Academic literature on the topic 'Paleoenviroment'

The Verkhnyaya Sibiryachikha Cave was discovered in the vicinity of the Okladnikov Cave in the course of the IAET SB RAS survey excavation in 2020; the cave studies were continued in 2021. The karst cavity was documented as a paleontological site, Sibiryachikha-6, by the famous paleontologist N.V Ovodov in the late 20th century. In 2021, the existing test-pit was enlarged by 2 sq. m. Five stratigraphic units were established, four of which contain numerous paleontological materials. Lithic artifacts adding to the small assemblage of the previous year were found in two strata. Preliminary absolute AMS dates indicate that the cave was recurrently visited by ancient people during the Upper Paleolithic and late Middle Paleolithic. The species composition, interspecies ratio, and set of preserved bone remains of the lower layers are typical for cave taphocenoses formed as a result of food activity of large predators, primarily cave hyenas. The taphocenosis of the site is dominated by species of open spaces; a smaller numbers of species offorest-steppe, forest, and rocky biotopes were identified. The study of the Verkhnyaya Sibiryachikha Cave sediments, synchronous to culture-bearing deposits of Okladnikov Cave by preliminary absolute dating, provides an opportunity for detailed reconstruction of paleoenviroment during the Neanderthal habitation. The results of the latest field season suggest that the Upper Sibiryachikha Cave was a den of predators during the late Pleistocene, occasionally visited by various populations of ancient humans.

During the Maastrichtian, two lithostratigraphic units were deposited in the central Chiapas region; the Ocozocoautla and Angostura formations. The first unit crops out northwest of the city of Tuxtla Gutiérrez in central Chiapas. It is a complex lithological unit mainly composed of siliciclastic rocks interbedded with limestone. Overlying it, the Angostura limestone is recognized. This study focuses on a taxonomic study of the larger benthic and planktic foraminifera from both formations in order to assign age and to infer the paleoenviroment. The Ocozocoautla Formation includes an association of benthic as well as significant planktic foraminifera. Based on the microfossils stratigraphic distribution, two biozones were defined: the Pseudorbitoides rutteni–Ayalaina rutteni Assemblage Zone of earliest Maastrichtian and the upper part of the Gansserina gansseri Interval Zone of early Maastrichtian. The Angostura Formation contains dasycladacean algae and larger foraminifera considered as important age markers in shallow-water environments. Two foraminiferal interval zones were defined, Praechubbina breviclaustra Interval Zone of early late Maastrichtian and Chubbina jamaicensis Total Range Zone of late to latest Maastrichian age. The microfacies (grainstone, wackestone–packstone, wackestone) as well as the foraminiferal assemblage enable the paleoenvironment to be reconstructed, suggesting a deposit that developed in an open-water marine setting with moderate to high energy, characterized by benthic and planktic foraminifera in the Ocozocoautla Formation, while in the Angostura Formation a shallow-water marine protected environment is inferred. The paleobiogeographical distribution of the assemblage from both the Ocozocoautla and Angostura formations mostly contains endemic benthic foraminifera of the Caribbean Province and other few Tethysian forms of the Angostura Formation.

Abstract Marsh rats of the species Holochilus vulpinus inhabit mesic and humid environments. For this reason, it is frequently used in paleoenviromental studies to infer past humid conditions. Holocene archeological record indicates that H. vulpinus had a wider geographical distribution than today. Its regional extinction in north Patagonia at the XIX century was attributed to the dry and cold Little Ice Age (LIA). Here we present the finding of a specimen of H. vulpinus from northeastern Patagonia (Valcheta stream, Río Negro province, Argentina), just at the end of LIA. Implications of this novel historical record are discussed.

The paleoenviromental conditions during the depositional interval of sapropel S1 in the northeastern Aegean (gravity core M-4, length 2.53 m; south Limnos basin) are studied based on quantitative micropaleontological (benthic and planktonic foraminifera) and geochemical (OC, δ13Corg) analyses. Special feature of core M-4 is the thickness of S1 layer (96 cm). Our study points that sapropelic layer S1a has been deposited in more dysoxic and warmer conditions in respect to S1b. Both primary productivity and preservation of organic material are more intense during the lower part of S1. An interruption of the sapropelic conditions at 8.0 Ka BP which is mainly characterized by the increase of agglutinated foraminiferal forms confirms both higher oxygen bottom conditions and freshwater input.

