The proposed Joint Research Project (JRP) is a state-of-the-art study of one of the most intriguing and controversial topics in Earth Sciences: the mass extinction that occurred at the end of the Permian period, approximately 250 million years (Ma) ago, which was the most devastating loss of life in Earth's history. The geochemical records of the biotic crisis of the Permian-Triassic (P/Tr) transition, 251.4±0.3 Ma, encompass large positive and negative secular excursions in the carbonate and organic carbon, sulfur, and strontium isotope abundances, changes in the concentrations of redox-sensitive elements, as well as in abundance and carbon isotope composition of biomarker hydrocarbons. Open sections with continuous sedimentation along the Permian-Triassic transition are rare, but their study is of great value for understanding the causes and effects of the P/Tr environmental changes. Such complete successions occur in some regions of Croatia.
The proposed JRP addresses the causes of the P/Tr biotic crisis by using combined biogeochemical molecular and isotopic data from sedimentologically, stratigraphically and palaeontologically characterized sedimentary rocks. The main field study will examine Upper Permian to Lower Triassic deposits in the Velebit Mt., SW Croatia. In this region, approximately 900 meters thick carbonate sequence, deposited from the Middle Permian up to the earliest Triassic (~270-251 Ma), was the ancestor of the Mesozoic Adriatic Carbonate Platform (AdCP). Geological studies in the Velebit Mt. were interrupted almost 15 years ago due to war activities. A JRP will help to relive this research, taking advantage of an ongoing project of the Croatian Geological Survey and the National Oil Company (INA-Naftaplin) on a geological reconnaissance profile across this part of the former AdCP foundation. Three other Croatian reference P/Tr sections (Evaporitic Complex of Central Dinarides, Gorski Kotar region, and Samoborska Gora Mt.) characterized by a range of shallow marine depositional environments (subtidal to supratidal) will be studied. The new data set, based on carbonate and associated organic carbon isotope composition, and the abundance and carbon isotope composition of diagnostic hydrocarbon biomarkers, will provide an excellent opportunity to study the interrelationships of depositional facies, diagenetic alteration patterns, biological and palaeoenvironmental changes, and ultimately petroleum potential. In particular, the comparison of the molecular and isotopic biogeochemistry with published and additional sedimentological and palaeontological information over a range of deposits of comparable age within the neighboring countries (Slovenia, Hungary) should allow to discriminate local palaeoenvironmental signals from those due to the global secular changes.
The project joins and combines capabilities and expertise of sedimentologists, palaeontologists, petroleum geologists, mineralogists and geochemists, stimulating efforts of young researchers through strengthening an interdisciplinary research.
In a global scale, the understanding of the biogeochemical carbon cycle, the production and consumption of carbon dioxide and methane, as well as the correlation of biogeochemical changes, with biotic and climatic changes of the P/Tr transition provide a suitable platform against which the potential for future changes in greenhouse gas concentrations as a consequence of anthropogenic activity and their impact on climate and life can be assessed.