Squeezed diapirs of the Chernyshev Swell (the Timan Pechora Basin): integrated study and petroleum habitat

A multidisciplinary study including 2D and 3D seismic surveying, magnetotelluric, gravimetric, and magnetometric measurements was conducted to unravel the geological structure of the Chernyshev Swell's and the adjacent areas of the Kosyu-Rogov Foredeep Basin. Integrated interpretation of these data and vintage information allowed the introduction of a new concept of this areas' structural development. It suggests that the structural evolution was largely influenced by the diapirism of the Upper Ordovician salt. The salt started to move towards the Chernyshev Swell from the Kosyu-Rogov Foredeep Basin with the development of diapiric walls as early as the Silurian. The salt walls underwent compression during the Uralian collisional folding from the second half of the Artinskian age. It resulted in the squeezing of the diapirs and salt's extrusion to the surface, followed by extensive thrusting. The salt-related deformations continued throughout the Mesozoic and Cenozoic activated by the intraplate stresses. The study area's structural evolution created favourable conditions for the development of a large oil and gas trap in the 3-way structural closure juxtaposed against the thrust zone. It includes regionally productive suprasalt Silu-rian-Permian deposits sealed updip by the allochthonous salt. © 2021, VNIGNI-2 OOO. All rights reserved

Syntaxonomy and biogeography of the Irano-Turanian mires and springs

Aims: To develop the first comprehensive syntaxonomic classification for patchy montane mire and spring vegetation across the Irano-Turanian phytogeographical region in Iran, Tajikistan and Kyrgyzstan and to explore the effects of the main environmental and geographic gradients on their distribution. Location: Alborz Mountain range (Iran), Pamir-Alai Mountains (Tajikistan) and Tian Shan Mountains (Kyrgyzstan); total area of about 3,000,000 km2. Methods: A database of 1,015 vegetation relevés including a total of 675 vascular and bryophyte taxa was established, covering the large mountains ranges of the Irano-Turanian regions in Iran, Tajikistan and Kyrgyzstan, at altitude ranging from 1,300 to 4,505 m a.s.l. A semi-supervised k-means analysis was performed. Additional analyses were carried out to show differences among predefined vegetation groups in terms of phytogeographical, climatic and compositional factors. Results: Two large groups of mire communities, referable to mires and springs were identified. Twenty associations, one subassociation and four alliances of these wetlands, belonging to three orders and three classes, were defined. Among them, ten associations, one subassociation and two alliances were formally described as new syntaxa. Moreover, a new order Caricetalia orbicularis, that comprises phytogeographically unique vegetation of the Irano-Turanian mires, is proposed. Conclusions: Based on our results and comparison between the Irano-Turanian and other phytogeographical regions, we propose a first comprehensive syntaxonomic synopsis for the IranoTuranian mires and springs. Despite some identical character species and their vicariant nature, the Irano-Turanian, Euro-Siberian and Mediterranean mires and springs show considerable compositional differences. Irano-Turanian wetlands contain a large and distinct set of endemic plant species, which are mixed with Euro-Siberian species in the west and north, but predominate in the eastern locations. They have patchy pattern and scattered distribution and serve as inland hotspots of wetland vegetation in the vast dry landscape of SW and Central Asia