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Dissertations / Theses on the topic 'Region Quaternary'

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Published: 10 December 2022

Last updated: 29 January 2023

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1

Balzer, Solweig A. "Quaternary geology and dispersal patterns, Winagami region, Alberta." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp02/NQ59928.pdf.

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2

O'Brien, Charlotte Elizabeth. "Quaternary vegetation history of the Medoc Region, S.W. France." Thesis, Coventry University, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.366370.

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3

Hunt, Jonathan Brewster. "Quaternary tephrology and tephrochronology of the North Atlantic region." Thesis, University of Edinburgh, 1996. http://hdl.handle.net/1842/12096.

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Late Quaternary Climatic Oscillations are known to be intense, and in some cases too rapid to be resolved reliably using a radiocarbon chronology. Tephrochronology, the use of widespread and isochronous layers of volcanic ash is increasingly seen as a valuable tool in the inter-environmental correlation of proxy- palaeonclimatic indicators. A fundamental assumption that underpins tephrochronology in the North Atlantic is the acceptance that tephra horizons can be fingerprinted uniquely, by the major/minor element compositions of their vitric shards. This thesis concentrates on the analytical (Electron Probe Microanalysis) methodology required in the accurate and precise determination of this fingerprint, on factors which inhibit successful correlation using such fingerprints and on the application of geochemical signatures to the establishment of a meaningful regional tephrochronology. In addition, studies of tephra deposition and re-mobilisation have also been undertaken following the 1991 eruption of Hekla, with results indicating the need for caution in interpreting mass-loading and mapping of tephra isochrons. The principal tephrostratigraphy within this thesis relates to the Late Glacial and early Holocene, and is used in an attempt to achieve correlations between marine, terrestrial and ice-sheet environments. At least seven tephra isochrons are shown to be present in the North Atlantic region in the interval ca. 14,000 ¹⁴C yrs BP to ca. 9,000 ¹⁴C yrs BP, with one interpretation of evidence from the UK continental shelf suggestive of further horizons. Rigorous investigation of these tephras has revealed the potential inadequacies of major elements as unambiguous indices in the correlation and differentiation of Iceland-derived tephras. This is summarised by the term "geochemical equifinality", associated with higher eruption frequencies of known individual volcanic centres than previously recognised. It is apparent that, (i) geochemical data must be supplemented by more rigorous investigations of stratigraphical context; and (ii) new analytical techniques must be applied to the characterisation of potential trace elements signatures.

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4

Merritts, Dorothy Jane. "Geomorphic response to late Quaternary tectonism: Coastal northern California, Mendocino triple junction region." Diss., The University of Arizona, 1987. http://hdl.handle.net/10150/184316.

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Different patterns of uniform-uplift periods associated with passage of the Mendocino triple junction (MTJ) and a change in tectonic regime are based on altudinal spacing analyses of nine flights of marine terraces. Rates of uplift appear to increase from <1 m/ka to 4-5 m/ka, with periods of most rapid uplift that are progressively younger toward the triple junction. The MTJ was about 55 km to the south at about 1 ma ago, where uplift has been uniform at about 1.3 m/ka during the last 300 ka. Maximum uplift of about 4 m/ka is occurring 20-40 km south of the MTJ; prior to about 100-150 ka uplift was slow, being only 0.2-0.5 m/ka. Ten km to the north of the MTJ, accelerated uplift has occurred only during the last 60 ka. Relative strength of soil development in sandy marine deposits on five Pleistocene and Holocene (1.7 to 120 ka) marine terraces near the MTJ is one basis for relative age estimates and correlation of terrace soils. Organic carbon content in the upper 70 cm of the soil profile increases exponentially, and pH decreases exponentially; for both properties steady state is attained by 40 ka. Whole profile content of clay, total free iron oxyhydroxides (Fe(d)), and total free and para-crystalline aluminum oxyhydroxides increase nearly linearly until at least 120 ka. Comparison of these soils with four marine terrace soils (103-405 ka) 100-120 km to the south indicates that maximum percent values of clay and Fe(d) increase exponentially, with highest values reached at about 120 ka. Analysis of three-dimensional morphological properties of 25 coastal drainage basins that have evolved in areas of low (<1 m/ka), intermediate (1-3 m/ka), and high (>3 m/ka) rates of uplift near the MTJ identified channel slopes as the best indicator of tectonism in the landscape. Lower order tributaries reflect tectonically-controlled differences best. The largest streams examined, of third order, are able to adjust to most base-level change and maintain their profile form, whereas lower order streams farther upstream tend to accumulate the effects of net base-level fall, and have steepest profiles in the areas of highest uplift. Although first order streams are excellent indicators of highest uplift rate areas and regional differential tilting, they are less useful in distinguishing between low and intermediate uplift rate areas. Analysis of the longitudinal profile of the main trunk stream of 10 of the 25 drainage basins with the stream-gradient index (Hack, 1957) was useful to broadly categorize uplift rates, and to distinguish between low and intermediate uplift rate streams.

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5

Moseley, Gina Elaine. "Mid to late quaternary sea level change of the circum-Caribbean region." Thesis, University of Bristol, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.508171.

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6

Bourne, Anna Julie. "The late Quaternary tephrochronology of the Adriatic region : implications for the synchronisation of marine records." Thesis, University of London, 2012. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.549601.

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Tephrochronologies for three marine core sequences from the Adriatic Sea have been constructed. Two of the sequences, PRAD 1-2 and RF93-77, are located in the central Adriatic and the third, SA03-03, lies in the southern Adriatic. Isotopic and biostratigraphic records are available for all three sequences, features of which have been used as isochronous markers in the region. This project aimed to establish whether tephra layers provide (a) secure, independent isochronous tie-lines and (b) a robust methodology for testing correlations based on other methods. A total of 54 tephra layers have been identified within these sequences, of which only 8 are visible layers, the remainder being classified as cryptotephras. Geochemical characterisation of the ash layers has been undertaken using electron microprobe analysis and laser-ablation trace element methods. Geochemical correlation to the detailed tephra record from Lago Grande di Monticchio was performed using chemical element biplots and discriminant function analysis. Bayesian-based age models were generated for the three Adriatic records using available chronological information that are independent of assumptions of synchroneity between proxy marker events. These models allowed comparisons with tephra and palaeoenvironmental data from Lago Grande di Monticchio and other Mediterranean sites. The results support some assumptions of synchronous regional changes, but not others. The key outcomes are (a) the recognition of additional (non-visible) distal ash layers that enhance the potential for correlating marine and terrestrial records in the central Mediterranean; (b) volcanic ash records preserved in Lago Grande di Monticchio and in some localities proximal to volcanic sources appear to be incomplete; and (c) isotopic records in Adriatic sediment sequences reflect regional forcing factors more than local conditions.

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7

McMartin, Isabelle. "Quaternary geology and environmental geochemistry of the Flin Flon region, Manitoba and Saskatchewan." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape4/PQDD_0022/NQ52328.pdf.

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8

Smith, Andrew David. "Late Quaternary tectonics, sedimentation and sea-level changes in the North Aegean region." Thesis, University of Cambridge, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.321021.

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9

McMartin, Isabelle Carleton University Dissertation Earth Sciences. "Quaternary geology and environmental geochemistry of the Flin Flon Region, Manitoba and Saskatchewan." Ottawa, 2000.

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10

Woolfenden, Wallace Bird 1941. "Late Quaternary vegetation history of the southern Owens Valley region, Inyo County, California." Diss., The University of Arizona, 1996. http://hdl.handle.net/10150/282184.

