The history of climatic changes in the Asian Summer Monsoon system over the Tibetan Plateau during the Holocene has been the subject of significant research due to the importance of the plateau as the headwaters for many major rivers providing water resources to the surrounding large, populous countries. In general, previous research has concluded that monsoon rainfall and summer temperatures peaked during the early Holocene (9-11 ka BP) in Tibet, coincident with peak Northern Hemisphere summer insolation. Atmospheric teleconnections with upstream Northern Hemisphere westerly circulation patterns influenced by North Atlantic sea surface temperature changes have also been noted at millennial and centennial timescales. However, recent studies have noted that the timing of peak monsoon warmth and wetness during the Holocene are not synchronous across the entirety of the Tibetan Plateau, and studies of modern precipitation indicate several distinct regions of monsoon precipitation variability at interannual scales, suggesting the monsoon response to past and future climate change may be regionally heterogeneous for the plateau. Clear assessment of this regionality within the monsoon climate region is a topic of continuing research, but it has been hindered by lack of climate records in remote areas, dating difficulties, and concerns over the comparability of interpreted climate-proxy relationships between the many different biological, hydrological, and geochemical proxies applied. The first part of this dissertation uses ¹⁴C and U-Th series geochronology, sedimentology, and GIS analysis of exposed lake shoreline sediments surrounding the numerous closed-basin lake systems of the central and western Tibetan Plateau to investigate regional heterogeneity in monsoon rainfall, and to develop a new well-dated lake level record from the Ngangla Ring Tso lake system in the poorly studied southwestern region. The major conclusions are: 1) peak early Holocene monsoon rainfall, recorded by the highest paleoshorelines surrounding 130 lake systems, intensified more relative to today in the western part (west of 86°E longitude) of the Tibetan Plateau when compared to eastern regions, closely following regions of modern rainfall variability; 2) monsoon rainfall in the Ngangla Ring Tso region peaked during the early Holocene insolation maximum, consistent with other records, remained significantly higher than modern until ~6.0 ka BP, but with abrupt reductions in monsoon rainfall associated with North Atlantic ice-rafted debris peaks. The warm and wet period of the early and middle Holocene was also likely coincident with the first major colonization of the Tibetan Plateau by prehistoric humans. Current research suggests early foragers employing stone tools first forayed into the middle elevation areas above 3,000 m elevation on the northeastern fringe of the plateau as early as 14.8 ka BP, and therefore the dominant hypothesis suggests plateau colonization proceeded from this direction, heading westward through the Holocene. However, well studied and dated archaeological sites from the high plateau are exceedingly rare, requiring further investigation. The second part of this dissertation presents new age controls for the Holocene Zhongba microlithic site in the southwestern Tibetan Plateau, using ¹⁴C dating of organic and carbonate-rich paleo-wetlands sediments hosting in situ stone artifacts. The major conclusions of this study are: 1) artifacts at the Zhongba site, which are typologically similar to microlithics across the plateau, can be no older than 6.5 ka BP, consistent with the prevailing east-to-west colonization hypothesis, and 2) microlithic tools continued to be important as late as 1.3 ka BP at the site, even though metal is found in sites of similar age elsewhere in Tibet.

This thesis contributes increased knowledge about climate variability during the late Quaternary in the eastern Mediterranean. Results from a paleoclimate review reveal that regional wetter conditions from 6000 to 5400 years BP were replaced by a less wet period from 5400 to 4600 years BP and to fully arid conditions around 4600 years BP. The data available, however, show that there is not enough evidence to support the notion of a widespread climate event with rapidly drying conditions in the region around 4200 years ago. The review further highlights the lack of paleoclimate data from the archaeologically rich Peloponnese Peninsula. This gap is addressed in this thesis by the provision of new paleoclimate records from the Peloponnese. One stalagmite from Kapsia Cave and two stalagmites from Glyfada Cave were dated and analyzed for stable oxygen (δ18O) and carbon (δ13C) isotopes. The Glyfada record covers a period from ~78 ka to ~37 ka and shows that the climate in this region responded rapidly to changes in temperatures over Greenland. During Greenland stadial (interstadial) conditions colder (warmer) and drier (wetter) conditions are reflected by depleted (enriched) δ13C-values in the speleothems. The Kapsia record covers a period from ~2900 to ~1100 years BP. A comparison between the modern stalagmite top isotopes and meteorological data shows that a main control on stalagmite δ18O is wet season precipitation amount. The δ18O record from Kapsia indicates cyclical humidity changes of close to 500 years, with rapid shifts toward wetter conditions followed by slowly developing aridity. Superimposed on this signal is a centennial signal of precipitation variability. A second speleothem from Kapsia with multiple horizons of fine sediments from past flood events intercalated with the calcite is used to develop a new, quick and non-destructive method for tracing flood events in speleothems by analyzing a thick section with an XRF core scanner. / <p>At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 3: Submitted. Paper 4: Accepted.</p>

