Late Pleistocene-Holocene Sediments Research Articles

Textural analysis and environmental implications of the Late Pleistocene-Holocene sediments of the Faiyum paleolake, Egypt

Textural analysis and environmental implications of the Late Pleistocene-Holocene sediments of the Faiyum paleolake, Egypt

An overview and update of South American and Antarctic fossil rheidae and putative ratitae (Aves, Palaeognathae)

A comprehensive overview of all the South American and Antarctic fossil records of Rheiformes and close relatives, accompanied by updated stratigraphic data, is provided here. Fossil rheas are represented by fragmentary remains of hindlimb bones and several footprints that include paleospecies, extinct representatives of the living species as well as putative ratites. To date, the oldest record corresponds to the early Eocene of Argentina, Brazil and maybe Antarctica, thus the Palaeocene antiquity of several fossil sites with rheas is no longer valid. Neogene sediments present records of the exclusively fossil taxon Opisthodactylus as well as ‘Pterocnemia’. Most of the Quaternary records come from late Pleistocene-Holocene sediments from Argentina, Chile, Uruguay, Bolivia, and Brazil and are represented by extinct representatives of living species. Finally, Argentina is the country with the highest number of fossil records and taxa.

Morphology and Late Pleistocene–Holocene sedimentation of the Strait of Istanbul (Bosphorus): a review

Abstract The Bosphorus (Istanbul) Strait is a natural strait that connects the Black Sea with the Aegean Sea via the Sea of Marmara and the Dardanelles Strait. It is a 31 km-long and 3.5 km-wide winding channel, with an irregular bottom morphology. It has depressions up to 110 m deep, and two sills with depths of 35 and 58 m in the south and north, respectively. Presently, a two-layer water exchange exists through the strait, with the Mediterranean and Black Sea waters forming the lower and upper layers, respectively. The Bosphorus channel extends as shelf valleys on the Black Sea and Sea of Marmara shelves. However, it operated as a river valley or an estuary during the stadial lowstand periods. The infill sedimentary succession of the Bosphorus channel is up to 100 m thick above the Paleozoic–Cretaceous basement with an irregular topography. The oldest sediments are sandy to muddy fluvial–lacustrine facies of late Pleistocene age, which are preserved only in up to 160 m-deep scoured depressions of the basement. They are overlain by mid–late Holocene estuarine–marine shelly sandy to muddy sediments with patches of bioherms and shelly lag deposits. The Bosphorus outlet areas of the Black Sea and Sea of Marmara are characterized by a submarine fan and a shelf valley, respectively. The fan system in the Black Sea started depositing c. 900 years after the initial vigorous marine water incursion at c. 8.4 14 C ka BP. On the Marmara shelf, extension of the Bosphorus channel is a sinuous shelf valley with a channel–levee complex that was deposited by the Black Sea outflow during 11–10 14 C ka BP. Catastrophic floodings of the Sea of Marmara by torrential Black Sea outflows during the Greenland Interstadial melt-water pulses, as well as the strong Mediterranean current towards the Black Sea during the interglacial periods, were responsible for carving out the Bosphorus channel and the shelf valleys, as well as removing the sediments belonging to the earlier periods.

Late Pleistocene-Holocene sedimentary evolution in the coastal zone of the Red River Delta

The Red River Delta is considered one of the largest megadelta systems in Asia. The formation of this delta has been controlled by the continent-ocean interaction and sea-level fluctuation during the Cenozoic. In this study, we present a new sequence stratigraphic framework of the Red River Delta based on borehole lithofacies analysis and high resolution seismic data. The Late Pleistocene–Holocene sediments in the coastal zone of the Red River Delta were subdivided into three systems tracts: (1) the lowstand systems tract (LST) is characterized by a Late Pleistocene alluvial silty sand facies complex (arLSTQ13b); (2) the transgressive systems tract (TST) is illustrated by the coastal marsh facies complex and the lagoonal greenish-gray clay facies of Early-Middle Holocene (amt, mtTSTQ21−2); and (3) the highstand systems tract (HST) is composed of the Middle-Late Holocene deltaic clayish silt facies complex (amhHSTQ22−3). The boundaries between these three systems tracts are not isochronous, namely: (1) The LST-HST boundary has been associated with the Würm 2 Glaciation, which occurred at ~40-18 Ka.; (2) The TST-LST boundary is identified by a transgressive erosion surface, whose age ranges from ~12-5 Ka.; and (3) the HST-TST boundary is an unconformity between the submarine deltaic facies complex and the Middle Holocene marine flooding plain.

