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Response to Marks (2025): Contemporary global warming versus climate change in the Holocene

Summerhayes Colin, Head Martin J., Gałuszka Agnieszka, Fiałkiewicz-Kozieł Barbara, Waters Colin N., Robin Libby, Sörlin Sverker, Cearreta Alejandro, Wallenhorst Nathanaël, Zalasiewicz Jan

Przegląd Geologiczny

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2025

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Vol. 73, nr 5

469--476

EN

The Holocene geological record provides the most immediate context for understanding and interpreting the climate of the present and future Earth System. Marks (2025) suggests a Holocene climate steered largely by cyclical solar forcing, and that modern warming, driven by increased solar activity, will be replaced within the coming 3 kyr by cooling almost everywhere. This view contrasts with palaeoclimate data, instrumental records, an understanding of climate drivers and feedbacks, and global and regional climate modelling studies, which show that Holocene climate was largely controlled by slow Milankovitch-related changes. Superimposed on these were minor solar fluctuations with a higher frequency. Solar activity was at the same ‘high’ level in the 1780s, 1860s and 1980s, making it a highly unlikely cause of recent warming. Modern global warming has two main drivers: 1) anthropogenic greenhouse gases, which rose steeply after 1950; and 2) both water vapour, which increases as the ocean warms, and clouds. Atmospheric CO2 levels are higher than at any other time since the Middle Miocene, making global temperatures warmer than any multi-century interval since the Last Interglacial. Earth ’s climate has left its equable Holocene state. The long residence time of CO2 ensures persistent warming for tens of millennia.

2

Response to Dąbski (2025) : Global climate change, CO2 and climatic catastrophes

Summerhayes Colin, Zalasiewicz Jan, Head Martin J., Gałuszka Agnieszka, Waters Colin N., Sörlin Sverker, Cearreta Alejandro, Robin Libby, Wallenhorst Nathanaël, Fiałkiewicz-Kozieł Barbara

Przegląd Geologiczny

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2025

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Vol. 73, nr 11

955--965

EN

Dąbski (2025) challenges the conventional understanding of climate change in asserting that atmospheric carbon dioxide has not strongly influenced global temperatures in the geological past or present. He claims that other factors including solar irradiance, oceanic oscillations, and changes in atmospheric aerosols explain much of the warming documented since pre-industrial times; and that current climate trends are not a matter of urgent concern. These views expand upon those by Marks (2025) to which we have already responded (Summerhayes et al., 2025). We refute these views and correct a common misunderstanding: atmospheric carbon dioxide was a powerful amplifier, not trigger, of global warming during past glacial-interglacial cycles (the trigger was Milankovitch forcing). In contrast, contemporary global warming has over-ridden Milankovitch forcing, being driven directly by anthropogenic greenhouse gas emissions, notably carbon dioxide which continues to accumulate in the atmosphere and oceans, locking global temperatures and its derived effects (e.g., sea level, extreme climate events, biological consequences) into a long-term upwards trajectory.

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Reply to Response by Summerhayes et al. to Marks (2025) : Contemporary global warming versus climate change in the Holocene

Marks Leszek

Przegląd Geologiczny

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2025

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Vol. 73, nr 5

477--485

EN

The natural input of solar energy is transformed by various external and internal factors to modulate climate on the Earth and there is a close relationship between insolation changes and long-term hydroclimate trends. Latitudinal insolation in the Holocene depended on the Earth ’s orbital parameters (Milankovic cycles). A train of thought of Summerhayes et al. (2025) is charged with the concept of the dominant role in climate change of the antrhopogenic emission of greenhouse gases, mostly CO2, and they reject the evidence on considerably higher temperatures than the current warming in the Early and Middle Holocene, Late and Middle Pleistocene interglacials and during the Early Pleistocene. Changes in incoming solar radiation during the Northern Hemisphere summers and a general weakening ofsummer monsoons in the Middle and Late Holocene resulted in a global disasterfor ancient civilizations. Contrary to the hurray optimistic point of view of Summerhayes et al. (2025), much is to be done to understand the modern climate change, based on the multilateral analysis of geological proxies. It is a reasonable way not to promote the simplistic prognoses of climate change. The contribution of CO2 to the modern warming is still an open question.

