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INQUA Focus Group SACCOM: 1709 “Ponto-Caspian Stratigraphy and Geochronology (POCAS)”статья
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Дата последнего поиска статьи во внешних источниках: 4 июня 2021 г.
- Авторы: Yanko-Hombach Valentina, Makeev Alexander, Yanina Tamara, Lahijani Hamid
- Журнал: Quaternary International
- Том: 590
- Год издания: 2021
- Издательство: Pergamon Press Ltd.
- Местоположение издательства: United Kingdom
- Первая страница: 1
- Последняя страница: 4
- Номер статьи: 1040-6182
- DOI: 10.1016/j.quaint.2021.04.030
- Аннотация: INQUA Focus Group 1709 “Ponto-Caspian Stratigraphy and Geochronology (POCAS) was created within the INQUA SACCOM forthe term 2017–2021 (Yanko-Hombach et al., 2018). It is devoted to the study of the geology of the Ponto-Caspian region during the Quaternary as a single geographic entity, bypassing linguistic/political/disciplinary boundaries, linking continents (Europe and Asia) more closely, and encouraging East-West dialogue and cooperation among researchers.The Ponto-Caspian is defined here as a chain of intercontinental basins that encompasses the Caspian, Black, Azov seas, the Kerch Strait, the Manych Valley, and their coasts. This chain represents a unique oceanographic system of relict Paratethys basins which were repeatedly connected and isolated from each other during the Quaternary. This predetermined their environmental conditions and hydrologic regimes, and imposed specific impacts on diverse biological populations. Due toits geographical location and semi-isolation from the open ocean, Ponto-Caspian region acts as a paleoenvironmental amplifier and a sensitive recorder of climatic events, in particular glacial-interglacial cycles on the Eastern European Plain and mountains, as well as transgressive-regressive sea-level variations of the World’s Ocean; thus, it can beconsidered as a stratotype region where geological history is well recorded in a long series of marine and continental sediments to be used for the development of the Pleistocene stratigraphy and geochronology of Northern Eurasia.Study of Quaternary stratigraphy and geochronology in the Ponto-Caspian region dates back to the XIX century. The basic stratigraphic scale was first suggested by N.I. Andrusov and later modified by N.M. Arkhangel’sky, A.D. Strakhov, L.A Nevessakaya, P.V. Fedorov, T.A. Yanina, and V.V. Yanko-Hombah (among many others). This scale is based on the study of outcrops, many of which represent stratotypes for certain stratigraphic units. They were formed on the sea bottom andlater exposed by tectonic uplift on coastal terraces. The stratotypes represent designated exposures of a named and layered stratigraphic unit that serve as the standard of reference, have good preservation, and are easily accessible. Many of them were observed during the IGCP 521, IGCP 610 (Yanko-Hombach et al., 2019), and INQUA 0501 projects that established an international team of multidisciplinary scientists of more than 300 people from 27 different countries. In the course of this fieldwork, a huge amount of the data was collected. However, obtained results are sometimes rather controversial. For example, there is ongoing dispute over the number and duration of the transgressions and regressions of the ancient basins as well as their status and size. There is furthermore no agreement on correlation of these events to global sea-level reconstructions. There is also no consensus on the reasons for huge fluctuations in the sea level of the Caspian Sea, which has changed several times from minus 140 to plus 50 m during the Pleistocene.Bringing the international community together to solve a number of contentious issues on stratigraphy, geochronology, and periodization of the history of the Ponto-Caspian will allow synthesis of the data accumulated by new research methods over a long period of time. The INQUA POCAS community includes about 260 scientists from 21 countries: Azerbaijan, Belgium, Bulgaria, Canada, Georgia, Germany, Greece, France, Israel, Italy, Kazakhstan, Latvia, Romania, Russia, TheNetherlands, Switzerland, Turkey, Turkmenistan, UK, Ukraine, and