KOCH, R., HORNUNG, T., PFEIFENBERGER, S., WAGNER, K., WEISS, CH. (2003)
im Kimmeridge 1-3 der Nördlichen Frankenalb
(Exkursion F am 24. April 2003)
transitions in the Kimmeridgian 1-3 of the Northern Franconian Switzerland
(Field trip F, 24. April 2003)
The Upper Jurassic of Southern
Germany with a maximum thickness of 500 metres was studied for over 110 years,
but already in the past 20 years modern sedimentological-facies and paleontological investigations became established.
The "classic" differentiation into "massive limestones" (= Bioherms or reef-facies) and "well-bedded limestones"
(= "Normal facies") was broadened into new sedimentological-ecological approaches like reef-evolution, reef-genesis,
biogenous sedimentation, etc. (bibliography of new datasets see in the publication).
With regard to present data, the "conservative" postulate of the Ries-Wiesent-Reef as a "facies-barrier" between
the marl-dominating franconian basin and the franconian-swabian carbonate platform ought to be disproved: the
crucial point of the new interpretation concerning the genesis of unbedded limestones is the discovered occurrence
of a peloid-lithoclast-ooidal sandy facies, associated in small basins with spongial reefal buildups. The concept of
the greater marl-dominating Franconian basins could be integrated within this new thesis, validated for the
Franconian and the Swabian area.
This model has a close relationship to the genesis of present shallow marine carbonate platforms and shelves. Thus,
advisements about exploration of these limestones - like in other stratigraphic formations - might be adequate and
considerable. With this knowledge, technical patterns of different facies variations like pure carbonates and dolomites
can be explained better and more effective, also in terms of diagenesis of building and nature stones.
Based on this new approach, several research groups of different universities and geological surveys are engaged
with realization into practice very successfully.
|published in: Jber. Mitt. oberrhein. Geol. Ver. N.F. 85: 169-203, Stuttgart.|