Research of Chris van Baak
Mediterranean-Paratethys connectivity during the late Miocene to Recent
The Black Sea and Caspian Sea are the present-day remnants of the former Paratethys, a large epicontinental sea that spanned large parts of continental Eurasia. Hydrological interactions between these seas in the Eurasian continental interior and with adjacent seas (e.g. Mediterranean Sea) are determined by the hydrological budget and connectivity through shallow marine gateways.
The high sensitivity of these seas to changes in the hydrological budget has resulted in a very dynamic sea-level history. This has resulted in frequent changes in salinity and especially in the Caspian Sea, large variations in surface area. However, a process-based understanding of forcing mechanisms and environmental impacts of these major sea-level variations is severely hampered by a lack of high-resolution age constraints.
Unraveling geodynamic and paleoclimatic causes of sea-level change in semi-isolated basins
For my project I use high-resolution geochronology together with integrated stratigraphy and paleomagnetism to:
a) unravel internal (geodynamics, tectonic uplift/subsidence) from external (climate, glacio-eustatic sea-level change) forcing factors and
b) to resolve the effects of Paratethys restriction (regional climate perturbations, biotic crises, aridification).
The key to my project is to first establish a detailed chronologic framework for the Late Miocene and Plio-Pleisotocene successions of the Black Sea and Caspian Sea. This will be used to unravel the tectonic and climatic changes that seriously affected the Eastern Paratethys region. Such a multi-disciplinary approach is the only way to attain a comprehensive system view on Paratethys evolution.
Samples are obtained by doing fieldwork throughout Paratethys, focusing on the main sub-basins, the Dacian Basin in Romania, the Black Sea (Russia and DSDP) and the South Caspian Basin (Azerbaijan). Fieldwork is done together with partners in these countries, adding local expertise to our chronostratigraphic framework.
The following topics are studied for a time period when progressive sea retreat and variations in interbasinal connectivity generated extreme environmental changes throughout the Paratethys domain:
1) Paratethys-Mediterranean co-evolution during the Messinian salinity crisisThe Messinian salinity crisis (MSC) in the Mediterranean Sea (5.97-5.33 Ma) is increasingly better understood but one vital aspect is still missing: the role of Paratethys on the hydrological budget of the Mediterranean. Paratethys at the time forms a brackish-marine basin of similar surface area to the Mediterranean. Immediately prior to the MSC, a marine connection is created between Paratethys and the Mediterranean which lasts throughout most of the MSC.
My project provides new age constraints throughout Paratethys which enable bed-to-bed correlations to the Mediterranean. Based on these age constraints, we assess the paradigm of dessicating Paratethyan basins caused by the Messinian salinity crisis.
Field locations: Azerbijan, Russia, DSDP site 380A and 381 (Black Sea), Romania
Adzhiveli section in the Gobustan region of Azerbaijan, a key section for both the Late Miocene and Pliocene South Caspian Basin.
2) Age constraints for the Pliocene Productive Series, South Caspian Basin (Azerbaijan)During the Pliocene up to 5 km of fluvio-deltaic sediments are deposited in the South Caspian Basin. These deposits form the main reservoir intervals in the South Caspian oil-producing region. Time constraints are however difficult to obtain because of the general lack of fauna and therefore the sedimentary succession is subdivided into lithostratigraphic units. Magnetostratigraphy provides an excellent tool to create a high-resolution time frame for these deposits. Our chronostratigraphic constaints not only allow us to subdivide Pliocene Productive Series, but also provide new insights on the onset and termination of these fluvio-lacustrine deposits in the South Caspian Basin.
Field locations: Azerbaijan (Apsheron Peninsula, Gobustan region, Kura basin)
Jeirankechmez section with Plio-Pleistocene deposits of the Productive Series and Akchagyl.
3) Plio-Pleistocene sea-level change in the Black Sea and Caspian Sea: Climate or tectonics?Global climatic changes in the Plio-Pleistocene from the mid-Pliocene warm period into Pleistocene northern hemisphere glaciations cause rapid and dramatic palaeoenvironmental changes in the Black Sea and Caspian Sea. Global sea-level fluctuations cause the repeated isolation from, and reconnection with the Mediterranean Sea, causing sea-level to be dependent on the local hydrological budget. The formation of continental glaciations directs meltwater directly into the Paratethyan basins once ice sheets penetrate the drainage basin. At the same time, tectonic activity in the Bosporus region changes the elevation of the sill-level to the Mediterranean. An understanding of these processes on palaeoenvironment for long time scales is however generally lacking because of the lack of high-resolution age constraints.
Increased understanding and new paleomagnetic techniques allow for the first time to date DSDP records in the Black Sea. Together with age constraints from land-based sections we create a chronostratigraphic framework for the Plio-Pleistocene of the Black Sea and Caspian Sea.
Field locations: Azerbijan, DSDP sites 379A and 380/380A (Black Sea), Romania
Drilling samples in Bulgaria.