Quaternary International最新文献

The lower reaches of the Yellow River have witnessed numerous episodes of flooding and considerable shifts in its course. Examining flood records within the Yellow River basin offers invaluable insights into ancient human settlements, agricultural practices, trade routes, and technological advancements of ancient Chinese civilizations. However, dating these fluvial sediments poses a considerable challenge due to either the scarcity of organic material for radiocarbon (¹⁴C) dating or the potential incomplete bleaching of sediments for optically stimulated luminescence (OSL) techniques. This study focused on the Anshang site located in Henan Province, we obtained OSL ages from distinct grain size fractions of quartz and cross-verified them with independent acceleration mass spectrometry (AMS) ¹⁴C ages. The findings revealed that both coarse quartz grains (CG) and medium quartz grains (MG) underwent complete bleaching in silt-dominated flood deposits and shallow lacustrine deposits. Conversely, the OSL ages of CG and MG quartz were notably overestimated by approximately 3–6 ka in silty clay-dominated flood deposits. Upon comparing the OSL ages with AMS ¹⁴C ages, it was evident that bulk organic matter AMS ¹⁴C ages aligned with CG OSL ages in shallow lacustrine deposits, but they appeared older than CG OSL ages in flood deposits. However, the AMS ¹⁴C ages from plant demonstrated good consistency. Consequently, we successfully identified flood-lacustrine sediments dating back to approximately ∼13 ka, ∼8–3 ka, ∼2.6 ka, ∼1 ka, and the last few hundred years, aligning well with historical documentation and earlier research. The regional evidence presented herein enhances our understanding of the applicability of OSL dating and AMS ¹⁴C dating in fluvial-lacustrine sediments. Armed with these new ages, we constructed a reference chronology for archaeological localities situated in the fluvial sediments of the lower reaches of the Yellow River.

A detailed record of sea level changes and climate oscillations in the Gulf of Saros during the late Pleistocene to the Holocene is provided by high-resolution seismic reflection profiles and analysis of a sediment core. The seismic stratigraphy reveals the formation of four main depositional units bounded by prominent reflection surfaces, reflecting high sea level variations. The Last Glacial Maximum period in the gulf is associated with the lowstand sea level, forming the deepest marine terrace at −148 m. The increasing sea level due to post-glacial warming was accompanied by the deposition of transgressive units characterized by coastal onlaps together with local channel-fills. This transgressive phase was modulated by three brief still-stands sea levels at 17 cal ka BP, 14.6 cal ka BP and 13.6 cal ka BP, producing the younger marine terraces in the gulf at −135 m, −112 m and −90 m, respectively. A comparison of their depths with the global sea level curve reveals elevation differences with decreasing subsidence rates from the older to younger ages, implying tectonic subsidence along the gulf floor.

The close correlation of multi-proxy data from core SAG-22 in the gulf with the northern Aegean and Anatolia data strongly indicates that the timings of the past climate events generally agree with the global and regional climate patterns. The warm climate around the gulf during the late phase of Bølling/Allerød (13.3–12.6 cal ka BP) is represented by high marine biological productivity and improved ventilation in the deeper water due to subsequent transgression. Permafrost formation in the catchment area during the following cold and dry Younger Dryas period (12.6–11.7 cal ka BP) resulted in reduced soil erosion and sediment input to the gulf. Noticeable warming during the Early Holocene between 11.2 cal ka BP and 9.4 cal ka BP is recorded by the multi-proxy data of the core when the enhanced marine biological productivity occurred above the poorly oxygenated deep water column. The climatic deterioration to a cooler and drier phase during the Early to Middle Holocene transition (9.4–7.8 cal ka BP) resulted in intense physical weathering and erosion, causing the highest sedimentation in the gulf. The later period of the Holocene is associated with the formation of two discrete sapropels at 7.8 cal ka BP and 5.4 cal ka BP that were accompanied by warm and wet climates around the gulf.