4

Late Glacial and Early Holocene palaeoenvironmental changes in the Kuyavian Lakeland, Smólsk site, central Poland

Stachowicz-Rybka Renata, Kittel Piotr, Nalepka Dorota, Płóciennik Mateusz, Alexandrowicz Witold P., Pawłowski Dominik, Rzodkiewicz Monika, Okupny Daniel, Gruszczyńska Agnieszka, Stachowicz Krzysztof, Korzeń Katarzyna, Muzolf Błażej, Kortys Bartosz, Luoto Tomi P., Papiernik Piotr

Geological Quarterly

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2025

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Vol. 69, No. 1

art., no. 4

EN

High-resolution biological proxies (pollen, macrofossils, Cladocera, Chironomidae, malacological analysis and diatoms), geochemical analyses, and AMS radiocarbon dating were employed to reconstruct the responses of the Smólsk palaeolake (Kuyavian Lakeland, central Poland) to rapid climatic and environmental changes during the Late Glacial-Early Holocene transition. The integration of palaeoecological and geochemical data enabled detailed insights into the dynamics of short-term shifts in terrestrial and aquatic ecosystems triggered by abrupt climate events. Precise age control and high-resolution sampling allowed the identification of temporal leads and lags between proxy responses to climatic shifts during this transitional period. Key findings include: (1) the coolest lake development phase, corresponding to the Late Glacial (9.050–5.400 m; 13,835–12,800 cal14C BP); (2) evidence of an open landscape and decreased water levels in the Late Glacial, resulting in intensified catchment erosion; (3) a change in sediment deposition at a depth of 5.35 m (~11,000 cal14C BP), marked by a transition from silt to calcareous gyttja and peat, indicating a lowering of groundwater levels and improved climatic conditions at the beginning of the Holocene; (4) a hiatus between the Late Glacial and Early Holocene recorded across all proxies; and (5) progressive eutrophication during the Holocene, characterized by reed belt development, reduced sedimentation, and the cessation of terrigenous sediment input. These findings highlight the lake system’s sensitivity to rapid climatic and environmental changes during this critical period.

5

Record of environmental changes during the Holocene in the light of malacological studies of river sediments in the Łapszanka Stream valley (Spisz area, Carpathians, Southern Poland)

Alexandrowicz Witold Paweł

Annales Societatis Geologorum Poloniae

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2024

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Vol. 94, No. 2

187--204

EN

The analysis included alluvial sediments in the Łapszanka Stream valley in the Spisz area (Carpathians, Southern Poland). Seven gravel levels were distinguished in the sedimentary sequence, which is a record of periods of intense fluvial activity correlated with wet climate phases. They fall in the Early Holocene (10 100–8900 y BP), the beginning of the Middle Holocene (7900–6600 y BP), the Middle Holocene (6100–5900 y BP), the beginning of the Late Holocene (5100–4000 y BP), the Iron Age Cold Epoch, the Dark Ages Cold Period and the Little Ice Age. The gravels are separated by layers of mud, containing an abundant mollusc fauna. It was possible to distinguish five types of fauna assemblages corresponding to the environmental changes in the Spisz area during the Holocene. The malacofauna indicates that forests covered this area to a large extent during almost the entire period analysed. During the Early Holocene, the area was dominated by coniferous forests, and the fauna contained numerous cold-tolerant taxa. The Middle Holocene saw the emergence of mixed forests inhabited by mollusc communities that included species with high ecological tolerance. A malacofauna containing moisture-loving forest assemblages is characteristic of the sediments of the Late Holocene. The occurrence of muds (agricultural muds) with open-country snails at the top of the sequence indicates increased anthropogenic impact and associated deforestation during the last 500 years.