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This study analyzes the pollen, spores, and algae in the upper 90 m section of a mostly continuous, well dated, 323 m core (OL-92) from Owens Lake, southeastern California. The entire core has produced a paleoclimatic record for the past ∼800 ka. The 90 m interval dates from ∼9 ka to ∼151 ka beginning with the penultimate glaciation and ending during the termination of the last glaciation. The record shows high amplitude fluctuations in the abundances of pine, juniper, saltbush, sagebrush, chenopods/amaranths, and Ambrosia-type pollen. High percentages of juniper pollen with low percentages of desertscrub pollen during the intervals ∼150 ka to ∼120 ka and 73 ka to ∼20 ka alternate with low juniper pollen and relatively high percentages of desertscrub and oak pollen during the intervals ∼118 ka to ∼103 ka and ∼18 ka ∼10 ka and into the Holocene. Sagebrush pollen varies with juniper pollen but has a tendency to lead it in time. Pine and fir pollen tends to vary inversely with juniper over the long term. These trends are interpreted as vegetation change in response to glacial-interglacial cycles: During cold-wet glacial climates there was a downslope expansion of juniper woodland and sagebrush scrub, contraction of Sierra Nevada mixed conifer forest, and displacement of warm desertscrub, suggesting average temperature and precipitation departures from modern values ranging from -2°C to -6°C and from +100 mm to +350 mm. Conversely under warmer and drier interglacials warm desert shrubs expanded their range in the lowlands, juniper and sagebrush retreated upslope, and the Sierran forests expanded. Estimated average temperature and precipitation departures from modern values ranged from -0.5°C to +3.7°C and +13 to -26 mm. Comparison of the pollen spectra spanning the penultimate and ultimate glacial maxima shows the former to have been longer and more intense, in accord with the Sierra Nevada glacial record. Similarly, the higher abundances of Ambrosia pollen during the last interglaciation, compared to the Holocene, indicate warmer temperatures in the former. The presence of high oak percentages also during the last interglaciation suggest an expansion of the summer monsoon. Finally, the match of the juniper curve with the marine oxygen isotope chronostratigraphy suggests a link between vegetation change in the southern Owens Valley and global climate.

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11

Porinchu, David Francis. "A chironomid-inferred Late-Quaternary climate reconstruction of the lower Lena River region, Siberia." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp01/MQ30018.pdf.

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12

Turner, Rebecca. "Late Quaternary fire histories in the Eastern Mediterranean region from lake sedimentary micro-charcoals." Thesis, University of Plymouth, 2007. http://hdl.handle.net/10026.1/748.

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The Eastern Mediterranean has a long history of human occupation, which spans the transition from hunter-gatherers to the establishment of early agro-pastoralist communities, coinciding with the Last Glacial: Interglacial transition. Over the same timeframe a delay in postglacial woodland recolonisation in the region has been identified. Fire has long been used by people to manage and manipulate the landscape, and has been hypothesised to have played a role in this delay. This thesis employed lacustrine micro charcoal (particles less than 180 !lm) remains to reconstruct Late Quaternary fire histories for Central Turkey and the Levant, and examine the possible role that fire may have played in retarding woodland development in the region. Microcharcoals were analysed in cores taken from four sites in Central Turkey (Akgöl, Eski Acıgöl, C̦atalhöyük and Nar Gölü) and one site in Israel (Lake Hula) that cover varying time intervals from the Last Glacial through to the Late Holocene. In order to develop a standardised analytical procedure for microcharcoals, a series of published extraction and quantification techniques along with a new approach using heavy liquid separation were rigorously tested on 'control' samples that contained a known volume of microscopic charcoal. As a result of this investigation a novel, two step extraction procedure based on the use of heavy liquid separation was developed and applied alongside a contiguous high resolution sampling strategy. Using this approach, fire activity was reconstructed based on cores from each of the sites and these data were compared with existing multi-proxy data (stable oxygen isotopes, pollen and archaeological data). Results show clear links between climate, biomass, people and fire, although these relationships changed over time. Regional fire activity during the Last Glacial: Holocene transition was apparently controlled by climate through the influence it exerted on biomass availability, whereas links between people and fire activity are most evident during the Late Holocene. Humans do not seem to have retarded the Early Holocene spread of woodland through the use of fires, although it is possible that natural fire activity served to maintain the open parkland vegetation communities may have played a role. During the Mid Holocene a mixture of climatic and anthropogenic controls apparently influenced regional fire activity. Evidence was also identified of a ca.l ,500 year periodicity in fire history from Central Turkey which may reflect teleconnections to climatic changes in the North Atlantic. This research also highlighted the potential of using microscopic charcoal to infer the spatial resolution of fire history reconstructions from lake basins of different sizes and types through comparisons of influx values.

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13

Nealon, John S. "Pre-Illinoian Glaciation and Landscape Evolution in the Cincinnati, Ohio / Northern Kentucky Region." University of Cincinnati / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1367940441.

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14

Klude, Matthias. "ZnSe-based laser diodes with quaternary CdZnSSe quantum wells as active region chances and limitations /." [S.l.] : [s.n.], 2002. http://deposit.ddb.de/cgi-bin/dokserv?idn=965575136.

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15

Isenor, Fenton Murdoch. "Applied Quaternary geology and till geochemistry of the Loch Lomond Region, Cape Breton Island, Nova Scotia." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape4/PQDD_0017/MQ54529.pdf.

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16

Schwab, Christian [Verfasser]. "Late Quaternary changes in paleoproductivity and hydrography in the Azores region deduced from coccolithophore assemblages / Christian Schwab." Kiel : Universitätsbibliothek Kiel, 2013. http://d-nb.info/1035182114/34.

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17

Mulock-Houwer, Anne. "Late quaternary environmental reconstruction and climate modelling in the winter rainfall region of the Western Cape, South Africa." Master's thesis, University of Cape Town, 2001. http://hdl.handle.net/11427/6069.

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Bibliography: leaves 124-144.
The southwestern Cape of South Africa is a floristically diverse region experiencing winter rainfall, and is important as it represents a significant southern hemisphere example of a Mediterranean climate regime. Acquiring palaeoenvironmental data from this region is imperative in understanding the climatic changes that have occurred during the Late Quaternary, with a view to improved palaeclimatic modelling. The spatial distribution of studies for the Late Quternary in the southwestern Cape is uneven and palaeoenvironmental reconstructions have been largely restricted to sites, which are easilty accessible, and appropriate only for the methods being used (e.g. palynology for wetlands). Moreover, many of the palaeoenvironmental reconstructions implemented thus far fall outside the winter rainfall region sensu stricto. Hence spatial differentiation in climatic response may have remained obscured due to the 'selection' of sites used.

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18

Pietsch, Timothy J. "Fluvial geomorphology and late quaternary geochronology of the Gwydir fan-plain." Access electronically, 2005. http://www.library.uow.edu.au/adt-NWU/public/adt-NWU20060720.153247/index.html.

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19

Biltekin, Demet. "Vegetation and climate of north anatolian and north aegean region since 7 Ma according to pollen analysis." Phd thesis, Université Claude Bernard - Lyon I, 2010. http://tel.archives-ouvertes.fr/tel-00720892.

