Papers by Sergey Krivonogov
Springer eBooks, 2003
... The results of a palynological study of the cores with 14 radio-carbon dates revealed the fol... more ... The results of a palynological study of the cores with 14 radio-carbon dates revealed the following vegetation history since the late glacial. ... Pollen Record from the Eastern Shore of Lake Baikal 211 FIG ... Solid circles, radiocarbon ages; open circles, calibrated ages (calendar years ...
Springer eBooks, 2003
... The records of Holocene regressions can be recognized only in the near-shore sediments ofLake... more ... The records of Holocene regressions can be recognized only in the near-shore sediments ofLake Hovsgol. ... It should be noted that in the late glacial and Holocene, it coincides with the water-level fluctua-tions of the lakes in northwestern Mongolia (Walter and Batnasan ...
Russian Journal of Pacific Geology, May 1, 2019
The Itmurundy zone of the northern Balkhash area is a Pacific-type orogenic belt. It possesses a ... more The Itmurundy zone of the northern Balkhash area is a Pacific-type orogenic belt. It possesses a complex geological structure and hosts rocks of mantle, accretionary and post-orogenic associations. The volcanic and sedimentary rocks of the accretionary association belong to three suites: Itmurundy (O 1-2), Kazyk (O 2-3) and Tyuretai (O 3-S 1). The suites are separated by tectonic unconformities or faults of three orders: 1) large regional faults; 2) medium faults separating mantle and oceanic accreted rocks; 3) small faults separating packages consisting of oceanic sediments. The Itmurundy Fm. (O 1-2) is the most lithologically variable consisting of oceanic basalt, pelagic chert, hemipelagic siliceous mudstone and siltstone, and trench greywacke sandstone. The packages, each consisting of chert-siliceous mudstone, are separated from each other by 2 nd and 3 rd order faults of probably thrust nature, i.e. they are parts of duplex structures. The presence of duplex structures and the high degree of deformation of Itmurundy Fm. rocks are typical of accretionary complexes. The associations of volcanic and sedimentary rocks under study represent a full section of oceanic plate stratigraphy (OPS): basalt (MORB, OIB)-chert (pelagic)-siliceous mudstone, siltstone and shale (hemipelagic)-trench sandstones (greywacke). The structural position and the lithology of Itmurundy rocks accord well with the model of formation of accretionary complexes at Pacific-type convergent margins, in particular, those in the western Pacific.
Nuclear Instruments & Methods in Physics Research Section B-beam Interactions With Materials and Atoms, Jun 1, 2007
Pre-AD 1955 mollusc shell samples for the Caspian and Aral Seas were obtained from collections of... more Pre-AD 1955 mollusc shell samples for the Caspian and Aral Seas were obtained from collections of the Paleontological Institute (Russian Academy of Sciences, Moscow) and Zoological Institute (Russian Academy of Sciences, St. Petersburg). They were collected at the end of nineteenth century and in the 1930-1950s. For the Caspian Sea, mean apparent 14 C age of shells (R) is ca. 410 yrs and DR is about +5 yrs. For Aral Sea, the first study of apparent 14 C age of 'pre-bomb' molluscs shows the R value as ca. 170 yrs and DR value is ca. À130 yrs. These values may be used to correct 14 C data previously obtained from this region and should be used for the future research.
Irrigation and Drainage Systems, Oct 26, 2007
The lake level history, here based on the relative abundance of Ca (gypsum), is used for tracing ... more The lake level history, here based on the relative abundance of Ca (gypsum), is used for tracing past hydrological conditions in Central Asia. Lake level was close to a minimum before approximately AD 300, at about AD 600, AD 1220 and AD 1400. Since 1960 the lake level is lowering again. Lake water level was lowest during the 14 th or early 15 th centuries as indicated by a coeval settlement, which today is still under water near the well-dated mausoleum of Kerderi. Pollen data from riparian vegetation indicate relatively moist conditions between AD 400 and AD 900, intermitted by short intervals with drier conditions (AD 550-600; AD 650-700). Riverbanks were again dry from AD 900-1150, AD 1450-1550, and from AD 1970 onward moisture decreased steadily. Irrigation activities were at a maximum between 300 BC and AD 300 (Classical Antiquity) and between AD 800 and AD 1300 (Medieval Age) and after AD 1960.