6

The record of geochemical changes in the biogenic-calcareous sediments of a kettle-hole in a young glacial landscape (western Kashubian Lakeland, North Poland)

Wojciechowski Adam, Jonczak Jerzy

Studia Quaternaria

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2023

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Vol. 40, Nr 2

41--56

EN

The paper was focused on the reconstruction of past-environmental conditions dynamics based on the geochemical characteristics of sediments filling kettle-hole located in the western part of the Kashubian Lakeland, North Poland). Stratigraphic variability of litho geochemical constituents and a set of 13 elements (TOC, N, P, Na, Ca, Mg, K, Al, Fe, Mn, Cu, Ni, Zn) were applied for Holocene reconstruction of certain processes and conditions in the studied kettle-hole. The detailed geochemical analysis allowed us to identify 6 phases in its development: Masz-1 stage covering sedimentation of sedge-moss peat over melting dead ice at the turn of the Preboreal and Boreal periods; Masz-2 stage of the initial phase of lake development with deep-water sedimentation; Late Boreal and Atlantic stage Masz-3 related to sedimentation of lacustrine chalk; Subboreal stage Masz-4 representing the beginning of lake terrestrialization; Subatlantic stage Masz-5 of lowland bog, and Masz-6 stage covering final phase of peatland evolution due to human activity. Principle component analysis highlighted the importance of two major factors controlling the geochemical variability of the studied sediments. These are the varied origin of supplying water reflected in the sedimentation of organic-calcareous sediments (PC1), and oxidative-reduction conditions determined by water level fluctuations (PC2).

7

Reakcja roślinności na chłodne oscylacje klimatyczne podczas holocenu : wstępne wyniki analizy pyłkowej osadów Jeziora Bocznego (Kraina Wielkich Jezior Mazurskich)

Żuk-Kempa Edyta, Fiłoc Magdalena, Kupryjanowicz Mirosława

Przegląd Geologiczny

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2023

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Vol. 71, nr 10

530--532

EN

This article presents the preliminary results of palynological research, the main objectives of which were to study the climate changes impact on the vegetation from end last glaciation to the present day in the Great Masurian Lakes District. In the pollen diagram from the Lake Boczne profile, 12 local pollen assemblage zones (LPAZ) were distinguished. The pollen zoneand subzones illustrate successive stages of vegetation development around Lake Boczne. The existence of a sedimentary gap in the analysed profile covering a significant part of the Middle Holocene was documented, which could be associated with a cooling and/or a more humid climate. Moreover, some changes in the pollen record may have reflected changes in vegetation due to cold climate oscillations.

8

Palaeoenvironmental and palaeoclimatic inferences based on X-ray computer tomography: a case study of alkaline lake deposits in Hungary

Alzoubi Nour N., Gulyas Sandor, Geiger Janos

Geologos

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2023

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Vol. 29, No. 1

33--49

EN

Widely distributed freshwater carbonate sediments, i.e., limestone, dolomitic limestone and dolomite, developed in inter-dune alkaline ponds of the Danube-Tisza Interfluve in the centre of the Carpathian Basin during the Holocene. The key parameters that determine the formation of any given type of carbonate mineral (calcite, dolomite) are temperature, evaporation rate, pH and ion concentrations, in addition to CO2 absorption by aquatic plants. CT analysis is capable of recording small-scale density variations attributable to compositional differences of sedimentary rocks. As the type and proportion of rock-forming minerals and other components is an artifact of past environmental and climatic conditions, CT values may act as potential palaeoenvironmental proxies. The present study compares variations in rock-forming components obtained for freshwater carbonates utilizing the CT method with already available geochemical and palaeoecological proxy data. Variations in molluscan ecology and isotope geochemistry, sedimentation times and CT-based rock density values all indicate the relevance of millennial-scale, climate-driven changes in carbonate formation. As previously observed, the emergence of colder conditions in the North Atlantic, which resulted in increased cyclonic activity and heavier rainfall in western Europe and the Danube watershed area between 10.3 and 9.3 kyr cal BP, resulted in the emergence of humid conditions favouring a rise in the groundwater table at our site and precipitation of calcite from pore waters as opposed to high-magnesium calcite. This is clearly reflected in a negative shift in CT density values in our dated rock samples.

