ROLE OF SUPPLY IN LACUSTRINE SEQUENCES:
THE CASE OF THE PANONIAN BASIN
The project includes a number of research
activities focussed in the understanding of the role of supply
in building the sequence architecture using the case-study
of the Panonian Basin and in identifying the specificity of
sequence stratigraphy in deep lakes as compared to the classical
sequence stratigraphy models.
These activities are grouped in three interrelated
MODULES:
MODULE 1 (University of Texas at Austin, Utrecht University)
PHYSICAL EXPERIMENT: ROLE OF SUPPLY ON SHELF
EDGE INCISION
This physical experiment is run in sedimentological
laboratory at the University of Utrecht. The concept of the
experiment is to test hypotheses regarding the relative importance
of sediment supply and base-level fall in the generation of
incised versus non-incised configurations at the shelf edge,
in the generation of turbidity currents on the shelf margin.
The experiment is supervised by Ron Steel (University of Texas,
Austin), George Postma (University of Utrecht) and Piret Plink-Bjorklund
(University of Gothenburg).
The key aspect of the work is to see if we
can, with physical experiments, dampen the tendency for incision
in river channels at the shelf edge, by increasing sediment/water
ratio in the shelf edge discharge and/or suspended sediment
concentration in this discharge. The likelihood that this
happens has been already suggested by numerical experiments,
and by field observations on Eocene shelf margins on Spitsbergen.
The importance of the work is that it will open for alternative
scenarios to the conventional belief that incision or lack
of incision at the shelf edge is due primarily to magnitude
of sea-level fall at and below the shelf edge.
MODULE 2 (Eötvös University Budapest, University
of Texas at Austin)
PANNONIAN BASIN SEQUENCE STRATIGRAPHY
The high level of existing work on sequence
stratigraphy stratigraphy analysis in the Pannonian basin-fill
provides an excellent natural laboratory for testing the applicability
of the results from the analogue experiments in Utrecht. In
general, the possible changes on sequence pattern associated
with the changes from marine to fresh water conditions within
the Pannonian basin are examined. More specifically, in the
interpretation of the Pannonian clinoform details, the following
three aspects is weighted:
1. Application of the Utrecht
experimental results in terms of whether the lake-basin turbidites
are generating shelf-break-attached sheets (little or no incision)
or are by-passing the slope in channels/canyons to generate
basin-floor fans/lobes.
2. A general re-consideration
of the sequence stratigraphic methodology as applied to deep-lake
basins. It is known that sediment supply and base level are
much more closely tied to each other in lake basins than in
open-marine basins, and that climate is more directly affecting
lakes than it does the open sea. This is likely to have an
important effect on the development of systems tracts in the
lake basin. In the sediment supply model, close attention
will be paid to when sediment discharge is likely to have
been maximum (during early lake-level rise?) and where waxing
and waning of discharge occurs in the base-level cycle. It
is also investigated how realistic it is to have a well-developed
highstand systems tract in lake basins (when lake level is
highest and initially falling, fluvial input may be lowest).
3. Construction of a general
sequence-stratigraphic model for deep-lake basins, by using
1) and 2) above, together with an analysis of the Pannonian
clinoform architectures and trajectories. In building the
general model an attempt is made to incorporate literature
data and ideas from other areas such as the Caspian, from
Laramide lake basins in USA, and from Chinese basins.
MODULE 3 (Eötvös University Budapest)
THE TISZA ALLUVIAL PLAIN
This module is designed as a complement to
MODULE 2, but also as an introduction to a project which may
be further developed in the next future. The aim is the understanding
of the recent and sub-recent conditions of climate, hinterland
drainage, changes in supply, rate of aggradation, and fluvial
regime prevailing at the Pannonian basin with particular focus
at the Tisza alluvial plain. The recent and sub-recent picture
of the observable conditions may be used as analogue to other
time slices from older sequences analyzed in MODULE 2.
In addition, the study contributes to the
reconstruction of the paleogeographic conditions during the
latest stage filling up of the Pannonian basin system, and
illustrates the transition from aggrading to degrading conditions
during late Quaternary to Holocene times.
The work is principally based on literature
analysis, making also use of the detailed available data and
knowledge so far acquired by our Institute on the Tisza river
system.
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