The Mesozoic-Cenozoic tectonic evolution of the Greater Caucasus

Abstract

The Greater Caucasus (GC) fold-and-thrust belt lies on the southern deformed edge of the Scythian Platform (SP) and results from the Cenozoic structural inversion of a deep marine Mesozoic basin in response to the northward displacement of the Transcaucasus (lying south of the GC) subsequent to the Arabia-Eurasia collision. A review of existing and newly acquired data has allowed a reconstruction of the GC history through the Mesozoic and Cenozoic eras. In Permo(?)-Triassic times, rifting developed along at least the northern part of the belt. Structural inversion of the basin occurred during the Late Triassic corresponding to the Eo-Cimmerian orogeny, documented SE of the GC and probably linked to the accretion of what are now Iranian terranes along the continental margin. Renewed development of extensional basin formation in the area of the present-day GC began in Sinemurian-Pliensbachian times with rift activity encompassing the Mid-Jurassic. Rifting led to extreme thinning of the underlying continental crust by the Aalenian and concomitant extrusion of mid-ocean ridge basalt lavas. A Bathonian unconformity is observed on both sides of the basin and may either correspond to the end of active rifting and the onset of post-rift basin development or be the record of collision further south along the former Mesozoic active margin. The post-rift phase began with deposition of Late Jurassic platform-type sediments onto the margins and a flysch-like unit in its deeper part, which has transgressed the basin during the Cretaceous and Early Cenozoic. An initial phase of shortening occurred in the Late Eocene under a NE-SW compressional stress regime. A second shortening event that began in the Mid-Miocene (Sarmatian), accompanied by significant uplift of the belt, continues at present. It is related to the final collision of Arabia with Eurasia and led to the development of the present-day south-vergent GC fold-and-thrust belt. Some north-vergent retrothrusts are present in the western GC and a few more in the eastern GC, where a fan-shaped belt can be observed. The mechanisms responsible for the large-scale structure of the belt remain a matter of debate because the deep crustal structure of the GC is not well known. Some (mainly Russian) geoscientists have argued that the GC is an inverted basin squeezed between deep (near)-vertical faults representing the boundaries between the GC and the SP to the north and the GC and the Transcaucasus to the south. Another model, supported in part by the distribution of earthquake hypocentres, proposes the existence of south-vergent thrusts flattening at depth, along which the Transcaucasus plunges beneath the GC and the SP. In this model, a thick-skinned mode of deformation prevailed in the central part of the GC whereas the western and eastern parts display the attributes of thin-skinned fold-and-thrust belts, although, in general, the two styles of deformation coexist along the belt. The present-day high elevation observed only in the central part of the belt would have resulted...

The Middle Jurassic succession in the central sector of the Pieniny Klippen Belt (Sprzycne Creek): implications for the timing of the Czorsztyn Ridge development

“…From a broader paleogeographic perspective, we stress that facies changes at the Aalenian/Bajocian and Early/Late Bajocian boundaries, associated with early tectonic evolution of the Czorsztyn Ridge, coincide with episodes of the 'midCimmerian tectonic event' represented by unconformities, hiatuses and facies changeover in the Tethyan/north PeriTethyan realms and adjoining boreal areas, for example, in the Iberian Basin (García-Frank et al 2008), Paris Basin (Jacquin et al 1998, North Sea (Underhill & Partington 1994), basins of the Caucasus (Saintot et al 2006), Alborz & Kopet-Dagh (Fürsich et al 2009). …”

The First Experience in Diagnosing the Geodynamic Mechanisms of Folding by the Factor Analysis of Folded Structure Parameters (Greater Caucasus)

“…Структуре и истории развития мегантиклино-рия Большого Кавказа посвящено большое число монографий и крупных статей [Milanovsky, Khain, 1963;Milanovsky, 1968;Sholpo, 1978;Dotduyev, 1987;Sholpo et al, 1993;Saintot et al, 2006;Leonov, 2007;Marinin, Rastsvetaev, 2008;Somin, 2011]. Основная альпийская структура внутри Большого Кавказа, имеющая интенсивную складчатость, вытянута относительно узкой полосой (50-65 км) в основном между двумя крупными долгоживущими разлома-ми глубокого заложения -Пшекиш-Тырныаузским на севере и Рача-Лечхумским на юге (рис.…”

“…На основании имеющихся угловых несогласий и перерывов в осадконакоплении многие исследователи [Milanovsky, Khain, 1963;Saintot et al, 2006, Trifonov, Sokolov, 2014и др. ] традиционно считают, что основная альпийская складчатость началась после эоцена и закончилась перед сарматом (средний миоцен).…”

Features of Caucasian Segment of the Alpine-Himalayan Convergence Zone: Geological, Volcanological, Neotectonical, and Geophysical Data

“…Pressure is transmitted from the Arabian to the area of the Greater Caucasus (Arabi-(Arabian-Caucasian syntaxis). The current invasion of the Arabian wedge into the Eurasian plate occurs along the Bitlis-Zagros toward the Greater Caucasus, and its displacement relative to Eurasia takes place at a rate of several centimeters per year (Saintot et al, 2006). Reducing the space between Arabian indenter and Eurasian plate in the LateAlpian time reaches a total of 400 km, but it is unevenly distributed over the area (Leonov, 2007).…”