9

Human impact recorded in lake environment (Charzykowskie Lake, N Poland) during the last 6,200 years

Mirosław-Grabowska Joanna, Zawisza Edyta, Obremska Milena, Kowalczyk Joanna, Zbucki Łukasz, Tobolski Kazimierz

Acta Geologica Polonica

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2023

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Vol. 73, no. 3

467–-478

EN

Based on geochemical and biological investigations of a 6-m-long sediment core, a reconstruction of the envi-ronmental conditions in Charzykowskie Lake (northern Poland) is presented. The analyzed sediments consist of fine calcareous detritus gyttja interbedded by lake marl. The results of palynological analysis document the vegetation development around and in the studied lake and confirm the middle and late Holocene age of the sedimentation of the deposits. The identification of 22 taxa of subfossil Cladocera shows the biodiversity of the fauna and reflects the changes in the trophic and water level. The concentrations of various chemical elements suggest the origin of the sediments. Geochemical, including isotope, and biological data, made it possible to reconstruct the environmental conditions, as well as traces of human influence over the last ca. 6,200 years. Four stages of human impact have been documented by the pollen data. The first traces of human groups in the vicinity of Charzykowskie Lake are preserved in sediments from about 4,000 years ago. The human activity is poorly recorded in the Cladocera and in the geochemical compositions of the lake sediments, probably due to the size and depth of the lake and its isolation.

10

The arid regions of Daryalyk Takyr and Telikol: ethno-geoarchaeological study of a strategic transhumance rangeland on the right bank of the Syr Darya delta, Kazakhstan

Deom Jean-Marc, Sala Renato

Studia Quaternaria

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2022

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Vol. 39, Nr 2

95--111

EN

A previously unexplored 20,000 km2 area comprising the Daryalyk Takyr desert and the lacustrine landscapes of Telikol and Aschykol at the confluence of the Chu, Sarysu and Syr Darya rivers is presented here as object of a threefold geological, archaeological and ethnographic analysis assessing its historical importance. According to paleohydrological reconstructions, synchronous fluvial activity of the three rivers occurred during the Late Pleistocene. In the Holocene, the right branches of the Syr Darya delta were separated from the Chu-Sarysu confluence by alluvial sediments, becoming active only intermittently during undated flood events apparently strong enough to establish an ephemeral lake in the region. Geoarchaeological surveys analyzing surface finds indicate the densest occupation during the Late Neolithic and Bronze Age. From medieval to modem times, historical sources attest to the seasonal use of the Telikol region as a pastoral transit between the Syr Darya banks and the steppes of Central Kazakhstan. They are confirmed by ethnographic data about Telikol during its last phase of occupation (1870-1910) illustrating that land use in this area (and, probably, in all semi-desert regions in Kazakhstan) was not governed by property rights but by tribal political compromises between residential and transitory herders, occasionally exposing it to overgrazing.

11

Molluscan assemblages in sediments of a landslide on Majerz Hill near Niedzica (Inner Carpathians, Southern Poland) – phases of development and environmental changes

Alexandrowicz Witold Paweł

Geology, Geophysics and Environment

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2022

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Vol. 48, no. 1

51--68

EN

A detailed malacological analysis was made of sediments associated with a small landslide which had developed on the north-eastern slope of Majerz Hill near Niedzica (Inner Carpathians, Southern Poland). The age of the development and environmental changes associated with particular phases of the landslide was determined by means of radiocarbon dating. The analyses made it possible to distinguish two periods of landslide activation falling on the turn of the Early/Middle Holocene and on the Late Holocene (probably on the Iron Age Cold Period). These phases are closely related to periods of increased mass movements, both of landslides and debris flows in other European mountains, stages of glacial advance in the Alps, periods of increased fluvial activity in rivers and elevated water levels in European lakes. The molluscan assemblages also enabled the reconstruction of environmental conditions before the landslide formation, during periods of dormancy, and after the end of its activity.

12

Application of malacological analysis to reconstruction of regional and local environmental changes : the Cisowa Skała locality (the Carpathians, southern Poland)

Skoczylas-Śniaz Sylwia, Alexandrowicz Witold Paweł

Geological Quarterly

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2022

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Vol. 66, No. 1

art. no. 5

EN

An isolated limestone hill (Cisowa Skała), located in the Podhale Basin in southern Poland, has yielded mollusc shells and small vertebrate bones in deposits filling small karst forms such as rock shelters, characteristic molluscan assemblages can be identified, the succession of which reflects changes in the environment and also microhabitat variations depending on local factors, such as slope exposure and type of vegetation. These local factors markedly affect regional environmental trends determined primarily by climate change and, during the last several hundred years, also by human activity. Such malacological analysis enables effective palaeogeographical reconstructions, both on the scale of geographical regions and for microhabitats.