Doklady Earth Sciences, Jun 1, 2008
Climate of The Past, Jul 1, 2009
In this study a radiocarbon-dated pollen record from Lake Kotokel (52 • 47 N, 108 • 07 E, 458 m a... more In this study a radiocarbon-dated pollen record from Lake Kotokel (52 • 47 N, 108 • 07 E, 458 m a.s.l.) located in southern Siberia east of Lake Baikal was used to derive quantitative characteristics of regional vegetation and climate from about 15 kyr BP (1 kyr=1000 cal. yr) until today. Quantitative reconstruction of the late glacial vegetation and climate dynamics suggests that open steppe and tundra communities predominated in the study area prior to ca. 13.5 kyr BP and again during the Younger Dryas interval, between 12.8 and 11.6 kyr BP. The pollen-based climate reconstruction suggests lower-than-present mean January (∼−38 • C) and July (∼12 • C) temperatures and annual precipitation (∼270-300 mm) values during these time intervals. Boreal woodland replaced the primarily open landscape around Kotokel three times at about 14.8-14.7 kyr BP, during the Allerød Interstadial between 13.3-12.8 kyr BP and with the onset of the Holocene interglacial between 11.5 and 10.5 kyr BP, presumably in response to a noticeable increase in precipitation, and in July and January temperatures. The maximal spread of the boreal forest (taiga) communities in the region is associated with a warmer and wetter-than-present climate (T w ∼17-18 • C, T c ∼−19 • C, P ann ∼500-550 mm) that occurred ca. 10.8-7.3 kyr BP. During this time interval woody vegetation covered more than 50% of the area within a 21×21 km window around the lake. The pollen-based best modern analogue reconstruction suggests a decrease in woody cover percentages and in all cli
Gondwana Research, Oct 1, 2017
<p&amp... more <p>Holocene moisture evolution in the arid Central Asia region, dominated by the westerly circulation system, has been shown to be in drastic contrast with that in Asian monsoonal regions. Yet, water isotope records, including stalagmite oxygen isotopes and terrestrial long-chain n-alkane/acid hydrogen isotopes, show many common features in the two regions. Here we present several new isotopic records from the arid Central Asia region to examine the isotopic differences from various archives/media, together with existing water isotopic records from both regions. Isotopic records more reflecting terrestrial signal in arid regions appear to follow the pattern in monsoonal regions, while those likely affected by isotopic enrichment due to lake water evaporation display various patterns, and not necessarily resemble moisture changes inferred from the same lakes. It thus appears that the terrestrial water isotopes in both regions may record the isotopic signature in precipitation, but not necessarily linked to aridity changes. Meanwhile, those isotopic records affected by lake evaporation, after subtracting the original precipitation isotopic signal, show good correspondence to moisture changes.</p>
AGU Fall Meeting Abstracts, Dec 1, 2019
Invited - Oral Session GC51C - Environmental Change and Civilization Evolution Along the Ancient ... more Invited - Oral Session GC51C - Environmental Change and Civilization Evolution Along the Ancient Silk Road and the Hindu Kush-Himalaya I - abstract #GC51C-03
Geochimica et Cosmochimica Acta, 2021
Abstract Branched glycerol dialkyl glycerol tetraethers (brGDGTs) are microbial molecular fossils... more Abstract Branched glycerol dialkyl glycerol tetraethers (brGDGTs) are microbial molecular fossils ubiquitous in natural environments. The correlation between the Methylation Index of brGDGTs (the M B T 5 M E ' paleothermometer) and temperature offers an important tool for reconstructing past terrestrial temperatures. However, factors other than temperature could also affect the distribution of brGDGTs in lacustrine systems, hampering the quantitative application of this paleothermometer. Here we investigated brGDGT distributions in contemporary sediments collected from 52 lakes in mid-latitude Asia. Combined with published brGDGT data from other lakes across the globe, we have found a strong salinity control on the relative abundance of 5-methyl brGDGTs versus their late-eluting isomers (including 6-methyl, 7-methyl, and unknown isomers). This allows the development of novel indices based on the isomerization of brGDGTs for tracing past lake water salinity. We also demonstrate that salinity-controlled isomerization of pentamethylated and hexamethylated brGDGTs can significantly impact the M B T 5 M E ' paleothermometer, potentially leading to an overestimation of past temperature, but the temperature signal can be extracted out of the M B T 5 M E ' index after correcting the salinity effect. As demonstrated in application to a Lake Qinghai (China) sediment core spanning the last 18 kyr, our finding could facilitate the simultaneous retrieval of reliable temperature and salinity records using brGDGTs in lacustrine settings, in particular for lakes that have experienced large salinity changes during the geological past.
