The opening of the Neo-Tethys started in the Middle Anisian and is
recorded in the drowning succession of the shallow-water Ravni/Steinalm
Carbonate Ramp and the subsequent deposition of deep-marine limestones,
e.g., the red nodular limestones of the Bulog Group and equivalents. In the
Inner Dinarides of southwest Serbia the continental break-up of the Neo-
Tethys Ocean is characterized by the formation of a horst-and-graben
topography. The change from deposition of shallow-water carbonates formed
in an epicontinental sea (graben stage of the Neo-Tethys Wilson Cycle) to red
nodular deep-marine limestones (Bulog Limestone) in the late Pelsonian
(Middle Anisian) is relatively abrupt due to the rapid decrease of carbonate
production. The deeper-water Bulog Limestone, deposited in the early stage
of the passive continental margin evolution of the western Neo-Tethys can be
dated by conodonts and in rare cases also by ammonoids quite exactly, and
therefore it is possible to reconstruct the Pelsonian to Illyrian sedimentological
evolution precisely: 1) The late Pelsonian is characterized by the drowning of
the shallow-water Ravni Carbonate Ramp and a rapid deepening of the
depositional realm. Extension led to the formation of neptunian dikes in the
shallow-water Ravni Formation, filled with deeper-marine red micrite, and
the formation of a horst-and-graben morphology. Whereas some of the horsts
uplifted and emerged in the grabens near to the newly formed escarpments
thick breccia successions were deposited with a fining-upward trend during
the early-middle Illyrian. On top of other horsts, the grabens, or the newly
formed gentle slopes red nodular limestones were deposited. In cases layers
with enriched ammonoids formed (Fossillagerstätten). 2) The early-middle
Illyrian ongoing subsidence resulted in the deposition of more and more
condensed red nodular limestones with hardground formation. 3) Around the
middle/late Illyrian boundary a new pulse of tectonic motions resulted in the
tilting of blocks, the formation of new escarpments and again mobilization of
mass transport deposits. In addition, a second generation of neptunian dikes
was formed. They crosscut the late Pelsonian to middle Illyrian Bulog
Limestone, the Pelsonian Ravni Formation, and the older generation of
neptunian dikes in the shallow-water Ravni Formation. All formerly emerged