Climate Signals in the Late Quaternary Bottom Sediments of Lake Baunt (Northern Transbaikalia)

Abstract —The bottom sediments of lakes with different mineralization located in the basins of inland areas are high-resolution archives of climate and environmental changes. We present results of study of the Late Pleistocene–Holocene sediments of freshwater Lake Baunt, one of the lakes of the Baunt (Tsipa) depression in the permafrost zone in northern Buryatia. The sediments were studied by XRD, IR spectroscopy, laser granulometry, elemental analysis, AMS dating, etc. Mineral analysis of the bottom sediments with an age of ~18 ka has revealed predominant phyllosilicates, quartz, and feldspars. Mathematical modeling of complex XRD spectra made it possible to identify chlorite, muscovite, illite, mixed-layer illite–smectite and chlorite–smectite, and kaolinite among the phyllosilicates. We have determined their structural and crystal-chemical features and quantitative proportions in the section (800 cm long core), which vary in accordance with the climate cycles and lake level fluctuations. The results obtained helped to reconstruct the evolution of the Lake Baunt basin controlled by the regional climate throughout the Late Pleistocene–Holocene. This paper continues a series of our publications concerned with the reconstruction of the Late Pleistocene–Holocene climate in East Siberia by comprehensive studies of the mineral composition of sedimentary sections of small lakes.

Impact of sedimentation history for As distribution in Late Pleistocene-Holocene sediments in the Hetao Basin, China

PurposeTo understand the impact of geochemical sedimentation history for arsenic (As) distribution in the sediment profiles of the Hetao Basin, we (1) evaluated sediments provenance and variations of weathering intensities, (2) attempted to reconstruct the depositional environments, and (3) explored the As and Fe speciation in the sediments. Combining the information above, different sedimentation facies were distinguished in the vertical profiles.MethodsTwo sediments cores were drilled up to 80 m depth. Major and trace element compositions, including rare earth elements (REE), were analyzed. Carbon isotope ratios (δ13Corg) of embedded organic matter in the sediments were analyzed by isotope ratio mass spectrometry (IR-MS). Arsenic and Fe speciation of the sediments were determined by sequential extractions.Results and discussionThe similar REE geochemistry of rocks from the Lang Mountains and sediments in the Hetao Basin indicated that the sediments originated from the Lang Mountains. The C/N ratio (~ 4 to ~ 10) in combination with δ13Corg (− 27‰ to −2 4‰) suggested that sediments were mainly deposited in aquatic environments. The unconfined aquifer equaled the lacustrine deposit with less intensive weathering during last glacial maximum (LGM). Here, the As content (average, 5.4 mg kg−1) was higher than in the aquifer sediments below (average, 3.6 mg kg−1).ConclusionHigher content of releasable As in combination with paleolake-derived organic matter aquifer sediments probably contributes to higher groundwater As concentration in the unconfined aquifer. This study provides the first insight into the impact of sedimentation history on As distributions in sediment profiles in the Hetao Basin.

Phyllosilicates in bottom sediments of Lake Baunt (northern Transbaikalia) as indicators of paleoclimate

The lacustrine sediments are unique natural archives that store records of environmental and climatic changes. We present results of study of the Late PleistoceneHolocene sediments of freshwater Lake Baunt, located in the permafrost zone in northern Transbaikalia. The sediments were studied by X-ray diffraction (XRD), IR spectroscopy, laser granulometry, elemental analysis, AMS dating, etc. The results of mineral analysis of the bottom sediments with an age of ~18 ka showed that they are mainly represented by phyllosilicates, quartz, and feldspars. By the mathematical modeling of complex XRD patterns chlorite, muscovite, illite, mixed-layer illitesmectite and chloritesmectite, and kaolinite identified among the phyllosilicates. It was established that variations of their structural features as well as quantitative proportions in the section are in high correlation with the climate changes and lake level fluctuations. The results obtained helped to reconstruct the evolution of the Lake Baunt basin controlled by the regional climate throughout the Late PleistoceneHolocene.