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This study concerns a long marine section (DSDP Site 380: Late Miocene to Present) and onshore exposed sections from the Late Miocene and/or Early Pliocene. The main target of this study is to reconstruct vegetation and climate in the North Anatolia and North Aegean region for the last 7 Ma. Two vegetation types were alternately dominant: thermophilous forests and open vegetations including Artemisia steppes. During the Late Miocene, most of the tropical and subtropical plants declined because of the climatic deterioration. However, some of them survived during the Late Pliocene, such as those which constituted coastal swamp forests (Glyptostrobus, Engelhardia, Sapotaceae, Nyssa) or composed deciduous mixed forests with mesothermic trees. Simultaneously, herbaceous assemblages became a prevalent vegetation component despite steppe elements (Artemisia, Ephedra, Hippophae rhamnoides) did not significantly develop. At 2.6 Ma, as a response to the onset of Arctic glaciations, subtropical elements rarefied despite some taxa persisted (Glyptostrobus, Engelhardia, Sapotaceae, Nyssa). In parallel, deciduous mixed forest assemblages composed of mesothermic trees (deciduous Quercus, Betula, Alnus, Liquidambar, Fagus, Carpinus, Tilia, Acer, Ulmus, Zelkova, Carya, Pterocarya) almost disappeared too while steppe environments strongly enlarged. Then, Artemisia steppic phases developed during longer temporal intervals than mesophilous tree phases all along the glacial-interglacial cycles (first with a period of 41 kyrs, then 100 kyrs). Since 1.8 Ma, herbaceous ecosystems including Artemisia steppes still continuously enlarged up today. Such an expansion of Artemisia steppes in the Ponto-Euxinian region was observed at the earliest Pliocene but their earliest settlement in Anatolia seems to have occurred in the Early Miocene. The development of the Artemisa steppes in Anatolia might result from the uplift of the Tibetan Plateau. Relictuous plants such as Carpinus orientalis, Pterocarya, Liquidambar orientalis, Zelkova persisted up today. This story can be explained by some influence of the Asian monsoon which reinforced as a result from the uplifted Tibetan Plateau.

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20

Koutsouris, Alexander. "Data resolution effects onwater resource planning andmanagement : The Kisumu – Lake Victoria region study." Thesis, Stockholm University, Department of Physical Geography and Quaternary Geology, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-36565.

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In the Kisumu District, Kenya, unreliable rainfall pattern has been identified as one of the main causes for poverty in rural areas. The negative effects of such unreliable patterns could be mitigated through improved water resource management and planning. However, estimates of current (and future) water availability will likely differ depending on whether managers draw upon data gathered at a local-scale or regional-scale. This is particularly important in developing regions where, due to lack of data availability, managers are often limited in their choice of data resolution. This study investigates the potential effect of spatial resolution of data on water management and planning by comparing hydro-climatic trends in local-scale data with trends in regional-scale data. The influence of adopting local-scale versus regional-scale data is further demonstrated by estimate the storage requirements of proposed irrigation ponds for farmers in the Orongo village of the Kisumu District located in Kenya, Africa. Results indicate a low correlation between local and regional hydro-climatic trends. Data spatial scale directly influences water resources management leading to a 300% difference in estimated storage requirement for the average farmer.

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21

Heinrichs, Mark L. "A late-quaternary paleoecological analysis in the Engelmann Spruce-Subalpine Fir biogeoclimatic zone of the Okanagan/Ashnola region, British Columbia, Canada." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape9/PQDD_0007/NQ41358.pdf.

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22

Ahlborn, Marieke [Verfasser], Roland [Akademischer Betreuer] Mäusbacher, and Peter [Akademischer Betreuer] Frenzel. "Moisture availability in the Tangra Yumco region during the Late Quaternary and the implications for the precipitation regime on the southern Tibetan Plateau / Marieke Ahlborn. Gutachter: Roland Mäusbacher ; Peter Frenzel." Jena : Thüringer Universitäts- und Landesbibliothek Jena, 2015. http://d-nb.info/1080522034/34.

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23

Norström, Elin. "Late Quaternary climate and environmental change in the summer rainfall region of South Africa : a study using trees and wetland peat cores as natural archives /." Stockholm : Department of Physical Geography and Quaternary Geology, Stockholm university, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-7375.

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24

Foerster, Verena Elisabeth [Verfasser], Frank [Akademischer Betreuer] Schäbitz, and Olaf [Akademischer Betreuer] Bubenzer. "Late Quaternary climate variability in the source region of Homo sapiens. Dry-wet cycles in Chew Bahir, southern Ethiopia / Verena Elisabeth Foerster. Gutachter: Frank Schäbitz ; Olaf Bubenzer." Köln : Universitäts- und Stadtbibliothek Köln, 2014. http://d-nb.info/1071369873/34.

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25

Rodríguez, Rosero Luis Fernando [Verfasser], Hermann [Akademischer Betreuer] Behling, and Michael [Akademischer Betreuer] Kessel. "Reconstruction of late Quaternary landscape dynamics in the Podocarpus National Park region southern Andes of Ecuador / Luis Fernando Rodríguez Rosero. Gutachter: Hermann Behling ; Michael Kessel. Betreuer: Hermann Behling." Göttingen : Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2013. http://d-nb.info/1044307331/34.

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26

Nandini-Weiß, Sri Durgesh [Verfasser], Matthias [Akademischer Betreuer] Prange, Michael [Gutachter] Schulz, and Martin [Gutachter] Claussen. "Hydroclimate variations in the Caspian Sea region from the late Quaternary to the future : a model perspective / Sri Durgesh Nandini-Weiß ; Gutachter: Michael Schulz, Martin Claussen ; Betreuer: Matthias Prange." Bremen : Staats- und Universitätsbibliothek Bremen, 2019. http://d-nb.info/119900359X/34.

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27

Mitchell, W. A. "Glaciation of upper Wensleydale and adjoining watershed regions." Thesis, Royal Holloway, University of London, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.322134.

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28

Kodybka, Richard Joseph. "Aspects of the Quaternary evolution of the plateau regions of the northern Ruby Range, southwest Yukon Territory." Thesis, University of Ottawa (Canada), 1994. http://hdl.handle.net/10393/6921.

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The main objective of this thesis was to offer explanations on the evolution of the plateau surfaces in the northern Ruby Range, Yukon Territory. Specifically, to determine whether the geological and geomorphological evidence from the plateau surfaces could support the belief that these regions were subjected to glaciation, or does the evidence indicate other evolutionary processes. The more traditional geological techniques of geochemical and heavy mineral compositional analyses have been used previously in both geological and glacial related studies in the Canadian Shield and other regions of Canada, and have aided in the description of environments. However these types of analyses have had limited application in alpine environments with expensive plateau regions, such as those experienced in the northern Ruby Range. The data also made it possible to delineate, in a regional context, mineralized zones that have not yet been identified. This pursuit constituted an ancillary objective in this thesis. It was determined that the average proportion of heavy minerals identified was similar for both plateau and valley sediment samples. The range of the proportions was found to vary considerably in most minerals. The significance of these comparisons was not clear, but probably indicated that the sediments from both plateau and valley sites did not vary greatly in heavy mineral species and proportions, but demonstrated a variable range. As well, there was no appreciable difference in the heavy mineral assemblages between plateau and valley sediment samples, except for the relative lack of allanite from plateaus, and goethite from valleys. The data did not support a clear association between heavy mineral assemblages from plateau and valley sediments, and those derived from bedrock within or outside the study area. However, the sediment assemblages may not be exclusively related to local bedrock sources. The provenance of orthopyroxene, goethite, and allanite may be attributed, in part, to bedrock from outside the study area, volcanic ash, and meteoritic impacts, or a combination of these. The occurrence of these minerals may also be associated with mineral alterations. Both the heavy mineral and geochemical data indicated there were no discernable dispersal patterns in either an up-valley or down-valley direction. The random dispersals of minerals and elements in the valleys can be characterized as secondary, epigenetic dispersals, and can be further classified as resembling clastic, hydromorphic, or biogenic patterns. Heavy mineral and element analyses performed on surficial sediments from the plateau surfaces indicated that some of the material may not be of local origin, and discernable dispersal trends were evident in certain heavy minerals and elements which were traced to known sources of mineralizations. The most striking characteristics of these trends were their continuous form, spanning many kilometres, and their patterns which extended over extensive plateau surfaces that were dissected by numerous valleys. (Abstract shortened by UMI.)