Palaeobotanical records of Holocene climate change in the southern Coast Mountains identify a cooler/wetter Neoglacial period subsequent to 6600 BP. Geomorphic evidence of alpine glacier advance suggests that there were three distinct cooler/wetter periods during the Neoglacial, but this pattern has not been identified in palaeobotanical studies. By careful selection of a sensitive alpine site this thesis has recognised this structure in a palynological record of Neoglacial climate. This continuous record of Neoglacial climate which has the same basis as records of early Holocene climate (i.e. palynological) and hence allows more direct comparisons of the two periods. Pollen spectra, conifer needle macrofossils, organic matter content, and magnetic susceptibility were assessed for a 4800 year continuous sequence of sediment from an alpine lake. Calibration of the Picea/Pinus pollen ratio by using an altitudinal transect of surface pollen samples allowed partial quantification of shifts in treeline. Treeline at the site was at least 85 m above the present level from 4800-3800 BP, suggesting that summer temperatures were at least 0.6°C above the present. High treeline until 3800 BP indicates a relatively late date for the Hypsithermal/Neoglacial transition at this site. Alternatively, the apparent complexity of this transition in the Coast Mountains may be due to difficulties of separating temperature and precipitation signals in many climatic records. Treeline declined to near present levels by 2500 BP and was lower than present from 2500-1500 BP and from 1200 BP until close to the present. Estimates of equilibrium line altitude depression for Coast Mountain glaciers during the Little Ice Age suggest that these periods of lower treeline were due to a cooling of up to 0.8°C. During the last 5000 years the Southern Coast Mountains have experienced fluctuations on the order of 1.5°C.

The main subject of the present research is the geological development of the south-eastern Baltic Sea in Holocene (11000 – 0 calendar years before the present) and prediction of its development in the future (0-1000 calendar years after the present). The present is calendar years 2000AD. The working area is estimated between longitude 18ºE - 21º30’E and latitude between 54ºN - 56º30’N including the onshore and offshore of Lithuania. The quantitative and qualitative geological information and the geological interpretation allowed the 4D modeling of the south-eastern Baltic Sea. Detailed comparison of the influence of isostatic and eustatic components has made it possible to distinguish between these two factors and to create the isostatic intensity models. Last investigations of the global sea level rise (IPCC 2001, 2007) and the model of the recent tectonic activity in the region were used for creation of the prognosis scenarios of relief development in the future. The 4D models created in this dissertation are very well understandable for specialists and for wider readership not engaged in scientific research. The results presented in the dissertation can be useful also by archaeologists and biologists. The results of the model show all the drawbacks of geological material collected so far and outline new perspectives for marine geologists, i.e. demonstrate what works should be done in the future to get more precise results. / Pagrindinis tyrimų tikslas buvo atkurti pietrytinės Baltijos jūros raidą holocene (11000 – 0 kalendorinių metų iki dabar) ir atlikti jūros raidos prognozę iki 1000 metų nuo dabar. Tirtasis regionas apima Lietuvos teritoriją (tiek atviroje jūroje, tiek sausumoje), jo koordinatės yra 18ºE - 21º30’E rytų ilgumos ir 54ºN - 56º30‘N šiaurės platumos. Kokybinė ir kiekybinė geologinė informacija bei jos geologinė interpretacija leido sukurti pietrytinės Baltijos jūros raidos 4D modelius. Detalus kiekybinis eustatinių bei izostatinių vandens lygio pokyčių palyginimas leido atskirti šiuos faktorius bei nustatyti izostatinio komponento intensyvumą holoceno metu. Kiekybiškai įvertinus tektoninius judesius ir vandens lygio pokyčius buvo atlikta pietrytinės Baltijos jūros raidos prognozė. Erdviniai 4 D modeliai pateikti šiame darbe yra lengvai suprantami ne tik specialistams, tačiau ir plačiai visuomenei. Disertacijoje pateikti modeliai gali būti naudingi archeologams bei biologams, tuo pačiu geologams parodydami esančių duomenų trūkumus bei nubrėžiantys naujas perspektyvas tyrimams, kurie turėtų būti atlikti norint gauti kiek galima detalesnius rezultatus.

