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1

The power of colour in geoheritage studies and marketing: some tentative reflections

Ruban Dmitry A., Mikhailenko Anna V., Yashalova Natalia N.

Geologos

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2021

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Vol. 27, No. 1

57--65

EN

Colour is a common physical property in exposures of unique geological objects, but is only marginally addressed in geoheritage literature. We here present our point of view on how this feature can be treated in geoheritage studies, with the general aim at setting up a broad discussion. Three functions of colour in geoheritage are outlined, namely geological interpretation (e.g., compositional and genetic peculiarities of sedimentary rocks), higher visibility due to colour contrast and aesthetic attractiveness to geotourists. Assessment of colour at geosites is challenging, especially because of uncertain colour nomenclatures. We propose to focus on colour identification, calculation of the number of colours, qualitative evaluation of colour contrast and comparison of colours of a given geological object to its landscape context. Geoheritage colours may have different meanings to geosite visitors, and colour-emotion associations revealed by national and international studies are important to trace these meanings.

2

Caves as geoheritage resource in remote desert areas: a preliminary evaluation of Djara Cave in the Western Desert of Egypt

Abdel Maksoud Kholoud M., Baghdadi Mahmoud I., Ruban Dmitry A.

Geologos

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2021

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Vol. 27, No. 2

105--113

EN

Caves are rare in northeast Africa and, thus, deserve attention as potential geoheritage objects (geosites). Assessment of Djara Cave and its vicinity (Western Desert, Egypt) has permitted to document unique features, such as the cave itself as a peculiar subsurface landform, speleothems providing data for palaeoenvironmental reconstructions, rock art demonstrating elements of past landscapes, siliceous nodules weathered from Eocene limestones and a network of dry drainage channels indicative of wetter palaeoenvironments. These features are assigned to geomorphological, sedimentological and palaeogeographical types of geoheritage. Djara Cave and its vicinity are proposed as a geosite of national rank; it is vulnerable to anthropogenic stress and needs geoconservation measures and instalment of interpretative signs. This geosite is already popular among tourists, and can be used for further tourism development. More generally, the presence of caves in Egyptian desert areas makes possible the recognition of national speleological heritage that requires special country-level strategies of management.

3

The Nowdan anticline of the Zagros orogen as a geoheritage ‘window’ into the late Mesozoic-Cenozoic evolution of the African-Arabian continental margin

Habibi Tahereh, Ruban Dmitry A., Yashalova Natalia N.

Geologos

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2020

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Vol. 26, No. 1

65--73

EN

Geological heritage can contribute to our understanding of the long-term evolution of important sectors of our planet. Cretaceous–Neogene rocks (chiefly carbonates) crop out in the Nowdan anticline of the Zagros orogen. Field investigations have permitted the establishment of 10 key localities (stratigraphical reference sections) that represent these rocks within this anticline, which is a single large geosite. The formations are related to the main phases in the evolution of the northeastern sector of the African–Arabian continental margin. For instance, carbonate rocks of the Asmari Formation mark changes in the affinity of the study area, from the African–Arabian plate to only the Arabian plate, separated in conjunction with Red Sea rifting during the Oligocene. Information on the palaeogeographical changes is really precious to geoscientists and geotourists alike, and contributes to the great value of the Nowdan anticline geosite. Evidence from the latter, as well as from a few other places (i.e., the Mountainous Adygeya geodiversity hotspot in Russia, the North Coast of São Paulo in Brazil and the possible Gondwanan geopark in Namibia) illustrates the necessity of distinguishing a palaeomapping subtype in palaeogeographical characterisation of geological heritage.

4

The human imprint on the unique geological landscape of the Western Caucasus

Mikhailenko Anna V., Ruban Dmitry A., Zorina Svetlana O., Nikashin Konstantin I., Yashalova Natalia N.

Geologos

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2020

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Vol. 26, No. 3

233--244

EN

Human intervention in the geological environment is commonly thought to pose a threat to geoheritage. However, new information from the Western Caucasus where unique geological features are concentrated in Mountainous Adygeya, implies that man-made features in fact add value to geoheritage. Such features include a lengthy artificial niche in the Guama Gorge, accumulations of large artificial clasts along the road leading to the Lagonaki Highland and the Khadzhokh Quarry with the artificial Red Lake. These contribute to the regional uniqueness of geosites and can be classified as geomorphological, sedimentary, economical and hydro(geo)logical geoheritage types. Interestingly, these artificial features have natural analogues in the study area. Such integrity of local geological landscapes urgently require special interpretations for guided excursions and explanatory panels for correct comprehension of the origin of these unique features on the part of unprepared tourists. Generally, the human imprint on geological landscapes of Mountainous Adygeya is significant and occasionally positive, which makes the entire geodiversity hotspot of special, international interest and an object for further investigations.