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29

Smith, Brett. "The late quaternary history of Southern hemisphere mediterranean climate regions in the Western Cape, South Africa, and Southwestern Australia." Doctoral thesis, University of Cape Town, 2010. http://hdl.handle.net/11427/12162.

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Includes abstract.
Includes bibliographical references (leaves 215-241).
The study is focused on four study sites, two in the Western Cape, namely the Bruno section and Lake Michelle and two in southwestern Australia, namely Wambellup Swamp and Devil's Pool. These sites were chosen as they are well situated to investigate the complex interaction between Late Quaternary climate change, the influence of fluctuating sea levels and the impact of human interaction with the environments in question and provide a regional picture of these interactions.

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30

Seong, Yeong Bae. "Quaternary Glaciation and Its Role on Landscape Evolution of the Muztag Ata-Kongur Shan and K2 Regions in the Westernmost Himalaya-Tibetan Orogen." University of Cincinnati / OhioLINK, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1174999352.

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31

Passos, Marcel Silva. "Depósitos sedimentares Pleistocenos-Holocenos da zona de confluência dos rios Solimões e Purus, Amazônia Ocidental." Universidade Federal do Amazonas, 2016. http://tede.ufam.edu.br/handle/tede/5524.

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The Solimões River, at the confluence zone with the Purus River (Western Amazonia) features 3 levels of Pleistocene-Holocenos river terraces, informally called Superior (TS), Intermediário (TI) and Inferior (TInf), defined in this study based in remote sensing data, sedimentology, stratigraphy and geochronology. In general, the terraces display symmetrical distribution, form parallel tracks to the river and extend for tens of kilometers. Located between the elevations 15-75 m, display aged 750-204,000 years BP and internally consist of interbedded sand and mud layers (silt and clay) forming pairs of Stratification Heterolytic Leaning (EHI). The TS (55,000 to 204,596 years BP) is characterized by raised ridges and depressions, showing dendritic drainage patterns to subdendritic and traces of old lines of lateral accretion. The terraces TI (28,400 to 37,240 years BP) and TInf (750-9315 years BP) are part of the active floodplain of the river, subject to seasonal flooding. TI provides relief plan with gentle undulations, displaying rows of lateral accretion and dozens of lakes with elongated shapes, rounded and curved, while the TInf is the closest unit to the main channels, making the marginal bars and islands, stands out for most density lines accretion and lakes. The symmetry of the levels of the terraces of the Solimões River, as well as the features of paleochannels and the presence of EHI, show your past meandering fluvial style that prevailed in the Late Pleistocene, leading to the conclusion that the migrated channel for tens of kilometers. However, recent data show that this river has a high degree of stability, defined primarily based on the channel low migration rate (around 0.32% / year), and by the presence of islands and marginal bars and muddy fitoestabilizadas that define the current anastomosing-anabranching style. The change of fluvial style in the Pleistocene-Holocene boundary can be mainly related to climatic variations, tectonics and glaciostatic. The rise in the sea to the current level, between 18,000 and 6,000 and years BP, blocked the mouth of Solimões-Amazonas river system, causing a decrease in slope and greater input of fine sediments, which in combination with the increased humidity (which allowed phytostabilization the islands and margins) made this system more stable and allowed the installation of the current anastomosing-anabranching style. The predominance of this style can be extended to the east, to the confluence region with the Madeira River.
O Rio Solimões, na zona de confluência com o Rio Purus (Amazônia Ocidental), apresenta 3 níveis de terraços fluviais pleistocenos-holocenos, denominados informalmente de Superior (TS), Intermediário (TI) e Inferior (TInf), definidos neste estudo com base em dados de sensores remotos, sedimentológicos, estratigráficos e geocronológicos. Em geral, os terraços exibem distribuição simétrica, formam faixas paralelas ao rio e se estendem por dezenas de quilômetros. Localizam entre as cotas de 15 a 75 m, exibem idades entre 750 a 204.000 anos AP e, internamente, são constituídos por intercalações de camadas de areia e lama (silte e argila), que formam os pares da Estratificação Heterolítica Inclinada (EHI). O TS (55.000 a 204.596 anos AP) é caracterizado pelo relevo de cristas e depressões, exibe padrões de drenagem dendrítico a subdendrítico e vestígios de antigas linhas de acreção lateral. Os terraços TI (28.400 a 37.240 anos AP) e TInf (750 a 9.315 anos AP) fazem parte da planície aluvial ativa deste rio, estando sujeitos às inundações sazonais. O TI apresenta relevo plano com suaves ondulações, exibindo linhas de acreção lateral e dezenas de lagos com formas alongadas, arredondadas e curvadas, enquanto o TInf é a unidade mais próxima aos canais principais, compondo as barras marginais e ilhas e, se destaca pela maior densidade de linhas de acreção e lagos. A simetria dos níveis dos terraços do Rio Solimões, bem como as feições de paleocanais e a presença da EHI, evidenciam o seu pretérito estilo fluvial meandrante que predominou no Pleistoceno Superior, permitindo inferir que o canal migrou por dezenas de quilômetros. Entretanto, os dados atuais mostram que este rio tem um elevado grau de estabilidade, definido principalmente com base na baixa taxa de migração dos canais (em torno de 0,32%/ano), bem como pela presença de ilhas e barras marginais lamosas e fitoestabilizadas que definem o atual estilo anastomosado-anabranching. A mudança do estilo fluvial no limite Pleistoceno-Holoceno pode ser relacionada principalmente as variações climáticas, tectônicas e glacioeustáticas. A subida do mar até o nível atual, entre 18.000 e 6.000 e anos AP, bloqueou a foz do sistema fluvial Solimões-Amazonas, provocando a diminuição da declividade e maior aporte de sedimentos finos, que em associação com o aumento da umidade (que permitiu a fitoestabilização das ilhas e margens) tornaram este sistema mais estável, e permitiu a instalação do atual estilo anastomosado-anabranching. A predominância deste estilo pode ser estendida a leste, até a região de confluência com o rio Madeira.

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Gavel, Marine. "Nouveaux développements chimiques pour la conception d'inhibiteurs de glycosyltransférases Carbene-mediated quaternarization of the anomeric position of carbohydrates: synthesis of allylic ketopyranosides, access to the missing α-gluco and β-manno stereoisomers, and preparation of quaternary 2-deoxy 2-acetamido sugars Regio- and chemoselective deprotection of primary acetates by zirconium hydrides." Thesis, Normandie, 2019. http://www.theses.fr/2019NORMIR09.

