STRUCTURAL GEOLOGY DIVISION
Presentation 1: An overview on the geodynamic evolution of the Eastern Alps in Europe
Speaker 1: Dr. Martin Reiser, Geological Survey of Austria, Vienna
Location: Online
Date: April 1st, 2021, 12:00-1:00 pm Mountain Time
ABSTRACT 1
The European Alps are a collisional orogen that formed due to the converging movement of the Eurasian and Adriatic plates. Inherited metamorphic imprints and a twofold evolution during the Cretaceous and Cenozoic contribute to the complexity of the Alpine orogen. A first episode of crustal nappe stacking and subsequent metamorphism in the Adriatic plate started in Late Jurassic times, reaching its metamorphic peak around mid-Cretaceous times. This was followed by Late Cretaceous extension and exhumation of high-grade metamorphic units that are nowadays located along an east-west trending zone from the central Eastern Alps towards the east. Permian pegmatites from one of these high-grade units represent one of Europe’s largest lithium deposits. During Late Cretaceous times the Adriatic continental margin experienced a changeover from a passive to an active margin: the Penninic Ocean, a small appendix of the early North Atlantic Ocean separating the Adriatic and Eurasian plates, started to subduct beneath the Adriatic plate. The second chapter of the Alps’ evolution began when the ocean-continent subduction was superseded by continent-continent collision during Palaeogene times. When the European continental margin entered the subduction zone, its sedimentary cover was partially scraped off and incorporated into an accretionary wedge located along the northern margin of the Alps. Other parts of the European margin were subducted and underwent high pressure metamorphism at depths of about 60 km. Slab break-off of the oceanic lithosphere during Eocene times triggered magma generation and rapid uplift of the orogen. Continued shortening was accommodated by north and south vergent thrusts, thus turning the Alps into a doubly vergent orogen. From the Oligocene onwards, the eroded material from the Alps was deposited in large foreland basins, north and south of the Alps. During later stages, the proximal part of these basins was deformed and partially overthrust. In late Oligocene‐Miocene times, slab roll-back of the subducted European plate opened accommodation space towards the east. The thickened crust of the Eastern Alps collapsed and the lower plate was exposed in several tectonic windows, the most prominent being the Tauern window. The main valleys in the Eastern Alps follow large strike-slip faults that were generated in the course of this lateral extrusion. The Vienna Basin, a Neogene pull-apart basin that accommodates about 5.5 km of sediments, provides Austria’s main oil and gas reserves. It is located at the intersection between the Alps, the Carpathians and the Pannonian basin. General uplift of the Eastern Alps that also led to partial erosion of the Neogene sediments in the foreland basins prevailed from Miocene times onwards.
CSPG TECHNICAL DIVISION BIOGRAPHY
Martin is employed at the Austrian Geological Survey, where his primary task is mapping and basic research in crystalline basement rocks of the Austrian Alps. He obtained his PhD in structural geology and thermochronology from the University of Innsbruck. During his PhD and as a Visiting Assistant Professor in Innsbruck he taught classes in geological maps & cross sections, field mapping and GIS systems, as well as summer school courses on the Geology of the Alps for the University of New Orleans. Prior to his employment at the Austrian survey, he conducted several seasons of fieldwork in the Carpathians and Italian Alps.
Presentation 2: From mountain building to orogenic collapse: Cretaceous to Neogene geodynamic evolution of the Dinarides Orogen in the SE Europe
Speaker 2: Dr. Uros Stojadinovic, University of Belgrade, Serbia
Location: Online
Date: April 1st, 2021, 12:00-1:00 pm Mountain Time
ABSTRACT 2
The Dinarides Mountains in the southeastern Europe represent the southern branch of Alps-Carpathians- Dinarides orogenic system. The Dinarides orogen was structured in response to the closure of the Neotethys Ocean located between the continental margins of Adria and Europe (i.e., the Vardar Ocean). Following the Middle Triassic opening of the Vardar oceanic domain, its Late Jurassic–Eocene closure culminated during the latest Jurassic obduction of ophiolites over the continental margin of Adria. The ongoing Cretaceous Adria-Europe convergence led to the E-ward subduction of the remaining Neotethys oceanic lithosphere beneath the European upper plate (i.e., the Sava subduction system). The latest Cretaceous to Eocene Adria-Europe collision resulted in the formation of large foreland-vergent thrusts, associated with the migration of subduction zone by continental accretion. The break-off of the Neotethys slab beneath the Dinarides triggered the Oligocene–Miocene extension which reactivated the inherited thrust contacts as the asymmetric extensional detachments along the entire Dinarides margin. Intermediate depth crustal rocks that were previously buried by the Sava subduction/collision were rapidly exhumed as extensional core-complexes. The large-scale exhumation along the Dinarides margins was coeval with the formation of Pannonian Basin of Central Europe and associated deposition of Neogene sediments in the hanging-wall of genetically related extensional detachments. Such basin-forming tectonics controlled the type petroleum plays, with the traps mainly represented by footwall tilt blocks and horsts developed in the tensional and subsidence domain. The thermal pulse created during the syn-rift cycle of active extensional faulting controlled the surface heat flow in the later post-rift phase of thermal subsidence. The southeastern Pannonian Basin formed over the basement comprised of the Dinarides units has heat flow values that exceed 100 mW/m2. The extension was followed by an overall tectonic inversion that started in the latest Miocene and is presently active. The inversion represents the effect of shortening due to the Adria plate indentation. The
CSPG TECHNICAL DIVISION youngest contractional event created strike-slip faulting, thrusting, and reverse faulting and folding. Such basin-modifying tectonics produced a greater variety of trap types, which include wrench faulted zones and en echelon folds.
BIOGRAPHY
I obtained my PhD degree at VU University Amsterdam, Netherlands in 2014. Since 2016 I am employed at the University of Belgrade, Serbia as assistant professor in dynamic geology. I am a structural geologist and thermochronologist who focuses on the evolution of continental subduction zones, syn-depositional tectonism, kinematics of neotectonic features, and remote sensing analysis of tectonically active areas.
CSPG TECHNICAL DIVISION