13

Faunistic analysis of the section Leb 1 in the Gardno-Łeba Coastal Plain, northern Poland

Wojciechowska Paulina, Wojciechowski Adam

Studia Quaternaria

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2021

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Vol. 38, Nr 2

117--126

EN

The article presents results of the faunistic analysis of the Leb 1 sediment core collected from the marginal zone of the Lake Łebsko. The 5 m long core contained 10,603 specimens of freshwater and brackish-marine fauna, represented by 13 taxa of molluscs, 3 species of ostracods, 2 taxa of foraminifers and a species of the order Coleoptera, and genera Balanus and Gammarus. Lithology of the sediments and species composition of the fauna permitted distinguishing 3 development phases of the Lake Łebsko: brackish-marine phase (500–400 cm), limnic phase with varied salinity (400–100 cm) and swamp phase (100–0 cm), indicating progressive overgrowing of the marginal zone of the lake since the 13th century.

14

Zmienność cech fizycznych i chemicznych wód źródlanych w zlewni Zagórzańskiego Potoku (Pogórze Spisko-Gubałowskie)

Czarny Gabriela, Pociask-Karteczka Joanna, Nieckarz Zenon

Przegląd Geologiczny

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2021

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Vol. 69, nr 3

150--160

EN

The aim of the paper is to examine the variability of physical and chemical characteristics of two springs located in the Zagórzański Stream catchment (Spisko-Gubałowskie Foothills, Podhale region). Calcareous tufa occurs at one of the investigated springs. Field studies were conducted once a month from 25th March 2017 to 28thFebruary 2018. Water of the studied springs represents the bicarbonate-calcium-magnesium type during almost the whole year. The chemical composition of both springs is characterized by seasonal variability. The highest concentrations of most ions occurred in the summer, when the rainfall was the lowest and during winter drought; while the lowest concentration - in the period of increased rainfall. The variability of physical and chemical parameters of the spring with tufa is smaller than the other one. The spring with calcareous tufa stands out by the higher concentration of Mg2+ and SO42- and the presence of radon. The unique landscape values of the surroundings and hydrogeochemical features of the spring with calcareous tufa favour this place as an interesting hydro-tourism attraction in the Bukowina Tatrzańska region.

15

Natural and anthropogenic changes in the environment during the Holocene at the Kraków region (Southern Poland) from study of mollusc assemblages

Alexandrowicz Witold Paweł

Geological Quarterly

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2021

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Vol. 65, No. 1

art. no. 9

EN

Malacological analysis was used to reconstruct Holocene environmental changes from profiles of calcareous tufa and fluvial deposits exposed in the Kobylanka stream valley, several kilometres west of Kraków in southern Poland. The abundant and diversified mollusc fauna was characterized by clear variability within the vertical succession where five types of molluscan assemblages were distinguished. The pattern of sedimentary and molluscan facies allowed characterization of two main intervals of environmental change during Holocene. In the lower interval, until the end of the Middle Holocene, human activity was not detected and environmental processes were controlled by natural factors. In the upper interval, corresponding to the Late Holocene, human impact can be seen, in the form of rapid deforestation and agricultural development. Anthropogenic impact has been particularly evident during the last millennium. The mollusc assemblages studied allowed accurate reconstruction of natural and anthropogenic factors affecting the natural environment.

16

Malakofauna martwicy wapiennej we wsi Rybna koło Krakowa (południowa Polska) jako wskaźnik zmian środowiska południowej krawędzi wyżyny krakowsko-częstochowskiej