Episodes, 2018
Pacific-type orogens (fold belts) hosting accretionary complexes are places keeping records of th... more Pacific-type orogens (fold belts) hosting accretionary complexes are places keeping records of the evolution of paleo-oceans, and formation and transformation of continental crust at their active convergent margins. Pacific-type orogeny induces destruction of crustal materials, their subduction to the deep mantle, generation of hydrouscarbonated plumes in the mantle transition zone (MTZ) and its related intra-plate magmatism. We propose a new approach for linking paleo-oceans, active margins and intra-plate magmatism in central and eastern Asia. The approach "stands" on three "whales": the model of Ocean Plate Stratigraphy (OPS), the parameters of Pacific-type convergent margins and a model of hydrous-carbonated plumes. The OPS model evolved from extensive studies of accretionary complexes in the western Pacific, in particular, in Japan; it allows differentiating oceanic plates of one paleoocean and evaluating their sizes and ages. An important issue for reconstructing the history of paleo-oceans is to estimate major parameters of the Pacific-type convergent margins: accreting vs. eroding, geometrical length, and life time. For the eroding margins we must define major periods of tectonic erosion and transportation of oceanic and continental materials to the deep mantle and evaluate a possibility of their accumulation in the MTZ. All this would allow us to develop a holistic model linking the evolution of paleooceans, the accretion and erosion of oceanic and continental crust materials at Pacific-type convergent margins, mantle metasomatism and intra-plate magmatism.
Russian Geology and Geophysics, 2019
—The evolution of peat deposits of the Vydrino bog (southern Baikal region) and concentration of ... more —The evolution of peat deposits of the Vydrino bog (southern Baikal region) and concentration of elements in them are discussed. The bog peat massif more than 4 m in thickness formed mostly during the Holocene. The beginning of peat formation dates back to the late Allerød (13.1 ka). At present, the Vydrino bog is a biogeocoenosis of the high-moor type with a transitional peat deposit. We have established that the bog nonuniformly accumulated chemical elements during its formation. Concentration of Pb, Sn, Cd, Zn, and Sb in recent vegetation and in the upper layer of the peat bog is mainly due to forest fires and anthropogenic air pollution. The anomalous enrichment of peat with Zn and Cu in the Early Holocene (12.1–8.8 ka) horizons proceeded through the periodic inflow of thermal groundwater into the bottom part of the peat deposit. Authigenic Zn and Cu sulfides formed on the inner membrane of the cell wall of sphagnum moss. Geochemical modeling has shown that Zn and Cu sulfides can form abiotically.
Russian Geology and Geophysics, 2018
The Chulym and Kargat Rivers flow through chains of saucer-shaped depressions, which are swampy m... more The Chulym and Kargat Rivers flow through chains of saucer-shaped depressions, which are swampy meadows or drainage lakes. In the past, all of them were lakes short-lived in different Holocene periods. These depressions accumulated a significant amount of the Chulym and Kargat runoff and thus influenced the water balance of Lake Chany. Our studies have reconstructed the history of these depressions. A model describing their filling with sediments is proposed. The lacustrine sediments penetrated by boreholes and pits are dated by the radiocarbon method at 6.3–2.0 cal. kyr BP. The data obtained explane the long existence of Lake Chany as a shallow basin and rise in its level at ~ 2 kyr BP.
Russian Geology and Geophysics, 2017
The article presents the results of pyrolysis (Rock-Eval) and pyrolysis–gas chromatography–mass s... more The article presents the results of pyrolysis (Rock-Eval) and pyrolysis–gas chromatography–mass spectrometry analysis of organic matter (OM) in the Holocene sediments of the Black Sea. The studied samples represent two parts of the sedimentary column: coccolith ooze with 2.8% Corg at the top and sapropels oozes with 8.5% Corg at the bottom. The deposition of Holocene sediments was inferred to take place under euxinic conditions, which are more favorable for organic-matter preservation and sapropel deposition during the Old Black Sea stage. The results show that the modern processes of microbially mediated methane oxidation in the Old Black Sea oozes are interpreted as the main cause of their apparently lower degree of diagenetic transformation as compared to that of coccolith oozes.
Procedia Earth and Planetary Science, 2013
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Papers by Sergey Krivonogov