5

The siliciclastics/carbonates shift in the Jurassic of the Western Caucasus (central northern Neo-Tethys): reconsidering research over the last 50 years

Ruban Dmitry A.

Geologos

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2019

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Vol. 25, No. 2

153--162

EN

A chain of carbonate platforms evolved in the northern Neo-Tethys during the Late Jurassic, but current knowledge remains incomplete as long as data from several larger regions, such as the Western Caucasus, are not included. In order to fill this gap, it is here suggested to reconsider the information accumulated chiefly during Soviet times. Although these data are too general, they still matter with regard to some regional characteristics and tentative interpretations. Available data on the spatio-temporal distribution of Bajocian-Callovian sedimentary rocks are summarised in a novel way which permits documentation of depositional trends at six representative localities in the Western Caucasus. The extent of the carbonate platform increased at two localities since the Late Callovian and at a third since the Middle Oxfordian. Three additional sites were characterised either by non-deposition or deep-marine sedimentation. The onset of carbonate platform development marked a remarkable shift from chiefly siliciclastic to carbonate deposition, although this event was not sudden everywhere. The Bathonian pulse of tectonic activity, coupled with the eustatic sea level rise, allowed shelves to expand during the Callovian-Oxfordian, with a reduction in siliciclastic input from islands and seawater that became well oxygenated and warmer. These conditions were conducive to biogenic carbonate production, allowing the carbonate platform to expand subsequently.

6

Long-term shoreline shifts on continental blocks during the Bajocian: an updated interpretation based on synthetic stratigraphical and palaeogeographical developments on regional scales

Ruban Dmitry A., Sallam Emad S.

Geologos

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2019

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Vol. 25, No. 1

43--50

EN

Available reconstructions of Jurassic global sea level changes differ and are in need of an update. New stratigraphical charts and palaeogeographical developments for a number of large continental blocks or their portions of these (e.g., Germany, India, northeast Africa, northwest Australia, the Russian Platform and western Siberia) reveal regional long-term shoreline shifts (i.e., transgressions and regressions) during the Bajocian Stage (168.3–170.3 Ma). A comparison of these allows to document only a single coherent feature, namely the earliest Bajocian transgression, in the majority of the continental blocks considered. Undoubtedly, this event was triggered by a eustatic rise. However, long-term shoreline shifts were either weak to absent or differed between the blocks during almost the entire Bajocian, thus providing evidence of the apparent stability of global sea level and the importance of regional tectonic activity as a control mechanism on particular transgressions and regressions. Interestingly, it appears that the earliest Bajocian eustatic rise was a constituent of a long-term eustatic pattern; the nature of this event has yet to be fully understood. Generally, the findings presented here are in better agreement with Anthony Hallam’s view of Jurassic eustasy and question some other global sea level reconstructions.

7

The late Silurian-Middle Devonian long-term eustatic cycle as a possible control on the global generic diversity dynamics of bivalves and gastropods

Ruban Dmitry A.

Geologos

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2013

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Vol. 19, No. 3

193--200

EN

A long-term eustatic cycle (fall and subsequent rise of the global sea level) embraced the late Silurian-Middle Devonian time interval. Potentially, these sea-level changes could drive global biodiversity. The stratigraphic ranges of 204 bivalve genera and 279 gastropod genera included into the famous Sepkoski database allow reconstructing changes in the total diversity and the number of originations and extinctions of these important groups of marine benthic macro- -invertebrates during this interval. None of the recorded parameters coincided with the long-term global sea-level cycle. It cannot be not excluded, however, that the global sea-level changes did not affect the regions favourable for bivalve and gastropod radiation because of regional tectonic mechanisms; neither can it be excluded that the eustatic control persisted together with many other extrinsic and intrinsic controls. Interestingly, the generic diversity of gastropods increased together with a cooling trend, and vice versa. Additionally, the Ludlow, Eifelian, and Givetian biotic crises affected, probably, both fossil groups under study. There was also a coincidence of the relatively high bivalve generic diversity, initial radiation of gastropods and the entire biota, and the diversification of brachiopods with the Early Devonian global sea-level lowstand, and this may be interpreted as evidence of a certain eustatic control on the marine biodiversity.

