Palaeozoic and Mesozoic Geological Development in Bosnia and Herzegovina

The Geological Foundation of Bosnia and Herzegovina

Sediments were fractured and collected. The deposition of Silurian sediments, which subsequently serve as the basis for all other geological strata and the relief of Bosnia and Herzegovina, ceased more than 400 million years ago. Upon this Silurian base, layers from the early and late Palaeozoic era (i.e., the Devonian and Carboniferous periods) were deposited in the same ocean basin.

Palaeozoic Sediments: Composition and Distribution

The Palaeozoic sediments are presented mostly as clastic and less commonly as carbonate formations, which are metamorphosed in some places. Palaeozoic sediments can mainly be found in the following regions:

• The Una-Sana area
• The Central Bosnian Schist Mountains
• Eastern and south-eastern Bosnia
• The Posavina and Motajica regions

The Central Bosnian Palaeozoic complex stretches from the Ivan Saddle in the southeast to the northwest of Jajce, situated between the Sarajevo-Zenica basins in the northeast and the Gornji Vrbas-Uskoplje basin in the southwest.

Regional Palaeozoic Complexes

The Praćanski Palaeozoic

The Palaeozoic in the southeast Bosnian area is known as the Praćanski Palaeozoic, which extends to the east and northeast of Mount Jahorina toward the Drina River. In the Praćanski Palaeozoic, chalk cliffs from the Devonian era are mainly represented. Besides the Devonian deposits, Carboniferous sediments can also be found.

Drina and Una-Sana Palaeozoic

Northeast of the Praćanski Palaeozoic is the Drina Palaeozoic, which extends from Srebrenica to Zvornik in the Adriatic gulf and the lower stream of Drinjača.

Palaeozoic sediments are also developed in the surrounding areas of Ključ and Sanski Most. This area is called the Una-Sana Palaeozoic. In the Una-Sana Palaeozoic, deposits from the Devonian era are represented in Bosanski Novi and Ljubija. The Carboniferous period consists of different clastics, which include both igneous rocks and minor amounts of dolomite and limestone.

The Mesozoic Orogenic Cycle

The next major era in the evolution of the Earth’s crust in Bosnia and Herzegovina is the Mesozoic Orogenic Cycle, which is divided into three periods:

1. The Triassic
2. The Jurassic
3. The Cretaceous

Sedimentation, tectonic activity, and magmatic changes related to the Mesozoic deposits spanned a period from approximately 220 million to 70 million years ago. Mesozoic sediments are widespread throughout the interior, central, and outer zones of the Dinarides.