USA.The IFG 1709 POCAS project complements the INQUA SACCOM, CMP, and TERPRO Commissions as well as IGCP 521, 610 and INQUA0501. The project also collaborates with geological surveys, archaeological expeditions, and corresponding museums in all countries bordering the “CORRIDOR.”The Project is linked to the projects “Uncovering the Mediterranean salt giant (MEDSALT)” COST Action CA15103; No. 557 “Theoretical justification of the interaction between nature and human society in the the northwestern Black Sea during the Late Pleistocene and Holocene” supported by the Ministry of Education and Science of Ukraine; RSF 16-17-10103 “The Caspian Sea System in the Conditions of Global Quaternary Climate Change”; RSFBR 19-05-01004 “Chronology of paleogeographicevents of the late Pleistocene of the Dagestan coast of The Caspian Sea”; 18-05-00296 “Kerch Strait in Global Climate Change (Late Pleistocene-Holocene) ”; 19-77-10077 “Chronology of paleogeographic events of the South-East Plain in the Pleistocene and Holocene: new approaches and methods.”Dissemination of project events and activities occurred via regular updating of project websites http://www.avalon-institute.org/inqua/and the mailing list of project contributors, which increased from 957 in 2013 to 1254 in 2019, as well as social networks (Facebook for English and non-English-speakers, and Вконтакте for mostly Russian speakers) https://www.facebook.com/groups/180481035443572/, http://vk.com/album115218532_181815723.The 3d Plenary Conference and Field Trip of the INQUA IFG 1709 POCAS was carried out in I.R. Iran (Tehran). It focuses on the late Miocene-Plio/Pleistocene geological history of the Southern Caspian Coast, Iran along the West Alborz Mountains. This subject is very important in shedding light in a better understanding of tectonic- climatic interactions during the Plio/Quaternary period in this region.The meeting covered six days in total. Two days (12–13 October) were spent in Plenary Sessions, and four days (14–17 October) are dedicated to the Field Trips. Two Plenary Sessions and round table were held in the Iranian National Institute for Oceanography and Atmospheric Science (INIOAS) headquarter in Tehran, I.R. Iran. The Sessions were organized in three panels: Panel 1. GENERAL QUESTIONS OF THE CORRIDOR, moderators Nikolay ESIN (Russia) and Alexander KISLOV (Russia). ThePanel included six ORAL presentations. The keynote talk “Iranian Plateau in the Late Quaternary; When it was GREEN!” was given by H.Nazari. (Iran). Panel 2. BLACK SEA, SEA OF AZOV, SEA OF MARMARA REGION, moderators Valentina YANKO-HOMBACH (Ukraine, Canada) and M. ERGÜN (Turkey). The Panel included six ORAL presentations.Panel 3 CASPIAN SEA REGION, moderators T. YANINA (Russia) and E. ALIYEVA (Azerbaijan). The Panel included twenty one ORAL presentations.The keynote talk “Correlation of regiostages and history of marine Ponto-Caspian basins at the boundary between Neogene andPleistocene” was given by A. Chepalyga (Russia). The Poster session headed by A. M. NADERI BENI (I.R.Iran) & A. BERDNIKOVA (Russia) included fifteen presentations. The meeting brought together multidisciplinary scientists from many countries to enhance the West-East scientific dialogue and provide a foundation for collaboration on correlation and integration of subjects important for the INQUA IFG 1709 POCAS. It enabled participants: (1) To discuss the actual status ofthe project and progress made by participants. Particular attention was given to scientific approaches and methodology to integrate and correlate new data on stratigraphy and geochronology of the Ponto-Caspian region. (2) To introduce young generation of scientists, especially from developing countries, to new analytical techniques and state-of the-art interpretation of data. (3) Encourage east-west dialogue and integrate multidisciplinary researchers from different countries into the international R&D community. The content of the Programme of the Conference, Proceeding and the Field Trip Guide can be downloaded from http://www.avalon-institute.org/inqua/meeting_next.php. The Proceedings of the Conference