8

Megaclasts in geoconservation: sedimentological questions, anthropogenic influence, and geotourism potential

Lubova Katrin A., Zayats Pavel P., Ruban Dmitry A., Tiess Günter

Geologos

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2013

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Vol. 19, No. 4

321--335

EN

Megaclasts are sedimentary particles larger than boulders. Their huge size and scattered occurrence make them objects that deserve geological heritage, requiring conservation. Investigation of megaclasts for the purpose faces difficulties because of the distinction between boulders and megaclasts. Local study of Quaternary large stones in Mountainous Adygeja (W Caucasus, SW Russia) suggests ~ 2 m as a suitable size criterion, although only locally. Shape, occurrence, and origin of megaclasts require additional attention. Geoconservation may result in anthropogenic disturbances of the natural landscape through removal of vegetation, access constructions, and restoration. The geotourism potential of megaclasts is partly determined by their huge size and their rare and scattered occurrence. Aesthetic qualities, local legends, and co-occurrence with prehistoric megalithic constructions increase this potential. The Maiden’s Stone in Mountainous Adygeja, which is ~ 35 m long, has been a tourist attraction already for decades. It is an impressive example of geoconconservation and geotourism connected with megaclasts. Generally, megaclasts increase the value (including the scientific importance) of the geological heritage of Mountainous Adygeja, where a geopark might be established.

9

Cenozoic synthem stratigraphic architecture of the SE Brazilian shelf and its global eustatic context: evidence from the Pelotas Basin (offshore Brazil)

Zerfass Geise de Santana dos Anjos, Ruban Dmitry A., Chemale Farid Jr., Zerfass Henrique

Geologos

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2013

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Vol. 19, No. 4

273--290

EN

The Pelotas Basin, located on the SE Brazilian shelf, has evolved since the Aptian. Stratigraphical data from the basin can be used for delineation of the unconformity-bounded units (synthems) on the shelf, which is a first step towards a full understanding of its stratigraphic architecture, evolution, and hydrocarbon potential. Hiatuses in the Cenozoic succession of the Pelotas Basin are established with both biostratigraphic (planktonic foraminifers and calcareous nannofossils) and isotopic (87Sr/86Sr) data. The seven recognised hiatuses are dated respectively as (1) Palaeocene (Danian-Thanetian), (2) Palaeocene/Eocene boundary (Thanetian-Ypresian), (3) Eocene (Ypresian-Lutetian), (4) Eocene-Oligocene (Lutetian-Rupelian), (5) early-late Oligocene (Rupelian-Chattian), (6) early Miocene (Aquitanian-Burdigalian), and (7) middle-late Miocene (Serravallian-Tortonian). These intervals between the hiatuses are correlated with those of the Santos and Campos Basins north from the Pelotas Basin. The breaks in sedimentation that these basins have in common occurred (1) at the Palaeocene-Eocene and (2) Eocene-Oligocene transitions, (3) in the early Miocene, and (4) in the middle-late Miocene. These main unconformities outline five synthems on the SE Brazilian shelf, viz. the SEBS-1 (Palaeocene), SEBS-2 (Eocene), SEBS-3 (Oligocene), SEBS-4 (early-middle Miocene) and SEBS-5 (late Miocene-Holocene). The above unconformities are correlated with those established in the Cenozoic sedimentary successions of different regions such as Western Siberia, Arabia, NW and NE Africa, peninsular India, S Australia, the Gulf of Mexico, NW Europe, and South Africa. The only regional unconformity, near the Oligocene/Miocene boundary, coincides with the nearly-global sedimentation break. The latter was resulted from a climatic event, i.e., the ‘Mi-1 glaciation’. Thus, a eustatic origin is supposed for this regional unconformity. The other regional unconformities also correspond to global sea-level falls (probably with an exception for the Palaeocene/Eocene surface), which suggests that global eustatic movements controlled the development of the regional synthem architecture.

10

Mesozoic mass extinctions and angiosperm radiation: does the molecular clock tell something new?

Ruban Dmitry A.