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Ces travaux de thèse ont été consacrés au développement de voies de synthèses permettant l'obtention de structures cétopyranosidiques modulables en vue du développement d'outils chimiques dédiés à la glycobiologie. Nous avons tout d'abord travaillé au déploiement de séquences réactionnelles ouvrant l'accès à des glycophosphomimétiques possédant une unité triméthylène phosphonate. Par ailleurs, nous avons mis au point une nouvelle méthode de déprotection régiosélective de la position primaire de sucres peracétylés utilisant un mélange bimétallique de zirconium et d'aluminium permettant de faciliter l'accès à des (oligo)saccharides ayant des liens glycosidiques α-1,6. Enfin, en combinant ces développements chimiques, nous avons souhaité préparer des inhibiteurs potentiels de glycosyltransférases bi-substrats possédant à la fois un mime du groupe partant du donneur de glycosyle et de l'accepteur connectés à la position anomère quaternaire des cétopyranosides
The goal of this project is to challenge the hypothesis that a non-natural sugar with a quaternary anomeric position might be the central core of a powerful and selective inhibitor of glycosyltransferase. Our design is relying on a key quaternary anomeric centre that provide the unique opportunity to incorporate in a single innovative structure the acceptor, the donor and the leaving group released during the formation of the glycosidic linkage. The functionnalization of the ketopyranosides that will be at the centre of this new class of potent glycosyltransferases inhibitors rely on original synthetic methods allowing introduction of a trimethylene phosphonate and regioselective deprotection of primary position of acetylated sugars for building alpha-1,6 glycosidic linkages

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Davis, Angela C. "Quaternary mammal faunas and their stratigraphy in the northern Monaro region, southeastern Australia." Phd thesis, 1996. http://hdl.handle.net/1885/10775.

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This thesis documents the history of Quaternary mammalian faunas from the northern Monaro region of the southern highlands of Eastern Australia. The area currently has a cold semi-arid climate and, together with a series of fossil localities of different ages, provides an opportunity to examine the relationships between faunal changes and palaeoenvironments in this part of Australia during the Quaternary. Fossil material from seven localities within the northern Monaro region is described together with the geology of the sites in which they occur. The localities are Pilot Creek, Bunyan Siding, South Bunyan, Bulong, Tannery Creek, Ryries Creek and Rock Flat Creek, all on tributaries of the Murrumbidgee River near Cooma. Detailed stratigraphic studies, incorporating several dating techniques have been employed at the two major fossiliferous deposits, Pilot Creek and Bunyan Siding. A stratigraphic sequence 1s proposed in which the contained faunas are ordered chronologically. The oldest dated mammal fossil-bearing deposit in the region is at Bunyan Siding. It is an alluvial deposit and comprises two fossiliferous Quaternary units, which disconformably overlie Miocene palaeolake sediments of the Bunyan Formation. The Quaternary units are described as two new formations, the Jilliby Folmation and Nestle Brae Formation. They are interpreted as having been formed in a fluvial environment consisting of large and small meandering channels and adjacent floodplains. Dating of the site using palaeomagnetism and optically stimulated luminescence establishes a Middle Pleistocene age (120- 780 ka) for both units. Two local faunas are recognised at Bunyan Siding, the Jilliby Local Fauna and Nestle Brae Local Fauna, each defined and named after the stratigraphic units that contain them. The other major locality, Pilot Creek, is a valley-fill sequence comprising a series of channel cut-and:-fill units and marginal alluvial fans of Late Pleistocene and Holocene ages. Five stratigraphic units are recognised and described in detail including the description of two formations, Pilot Creek and Willow Bank. Each unit contains a local fauna. Fourteen radiocarbon dates enable absolute ages to be placed on some of the units. The oldest fossiliferous unit in the Pilot Creek sequence is the Pilot Creek Formation which has been radiometrically dated at circa 25 ka years BP. The next youngest unit in the sequence is an alluvial fan deposits, QF1 which has been dated at 11 ka. A third unit, the Willow Bank Formation, is a channel-fill unit which truncates both the Pilot Creek Formation and the QF1 unit. Dates from the Willow Bank Formation range from 6 ka to 2 ka. A second alluvial fan unit, QF2 inset into the Pilot Creek Formation, is dated at 4.5 ka. A recent alluvial unit, PESA, is at the top of the sequence. From the stratigraphy of th~ valley units five local faunas have been defined, providing a faunal record in the valley spanning the last 25 ka.

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Bussell, Martin Royd. "Quaternary vegetational and climatic changes recorded in cover beds of the South Wanganui Basin marine terraces, New Zealand." Phd thesis, 1988. http://hdl.handle.net/1885/141055.

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Niemann, Holger. "Late Quaternary vegetation, climate and fire dynamics in the Podocarpus National Park region, southeastern Ecuadorian Andes." Doctoral thesis, 2008. http://hdl.handle.net/11858/00-1735-0000-0006-B637-7.

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Brunschön, Corinna. "Late Quaternary landscape dynamics in the Podocarpus National Park region in the southeastern Andes of Ecuador." Doctoral thesis, 2010. http://hdl.handle.net/11858/00-1735-0000-0006-B697-2.

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Rodríguez, Fernando. "Reconstruction of late Quaternary landscape dynamics in the Podocarpus National Park region southern Andes of Ecuador." Thesis, 2012. http://hdl.handle.net/11858/00-1735-0000-0019-8636-2.

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Los Andes ecuatorianos albergan ecosistemas con la más alta biodiversidad sobre la tierra. Información preliminar sobre la dinámica de los ecosistemas en el pasado es necesaria para entender, conservar y manejar los ecosistemas y su biodiversidad. Tres muestras de sedimentos fueron datadas, Rabadilla de Vaca (RV) a 3244 m de altura y Valle Pequeño (VP) a 3200 m de altura, ambas en la parte central del Parque Nacional Podocarpus (PNP), y Lagunas Natosas Bosque (LNB) a 3495 m de altura, al sur del PNP al sur del Ecuador en la región llamada Depresión Andina. Estas muestras fueron estudiadas con base en análisis de polen, esporas y partículas de carbón. Los resultados revelan cambios en la vegetación en la zona de LNB durante los últimos 16,000 años, y en RVM y VP desde hace 2100 años. Durante el Plestoceno tardío (15,930 – 11,660 cal yr BP), la vegetación de páramo dominó el área y la presencia de Plantago rigida sugiere condiciones ambientales frías y húmedas en el área de LNB. La población de P. rigida disminuyó drásticamente durante el último período glacial y especialmente durante el “Younger Dryas”, que es un corto período frío (hace 12,800 a 11,500 años), y el límite superior del bosque (UFL) muy probablemente fue mas bajo que en la actualidad. Entre 11,660 – 4280 cal yr BP, ocurrió una marcada reducción de cobertura de páramo, acompañada por una expansión de la vegetación de subpáramo (arbusto enano leñoso). En la región de LNB, al sur del PNP, se evidención un cambio altitudinal hacia arriba del UFL. En este sitio se evidencia por primera vez la presencia de grandes extensiones de Polylepis en la región de la Depresión Andina. Alrededro de 4200 cal yr BP el regreso a condiciones climáticas frías y húmedas favoreció la expansión de los páramos. El Holoceno tardío hasta el presente se caracteriza por la contínua fluctuación entre vegetación de páramo y subpáramo. Sin embargo, alrededor de los 1200 cal yr BP, vegetación de subpáramo (arbustos enanos) fueron precuentes, lo que sugiere un incremento moderado en temperatura y humedad. En el área de RVM desde los 2100 hasta los 1720 cal yr BP, la dominancia de subpáramo sugiere condiciones climáticas más húmedas y cálidas. En el área de LNB después de los 500 cal yr BP, el incremento de vegetación de páramo indica condiciones más húmedas. Esto también se registró en la zona de RVM y VP desde 800 a 310 cal yr BP, donde la vegetación de páramo se expandió ampliamente y redujo la posibilidad de crecimiento de bosque. Inlfuenciada por condiciones más húmedas y fuegos (incendios) frecuentes, en el área de LNB, Polylepis estuvo casi ausente durante el Holoceno tardío. Aunque, restos de partículas de carbón indican la presencia humana desde hace más de 4000 años. La máxima concentración de partículas de carbón indican alta frecuencia de fuegos desde 1800 hasta 1600 cal yr BP y desde 600 a 400 cal yr BP. Comparando la vegetación y los regsitros de carbón entre los tres sitios, es evidente que el fuego favoreció la expansión de vegetación de páramo en detrimento de la vegetación de subpáramo y bosque montano alto (UMF). El fuego probablemente tuvo un rol importante en el control de los cambios del límite del bosque durante el Holoceno tardío. Sin embargo, es difícil establecer si cambios en las condiciones del clima también tuvieron un rol importante durante este período. Los fuegos se presentaron a distintos momentos entre los diferentes sitios, esto sugiere que existió influencia antropogénica. Es posible inferir cambios a nivel regional ocasionados por la variabilidad de clima; sin embargo, condiciones locales como temperatura, precipitación, vientos, radiación solar y geomorfología, también tienen un impacto fuerte en los patrones de la vegetación, los mismos que pueden determinar la estructura, heterogeneidad y distribución de los ecosistemas.