contain contributions from 110 scientists from eleven countries; 94% of the contributors are from developing countries. About 50% of participants are female. The conference was attended by high number of international students and ECRs.The Technical and Poster Sessions were followed by the Round Table that enabled participants to discuss the progress of the project andto plan future strategy in running them. It was decided to summarizeProject activities in a series of selected papers in the second INQUAPOCAS special volume of Quaternary International.Plans for 2020 were destroyed by COVID-19 pandemic. The POCAScommunity plans to make up for them in 2021. The following events areexpected to be performed: (1) IFG 1709 POCAS session at the InternationalGeographic Congress, Istanbul in 2021. (2) The IFG 1709 POCASThird Plenary Conference and Field Trip in Ukraine (Odessa) and Moldova(Tiraspol) in summer 2021. (3) A special IFG 1709 POCAS sessionat General Assembly of GSA on 10–13 October 2021 in Portland, Oregon,USA. (4) Summer school on the Caspian stratigraphical geochronologicalscale, Volgograd, Russia, May 2021. (5) ECR Field School,Paril 2021, Kazakhstan, Mangyshlak peninsula, summer 2021. (6)Quaternary Meeting (Krasnodar, Russia, May, September 2021). (7)Two regional meetings in Moscow devoted to the problems of stratigraphy,geochronology, and correlation of Quaternary sediments of thePonto-Caspian. (8) Monthly seminars for Early Stage Researchers (ESRs)devoted to the problems of stratigraphy and paleogeography of thePonto-Caspian and methods for studying them (Supervisors: T. Yanina,DCR, and V. Yanko-Hombach, DCR). (9) Assembling a Catalogue of thePonto-Caspian microfauna (foraminifera, ostracoda) and their SEMpictures required for biostratigraphy of the Ponto-Caspian (Supervisor:V. Yanko-Hombach, DCR, assistants T. Kondariuk, ESR, and A. Kravchuk,DCR, M. Zenina, DCR). (10) Revision of malacofauna of theNorthern Caspian and the Caspian Sea in order to clarify the biostratigraphicscheme (Supervisor: T. Yanina, DCR). (11) Field work in the:Lower and Middle Volga, Manych depression, Western Turkmenistan,Kerch Strait, Taman Peninsula, Caucasus’ coast, Dagestan supplementedby OSL and 14C dating. Few MSc and PhD Thesis were or will bedefended on different subjects of POCAS.This volume contains ten selected papers of research presented at theIFG 1709 POCAS meetings such as: (1) The Third Plenary Meeting in theIranian National Institute for Oceanography and Atmospheric Science(INIOAS), Tehran (I.R. Iran) in 2019 (http://www.avalon-institute.org/inqua/meeting_past.php). (2) Special POCAS session “Ponto-Caspianstratigraphy and geochronology: Understanding Caspian - Black Sea -Mediterranean Corridor evolution in the Quaternary” at the INQUA2019 Congress in Dublin, and (3) Special session at the PaleontologicalSociety of Russia on April 3, 2019 in St. Petersburg. All sessions arecharacterized by a high participation of undergraduate and graduatestudents and ECRs.Seven papers are devoted to the Caspian Region.The paper by A. Heidari et al. (2021, this volume) focuses onreconstruction of dominant paleoenvironments on northern and southernslopes of Alborz Mountain based on the modern and old environmentalevidences preserved in the soils. Different climates, vegetation,geology, relief, and time have led to various soil forming processes in thenorthern and southern slopes of Alborz that have resulted in differenttypes of soils. The results of this study demonstrated that the southernslope has been heavily influenced by glacial and aeolian deposits that insome cases have led to the top-down reverse distribution of the elementoxides in the soil. The obtained results indicate that there were strongclimatic changes on the southern slope of the Alborz Mountain Chainwhich were documented by changes in the geochemical, morphological,and physicochemical properties. The soils in the middle and westernparts of the northern slope very rarely were affected by loess or Aeoliandeposits. The deep to very deep soils in the northern slope with a humidclimate and mostly forest vegetation were mainly developed overlimestone. While