Lithology, biostratigraphy, and geochronology of the late pleistocene-holocene sediments on the coast of Onega bay of the White sea

This paper reports on the lithological, micropaleontological, and chronometric data (radiocarbon dating) for one of the areas of the White Sea coast. The sedimentary sequences were studied in the current lake basins, which were separated from the large basin at different times. The basin was situated in the head of the current Onega Bay. On the basis of these data, the bottom sediments were stratified and the Late Pleistocene-Holocene paleogeographic settings were reconstructed for the southeastern part of Onega Bay.

Lithology, Biostratigraphy, and Geochronology of the Late Pleistocene–Holocene Sediments on the Coast of Onega Bay of the White Sea

Lithology, Biostratigraphy, and Geochronology of the Late Pleistocene–Holocene Sediments on the Coast of Onega Bay of the White Sea

Widespread tephra layers in the Bering Sea sediments: distal clues to large explosive eruptions from the Aleutian volcanic arc

Tephra layers within marine sediments provide information on past explosive eruptions, which is especially important in the case of remote island arcs where data on proximal pyroclastic deposits can be scarce. Three Alaska-Aleutian tephras (labeled Br2, SR2, and SR4) were found in the late Pleistocene-Holocene sediments of the Bering Sea (north Pacific). We fingerprint glass from these tephras with the help of single-shard electron microprobe and LA-ICP-MS analyses and provide microprobe data on minerals from two of these tephras. The large compositional variability of the Alaska-Aleutian volcanoes permits the use of ratios of highly incompatible trace elements (Ba/Nb, Th/Nb, Th/La, La/Nb) for identification of distal tephra sources by comparison of these ratios in tephra glass and proximal bulk rock analyses. This method, along with mapped tephra dispersal, has allowed us to link tephras under study to Aniakchak, Semisopochnoi, and Okmok volcanoes, respectively. Our results indicate that tephra Br2 was derived from the ~ 3.6 ka Aniakchak II caldera-forming eruption (Alaska, USA). This is the first ever finding of the Aniakchak II tephra in Bering Sea sediments, which permits enlargement of its tephra volume and eruption magnitude to ~ 100 km3 and 6.8, respectively. Tephra SR2, dated at ~ 12.2 ka, is likely associated with a post-glacial caldera on the Semisopochnoi Island, Aleutians (USA). Tephra SR4 (dated at ~ 64.5 ka), likely was derived from an earlier undocumented eruption from Okmok volcano (Aleutians). All three regionally spread tephra layers are valuable isochrones, which can be used for correlating and dating of Bering Sea sediments.

Quaternary travertine of the Kurai fault zone (Gorny Altai)

In the Kurai fault zone, travertine forms a matrix cementing clastic material of colluvial and glacial deposits or rarely forming a stockwork in a system of fractures in Palaeozoic rocks. The regular change of composition of solutions in the process of travertine formation has resulted in change of stable Mg–calcite by Sr–aragonite. According to the carbon isotopic composition, the travertine has intermediate genesis between thermal and meteogene. The light oxygen isotopic composition of CaCO3 indicates formational water input. The carbonates inherited Y, Sr, U, and Ni and in some areas, V, As, and Zn from the endogeneous water sources. Given that the Kurai zone travertine cements the Late Pleistocene–Holocene sediments and 14C dating of the carbonates gives a range of >40 000–3475 ± 35 years, the faults serving as routes of migration of the solutions forming the travertine should be considered as active structures.

The influence of delta formation mechanism on geotechnical property sequence of the late Pleistocene-Holocene sediments in the Mekong River Delta.