The main subject of the present research is the geological development of the south-eastern Baltic Sea in Holocene (11000 – 0 calendar years before the present) and prediction of its development in the future (0-1000 calendar years after the present). The present is calendar years 2000AD. The working area is estimated between longitude 18ºE - 21º30’E and latitude between 54ºN - 56º30’N including the onshore and offshore of Lithuania. The quantitative and qualitative geological information and the geological interpretation allowed the 4D modeling of the south-eastern Baltic Sea. Detailed comparison of the influence of isostatic and eustatic components has made it possible to distinguish between these two factors and to create the isostatic intensity models. Last investigations of the global sea level rise (IPCC 2001, 2007) and the model of the recent tectonic activity in the region were used for creation of the prognosis scenarios of relief development in the future. The 4D models created in this dissertation are very well understandable for specialists and for wider readership not engaged in scientific research. The results presented in the dissertation can be useful also by archaeologists and biologists. The results of the model show all the drawbacks of geological material collected so far and outline new perspectives for marine geologists, i.e. demonstrate what works should be done in the future to get more precise results. / Pagrindinis tyrimų tikslas buvo atkurti pietrytinės Baltijos jūros raidą holocene (11000 – 0 kalendorinių metų iki dabar) ir atlikti jūros raidos prognozę iki 1000 metų nuo dabar. Tirtasis regionas apima Lietuvos teritoriją (tiek atviroje jūroje, tiek sausumoje), jo koordinatės yra 18ºE - 21º30’E rytų ilgumos ir 54ºN - 56º30‘N šiaurės platumos. Kokybinė ir kiekybinė geologinė informacija bei jos geologinė interpretacija leido sukurti pietrytinės Baltijos jūros raidos 4D modelius. Detalus kiekybinis eustatinių bei izostatinių vandens lygio pokyčių palyginimas leido atskirti šiuos faktorius bei nustatyti izostatinio komponento intensyvumą holoceno metu. Kiekybiškai įvertinus tektoninius judesius ir vandens lygio pokyčius buvo atlikta pietrytinės Baltijos jūros raidos prognozė. Erdviniai 4 D modeliai pateikti šiame darbe yra lengvai suprantami ne tik specialistams, tačiau ir plačiai visuomenei. Disertacijoje pateikti modeliai gali būti naudingi archeologams bei biologams, tuo pačiu geologams parodydami esančių duomenų trūkumus bei nubrėžiantys naujas perspektyvas tyrimams, kurie turėtų būti atlikti norint gauti kiek galima detalesnius rezultatus.