the arid/semi-arid climate and sparse herbaceousvegetation cover on the southern slope led to thinner soil cover which isaffected by present and past aeolian deposits, leading to polygeneticsoils.The paper by M. Konyushkova et al. (2021, this volume) focuses onthe spatial and seasonal salt translocation in the young soils studied attwo key sites located at the coastal plains of the Caspian Sea in Russia(northern Dagestan) and Iran (northern Golestan). Both key sites havesimilar aridity and lithology but differ in vegetation and microtopography.The study conducted at the detailed scale (n*100–101 m)demonstrates that spatial and seasonal variability of soil salinity is notstochastic and has a regularity (invariant patchiness) pronounced in theupper 10 cm of the younger Gomishan-1 site (50–70 yr.) and upper 50cm of the older Caspii-2 site (293 ± 13 years cal BP). Thus, the locationswith higher salinity stay more saline comparing to their surroundings inall seasons and vice versa, despite the significant seasonal change of saltcontent. Variability increases by the end of the dry season. The studyshows that these patterns have no relationship with vegetation andmicrotopography (R2 = 0.0) at the younger site (Gomishan-1, Iran) andhave a pronounced negative correlation with microtopography (R2 between0.261 and 0.446) and no correlation with vegetation (tamariskbushes) (R2 < 0.02) at the older site (Caspii-2, Russia). In other words, atthe youngest surface (Gomishan-1), no driving force is observed whichcan lead to spatial heterogeneity of soil salinity. The formation ofvegetation patchiness and microtopography formation are onlyobserved at the older site (Caspii-2). These facts suggest that spatialdifferences in soil salinity precedes and predetermines the spatial distributionof vegetation and microtopography in the study area.The paper by A. Makeev et al. (2021a, this volume) is devoted to thepedosedimentary environments in the Caspian Lowland during MIS 5(reference section Srednaya Akhtuba, Russia). The authors show thatthis outcrop was outside of the area of Late Khazarian marine transgressionduring MIS 5. This led to the formation of detailed andcontinuous pedosedimentary sequence with three pedogenetic levelsformed in fluvial heavy loams intermixed with thin loess layers. Theclimate was generally arid or semi-arid with seasonal winter freezingtypical for continental regions. Pedosedimentary sequence was developedon the river terrace with a high groundwater stand and was outsideof stream deposition which could lead to truncation of paleosols andsediment layers. It was influenced by fluctuations in the intensity of theseasonal floods. Thin loess layers were deposited during the brief episodes of low flood intensity, while fluvial heavy loams – at the time ofmore intensive flooding. Mollic Gleysols and Fluvic Chernozems havebeen formed in the arid or semi-arid climate with seasonal freezingunder productive wet meadows. Changes in the depositional environmentresulted in the formation of welded paleosols, marked by texturaldifference, cryogenic levels, and accretionary humus horizons.The paper by I. Semenkov et al. (2021, this volume) is devoted to thecomparison of chemical content of recent fine-textured soils on thesoutheast (Golestan, Iran) and northwest (Russia) coasts of the CaspianSea at altitudes of 25–26 m BSL. It is shown that the soils on the Russiancoast have a pronounced vertical differentiation of most elements(except for Cr, Cu, Mg and Si), which can be attributed to the deepergroundwater level. The soils on the Iranian coast have a uniform verticaldistribution of most elements except for As, P and Pb. The comparison oftwo coasts demonstrates that the topsoil of the Russian coast has highercontents of Ni, Si, V and Zn, the subsoil of the Russian coast has highercontents of Al, Cr, Fe, K, Mn, Ni, P, Si, Ti, V and Zn, and the subsoil of theIranian coast has higher contents of As, Cu, Cl , SO42– and HCO3. Basedon weathering indexes (R, PWI, Si/R, Si/Ses and Si/Fe), the recent soilson the Russian coast are significantly more weathered compared to thesoils on the Iranian coast. Obtained results