Alexandrowicz Witold Paweł

Biuletyn Państwowego Instytutu Geologicznego

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2021

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nr 478

1--14

PL

Liczne skorupki mięczaków znaleziono w odsłonięciu martwic wapiennych we wsi Rybna k. Krakowa. W 12 próbkach rozpoznano występowanie ponad 2500 okazów należących do 49 gatunków. W obrębie sekwencji malakologicznej możliwe było wydzielenie trzech zespołów faunistycznych. Najstarszy z nich (fauna M) odpowiada chłodnemu okresowi wczesnego holocenu i reprezentuje zacienione siedliska o dużej wilgotności, porośnięte krzewami lub rzadkimi lasami o znacznym udziale drzew iglastych. Jego cechą charakterystyczną jest obecność gatunków typowych dla zimnych faz klimatycznych. Drugi, młodszy zespół (fauna F) jest typowy dla ciepłego i wilgotnego klimatu fazy atlantyckiej. Charakteryzuje on siedliska zwartych lasów mieszanych i liściastych. Pojawiają się tu liczne formy o wysokich wymaganiach termicznych. Najmłodszy zespół (fauna O) wskazuje na rozległe antropogeniczne wylesienia na obszarze depozycji martwic wapiennych. Ta zmiana cech siedlisk przyrodniczych była prawdopodobnie związana z fazą intensywnego zasiedlenia okolic wsi Rybna i rozwoju rolnictwa we wczesnym średniowieczu.

EN

Numerous molluscan shells were found in an outcrop of calcareous tufa in the village of Rybna near Kraków. In 12 samples, over 2500 specimens belonging to 49 taxons were found. Three types of molluscan assemblages can be distinguished within the malacological sequences. The oldest of them (M-type fauna) corresponds to the cold period of the Early Holocene and represents shady habitats of significant moisture, covered with bushes or sparse coniferous forests. Its characteristic feature is the presence of cold-tolerant species typical for cold climate phases. The second, younger assemblage (F-type fauna) is typical for the warm and moist climate of the Atlantic Phase. It characterizes habitats of dense mixed and deciduous forests. Numerous forms of high thermal requirements are found here. The youngest assemblage (O-type fauna) implies extensive anthropogenic deforestations in the surrounding area. This change in the characteristics of natural environment was most likely associated with a phase of intense settlement in the village of Rybna and development of agriculture during the Middle Ages.

17

Unique finds in palynological spectra: acetolyze resistant vegetative forms of freshwater dinoflagellate based on the Lake Młynek record from northeastern Poland

Bińka Krzysztof, Welc Fabian, Nitychoruk Jerzy, Sieradz Dominika, Lewczuk Antoni

Studia Quaternaria

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2020

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Vol. 37, Nr 2

59--67

EN

The freshwater dinoflagellate represent microfossils which are very rarely noted in lake deposits. In Late Holocene sediments of the Lake Młynek, the Iława Lakeland, northern Poland, we identified intense blooms of algae of the genus Palatinus. They occurred primarily in the period of strong human impact during expansion of the Monastic State of the Teutonic Order. The most amazing thing is that samples in which conventional palynological maceration has been used dinoflagellate are represented by armored vegetative forms instead of cysts. During this laboratory processes, especially acetolysis, cellulosic thecae of armored forms should be destructed. This is the second known example of acetolysis resistant thecae of modern dinoflagellate, built by substance other than cellulose. Palatinus blooms were associated probably with the hydrotechnical works made by Teutonic Knights in the catchment, which caused supply and discharge of micronutrients e.g. selenium in the basin.

18

Holocene environmental history of the Bottomless Lake (Tăul fără fund) sphagnum peat bog in Bǎgǎu, Romania

Vári Tamás Zsolt, Molnár Dávid, Sümegi Pál, Sümegi Balázs Pál, Törőcsik Tünde, Szakál Edit, Benyó-Korcsmáros Réka

Studia Quaternaria

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2020

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Vol. 37, Nr 2

69--77

EN

This work focuses on the paleoenvironmental and palaeoclimatological history of the undisturbed core sequence of 8.6 m extracted from the Bottomless Lake (Tăul fără fund) sphagnum peat bog located in Bǎgǎu, Romania, which covers the last 8,600 years based on radiocarbon dating. By comparing results of archaeological and palaeoenvironmental investigations carried out so far in the area, results of the loss on ignition analyses and the data of the chronological analyses, it was possible to reconstruct climatic factors and anthropogenic impacts on the local environment. The undisturbed core sequence has above 86% organic matter content all along excluding the erosion horizons. Anthropogenic effects (building, woodcutting, pasturage, husbandry, farming) and changes in the local climate, vegetation, and environment increased the rate of the erosion and decreased the rate of the accumulation.