Geologos

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2012

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Vol. 18, No. 1

37--42

EN

Angiosperms evolved rapidly in the late Mesozoic. Data from the genetic-based approach called ’molecular clock’ permit an evaluation of the radiation of flowering plants through geological time and of the possible influences of Mesozoic mass extinctions. A total of 261 divergence ages of angiosperm families are considered. The radiation of flowering plants peaked in the Albian, early Campanian, and Maastrichtian. From the three late Mesozoic mass extinctions (Jurassic/Cretaceous, Cenomanian/Turonian, and Cretaceous/Palaeogene), only the Cretaceous/Palaeogene event coincided with a significant, abrupt, and long-term decline in angiosperm radiation. If their link will be further proven, this means that global-scale environmental perturbation precluded from many innovations in the development of plants. This decline was, however, not unprecedented in the history of the angiosperms. The implication of data from the molecular clock for evolutionary reconstructions is limited, primarily because this approach deals with only extant lineages.

11

Do partly outdated palaeontological data produce just a noise? An assessment of the Middle Devonian-Mississippian biodiversity dynamics in central Asia on the basis of Soviet-time compilations

Ruban Dmitry A.

Geologos

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2011

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Vol. 17, No. 1

29--47

EN

Interregional tracing of trends and events in the biotic evolution is an important task of modern palaeobiology. In Soviet times (1917-1991), numerous palaeontological data have collected for the territory of Russia and neighbouring U.S.S.R. countries. Later, these data were compiled and published in a series of reference volumes. Although this information cannot be updated in a conventional way, it remains valuable for quantitative analyses, particularly because of its comprehensive and unique character. Assessment of the previously collected data on the stratigraphic distribution of Middle Devonian-Mississippian marine invertebrates in three regions of central Asia (central Kazakhstan, Uzbekistan and Tajikistan) reveals some general patterns of biodiversity dynamics. The total number of genera generally declined during the Givetian-Famennian, whereas a remarkable diversity peak occurred in the Visean. This is consistent with the global pattern and, thus, permits to hypothesize a regional signature of the global trends. Changes in the extinction rate differ, however, between central Asia and the Earth in its entirety, which may be explained particularly by biases in either the regional or the global records. Evidence of the Givetian and Frasnian/Famennian mass extinctions is found in the three regions under study. Results of this tentative study indicate important directions for further research and suggest that central Asia is a highly important domain for studies of mid-Palaeozoic biodiversity dynamics.

12

The challenge of reconstructing the Phanerozoic sea level and the Pacific Basin tectonics

Ruban Dmitry A., Conrad Clinton P., Loon A. J. (Tom)

Geologos

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2010

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Vol. 16, No. 4

235--243

EN

The relationships between the interior dynamics of our planet and global sea level can be unravelled when plate-tectonic reconstructions are available for the entire Earth. A review of global tectonics reveals significant deficiencies in our understanding of the geodynamic evolution of the Pacific (Panthalassa or Proto-Pacific) during the Cambrian-Jurassic time-span. This particular, but major, shortcoming presents a true challenge for modern geoscientists, who are encouraged to produce a detailed plate-tectonic reconstruction of the Pacific for the pre-Cretaceous in order to advance our understanding of Phanerozoic sea-level change. A set of approaches, including geological/geophysical modelling, investigation of accretionary prisms, palaeobiogeographical studies, and careful examination of eustatic sea-level changes, are proposed that will help geoscientists tackle the challenge of understanding how Pacific geodynamics affected global sea level during the Phanerozoic.

13

Stratigraphic evidence of a Late Maeotian (Late Miocene) punctuated transgression in the Tanais Palaeobay (northern part of the Eastern Paratethys, South-West Russia)

Ruban Dmitry A.

Geologos

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2010

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Vol. 16, No. 3

169--181

EN

The Tanais Palaeobay was located in the northern periphery of the eastern Paratethys Sea during the Late Miocene. New data from the Safianovo section (Rostov Dome, South-West of Russia) confirm that skeletal limestones (coquinites) of the Merzhanovskaja Formation belong to the Congeria (Andrusoviconcha) amygdaloides navicula Zone of the upper Upper Maeotian (the Maeotian is a regional chronostratigraphic unit of the Upper Miocene). Correlation of reference sections of these Upper Maeotian deposits within the Rostov Dome results in pattern of the palaeobay transgression, which was punctuated. The relative importance of local and global controls on this trangsression is not yet clear.

14

The survival of megafauna after the end-Pleistocene impact: a lesson from the Cretaceous/Tertiary boundary

Ruban Dmitry A.