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Qu, Ding-Chuang. "Late quaternary climate in the Indo-Pacific warm pool reconstructed from the raised coral reefs of Sumba, Indonesia." Phd thesis, 2009. http://hdl.handle.net/1885/146502.

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Klude, Matthias [Verfasser]. "ZnSe-based laser diodes with quaternary CdZnSSe quantum wells as active region : chances and limitations / Matthias Klude." 2002. http://d-nb.info/965575136/34.

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Ferbey, Travis. "Quaternary geology, ice-flow history and till geochemistry of the Huckleberry Mine region, west-central British Columbia." Thesis, 2004. http://hdl.handle.net/1828/1260.

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The Huckleberry Mine region experienced a complex ice-flow history during the Late Wisconsinan Fraser Glaciation. Cross-cutting and superimposition relationships observed in the field, constrain the relative timing of ice-flow events and indicate that a westerly-directed ice-flow event was followed by a smaller magnitude east to northeast event. This ice-flow reversal can be explained by the existence of an ice divide in the central interior of British Columbia during the Fraser Glaciation maximum. Although ice thickness exceeded relief in the region during the glacial maximum, and glaciers flowed west, up-valley towards the Coast Mountains, locally, ice-flow direction appears to still have been influenced by topography. Basal tills dominate the local Quaternary stratigraphy. These grey, overconsolidated, clayey-silt diamictons typically overlie Early Jurassic Telkwa Formation andesites, but they can also locally overlie advance-phase glaciofluvial sands and gravels. In the vicinity of the Main and East Zone areas, it is common to find visible pyrite and chalcopyrite grains (up to 3 mm in size), and mineralized clasts (pyrite +/- chalcopyrite) in the till matrix. At a 19 m vertical exposure, multiple till units were identified. These basal tills are distinguished primarily by changes in colour, matrix texture, and gravel content. Stratigraphic, sedimentological, lithological, and geochemical data from this exposure provide evidence of an ice-flow reversal in the Huckleberry Mine region during the Fraser Glaciation maximum. Till geochemical data define the locations of known sources of copper mineralization in the Huckleberry Mine region. Maximum, minimum, and median copper values in near-surface basal till samples are 8924 ppm, 29 ppm, and 216 ppm, respectively (n=106), while those for sub-surface basal till samples are 4167 ppm, 18 ppm, and 187, respectively (n=230). Locally developed dispersal trains indicate that mineralization from these sources has been transported towards the east and west. These dispersal trains are detectable in both near-surface and sub-surface basal till samples and also provide further evidence of an ice-flow reversal in the Huckleberry Mine region. Two westward-directed dispersal trains, that are isolated or disconnected from dispersal of the Main Zone area, suggest and that there could be undiscovered bedrock mineralization on Huckleberry Mine property.

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Cucuzza, G. "Geology and geophysics of late Quaternary sediments from the inner and middle shelf off Townsville : Central Great Barrier Reef province." Master's thesis, 1990. http://hdl.handle.net/1885/140907.

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42

Sumner, P. D. (Paul). "On the geomorphic evidence for a late quaternary periglaciation of the main escarpment region of eastern southern Africa." Thesis, 2003. http://hdl.handle.net/2263/27688.

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Conflicting reports from geomorphic studies appear in the literature describing the environment of the southern African Main Escarpment region adjacent to the Lesotho Highlands during the cold phases of the Late Quaternary. Evidence cites limited glaciation and/or periglacial conditions with or without permafrost. The thesis emphasises debates and presents arguments for alternative interpretation of landforms previously described in the literature as indicative of specific cold environments. Field investigations into the distribution and characteristics of openwork accumulations in southern Africa show that blocky accumulations are found within a range of climatic conditions, including arid and semi-arid environments. Mode of emplacement is highlighted as the critical factor in association with a periglacial environment. Relict openwork block accumulations in the Lesotho highlands area around Thabana Ntlenyana, the highest summit in the escarpment range, supports the contention for a relatively arid periglacial environment during the Late Pleistocene. Findings militate against either deep snow cover or localised glaciation of insolation-protected south-facing slopes. The evidence for periglacial conditions is supported by the presence of relict sorted patterns that indicate deep seasonal freeze. Contemporary soil temperature monitoring indicates a near-surface current seasonal freeze of two and a half months which would have been prolonged and deepened under depressed temperature. No specific evidence for periglacial conditions is found for the escarpment region in the Amatola mountains.
Thesis (DPhil)--University of Pretoria, 2003.
Geography, Geoinformatics and Meteorology
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43

Lewis, Colin A. "Late Quaternary environmental phases in the Eastern Cape and adjacent Plettenberg Bay-Knysna region and Little Karoo, South Africa." 2011. http://hdl.handle.net/10962/d1006749.

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Four major climato-environmental phases have been identified in the Eastern Cape, Plettenberg Bay-Knysna region and Little Karoo between somewhat before ~ 40 000 cal. a BP and the present: the Birnam Interstadial from before 40 000 cal. a BP until ~ 24 000 cal. a BP; the Bottelnek Stadial (apparently equating with the Last Glacial Maximum) from ~24 000 cal. a BP until before ~ 18 350 cal. a BP; the Aliwal North (apparently equating with the Late Glacial) from before ~ 18 350 cal. a BP until ~ 11 000 cal. a BP; the Dinorben (apparently equating with the Holocene) from ~ 11 000 cal. a BP until the present. The evidence for, and the characteristics of, these phases is briefly described.

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44

Brunschön, Corinna [Verfasser]. "Late Quaternary landscape dynamics in the Podocarpus National Park region in the southeastern Andes of Ecuador / vorgelegt von Corinna Brunschön." 2010. http://d-nb.info/1008107107/34.

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45

Niemann, Holger [Verfasser]. "Late quaternary vegetation, climate and fire dynamics in the Podocarpus National Park region, southeastern Ecuadorian Andes / vorgelegt von Holger Niemann." 2008. http://d-nb.info/99111258X/34.

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46

Wellner, Julia Smith. "Late Quaternary glacial history of the Pennell Coast region, Antarctica, with implications for sea-level change and controls on ice sheet behavior; and, Late Quaternary statigraphic evolution of the west Louisiana continental shelf." Thesis, 2001. http://hdl.handle.net/1911/18046.