The aim of the study was to characterize a variety of microstructure development-levels and geotechnical property sequences of the late Pleistocene–Holocene deposits in the Mekong River delta (MRD), and the paper furthermore discusses the influences of delta formation mechanisms on them. The survey associated the geotechnical engineering and the sedimentary geology of the late Pleistocene–Holocene deposits at five sites and also undifferentiated Pleistocene sediments. A cross-section which was rebuilt in the delta progradation-direction and between the Mekong and Bassac rivers represents the stratigraphy. Each sedimentary unit was formed under a different delta formation mechanism and revealed a typical geotechnical property sequence. The mechanical behaviors of the sediment succession in the tide-dominated delta with significant fluvial-activity and material source tend to be more cohesionless soils and strengths than those in the tide- and wave-dominated delta and even the coast. The particular tendency of the mechanical behavior of the deposit succession can be reasonably estimated from the delta formation mechanism. The characteristics of the clay minerals from the Mekong River produced the argillaceous soil which does not have extremely high plasticity. The microstructure development-levels are low to very high indicating how to choose hydraulic conductivity value, k, for estimating overconsolidation ratio, OCR, by the piezocone penetration tests (CPTU). The OCR of sediments in the delta types strangely change with depth but none less than 1. The post-depositional processes significantly influenced the microstructure development, particularly the dehydrating and oxidizing processes.

Formation of subsurface shallow gas accumulations in Amurskiy Bay (Peter the Great Bay, Sea of Japan) as a result of postglacial sea-level change, paleoceanographic conditions and hydrological activity

We present new data on the study of subsurface gas accumulations in the sediments of Amurskiy Bay (the Sea of Japan). Geophysical research (single-channel continuous seismic profiling with airguns and high-resolution acoustic investigations with a high-frequency GeoPulse profiler) shows that the bay depression is filled by Pre-Quaternary sediments that are at least 0.8s (TWT) thick and overlaying Late Pleistocene–Holocene sediments that are up to 30m thick. The Pre-Quaternary deposits are possibly represented by coal-containing Mesozoic and Cenozoic rocks. Gas-related acoustic anomalies were found in the Late Pleistocene–Holocene silty sediments in the northern part of the bay. These gas-related anomalies have been divided into blanket column, turbidity and pillar anomalies. A single pockmark was also observed in the bottom relief of the bay. The gas accumulation area in the sediments is 19km long and 12km wide. The degassing of the Pre-Quaternary coal-containing deposits is assumed to be the major cause of gas. The formation of most of the gas anomalies in the Late Pleistocene–Holocene sediments and the trigger mechanism of gas migration may be associated with sea-level changes, paleoceanographic conditions, sedimentation features and the hydrodynamic regime in the bay. Increases in the number of diatoms and the presence of aberrant forms of some silicoflagellates have been observed in areas with high gas contents. Areas with numerous small underwater elevations or mounds were distinguished in the bay. In the northern part of the bay, the mounds correspond to ostraceous reefs or other local shellfish colonies. In the southern part of the bay, the elevations could be related to methane-derived authigenic carbonates, which formed pavements for the fixation of shellfish colonies and construction of reefs.

Gyrogonites and oospores, complementary viewpoints to improve the study of the charophytes (Charales)

Charophytes (Charales) are multicellular algae growing in fresh- to hypersaline waters and recorded as fossils by their oospores (formed by resistant organic walls) and gyrogonites (formed by intracellular calcification of the spiral cells surrounding the oospore). Preservation of oospores is mostly restricted to Late Pleistocene–Holocene sediments, whereas calcareous gyrogonites provide the fossil record of charophytes since the Late Silurian (425 Ma) and constitute the only link between living and fossil charophytes. Oospores and gyrogonites represent successive developmental stages occurring after fertilisation of the oogonia; however, gyrogonites do not develop in the extant genera Nitella and Tolypella section Tolypella of Tribe Nitelleae, and in most species of the subgenus Charopsis. For Tribe Chareae and Sphaerochara (Tolypella section Rothia), gyrogonites display more useful characters than the oospores, allowing easy identification of the extant genera Nitellopsis, Lychnothamnus, Lamprothamnium, Sphaerochara and Chara subgenus Chara. Determination to species level, and in particular the study of plastic species, needs a statistical approach. Extant oospores/gyrogonites can be used as modern analogues to infer palaeohydrological conditions and record past biodiversity. The ecological requirements of the living species provide important information for the restoration/conservation of wetlands and their management, and contribute to the reconstruction of Quaternary palaeoenvironments. The aim of the present paper is to highlight the importance of the gyrogonite, especially when studying extant charophytes, the application of both gyrogonites and oospores to palaeoenvironmental reconstructions, and to provide an accurate terminology and determination criteria for their study.