The aim of this research is to conduct an investigation on the soils, paleosols and landforms of the area of Mt Cusna ridge (Northern Apennines - Italy) in order to define the relationship between geomorphic evolution and soil development, to characterise the main pedogenetic processes and factors acting on soils in past and present times, and to provide new information to understanding the Holocene climatic variations in the area. For this purpose, several sets of field, laboratory and microscopic analyses were carried out. A comprehensive survey of the study area allowed the production of a geomorphological map (scale 1:10000, attached to this thesis) expanding and revising the existing cartography (Panizza et al., 1982). At the same time, also the soils were surveyed and described, in order to provide a detailed characterisation of the soil types of the area. Selected soil profiles were sampled and underwent a wide set of laboratory analyses, including measurements of pH, exchangeable bases and cation exchange capacity (CEC), organic carbon content, total nitrogen and exchangeable phosphorus; along these iron oxides were investigated with the measurement of total iron and its extractable forms; grain size analyses and x-ray diffractions on the clay fraction were also carried out; finally, micromorphology of soil thin sections and SEM observations and analyses were also carried out on a subset of significant horizons. Geomorphological survey results allowed to compare the active and inactive processes. Glacial and periglacial processes, though mainly inactive since the beginning of the Holocene, still give an important forcing on the present landscape through their deposits, produced during the Last Glacial period. During the Holocene, different phases of stability and instability could be detected from the activation an reactivation of slope dynamics as the result of both climate fluctuations and structural constraints. The result is a very diversified landscape in which erosion and deposition alternate in space and time. The present day conditions are characterised by a prevalence of washout and erosion activity, mainly on lithologies more susceptible to surface processes. Soils were attributed to different landscape units, highlighting differences in processes and development between them. Degree of pedogenesis, in fact, varies from weakly developed soils on the highest and steeper areas to deep and more weathered profiles at lower elevations and/or on flatter surfaces. Among the latter, the presence of a paleosurface, characterised by the presence of paleosol units truncated and buried by colluvial deposits, has been detected in the stable areas above 1650 m a.s.l.. Laboratory geopedological analyses showed how soil in the area are characterised by being mainly silty-clayey, with low values of pH and organic C which tends to concentrate at the surface and in many cases also in the uppermost horizon of buried soil units. Iron oxides are usually present in its crystalline form, with some exceptions in peculiar soils. The crystalline/total iron ratio (weathering index) is generally low, higher inside paleosurface buried units. Clay fraction mineralogy shows the presence of quartz and chlorite inherited from parent material; neoformed clay minerals consist in illite and mixed layer clays. Micromorphological analysis mainly involved paleosurface horizons. Colluvial units show the presence of variable quantities of pedorelicts (Brewer, 1967) in their groundmass, as well as features pointing to multiple depositional events. The buried unit shows different phases of clay illuviation relatable to environmental changes. In flat areas a 2Ab horizon is found between the two units, showing accumulation of excrements and organic material; features of frost action are also present. Particular conditions are related to higher elevations as well as areas with steeper slopes. Data obtained from field and analytical approaches allowed to outline the main pedogenetic processes acting in the area. Pedogenesis started since the glacial retreat: clay mineralogy and iron oxide content are compatible with a soil formation taking place during the Holocene. The main active process in the area is Brunification (Duchaufour, 1983), which drive the development of Regosols and Cambisols (FAO, 2014); these soils are better developed at lower elevations on flat areas and stable deposits, whereas soils on steeper slopes and higher elevations show evidences of a weaker pedogenesis. Luvisols (FAO, 2014) were also formed in the past and are mainly preserved as paleosols of the buried units related to the paleosurface; moreover the clayey pedofeatures of these paleosols allowed the identification of three different clay illuviation phases, preceding the Subboreal climatic recrudescence 14C dated (Compostella et al., 2012; Giraudi, 2014). During the Late Holocene in the area appears Podzolisation (Duchaufour, 1983) as a secondary process, as testified by the presence of cryptopodzolisation features in soil profiles from different areas. Traces of this process could be also found inside the 2Ab horizon, marking the top of the buried unit in some soil profiles surveyed on the paleosurface; this horizon can be characterised as an accumulation of insect excrements and organic material developed in cold conditions. A change in vegetation cover detected by anthracological assemblages (Compostella et al., 2012) seems to confirm this hypothesis. 14C dating (Compostella et al., 2012) and frost features inside the 2Ab horizon date its burial to the Little Ice Age (LIA), which marks a phase of general erosion causing colluvial deposition also in flatter areas, which probably happened in multiple events through time. The colluvial layers show apparent pedogenesis caused by the presence of pre-weathered soil material and signs of homogenisation probably related to cryoturbation processes. Finally, the presence of frost and solifluction features inside these recent soils point to the characterisation of the LIA as a drier period in which winter precipitation were less abundant and snow cover thinner. This study outlined the existence of complex interactions between pedogenic, geomorphic and environmental processes throughout the Holocene. The influence of these aspects on soil features could be detected and used to describe and interpret the present landscape in the light of its modifications through time.