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The Pennell Coast continental shelf is isolated from West Antarctic Ice Sheet drainage; for an ice sheet to ground in this region it must flow over the Transantarctic Mountains from East Antarctica. Features observed indicate that ice grounded on the Pennell shelf. Cores from the shelf sampled till, a pelletized unit, glacial-marine sediments, contourite deposits, and diatomaceous muds. The timing of ice sheet grounding is revealed by radiocarbon dates that indicate the ice sheet was grounded on the shelf during the Last Glacial Maximum and has a retreat history that differs from nearby drainage areas. Comparison to sea-level curves suggests that melting ice from the region contributed to the Holocene sea-level rise and that formation of that ice contributed to the fall in sea level immediately prior to the Last Glacial Maximum. Comparison between the Pennell Coast and drainage outlets of the West Antarctic Ice Sheet allows examination of controls on ice sheet behavior. There is a consistent pattern of erosional features on the crystalline bedrock of the inner shelf, mega-scale glacial lineations on the sedimentary strata of the outer shelf, and drumlins between the two. The troughs in the areas of sedimentary substrate are interpreted to have been occupied by fast-flowing ice and those in the areas of crystalline substrate by slower-moving ice. The Pennell shelf differs in that it has both crystalline and sedimentary substrates but no drumlins or lineations. Possible reasons for this difference include the size of the drainage basin, the narrow continental shelf, and the high sand content of the tills. Core and seismic data were used to conduct an analysis of the west Louisiana outer shelf depositional systems formed during the last glacial-eustatic cycle. Differences in deltaic deposition in the area illustrate the complex relationship between depositional patterns and sea-level change. Particularly salient is the difference between the two primary sequence boundaries. The oldest sequence boundary is a major erosional surface. The youngest sequence boundary is characterized by much smaller channels and is primarily an interfluve feature. The observed variations in each system can be used to refine sequence-stratigraphic models.

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Whitau, Rose Hannah. "Late Quaternary human-environment interaction in Bunuba and Gooniyandi country, Western Australia." Phd thesis, 2018. http://hdl.handle.net/1885/147693.

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In north Western Australia, records of palaeoenvironmental change are scarce or under explored, particularly terrestrial archives that allow for comparison with the archaeological record and examination of human-environment interaction in the past. The extent to which these records reflect localised vegetation responses to climate fluctuations, and the manner in which people adapted to these changes in climate and vegetation, has yet to be investigated within the context of stratified archaeological inquiry. Analysis of archaeobotanical proxies excavated in association with other cultural remains provide the obvious evidential link to this issue; however, archaeobotany is rarely applied in Australian archaeology due to a lack of application of appropriate field techniques, limited reference collections, and the poor preservation of organic remains. This research, which is part of the ARC Linkage Project: Lifeways of the First Australians, investigates human-environment interaction using archaeobotanical techniques at two sites in the Kimberley region of northern Western Australia: Riwi and Mount Behn rockshelter, during the late Quaternary. Located on the edge of the Great Sandy Desert in Gooniyandi country, Riwi has a discontinuous occupation sequence of about 45 ka, while Mount Behn rockshelter, located some 180 km northwest of Riwi in Bunuba country, has an occupation sequence of ~3 ka. Anthracology (wood charcoal), palynology (pollen and spores), and wood identification using X-ray microtomography are used alongside other research from the Lifeways Project to reconstruct vegetation, investigate humanenvironment interaction, and explore the taphonomy and representativeness of the different proxy data sets. The findings from each site are then located within a regional narrative of human-environment interaction.

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Jorgensen, Diane Clare. "Quaternary stratigraphy, palaeowinds and palaeoenvironments of carbonate aeolianite on the Garden Island Ridge and in the Naturaliste-Leeuwin region, southwest Western Australia." Thesis, 2012. https://researchonline.jcu.edu.au/29036/1/29036_Jorgensen_2012_thesis.pdf.

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Deposition of carbonate aeolianite has long been constrained by research models based on the isolated carbonate platforms of Bermuda and the Bahamas; however, models for Quaternary carbonate aeolianites differ depending on the interplay of several key factors that reflect location-specific circumstances. Consequently, real steps forward in carbonate aeolianite research require that the depositional system profile (e.g. steeprimmed platform, ramps), source (e.g. sediment supply) and processes (e.g. transportation, deposition and preservation of sediment) be understood and the timing of aeolianite deposition be constrained. Accordingly, these parameters are targeted in this research of carbonate aeolianite in the distally steepened ramp-like setting of Western Australia. The research conducted here is focussed on the Tamala Limestone of Western Australia, which is known for the thickest intervals of Pleistocene carbonate aeolianite in Australia and the most extensive aeolianite deposit of this age in the world (Ward, 1975; Brooke, 2001). Quaternary deposits in Western Australia form a complex depositional system composed of carbonate aeolianite, protosols, palaeosols, calcretes and marine deposits formed during different glacioeustatic sea levels. Two regions within the Tamala Limestone are investigated in this research, the Garden Island Ridge within the Perth region and the Naturaliste-Leeuwin region of the Margaret River area. The laterally discontinuous nature of the dune packages and the lack of distinctive marker horizons make unravelling the sedimentary sequence of the aeolian deposits complicated. To improve understanding of carbonate aeolianite transportation, deposition and preservation and the impact of these processes on the depositional model, the strategy employed here involves interrogation of the dune packages set within a chronostratigraphic framework. The temporal framework for this study is acquired through the application of whole-rock amino acid racemisation (AAR) dating. The calibrated age estimates of dune formation on the Garden Island Ridge show that major episodes of dune formation are attributed to interglacial highstands Marine Isotope Stage (MIS) 5 and MIS1 – more specifically during MIS5e/5d, MIS5a and MIS1. The depositional system profile of the Rottnest Shelf and the AAR dates of aeolian samples indicate that the formation of dunes on the Garden Island Ridge were linked to stands of sea level higher than at least ii the present 40 m isobath. AAR dating refines the palaeo-sea level during the MIS1 dune depositional episode to a sea level higher than at least the 10 m isobath. The Pleistocene-Holocene succession on the Garden Island Ridge comprises four broad facies – dune accumulation deposits, palaeosols, calcretes and marine deposits – and records three successive depositional episodes (MIS5d/5e, MIS5a and MIS1) that are separated by hiatal intervals. The MIS5d/5e depositional episode consists of transgressive-phase carbonate aeolianites, a marine highstand unit (Rottnest Limestone Member) and regressive-phase carbonate aeolianites bounded on top by a calcrete horizon with deep solution pipes and a terra rossa palaeosol. The MIS5a depositional episode comprises mostly composite sets of regressive-phase carbonate aeolianites that are usually separated by erosional contacts and/or protosols. The long hiatial period in dune development between MIS5a and MIS1 is marked by a discontinuous calcrete marker horizon and a discontinuous black palaeosol. The youngest depositional episode of MIS1 includes transgressive-phase aeolianites, marine limestones (Hershcell Limestone Member) and other unconsolidated deposits (i.e. swamp and beach sand deposits). The carbonate aeolianites of these depositional episodes exhibit a similar mix of skeletal and shell grains of Bryozoa, foraminifera, coralline algae, Mollusca, corals and echinoderms with a minor proportion of quartz grains. The approach taken in evaluating the stratigraphy and its palaeoenvironmental implications for the Tamala Limestone on the Garden Island Ridge in the Perth Basin was extended to the Tamala Limestone within the Naturaliste-Leeuwin region. The sedimentary succession at Whitecliff was deposited from frequent and short periods of carbonate dune sand accumulation and soil development. At Shelly Beach, a large, single set of aeolian cross-strata was deposited upon a red palaeosol and conglomeratic limestone that is most probably emplaced during MIS11 and is comparable to the Cowaramup Conglomerate. The calibrated AAR age estimates of dune formation at Whitecliff and Shelly Beach in the Naturaliste-Leeuwin region show that episodes of dune formation are attributed to the overall regressive phase of MIS5 at Whitecliff and phases during MIS8e, MIS9 or the regressive phase of MIS11 at Shelly Beach. The depositional system profile of the Naturaliste-Leeuwin shelf and the AAR dates of aeolian samples indicate that the formation of dunes was linked to stands of sea levels higher than the present 30 m isobath. The carbonate aeolianites in both regions are characterised by moderately sorted, medium sand with grainsize distributions that are finely skewed and mesokurtic, much like modern carbonate dune sediment in other world locations. The carbonate aeolianites display sedimentological characteristics that are consistent with an origin by aeolian transportation sourced from a marine environment and provide a detailed insight into sediment supply, transportation and deposition of sediment and its subsequent preservation. The carbonate aeolianites were sourced from the upwind beach environment, which was continually refreshed by sediment from the adjoining shallow marine shelf. The dominant source of sediment to the carbonate aeolianites was an enduring, highly productive, Foramol subtropical-temperate carbonate province on the Rottnest and Naturaliste shelves that was sensitive to the relative strength and position of the warm Leeuwin Current. The insoluble fraction of the carbonate aeolianite is dominated by terrigenous particles attributed to the fluvial discharge of nearby rivers and was not derived from dust from the mainland carried by offshore winds. Partial cementation of aeolianites occurred under freshwater or mixed vadose conditions, as indicated by the dominance of pendant meniscus, grain contact meniscus and partially rimmed cements. The foreset dips of large- and very-large scale tabular crossbeds and sedimentological analysis show that carbonate dune formation and migration occurred from persistent "fresh" winds (>9 m/s) and record the influence of the westerly wind belt of the Ferrel cell. However, on the Garden Island Ridge, dune formation and migration also records the influence of the southeast trade wind belt of the Hadley cell during MIS5e. The movement of the Hadley cell over the Garden Island Ridge is consistent with that expected to accompany the change from a glacial to an interglacial climate at the interglacial highstand of MIS5e. The Quaternary deposits in the distally steepened ramp-like morphologies of the Perth Basin show that the depositional model is controlled by a very sensitive relationship between climate, depositional system profile and pattern of sea-level change. The amount and composition of the sediment available for aeolian deposition is ultimately controlled by sea level – when the regions were adjacent to a shallow sea, 10-30/40 m deep that formed a highly productive Foramol subtropical to temperate carbonate province. However, the size and location of the aeolian accumulations are influenced by palaeoclimate, the depositional system profile and in the Leeuwin Region by the topography of the Leeuwin Block. The very sensitive relationship between climate, depositional system profile and the pattern of sea-level change controlled sediment production, mobilization, deposition and preservation.