Deep-seated gravitational slope deformation, large-scale rock failure, and active normal faulting along Mt. Morrone (Sulmona basin, Central Italy): Geomorphological and paleoseismological analyses

Active faulting is one of the main factors that induce deep-seated gravitational slope deformations (DGSDs). In this study, we investigate the relationships between the tectonic activity of the NW–SE normal fault system along Mt. Morrone, central Apennines, Italy, and the evolution of the associated sackung-type DGSD. The fault system is considered to be the source of M 6.5–7 earthquakes. Our investigations have revealed that the DGSD began to affect the Mt. Morrone SW slope after the Early Pleistocene. This was due to the progressive slope instability arising from the onset of the younger western fault, with the older eastern fault acting as the preferred sliding zone. Paleoseismological investigations based on the excavation of slope deposits across gravitational troughs revealed that the DGSD was also responsible for the displacement of Late Pleistocene–Holocene sediments accumulated in the sackung troughs. Moreover, we observed that the investigated DGSD can evolve into large-scale rock slides. Therefore, as well as active normal faulting, the DGSD should be considered as the source of a further geological hazard. Overall, our approach can be successfully applied to other contexts where active normal faults control the inception and evolution of a DGSD.

Neotectonics in Marajó Island, State of Pará (Brazil) revealed by vertical electric sounding integrated with remote sensing and geological data

Studies suggest that the Marajó Island has experienced neotectonic activity during its latest evolution. However, there are no data demonstrating the presence of tectonic structures in its shallow subsurface. This work integrates vertical electric sounding, morphostructural lineaments, and geological data aiming to show fault control on the Late Pleistocene-Holocene sedimentation of this area. Resistivity values were related to mud (< 90 Ωm), clayey sand (90 and 200 Ωm), sand (200 and 500 Ωm), as well as Fe-bearing sand and laterite (> 500 Ωm). The latest values were related to the unconformity with lateritic paleosol at the top of the Barreiras Formation. Despite the values ≤ 500 Ωm of both the Barreiras Formation and the Late Pleistocene-Holocene unit, the latter was distinguished along four electric sections due to the presence of this unconformity, combined with the integration of available 14C, and luminescence ages of Quaternary sediments. The electric sections recorded several places with lateral interruptions of resistivity values within short distances, which were related to faults. The Miocene strata were vertically displaced by normal faults, giving rise to new accommodation space where Late Pleistocene-Holocene sediments were deposited. Fault reactivation was crucial to renew sedimentation in eastern Marajó Island during its latest evolutionary stage.

Sedimentology and origin of Meyghan lake/playa deposits in Sanandaj–Sirjan zone, Iran

The inland lake/playa of Meyghan is a closed basin in the Sanandaj–Sirjan tectonic zone of Iran, containing largest mineable sodium sulfate deposit of the Middle East. The Late Pleistocene–Holocene sediments of this lake/playa were studied for sedimentological and mineralogical characteristics, brine evolution path and the record of climatic variations in the area. Minerals of this lake/playa are mainly evaporites along with some fine-grained clastic components. Evaporite minerals include calcite, gypsum, halite, glauberite, thernadite, polyhalite, natron along with minor volumes of bassanite and sylvite. Gypsum and halite abundances show increasing trend from margin to the center forming a Bull’s-eye pattern. Main clastic components are fine-grained quartz, muscovite, clay minerals, calcite and organic matters. Clay minerals are the most dominant clastic minerals in these sediments. In the surface sediments of Meyghan lake/playa, illite and chlorite abundances reduce from the margin to the center which is contrary to the general patterns of clay distribution in other playas. Inflowing water with low percentage of ions and Na–(Ca)–(Mg)–SO4–Cl–(CO3) type evolve into a brine with high ions concentration during the geochemical evolution and mineral deposition. Finally, geochemical evolution resulted in a Na–SO4–Cl type brine. While clastic components (calcite, quartz and so on) show increasing trend with depth, evaporites abundances show opposite trends. Furthermore, the average grain size of sediments increases with depth indicating higher energy in the past. Typical sedimentary structures of lake/playa environment that are present include efflorescent salt crusts composed of halite, tepees, polygonal structures as the most common sedimentological features of this basin as well as Puffy Grounds. In conclusion, sedimentary records of this lake/playa represent important climatic changes in the area from relatively more humid cold climate in the Late Pleistocene to semi-arid warm climate in the Holocene, with higher evaporation rate.