O afloramento Paleolago Cemitério, localizado na mina de fosfato a céu aberto da “Ultrafértil”, município de Catalão, Estado de Goiás, possui depósitos originados pelo preenchimento de uma depressão na parte central do Complexo Carbonatítico de Catalão I, onde sedimentos lacustres compostos por diatomitos, argilitos e esponjilitos, assentam-se discordantemente sobre um domo de rochas magmáticas carbonatíticas do Cretáceo Superior. O acúmulo de frústulas de diatomáceas e espículas de esponjas formou diatomitos espessos, nos quais abundam restos fósseis, os quais caracterizam uma paleoflora local, existente durante o Pleistoceno, em uma região hoje ocupada pelo Cerrado, no Centro-oeste do Brasil. O conteúdo micropaleontológico revelou a presença de esponjas e diatomáceas dulciaquícolas, indicando ambientes lênticos. Restos de vegetais como folhas, frutos e sementes, preservados na forma de impressões, compressões e adpressões indicam associações fossilíferas compostas por dicotiledôneas, fungos, algas e pteridófitas. O presente estudo tem como objetivo a análise da paleoflora do Paleolago Cemitério, visando a reconstrução das paleocomunidades, a determinação das condições paleoambientais e paleoclimáticas vigentes na região durante o Pleistoceno e o entendimento da origem e/ou evolução do Bioma Cerrado. As análises do material ocorreram através de microscopia de fluorescência, polínica e geoquímica, identificação taxonômica e uso da metodologia de Análise de Margem Foliar (LMA) e do Método de Coexistência (CA), os quais auxiliaram na caracterização do paleoclima sob o qual a flora fóssil teria vivido. Os resultados indicaram a existência de fogo pretérito pela presença de fusenita impregnada ao material orgânico das amostras, a presença de mata de galeria no em torno do paleolago, bem como demonstraram que as temperaturas eram diferentes das que ocorrem hoje para a região. Essa flora fóssil representa uma composição vegetacional única, uma vez que não há, atualmente, total congruência na distribuição dos táxons analisados para a região, como acontecia no passado. Por fim, o fogo parece ter tido um papel importante nos ecossistemas pretéritos da região como ainda o tem hoje no “Bioma Cerrado”.
The outcrop Cemetery Paleolake is situated at the phosphate mina of Ultrafértil Mining Company, in the Catalão city, Goiás State, in the Central region of the Brazil. The deposit was arisen from a filled depression in central part of the Carbonatitic Complex of Catalão I, where lacustrine sediments are settled on carbonatitic magmatics rocks of the Late Cretaceous age. The accumulation of freshwater diatom frustules and sponges spicules generated thick diatomite, in which are founded fossil plant remains, composed of leaves mainly. This lacustrine deposit has been considered as begin during the Late Pleistocene interval in which the fossil vegetal remains caracterize a local paleoflora in a region today ocupied by Cerrado. The micropaleontological contends in the spongilit brought freswater spongs and diatomace, showed lentic enviromental. Plants remains as leaves, fruits and seeds were preserveds as impressions, compressions and adpressions in fossiliferous assemblages compunds by dicotiledoneous, fungis, algae and pteridophytes. The goal of this approach is the analyses of the Cemetery Paleolake paleoflora looking for the paleocomunities reconstruction, the paleoenviromental and the determination of paleoclimatics conditions in the Central part of Brazil, during Pleistocene, and know of the origin /evolution of the Cerrado Biome. Material analyses were made throught fluorescence microscopy, pollinic and geochmistry, taxomomic identification, Leaf Margen Analysis (LMA) and Coexistence Approach (CA), which helped to characterize the paleoclima to that time. Results indicated the existence of preterite fire, throught fusenite impregnance on the organical material in the samples, the existence of a galery forest around the paleolake, as well showed that temperatures were diferent from nowadays. This fossil flora represent an only vegetacional composition, once today is not possible found the same plants distribution in that region like use to be happen in the past. Finaly, the fire seems like had been an important factor in the preterite ecossistems on the region, as yet happen today in the Cerrado Biome.

1 Abstract This thesis presents an analysis of fossil plants from the Cenomanian Peruc-Korycany Formation of the Bohemian Cretaceous Basin and from the Bückeberg Formation of the Lower Saxony Basin in Germany. Based on earlier studies, both areas provide sediments that are considered to have developed in tidally influenced fluvial systems. Studied fossil plants are represented by ginkgoalean plant leaves (Ertemophyllum, Tritaenia), branches of conifers (Frenelopsis) and lauroid angiosperms (Eucalyptolaurus). Frenelopsis, Eretmophyllum and Tritaenia are considered to be halophytic plants, while Lauroid angiosperms were considered to grow in fresh water conditions. The fossil plants were studied using cuticle analysis and two methods of stable carbon isotope analysis: Bulk carbon isotope analysis and Compound Specific Isotope analysis. For cuticle analysis samples were observed and documented macroscopically and microscopically. To specify the environmental conditions, recent samples from three salt marshes in Great Britain were studied and analysed using the same methods as the fossil samples. The data from all observations and measurements were processed and their interpretation supported the modelled environment based on the sedimentological data. Frenelopsis were growing in a haline environment with low...