Geologos

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2009

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Vol. 15, No. 2

129--132

EN

Survival of Pleistocene megafauna after the hypothesized impact of a bolide during the latest Pleistocene seems to be partly island-centered, whereas the survival of dinosaurs and ammonites after the comparable catastrophe at the Cretaceous/Tertiary boundary seems to have occurred in a fairly haphazard way within the areas affected by the impact. This poses some new questions about the possible mechanism behind the end-Pleistocene extinction, although it does not disprove an impact as a plausible cause.

15

Possible pitfalls in the procedure for paleobiodiversity-dynamics analysis

Ruban Dmitry A., Loon A. J. (Tom)

Geologos

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2008

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Vol. 14, No. 1

37--50

EN

The changes in the diversity of specific taxa during certain parts of the geological past (paleobiodiversity dynamics) can, in principle, be established by counting the number of the fossil taxa present (worldwide or in a specific study area) in rocks dated for the time interval under study. Numerous obstacles are present, however, for instance in the form of lacking field data, disappeared collections, ambiguous identifications, temporary ‘disappearence’ of taxa, and dating problems. One major problem is the fact that, particularly in regional studies in some countries, a local, regional or national chronostratigraphic terminology is used rather than the chronostratigraphy recommended by the International Stratigraphic Commision of the International Union of Geological Sciences. This hampers international correlation and makes precise global paleodiversity-dynamics analyses extremely difficult. A reliable insight into the true paleodiversity dynamics requires not only that the various problems are recognized, but also that their consequences are eliminated or, if this is impossible, minimized. This is particularly important if the effects of mass extinctions on fauna and flora are investigated. Each analysis of paleobiodiversity-dynamics analysis of phenomena related to mass extinctions should therefore try to quantify the impact that missing data or inaccuracies of any kind may have on the final results; such an analysis should, in addition, try to find a solution for the major problems, so as to avoid significant inaccuracies of the calculated values. Large electronic databases can help, since about a decade, to diminish possible errors in diversity estimates. Paleobiodiversity should preferably be expressed in the form of values with a certain band with, indicating the inaccuracy, rather than in the form of exact values.

PL

Zmiany w zróżnicowaniu gatunków w pewnych przedziałach czasu przeszłości geologicznej (dynamika paleo-bioróżnorodności) są z zasady ustalane poprzez zliczanie liczby taksonów skamieniałości (na świecie lub na wybranym obszarze) w skałach datowanych na badany interwał czasowy. Tym niemniej procedura ta napotyka wiele przeszkód, np. w postaci braku danych z jakiegoś obszaru, zagubionych kolekcji, niejednoznacznych identyfikacji, czasowego „zaniku” taksonów czy problemów datowania. Jednym z głównych problemów, zwłaszcza w badaniach regionalnych w niektórych krajach, jest stosowanie lokalnej, regionalnej lub krajowej terminologii chronostratygraficznej, a nie chronostratygrafii rekomendowanej przez Międzynarodową Komisję Stratygraficzną przy Międzynarodowej Unii Nauk Geologicznych. Utrudnia to międzynarodowe korelacje i czyni niezwykle trudnym przeprowadzenie precyzyjnej globalnej analizy dynamiki paleo-bioróżnorodności. Wiarygodny wgląd w prawdziwą dynamikę paleo-bioróżnorodności wymaga nie tylko rozpoznania różnych problemów, ale również wyeliminowania ich konsekwencji, a gdy to niemożliwe, zminimalizowania ich. Jest to szczególnie ważne w przypadku, gdy badane są następstwa masowego wymierania fauny i flory. Dlatego każda analiza dynamiki paleo-bioróżnorodności zjawisk związanych z masowym wymieraniem powinna zawierać próbę ilościowego oszacowania wpływu, jakie brakujące dane lub niedokładności jakiegokolwiek rodzaju mogą wywierać na końcowe wnioski. Taka analiza powinna próbować znaleźć rozwiązanie dla głównych problemów, ażeby uniknąć znaczących niedokładności w obliczonych wartościach. Duże elektroniczne bazy danych, dostępne od około 10 lat, mogą pomóc w zmniejszeniu możliwych błędów przy szacowaniu różnorodności. Najlepiej, gdyby paleo-bioróżnorodność była wyrażana w formie wartości w pewnym zakresie, wskazującym na niedokładność, a nie w formie precyzyjnej wartości.