contribute to the understandingof weathering and primary soil formation in the semi-aridlandscapes in the Caspian region.The paper by N. Taratunina et al. (2021, this volume) is concentratedon the Late Pleistocene cryogenesis features of a loess-paleosol sequencein the Srednyaya Akhtuba reference section, Lower Volga river valley,Russia. A conceptual model for the key stages in the development ofcryogenesis over the northern part of Lower Volga region during LatePleistocene has been suggested. The fourth cryogenic stage occurred atthe final phase of the Early Valdai glacial (MIS-4) during the Atelianregression of the Caspian Sea. Significant cracking of the horizonsoccurred with the formation formed during relatively brief episodes ofclimatic amelioration (MIS-5a, c) penetrating even into the Mikulinointerglacial soil (MIS-5e). The third stage is expressed in the form ofpseudomorph development that penetrates deeply into the horizon ofAtelian loess. Formation of these cryogenic structures occurred atmid-way though MIS-3 (about 45–42 ka ago), and was coincident with atransgressive episode of the Caspian Sea. At this time, the Volga valleywas under the influence of estuarine conditions that led to the depositionof the alluvial suite seen at the Srednyaya Akhtuba section. It could beshown that development of cryogenic phenomena was enhanced byflooding of the adjacent plain by the Volga River, raising the level of thewater table in the region and moistening the loessic sediments. Thesecond and the first episodes are preserved in the proxy record of theSrednyaya Akhtuba section and indicate that sedimentation was takingplace under a climatic regime increasingly dominated by conditions ofenhanced cooling and moisture availability: the third stage is observedat about 40 ka, the fourth – around 11 30 ka. In the Late Pleistocene, themain phase of development of cryogenic features in the Lower Volgaregion occurred during the cold periods of MIS-3 and 4. There are notraces of possible cryogenesis that correspond with the coldest, LateValdai glacial phase (broadly coeval with the global Last GlacialMaximum of MIS-2). Presumably, sediments of this age (as 21 well as theupper part of the paleosol forming layer 6–7) were destroyed by 22abrasion processes associated with Khvalynian expansion of the CaspianSea.The paper by T. Yanina et al. (2021, this volume) is devoted to thepaleogeography of the Atelian regression in the Caspian Sea. Based onseismic-acoustic profiles, static sounding, and engineering boreholes,the authors indicate that he Atelian regression is distinctly pronouncedin the Pleistocene deposits of the northern Caspian Sea at the base ofKhvalynian sediments. Between the Hyrcanian and Khvalynian transgressivelayers there are regressive series noted by inhomogeneous lithologyand stratigraphic position. The Atelian sediments arerepresented by interlayered clays and clay loams. Plant detritus occur asseparate inclusions, or forms layered concentrations including shells offreshwater and terrestrial molluscs suggesting aquatic or wetland environmentswith freshwater or freshened brackish-water shallow waterbodies. The palynological data provide evidence of diversified landscapesin the northern Caspian Lowland at the time of the Atelianregression – from forests dominated by conifers to periglacialforest-steppe and tundra-forest-steppe, mostly resulting from the climatefluctuations. The maximum of the Atelian regression and erosionalprocesses correspond to the maximum cooling of the Kalinino (MIS 4)glacial time. The final stages of the regression fell on the initial phases ofthe MIS 3 interstadial. The Caspian level dropped to 100 m BSL due tothe water discharge into the Pont vis Manych. The maximum lowstandof the Atelian regression can be correlated to the maximum of thepost-Karangatian regression of the Black Sea.The paper by A. Zastorozhnov et al. (2021, this volume) focuses onthe Pleistocene paleoenvironments in the Lower Volga region (Russia)using comprehensive multidisciplinary (lithological, biostratigraphic,OSL-dating) study of the Seroglazovka reference section in borehole andoutcrop. This Quaternary