Saturday, October 18, 2008

Field work preparations

These days I am doing my preparations for my mapping project. Usually one of the first things I do when going to an area I have not previously visited nor read much about is to learn the local stratigraphy, especially the lithostratigraphy. Knowing the terms and formation names makes it a lot easier to orientate in the literature and usually already gives a good, general clue about what kind of lithology I can expect to encounter in the field.

Lithostratigraphic Overview of Baden-Württemberg [5. Ausgabe Jan. 2004 (1. Ausg.1999), Bearbeiter: M. FRANZ & E. VILLINGER]

Above is an overview of the lithostratigraphy of the German state of Baden-Württemberg. In a simplified manner it can be subdivided into three lithostratigraphic areas, each with a slightly different sedimentation history in the Jurassic. You will notice simply by comparing the formation names that the three areas are starting to develop a divergent sedimentation regime sometime in the Upper Bajocian (Bajocium). I highlighted the lithostratigraphy relevant for my own mapping and placed a special emphasis on the Hauptrogenstein-Formation (a oolithic limestone complex) and the Opalinuston-Formation (mainly mudstones) which are the main targets and formations within my mapping area. The Opalinuston-Formation is named after the ammonite Leioceras opalinum (Reinecke, 1818). Hauptrogenstein means as much as "Main Fry Stone" referring to the similarity of the ooliths to fish eggs. The Hauptrogenstein can be sub-divided into Lower, Middle and Upper Hauptrogenstein and has a thickness of roughly 40 to 80 m in the Southern Upper Rhine graben region.

Overviews on the local stratigraphy can be freely downloaded on the website of the Landesamt für Geologie, Rohstoffe and Bergbau von Baden-Württemberg [State Office of Geology, Resources and Mining of the State of Baden-Württemberg].

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