Onset of Maikop sedimentation in the Talysh (Azerbaijan): climate or tectonics?

Onset of Maikop sedimentation in the Talysh (Azerbaijan): climate or tectonics?

van der Boon, A.

Molengraaff Fonds

2012

The Maikop series are composed of a thick succession of black shales, and are considered the most important source rock for hydrocarbons in the Caspian basin. The type section of this formation is located near the city of Maykop in Russia, north of the Greater Caucasus. Corresponding anoxic sediments can be traced in a vast area from Austria to China. Deposition of these sediments is linked to anoxic conditions that prevailed since the birth of the Paratethys and are related to decreased basin circulation. Due to the lack of (micro) organisms or ash layers, the onset of Maikop deposition has not been dated accurately so far. The Maikop is presently assumed to be of Oligocene to Miocene age. Precise dating of the start of Maikop sedimentation could aid in understanding the role of tectonics and climate change on the onset of anoxia in the Paratethys basin, as both have affected the region during the Paleogene. The Arabia-Eurasia collision has caused uplift, which could have caused a restriction in interaction with the Tethys Sea further south. Alternatively, basin restriction might have been caused by a major glacio-eustatic regression, associated with the transition from greenhouse to icehouse climate around the Eocene-Oligocene transition (EOT). In the Talysh, the mudstone-dominated sedimentary succession of the Pirembel formation is over 1.5 kilometers thick. This formation is generally interpreted as the lower part of the Maikop series. A multidisciplinary stratigraphic approach is used in this study, integrating magneto- and biostratigraphy of the transition to the Pirembel formation, combined with radiometric dating and geochemical analyses of the volcanic formation that underlies the Pirembel formation.

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Utrecht University

Geoscience Reports

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