidt-Kaler.
the Molasse foredeep were overridden and in part scooped out by the Alpine nappe complexes, while its central parts became filled with turbiditic sandwhich
Erdol und Erdgas in Gsterreich. Vienna,
Z.. 93: 36-49.
Sicht. Erdol-Erdgas K.
15 (3): 3.4.1-33-34.
tions. During the Oligocene and Miocene final phases of the Alpine orogeny, the southernmost parts of
K., 1977. Die &- und Gasexploration
I VW f.t.&m~
the area of part
Massif. The latest Cretaceous phase
in the Alpine foreland--a