19

Meteoryty, kratery uderzeniowe i inne ślady kosmicznej katastrofy w rejonie Moraska pod Poznaniem

Szczuciński Witold, Muszyński Andrzej

Przegląd Geologiczny

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2020

|

Vol. 68, Nr 8

637--644

EN

About 5,000 years ago near Morasko (the district of the present-day city of Poznań, western Poland) the largest known iron meteorite shower in Central Europe took place. The evidence of that impact, documented so far, comprises numerous iron meteorite fragments distributed over an area of approximately 3 km2 and at least six meteorite impact craters with a maximum diameter of about 100 m. The present paper reviews the most recent findings related to the meteorite, craters, processes of their formation, as well as the environmental effects of the impact in the Morasko area. The most important findings, reported in this review cover: 1) the recognition of two new minerals in the meteorite: moraskoite and czochralskiite; 2) the identification and detailed analysis of the ejecta layer around the craters and underlying paleosoil providing evidence for the mid-Holocene age of the impact; 3) the numerical modelling constraining the range of likely physical properties of the impactor, e.g. the diameter of the projectile forming the largest crater and its landing velocity (c. 1.5 m and 10km/s, respectively);4) the studies of the nearby lake and peat deposits revealing restricted environmental effects of the impact. The Morasko craters field is currently one of the best-studied examples of small/moderate-sized meteorite impact in unconsolidated sediments.

20

Element enrichment and provenance of the detrital component in Holocene sediments from the western Black Sea

Dekov Vesselin M., Darakchieva Valentina Y., Billström Kjell, Garbe-Schönberg C. Dieter, Kamenov George D., Gallinari Morgane, Dimitrov Lyubomir, Ragueneau Olivier, Kooijman Ellen

Oceanologia

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2020

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No. 62 (2)

139--163

EN

Concentrations of a large set of major and trace elements, and Sr, Nd and Pb isotope ratios were measured in Holocene sediments cored in the western deep Black Sea in order to unravel: (1) the controls of element enrichment, and (2) sources of the detrital component. The transition of the basin from oxic to euxinic resulted in enrichment or depletion in a number of elements in the deep-sea sediments. Authigenic Fe enrichment appears to depend on the amount of Fe mobilized from the sediment through the benthic redox shuttle mechanism and free H2S in the water column (degree of “euxinization”). Manganese enrichment is controlled by diagenetic reactions within the sediment: the dissolution of Mn minerals, Mn2+ diffusion upward and reprecipitation. Barium enrichment is also controlled by diagenetic reactions, sulfate reduction and methanogenesis, that take place above and below the sulfate-methane transition, respectively. The major part of V, Co, Ni, Cu, Zn, Cr, Mo, Cd and Sb is inferred to have co-precipitated with Fe in the euxinic deep waters and to have been incorporated into authigenic Fe-sulfides. Basin reservoir effect additionally influences the Mo enrichment. The U enrichment is interpreted to have a different origin in the two organic-rich stratigraphic units (II and I). It is inferred to be: (i) at the expense of the U inventory of the deepwater pool and a result of inorganic reduction of U at euxinic conditions in the lower Unit II; and (ii) at the expense of the U inventory of the surface water pool and a result of biogenic uptake and transfer to the sediment by the plankton in the upper Unit I. The high field strength elements are closely linked to the detrital component and their depletion in the organic-rich sediments reflects a dilution of the detrital component by the biogenic one. The enrichments of REE, Sn and Th are likely controlled by adsorption on clay minerals. Sr-Nd-Pb isotope compositions of the alumino-silicate component of the studied sediments are relatively uniform. They are most likely controlled by riverine suspended matter supplied mainly in the NW Black Sea (Danube Delta) and transported southward by marine currents, and to a lesser degree by suspended matter from the small rivers draining SE Bulgaria and NW Turkey. Wind-blown dust from the Sahara Desert appears to have a minor contribution to the alumino-silicate component of the sediments. The slight shift in the Pb isotopes in Unit I upper layers is possibly caused by the addition of anthropogenic Pb.