Jaroslav M. Gutak

Bio: Jaroslav M. Gutak is an academic researcher from Siberian State Industrial University. The author has contributed to research in topics: Devonian & Geopark. The author has an hindex of 4, co-authored 5 publications receiving 111 citations.

Notable Glaciokarsts of the World

Abstract: In this chapter, notable glaciokarsts of the world are presented. Geographical location, geologic and tectonic settings, climatic conditions, glaciation phases as well as surface and underground karst landforms are presented about each selected region. Obviously, the areal extent, the degree of exploration and the amount of publicly available information are different in each case. Historically, the first glaciokarst studies were based on the Alps, the Pyrenees, the Dinaric Alps and the British Isles, and they have remained in the focus since then. Hence, these regions are presented here in more detail, but even these presentations can be considered only short overviews. Some other glaciokarst terrains, such as Scandinavia or the Rocky Mountains, have also been thoroughly studied but later in history; nevertheless, there are abundant internationally available publications about them. Certain parts of the Balkan Peninsula, the Apennines or even Anatolia received high attention more recently and novel methods have been used to investigate their glaciokarst terrains. The Carpathians and the Appalachians, which are also discussed in this chapter, are extensively studied mountains in general, but glaciokarsts occupy a relatively small proportion in them. On the other hand, there are still regions, which are difficult to access, where glaciokarsts are poorly explored, and/or the available literature is limited (or the publications are only in Russian, for instance). Some of them, namely, the Altai Mountains, the Greater Caucasus, the Tian Shan, the Pamir and the Patagonian archipelago, are also briefly presented here. Finally, it is noted that our selection does not contain all glaciokarsts of the world because it is beyond the scope of this chapter.

New Marine Geoheritage from the Russian Altai

Abstract: Marine geoheritage comprises unique geological features of modern and ancient seas and oceans. The Russian Altai (southern Siberia) is a vast and geologically rich area, which was covered by a marginal sea of the Panthalassa Ocean in the Devonian. New geosites representing shallow- and deep-marine depositional environments and palaeoecosystems of submarine volcano slopes are proposed, namely, Melnichnye Sopki and Zavodskie Sopki. They are located near the town of Zmeinogorsk (Altai Region of the Russian Federation). These pieces of marine geoheritage are valuable on an international scale. Special geoconservation procedures are recommended to manage the proposed geosites efficiently. They can be included in a geopark, which is reasonable to create due to the concentration of geological and mining heritage in the study area.

The global Hangenberg Crisis (Devonian–Carboniferous transition): review of a first-order mass extinction

Abstract: Abstract The global Hangenberg Crisis near the Devonian–Carboniferous boundary (DCB) represents a mass extinction that is of the same scale as the so-called ‘Big Five’ first-order Phanerozoic events. It played an important role in the evolution of many faunal groups and destroyed complete ecosystems but affected marine and terrestrial environments at slightly different times within a short time span of c. 100–300 kyr. The lower crisis interval in the uppermost Famennian started as a prelude with a minor eustatic sea-level fall, followed rather abruptly by pantropically widespread black shale deposition (Hangenberg Black Shale and equivalents). This transgressive and hypoxic/anoxic phase coincided with a global carbonate crisis and perturbation of the global carbon cycle as evidenced by a distinctive positive carbon isotope excursion, probably as a consequence of climate/salinity-driven oceanic overturns and outer-shelf eutrophication. It is the main extinction level for marine biota, especially for ammonoids, trilobites, conodonts, stromatoporoids, corals, some sharks, and deeper-water ostracodes, but probably also for placoderms, chitinozoans and early tetrapods. Extinction rates were lower for brachiopods, neritic ostracodes, bryozoans and echinoderms. Extinction patterns were similar in widely separate basins of the western and eastern Prototethys, while a contemporaneous marine macrofauna record from high latitudes is missing altogether. The middle crisis interval is characterized by a gradual but major eustatic sea-level fall, probably in the scale of more than 100 m, that caused the progradation of shallow-water siliciclastics (Hangenberg Sandstone and equivalents) and produced widespread unconformities due to reworking and non-deposition. The glacio-eustatic origin of this global regression is proven by miospore correlation with widespread diamictites of South America and South and North Africa, and by the evidence for significant tropical mountain glaciers in eastern North America. This isolated and short-lived plunge from global greenhouse into icehouse conditions may follow the significant drawdown of atmospheric CO2 levels due to the prior massive burial of organic carbon during the global deposition of black shales. Increased carbon recycling by intensified terrestrial erosion in combination with the arrested burial of carbonates may have led to a gradual rise of CO2 levels, re-warming, and a parallel increase in the influx of land-derived nutrients. The upper crisis interval in the uppermost Famennian is characterized by initial post-glacial transgression and a second global carbon isotope spike, as well as by opportunistic faunal blooms and the early re-radiation of several fossil groups. Minor reworking events and unconformities give evidence for continuing smaller-scale oscillations of sea-level and palaeoclimate. These may explain the terrestrial floral change near the Famennian–Tournaisian boundary and contemporaneous, evolutionarily highly significant extinctions of survivors of the main crisis. Still poorly understood small-scale events wiped out the last clymeniid ammonoids, phacopid trilobites, placoderms and some widespread brachiopod and foraminiferan groups. The post-crisis interval in the lower Tournaisian is marked by continuing eustatic rise (e.g. flooding of the Old Red Continent), and significant radiations in a renewed greenhouse time. But the recovery had not yet reached the pre-crisis level when it was suddenly interrupted by the global, second-order Lower Alum Shale Event at the base of the middle Tournaisian.

Types of carbonate platforms : a genetic approach

Abstract: Many types of carbonate platforms have been described, from homoclinal ramps to rimmed shelves and a full spectrum of variations in between; the distinction between these different types can be problematic. Nevertheless, classification of carbonate platforms is not just a semantic or academic issue. For example, it is clearly important for the accurate interpretation of seismic images of facies geometry and for assessing the potential of stratigraphic traps. Even though predictive efficiency of conceptual models depends on the degree of comprehension of the genetic factors controlling depositional profiles and the distribution of facies belts, current models for classification of carbonate platforms are basically descriptive and mainly based on depositional profile, size, and attachment to or detachment from a landmass. A genetic approach considers the variability of depositional profiles among carbonate platforms as a function of the type of sediment that was produced (basically grain size), the locus of sediment production, and the hydraulic energy. Three groups of carbonate-producing biota may be distinguished according to their dependence upon light: (1) euphotic (good light) in shallow, wave-agitated areas; (2) oligophotic (poor light) in deeper, commonly non-wave-agitated areas; and (3) photo-independent biota in all water-depth ranges. Several platform types in wave-dominated seas can be considered in relation to genetic factors, even when simplifying the many possible scenarios. Euphotic framework-producing biota create rimmed shelves similar to modern reef platforms. Soft-substrate-dwelling biota, which produce gravel-sized carbonate in the shallow euphotic zone, create flat-topped open shelves. Oligophotic gravel-producing biota, such as some larger foraminifera and red algae, generate distally steepened ramps. Mud-dominated carbonate production, in either euphotic or oligophotic zones, generate homoclinal ramps. Carbonate production dominated by photo-independent biota (crinoids, sponges, bryozoans, etc.) above wave base give rise to open shelves or ramps, depending upon grain size, but may produce mounds if carbonate production occurs below the base of wave/current sweeping.