Chemical composition of late Pleistocene-Holocene pelagic sediments in Gakkel Ridge, Arctic Ocean

The paper presents data on the chemical composition of Late Pleistocene-Holocene sediments in the Gakkel Ridge according to data on sediment core PS 70/306-3, offers a hypothetical litho-stratigraphic model, and provides data on chemo-stratigraphic horizons distinguished based on the distribution of carbonates, organic carbon, metals (Fe, Mn, Cu, Zn, Co, Ni, V, Pb), As, and P in the core. Chemical transformations of sediments at the redox barrier are discussed, along with relations between the composition of the sediments and the facies sedimentation conditions.

Late Pleistocene–Holocene sedimentation surrounding an active seafloor gas-hydrate and cold-seep field on the Northern Gulf of Mexico Slope

A chronostratigraphic framework is constructed from sediments surrounding an active gas-hydrate and cold-seep field, situated on the northern Gulf of Mexico slope within federal offshore lease block Mississippi Canyon 118 (MC118). Accelerator mass spectrometer (AMS) radiocarbon dating, foraminiferal biostratigraphy and nannofossil biostratigraphy are used to constrain the age of sediments from 10 gravity cores collected around the field. X-ray fluorescence (XRF) core scanning is employed to develop continuous down-core elemental profiles, which are used to evaluate biogenic calcium and siliciclastic titanium sediment inputs, and provide a means to correlate sediments across the study area and infer changes in sedimentation through time. Spatial reconstruction of sedimentation surrounding the field indicates the following: (1) a consistent pattern of stratigraphic thinning in close proximity to the field over the past 14,000 yrs and (2), temporal changes in sedimentation that primarily reflect deglacial sea-level rise as well as regional factors such as Mississippi delta lobe switching. These results highlight the variability of sedimentation along a continental slope setting where marine cold seeps and gas hydrate persist, yet do not suggest slope failure or destabilization of the seafloor at this site, at least during the past 14,000 yrs. The evaluation of sedimentation at this location provides an important context for ongoing biogeochemical and geophysical monitoring of the MC118 site, which has been designated the first National Gas Hydrate Seafloor Observatory by the Gulf of Mexico Hydrate Research Consortium.

Establishing the Late Pleistocene–Holocene sedimentation boundary in the southern North Sea using OSL dating of shallow continental shelf sediments

This paper provides insight into the fate of Late Weichselian and Early Holocene sediments accumulated in the German sector of the southern North Sea. A combination of optically stimulated luminescence (OSL) dating and radiocarbon dating was applied to set up the chronology. Seven cores were studied to obtain ten quartz OSL samples and ten radiocarbon samples. The core locations were chosen along a southeast to northwest transect along the western side of the Elbe palaeovalley, giving a good coverage of the entire German North Sea area. All samples for OSL dating showed a significant scatter in the equivalent dose (De) distribution of quartz due to heterogeneous bleaching. The Minimum Age Model (MAM-3) was found to be the most suitable to extract true burial ages. It was inferred from the study that sedimentation did still occur during the late deglaciation period in many areas. These are mainly Late Weichselian glaciofluvial or glaciolacustrine sediments directly overlain by early Holocene fluvial and/or transgressive deposits and followed by modern marine sands. However, considerable late Weichselian erosion or a possible period of non-deposition was observed in the highland area to the northeast of the Dogger Bank and a small discontinuity in the near-shore region was noticed, probably due to early Holocene fluvial erosion. Relicts of a palaeo-river bank or terrace were identified in core 14VC to the east of the Dogger Bank. A possible interpretation of the Pleistocene–Holocene interface along the core transect is provided based on lithology and measured OSL and radiocarbon ages.