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49

Baboolal, Deeva Lata. "A 40,000-year record of vegetation and fire history from the Tate Vondo region, Northeastern Southpansberg, South Africa." Thesis, 2014. http://hdl.handle.net/10413/10992.

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Abstract:

Records from the Quaternary period are used to confirm possible inferred climatic changes, reveal the responses of species to these changes, and serve as an archive against which modern environmental dynamics can be assessed. Fueled by a need to understand current climatic changes, the call for palaeoclimatic research in the southern African subregion has become more compelling. In southern Africa, such research has been largely restricted to springs and swamps as the subregion lacks natural lakes, with some exception of a few coastal lakes such as Lake Sibaya and Lake Eteza. Due to the arid and semi-arid landscapes which prevail in southern Africa, there is a paucity of suitable sedimentary deposits in the region. The highly organic peat deposit of Mutale Wetland, situated in the Tate Vondo region of the northeastern Soutpansberg presents an ideal opportunity for conducting palaeoenvironmental research. The Mutale Wetland contains relatively old sediments dating back to >30,000 cal years BP, placing this record within the late Quaternary period. Palaeoenvironmental techniques including radiocarbon, pollen and charcoal analyses were applied to produce a palaeoenvironmental reconstruction for Tate Vondo. A 302 cm sedimentary core was extracted from the Mutale Wetland. Detailed analyses show that prior to ca. 34,000 cal yr BP, conditions were fairly warm and dry. This is inferred from a dominance of open grassland vegetation. An expansion of Podocarpus forests together with an increase in fynbos elements suggest a shift to cool, subhumid conditions during the LGM. Cooler conditions persisted until ca. 12,000 cal yr BP. Thereafter, a climatic amelioration was experienced. The appearance of low charcoal concentrations throughout the late Pleistocene suggests that fire was infrequent. Between ca. 4000 – 1500 cal yr BP, conditions became warmer and drier, inferred from the development of arid savanna vegetation. The sharp increase in charcoal after ca. 4000 cal yr BP, broadly coinciding with the arrival of the first agriculturalists in the area, has implications for the history of human occupation in the Soutpansberg rather than shifts in climate. The succession from savanna to fynbos vegetation together with expanded forests implies a return to cool and moist conditions from ca. 1500 – 400 cal yr BP. Arid savanna persists from ca. 400 to the present, implying warmer and drier conditions towards the present day. Furthermore, from ca. 400 cal yr BP, the pollen and charcoal record indicate that the majority of recent changes in vegetation have been driven by anthropogenic activity. This record has contributed to an improved understanding of late Quaternary changes in climate, vegetation history and human impact in the northeastern Soutpansberg.
Thesis (M.Sc.)-University of KwaZulu-Natal, Durban, 2014.

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50

Hsiao, Hsien-Ming, and 蕭憲明. "Prediction of the Metallic Glass Formation Regions for the Ag-Al-Cu-Zr Quaternary System by the Calculation of Phase Diagram (CALPHAD) Method." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/20197289621567324183.

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Abstract:

博士
國立臺灣科技大學
材料科學與工程系
103
Bulk metallic glasses (BMGs) have excellent potentials for various applications due to their excellent mechanical properties. But the fundamental investigations of metallic glasses are scarce in Taiwan, most of which are focusing on mechanical tests. The determination of metallic glass formation region was not studied ever. Therefore, the main purpose of this study focuses on the prediction of formation of metallic glasses by means of thermodynamic calculation, which is commonly used in the CALPHAD field. First of all, it is necessary to establish a reasonably correct thermodynamic dataset, which is consistant with experimental reusutls, such as phase equilibria, enthalpy of formation or activities of liquid or solid. Then the related metastable phase diagrams of binary or ternary systems could be introduced and drawn to predict formation of metallic glasses regions. The Cu-based alloys are inexpersive, and Zr- and Cu-based alloys have promising ability to form amorphous metallic glasses due to their wide range of the supercooled liquid region. Those alloys are favorable for application in industries. In this study, the Ag-Al-Cu-Zr quaternary and subternary systems are investigated thermodynamically to determine the formation of metallic glasses regions. Furthermore, once formation compositions of metallic glasses were predicted correctly, only few alloy samples were needed to be verified experimentally. Thus the expense and time of metallic glasses research woul be largly eliminated. Also the application of metallic glasses would be promoted and accepted in industries.

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