sequence is subdivided into a series of regionalhorizons and subhorizons that are correlated with adjacent sections ofthe Lower Volga and the Regional Stratigraphic Scale. This enabled toperform paleogeographic reconstructions of the geological history of theLower Volga region as well as clarification of the role of glacial refugia inthe settlement of certain species and their further colonization both theland and water.The paper by Mudie et al. (2021, this volume) focuses on the palynomorpsof the North-Western Black Sea. This is the first study to fill theknowledge gap concerning inter-regional variations in Black Sea palynomorphs,including terrigenous pollen + spores, freshwater algalspores, and organic remains of marine microplankton, micro- andmeiobenthos. It is also the first study to examine the potential influenceof gaseous hydrocarbon geochemical effects on Black Sea palynologicalassemblages and their linked microfossils sources (e.g. foraminifera,ostracodes and nematodes) in shelf and continental slope settings. Themain conclusion is that largest influence manifests as 1) very highconcentrations of terrigenous palynomorphs (pollen + spores) in thegas-prone sediments west of the Odessa-SinopFault Zone (OSFZ), and 2)as large proportions of FeS2-infilled pollen grains, particularlydown-slope below ca. 100 m BSL. In sharp contrast to the terrigenouspalynomorphs, the abundant phytoplanktonic marine dinocysts show nosignificant difference in total amounts/g in relation to CH4 or H2S levels.However, there is a notable increase in heterotrophic taxa both west ofthe OSFZ and with water depth that is largely related to the replacementof the toxic gonyaulacoid cyst species. Overall, these new findings needto be considered when applying classical models of nearshore-offshorepollen concentrations and pollen:dinocyst (P:D) ratios to the interpretationof paleo-sea levels and paleo-vegetation reconstructions in thePonto-Caspian seas. The data set also provide a unique opportunity fordirect comparison of the organic-walled planktonic and benthic microfossilpalynomorph assemblages with micropaleontological data reportedfor foraminifera, ostracodes and other meiobenthos as was showby Shnyukov and Yanko, 2020; Yanko et al. (2017).The paper by Mazneva et al. (2021, this volume) is devoted to thestratigraphy, lithology and composition of the Middle and Late Pleistoceneloess of the Western Ciscaucasia. The patterns of the spatialdistribution of the loess thickness, grain size, elemental and mineralogicalcomposition indicate that the main source of Aeolian dust is situatedin the east of the Ciscaucasia region. According to the authors, themain sources of dust are sand masses of the Lover Volga, Terek, Kumaand Kura rivers alluvium in the Caspian lowland. The Lower Don sandyprovince is a secondary source. A clear trend for the increase of averagedust accumulation rates has been established over the last three climaticmacrocycles. The most intensive increase in the rate of dust accumulationoccurred in the last interglacial-glacial macrocycle MISs 2–5.Average accumulation rates were ~1.8 times higher compared to MISs6–7 and ~2.3 times higher than during MISs 8–9. The progressivearidization of the climate in the region is a probable reason for this trend.A second paper by A. Makeev et al. (2021b, this volume) is devotedto the soils of archaeological monuments of the Bronze Age that areconsidered as a key to the Holocene landscape dynamics in the broadleafforest area of the Russian Plain. The study is based on detailedmorphological, chemical and microbiomorphic analyses of a paleosolburied under the kurgan of the Abashevo culture and a surface soil. Theresults confirm the stability of the forest environment at the southernboundary of the forest belt since the Bronze Age. The study also provethat the Abashevo people had complicated burial funeral rites based onconstruction techniques similar in a vast area bordering Caspian – BlackSea – Mediterranean Corridor from the North. Understanding constructiontechniques is important both for archaeology andpaleogeography.
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