The sedimentological interpretation
of seismic and borehole data derived from the Burdigalian Upper Marine
Molasse Group of the central North Alpine foreland basin enables a detailed
reconstruction of the shallow-marine architecture. The different seismic
facies are assigned to the shoreface/foreshore, nearshore, and offshore
depositional systems. Mapping of the seismic facies on the seismic line
reveals the presence of two prograding sequences (Luzern and St. Gallen
formations) that are separated by an unconformity.
The subsidence analysis suggests that the
evolution of the Upper Marine Molasse was primarily controlled by the interaction
between tectonic subsidence and sediment supply. The distal transgressions
of the Luzern and St. Gallen formations and the establishment of shallow-marine
environments were caused by enhanced subsidence rates in the distal reaches
associated with increased sediment supply rates. The development of the
sequence boundaries separating the Luzern and St. Gallen formations and
the regression at the end of the St. Gallen Formation, however, were controlled
by uplift in the distal part of the basin.
The subsidence and sediment flux analyses
of the Upper Marine Molasse allow an improved understanding of the tectonic
and denudation history of
1997. The American Association of Petroleum Geologists. All rights reserved.
1Manuscript received March
28, 1996; revised manuscript received October 16, 1996; final acceptance
February 24, 1997.
2Geologisches Institut, Universität
Bern, Baltzerstrasse 1, CH-3012 Bern, Switzerland. Present address: Friedrich-Schiller
Universität Jena, Institut für Geowissenschaften, 07749 Jena,
3Geoform AG, 8401 Winterthur,
4Geologisches Institut, Universität
Bern, Baltzerstrasse 1, CH-3012 Bern, Switzerland.
This project was
supported by the Swiss National Science Foundation (grant no. 21-36219.91).
We would like to thank B. Keller (Menggis and Lorenz, Luzern, Switzerland),
A. Pfiffner, J. Màtyàs, G. Schreuers, O. Kempf, P. Strunck
(University of Bern, Switzerland), and N. Ussami (University of São
Paulo, Brazil) for fruitful discussions. The critical review of T. E. Jordan
(Cornell University, Ithaca, New York) is kindly acknowledged. Thanks go
to SEAG (Schweizerische Erdöl AG) for allowing us to publish lines
8307 and 7525, as well as the geophysical and mud-log data of the Hünenberg
1 and Boswil 1 wells.