New widely accepted scenario of glacier-free landscape evolution in the north of West Siberia during MIS 2 (Sartanian cryochron) raises a challenge to find new regional stratigraphic markers in the absence of reliable continuous sedimentary units. The cryogenic and pedogenic structures have been long applied for the European Late Pleistocene stratigraphy in the extra-glacial regions. We argue that such structures might also provide important markers for the detailed stratigraphic scheme in the north of West Siberia. Two types of indicators were suggested. Firstly, morphological features and ranges of radiocarbon dates in epigenetic ice wedge pseudomorphs of higher terraces are sensitive to events of abrupt climate amelioration. Regional analysis of radiocarbon dates of ice wedge pseudomorphs indicated four warmer climatic events in the Late Pleistocene – the Early Holocene (ca. 18000–16500 cal BP, ca. 13800–12500 cal BP, ca. 11700–11100 cal BP, and ca. 10400–9000 cal BP). They correlate to climatic events of the Greenland ice core record with minor temporal lag. Secondly, more detailed cryogenic-paleosol-sedimentary sequences formed at lower terraces where sedimentation continued during MIS 2 are another type of suggested indicator. Their morphological and paleobotanical analyses and radiocarbon dating provided a reconstruction of local paleolandscape evolution with events of cryohydromorphic soil development (ca. 15700–15300 cal BP, ca. 11200–9000 cal BP). Similar late-glacial paleosols are encountered in the European loess sequences. We propose that the cryopedogenic horizons, including ice wedge pseudomorphs, cryoturbation structures, and cryohydromorphic paleosols, are reliable regional stratigraphic markers in the north of West Siberia for the Sartanian cryochron.

This article presents the results of malacological and isotope studies on lacustrine sediments from the Eemian interglacial site in the Piła (north-western Poland). Twenty species of molluscs were found in the analysed sediments. Changes in the taxonomic composition and the quantitative structure of malacofauna in the profile allowed distinguishing five types of assemblages corresponding to different phases of the lake's evolution. Ratios of oxygen and carbon isotopes (δ¹⁸O and δ¹³C) reflecting changes in the lake water composition were measured in shells of two predominating snail species, Valvata piscinalis (Müller, 1774) and Bithynia tentaculata (Linnaeus, 1758), and in opercula of Bithynia tentaculata. Significant variability in isotope contents was noted for shells in individual profile sections and between analysed taxa. The results of malacological and isotope studies were supplemented with lithological, stratigraphical and palynological data. On this basis, the sediments age was determined (optimal and suboptimal phases of the Eemian interglacial). Environmental changes of paleolake have been also reconstructed. The analysed sediments were initially deposited in the coastal, periodically drained zone of the reservoir. The younger part of the sequence represents the shallow part of the littoral zone of the permanent water body. The malacological and isotope data also allowed distinguishing two phases of increased water level in the reservoir, and changes in its trophic state probably generated by climatic factors.

The reconstruction of environmental changes at the termination of the Last Glaciation range in NE Europe during the Late Glacial is hampered by the multiplicity of processes underway at that time and during the Holocene that dynamically modified the Young Glacial landscape. In lake sediments, these changes are recorded in a manner that is almost always incomplete or disturbed. For this reason, the succession that was successfully reconstructed in two profiles from the Osinki site in NE Poland is extremely valuable. Palynological, Cladocera and geochemical analyses, as well as fragmentary malacofauna and diatom analyses, made it possible to trace the changes in the environment that took place in two differently functioning parts of a single lake, in not interrupted periods from the Oldest Dryas to the Younger Dryas. Detailed research results show that despite the proximity of natural environment components, their developments in both cases were conducted in different ways, what they prove to the changes in pollen record, Cladocera, and geochemical composition of sediments. Climate changes affected the changes in the vegetation, the composition of malacofauna, Cladocera and diatoms. They also influenced the erosion processes within the catchment and the oxidation-reduction conditions. On the basis of the research results, changes in water trophy, from oligotrophic to eutrophic, were also observed. In this case, we also observe significant differences between the two analysed profiles. These changes first occurred in Allerød in the shallow part of the lake, and then in its deeper zone in Young Dryas.

In addition, Late Weichselian profiles from the Poland–Belarus–Lithuania borderland area were analysed in detail, and the age of the bottom of sediments is usually estimated to the Allerød, and the Bølling. The results of analyses from Osinki and Osinki2 profiles (beginning of sedimentation in the Oldest Dryas) indicate that the reason for this discrepancy is to be found in, among other things, the methodological limitations of the palynological analysis for most of the sites. The above-standard amount of mineral sediment allows the age of the sediment to be established as being much older than if determined using only pollen analysis of organic sediments.