Most widely used applications of quantitative past vegetation reconstruction are based on pollen-vegetation relationship functions. To carry out detail vegetation reconstruction using this method, large amount of geographic data pre-processing is necessary. For this reason, large scale vegetation reconstructions are extremely rare. In this study data processing is carried out using automated GIS tools. Application of GIS enabled precise and detail reconstruction of the Late Glacial and Holocene forest vegetation composition, as well as the development of vegetation in Lithuania. New pollen investigations from cores and outcrops, created Lithuanian pollen database, evaluation of pollen-vegetation relationship functions in the environment of Lithuania and reconstruction of main tree species composition in the Late Glacial and Holocene, according to pollen database and selected pollen-vegetation relationship function are presented in this study. The created palaeovegetation maps enbled considerable detalization of knowledge about past vegetation in Lithuania. Consequently, main vegetation migration and distribution patterns were defined. / Plačiausiai naudojami kiekybinio praeities augalijos taksonominės sudėties atkūrimo pagal žiedadukių duomenis metodai remiasi žiedadulkių-augalijos priklausomybės funkcijomis. Norint atlikti detalų augalijos sudėties atkūrimą šiuo metodu, reikalingos itin didelės apimties geografinių duomenų apdorojimo procedūros, todėl stambiu masteliu augalijos sudėtis atkūriama itin retai. Šiame darbe duomenų apdorojimas atliekamas automatizuotomis GIS priemonėmis. GIS panaudojimas leido tiksliai ir detaliai atkurti Lietuvos vėlyvojo ledynmečio ir holoceno miško augalijos taksonominę sudėtį bei augalijos vystymosi raidą. Disertaciniame darbe pristatomi nauji gręžinių ir atodangų nuosėdų žiedadulkių tyrimai, sudaryta Lietuvos žiedadulkių duomenų bazė, atliktas įvairių žiedadulkių-augalijos priklausomybės funkcijų įvertinimas Lietuvos sąlygose, žiedadulkių duomenų bazės pagrindu pagal pasirinktą priklausomybės funkciją atkurta pagrindinių medžių taksonų sudėtis eilei vėlyvojo ledynmečio ir holoceno laikotarpių. Sudarytais praeities augalijos paplitimo žemėlapiais reikšmingai detalizuotos žinios apie praeities augaliją Lietuvoje, nustatyti pagrindiniai augalijos migracijos keliai ir jos paplitimo dėsningumai.

Plačiausiai naudojami kiekybinio praeities augalijos taksonominės sudėties atkūrimo pagal žiedadukių duomenis metodai remiasi žiedadulkių-augalijos priklausomybės funkcijomis. Norint atlikti detalų augalijos sudėties atkūrimą šiuo metodu, reikalingos itin didelės apimties geografinių duomenų apdorojimo procedūros, todėl stambiu masteliu augalijos sudėtis atkūriama itin retai. Šiame darbe duomenų apdorojimas atliekamas automatizuotomis GIS priemonėmis. GIS panaudojimas leido tiksliai ir detaliai atkurti Lietuvos vėlyvojo ledynmečio ir holoceno miško augalijos taksonominę sudėtį bei augalijos vystymosi raidą. Disertaciniame darbe pristatomi nauji gręžinių ir atodangų nuosėdų žiedadulkių tyrimai, sudaryta Lietuvos žiedadulkių duomenų bazė, atliktas įvairių žiedadulkių-augalijos priklausomybės funkcijų įvertinimas Lietuvos sąlygose, žiedadulkių duomenų bazės pagrindu pagal pasirinktą priklausomybės funkciją atkurta pagrindinių medžių taksonų sudėtis eilei vėlyvojo ledynmečio ir holoceno laikotarpių. Sudarytais praeities augalijos paplitimo žemėlapiais reikšmingai detalizuotos žinios apie praeities augaliją Lietuvoje, nustatyti pagrindiniai augalijos migracijos keliai ir jos paplitimo dėsningumai. / Most widely used applications of quantitative past vegetation reconstruction are based on pollen-vegetation relationship functions. To carry out detail vegetation reconstruction using this method, large amount of geographic data pre-processing is necessary. For this reason, large scale vegetation reconstructions are extremely rare. In this study data processing is carried out using automated GIS tools. Application of GIS enabled precise and detail reconstruction of the Late Glacial and Holocene forest vegetation composition, as well as the development of vegetation in Lithuania. New pollen investigations from cores and outcrops, created Lithuanian pollen database, evaluation of pollen-vegetation relationship functions in the environment of Lithuania and reconstruction of main tree species composition in the Late Glacial and Holocene, according to pollen database and selected pollen-vegetation relationship function are presented in this study. The created palaeovegetation maps enbled considerable detalization of knowledge about past vegetation in Lithuania. Consequently, main vegetation migration and distribution patterns were defined.

Despite the documented sensitivity of polar environments, long-term monitoring data are especially sparse in these regions. Diatom-based paleolimnology has contributed significantly to understanding the response of Arctic lakes to climate change, but most studies have been conducted in regions with relatively high lakewater buffering capacity. As such, Pim Island (Nunavut, Canada) is a region of limnological interest because, due to the local geology, its surface waters are of relatively lower pH and previous research suggests that such softwater lakes may be especially responsive to climate fluctuations and therefore provide the best paleoclimate records. This thesis has two separate but related chapters, as well as an exploratory study included in appendix. First, a novel approach using visible-near-infrared spectroscopy (VNIRS) was used to infer lakewater dissolved organic carbon (DOC), from a 160-lake calibration set from the Canadian Arctic. Historically sound and similar trends were reconstructed when compared against a Canadian diatom-based DOC and Swedish VNIRS-based total organic carbon (TOC) model on Arctic Holocene sediment records. Second, a diatom and spectroscopically-based multi-proxy approach was utilized on Holocene sedimentary records from two lakes on Pim Island to assess long-term environmental change from this region. Benthic and epiphytic diatom taxa dominated the pre-19th century assemblages, although marked shifts in dominant species were recorded during the mid-Holocene. The mid-Holocene diatom assemblages underwent an abrupt ecological shift from alkaliphilous Fragilaria sensu lato to slightly acidophilous Achnanthes and Navicula. The post-19th century was characterized by an increase in the planktonic species (Cyclotella radiosa), indicating marked lakeice reductions. Third, the limnological properties and modern diatom assemblages of ponds and lakes surveyed from 1979 to 2009 on Pim Island were examined as part of an exploratory study. The ponds and lakes displayed typical characteristics observed in high Arctic lacustrine environments (i.e. oligotrophic, very dilute) but with overall relatively low alkalinity. Poorly-buffered sites had diatom assemblages that were distinct from well-buffered lakes elsewhere in the High Arctic. Our findings contribute to an improved understanding of the interactions between local environments and limnological changes, and also provide insight on the biological responses of lakes to Holocene environmental change and allow us to compare responses to those in more alkaline sites. / Thesis (Master, Biology) -- Queen's University, 2010-12-22 19:53:45.03

This dissertation describes the results of archaeological survey and excavationsundertaken on the Mesa el Chaparral in the county of Mina in Nuevo Leon, Mexicoduring 2001. Sixty-six previously undocumented archaeological sites were discovered onthe arid surface. Excavations found no intact subsurface deposits, but a wealth of surfacedata was collected. Subsequent analyses demonstrated a forager lifeway for the majorityof the Holocene human occupation of the region in a remarkably stable pattern.To understand sites found on the deflated modern surface necessitatedcontemplation of the basic theories and models used in hunter-gatherer research. Thisallowed for the construction of new diagrams designed to hypothesize fundamentalrelationships between general aspects of the lifeway including environmental factors, sitesize and visibility issues, and human mobility patterns. From some basic continuums,more detailed diagrams were created that allow understanding and prediction of humanbehavior based upon data found from artifacts and features. After testing their salience,the models were dynamically combined with the site data and ethnographic analogies toarrive at an understanding of the human lifeways represented by the recoveredarchaeological data. This provided a fascinating look into the day-to-day lives of thegeneralized mobile foragers of prehistoric northeastern Mexico.Included in the recovered data are hearth features, lithic debitage and artifacts,and basic site descriptions. Archaeological locations ranged from small with a singlefeature to over a square kilometer with over 100 features, all located on the surface wherethey are subject to wind deflation and water erosion. Most of the sites containeddiagnostic artifacts from the entire Holocene, further compounding the analyticcomplexity of the project. Understanding the context of the data and making use of themodels and ethnographic analogies, it was estimated that every site represented anoccupation by a small band of mobile forgers making generalized use of the resourcesavailable in the region. Making residential moves often allowed people to survive in theharsh environment. Few lifeway changes were noted prior to Spanish influence in theregion from the time the environment became arid at the end of the Pleistocene.

No description available.