We discuss geological and biotic aspects of the extensive Akchagylian transgression that occurred in the Caspian region of Eurasia near the Plio-Pleistocene transition, in Piacenzian and Gelasian. It is shown that the onset of the Akchagylian marine sedimentation in Western Turkmenistan (ca. 3.2 Ma) preceded that in the Kura Basin (ca. 3.0 Ma). The position of the upper boundary of the Akchagylian remains uncertain (ca. 2.1 or 1.8 Ma). The analyzed biotic content of the Akchagylian includes molluscs, microfossils (pollen, dinocysts, foraminifers), and mammals. It is noted that specific forms of the Akchagylian aquatic biota co-occur with microfossils that clearly indicate a connection with the World Ocean or related seas. The palynology of the Akchagylian time signals a directed cooling in the Pliocene and Early Pleistocene with several warm and humid epochs. The Akchagylian transgression was preceded by a change of a structural-sedimentary pattern of the region. In the latest Miocene and Early Pliocene, a pre-existed longitudinal tectonic zonation of the Caucasian-Caspian segment of the Paratethys gradually changed into clearly transverse tectonic zonation. The latter was manifested in the tectonic uplift of the Greater Caucasus, its northern piedmonts and the Lesser Caucasus, and in the subsidence of the western parts of the South and Middle Caspian basins. The interplay of longitudinal and transverse tectonic features shaped the configuration of the Akchagylian brackish-water basin and controlled thickness of its deposits. It was the transverse zonation that dominated in the thickness pattern. The increasing role of the transverse zonation in the post-Akchagylian time is manifested in the magnitudes and rates of the Quaternary tectonic uplift. These parameters were calculated based on current heights of the top of the Akchagylian marine deposits in different parts of the basin. The highest magnitudes of uplift are found in the Eastern Caucasus (up to 1980 m on the NE slope and about 2500 m in the axial part) and in the west of the Lesser Caucasus in eastern Turkey (up to 1750 m). The maximum level of the Akchagylian transgression is estimated at 40–50 m above the present level of the World Ocean. We show a low probability of connection of the Akchagylian basin with the Mediterranean Sea or the Persian Gulf, and a high probability of its connection with the Arctic Ocean through the northern tributaries of the Kama River and the Pechora Basin in the NE of East European Plain.

A flowstone section in the Račiška pečina Cave (Classical Karst, SW Slovenia) records multiple chronostratigraphic and palaeoclimatic proxies that can be correlated with other records on the global scale (Mediterranean region, Japan). Its upper part has an excellent record of the Matuyama/Brunhes (M/B) magnetic reversal. The M/B reversal zone, which is 6 mm in thickness, was detected by a high-resolution palaeomagnetic analysis of the sequence. An age model based on oxygen isotopic stratigraphy locates this quick transition in mid-MIS 19, between 777.9 and 777.2 ka, with the midpoint at 777.7 ka. The transition is marked by abrupt changes in stable isotopic compositions, trace element concentrations and flowstone fabrics that point to temperature and precipitation changes. Two distinct maxima in trace element concentrations at the beginning and the end of the M/B transition indicate two periods of higher precipitation, with increased washes of clay minerals into the cave. In addition, the stable isotopic (δ¹³C and δ¹⁸O) compositions indicate that significant cooling and high precipitation occurred during the M/B reversal within the generally warm MIS 19.

During the Quaternary, the Lower Volga region was typically a shallow shelf of the Caspian Sea. This region regularly and distinctively responded to sea level fluctuations by changing both sediments and biota. This region is therefore a key to understanding the history of the transgressive-regressive cycles of the Caspian Sea during the Quaternary. There is a wealth of information about the Quaternary deposits of the Lower Volga region; however, their diversity of facies, erosional processes, and fragmented sections create difficulties in stratigraphic interpretation and the development of paleogeographic models. The studied 500-m section of borehole 8 Ulan-Khol is among the few in the Caspian region that allows for the sequential reconstruction of the Quaternary history of the region in one section. These borehole data offer a unique opportunity to reconstruct transgressive-regressive cycles in Pleistocene basins located in the most southeastern part of Europe (the Caspian region). Based on biostratigraphic, sedimentological, and paleomagnetic methods, we were able to define main Early, Middle, and Late Pleistocene units, which were correlated with regional stratigraphical units. Each unit corresponds to regional paleogeographic events and sedimentation modes characterized either by basinal (brackish water) or continental conditions when lagoons and fluvial landscapes dominated. The borehole interpretation integrated with regional data demonstrates a complex history of Caspian basin development during Apsheronian time (MIS 63–20) with the presence of a strong regression in its final stage, accompanied by a previously unknown advance of the Paleo-Volga valley to the latitude of Astrakhan city and further south. This regression and the formation of the Paleo-Volga valley continued during Tyurkyanian time (MIS 19). By the end of the Tyurkyanian, the regression was followed by a transgressive stage, which culminated in Bakunian time (MIS 18–12). The Khazarian stage (MIS 11–5) of Caspian Sea development was characterized by a constant change from alluvial-marine to marine and estuarine environments. The borehole data support our earlier conclusion that the Singilian deposits separate the lower (MIS 11–7) and upper (MIS 5) Khazarian units. New data support the existence of only one transgression of the Caspian Sea during Khvalynian time (MIS 3–2); after its maximum stage the sea level gradually decreased with the formation of coastlines at several terrace levels. Due to its high deposit thickness and rich paleontological, stratigraphic and lithological information, Ulan-Khol borehole 8 can be considered a key site for the Northern Caspian area.