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A total of 5065 specimens (5018 valves of bivalve and 47 gastropod shells) have been identified and classified into 27 species from 55 samples collected from raised glaciomarine and estuarine sediments, and glacial tills. The bivalves <i>Hiatella arctica</i>, <i>Mya truncate</i>, <i>Astarte borealis</i>, and <i>Serripes groenlandicus</i> are the most common species. Our samples record the dominance of infaunal suspension-feeders that are most abundant on soft substrates typically occurring in nearshore environments. The dominance of bivalves with respect to gastropods reflects an averaged record of the fossil assemblages inhabiting the high latitude nearshore environments. Six unique associations, which are comparable to the composition of modern communities inhabiting in fiords and on continental shelf from Canadian high arctic, and three distinctive taxa groups (deposit feeders, suspension-feeders, and rare taxa) are recognized by cluster analysis and Multidimensional Scaling conducted on presence-absence data. The trophic composition of paleocommunities in this study is as follows: suspension-feeders > deposit feeders > carnivores > browsers. The occurrence of <i>Mya pseudoarenaria</i> in fossil assemblages indicates an age of the fossils around early Holocene. <p>Most of the samples are not substantially transported nor significantly reworked. Shell disarticulation and fragmentation can result from sea ice scouring of the seafloor and the development of permafrost in raised marine sediments. The degree of shell disarticulation for the four most common taxa is generally low which likely reflects high sedimentation rates and rapid burial in nearshore environments, especially those from glaciomarine silts and estuarine deposits. Four common species exhibit different preservation potential based the degree of fragmentation and disarticulation (Serripes < Mya < Hiatella < Astarte). Shells with high (or low) degree of fragmentation for single species (i.e. Hiatella) also correspond to different energy conditions of the associated sediments facies from which the shells are recovered. The general absence of strongly bioeroded or encrusted shells among samples suggests rapid burial of the shells with only limited exposure on the sediment surface, or the absence of grazing, boring or encrusting taxa in the environment that is dominated by infaunal habit of most of the taxa represented in the shell assemblages. <p>Four taphofacies are recognized by cluster analysis on the basis of four taphonomic variables (fragmentation, corrasion, bioerosion, and encrustation) characterized by poor preservation, fair preservation, fair-good preservation, and fair preservation with poor corrasion respectively. Faunal succession and paleo-marine environments during the deglaciation in early Holocene are reconstructed from the seven sedimentation facies (glacial, beaches, shallow marine, proglacial, shallow marine or estuarine - pebbly sand and gravel with algal debris, shallow marine or estuarine - pebbly silt with algal debris, shallow marine or estuarine - interbedded silt and sand).

A total of 5065 specimens (5018 valves of bivalve and 47 gastropod shells) have been identified and classified into 27 species from 55 samples collected from raised glaciomarine and estuarine sediments, and glacial tills. The bivalves <i>Hiatella arctica</i>, <i>Mya truncate</i>, <i>Astarte borealis</i>, and <i>Serripes groenlandicus</i> are the most common species. Our samples record the dominance of infaunal suspension-feeders that are most abundant on soft substrates typically occurring in nearshore environments. The dominance of bivalves with respect to gastropods reflects an averaged record of the fossil assemblages inhabiting the high latitude nearshore environments. Six unique associations, which are comparable to the composition of modern communities inhabiting in fiords and on continental shelf from Canadian high arctic, and three distinctive taxa groups (deposit feeders, suspension-feeders, and rare taxa) are recognized by cluster analysis and Multidimensional Scaling conducted on presence-absence data. The trophic composition of paleocommunities in this study is as follows: suspension-feeders > deposit feeders > carnivores > browsers. The occurrence of <i>Mya pseudoarenaria</i> in fossil assemblages indicates an age of the fossils around early Holocene. <p>Most of the samples are not substantially transported nor significantly reworked. Shell disarticulation and fragmentation can result from sea ice scouring of the seafloor and the development of permafrost in raised marine sediments. The degree of shell disarticulation for the four most common taxa is generally low which likely reflects high sedimentation rates and rapid burial in nearshore environments, especially those from glaciomarine silts and estuarine deposits. Four common species exhibit different preservation potential based the degree of fragmentation and disarticulation (Serripes < Mya < Hiatella < Astarte). Shells with high (or low) degree of fragmentation for single species (i.e. Hiatella) also correspond to different energy conditions of the associated sediments facies from which the shells are recovered. The general absence of strongly bioeroded or encrusted shells among samples suggests rapid burial of the shells with only limited exposure on the sediment surface, or the absence of grazing, boring or encrusting taxa in the environment that is dominated by infaunal habit of most of the taxa represented in the shell assemblages. <p>Four taphofacies are recognized by cluster analysis on the basis of four taphonomic variables (fragmentation, corrasion, bioerosion, and encrustation) characterized by poor preservation, fair preservation, fair-good preservation, and fair preservation with poor corrasion respectively. Faunal succession and paleo-marine environments during the deglaciation in early Holocene are reconstructed from the seven sedimentation facies (glacial, beaches, shallow marine, proglacial, shallow marine or estuarine - pebbly sand and gravel with algal debris, shallow marine or estuarine - pebbly silt with algal debris, shallow marine or estuarine - interbedded silt and sand).

North of Grand Rapids, Manitoba, new exposures of a carbonate succession prompted study of the lithology and paleontology of the uppermost Ordovician along the northern edge of the Williston Basin in Manitoba. Modern concepts and approaches were applied in examining the sedimentary rocks and fossils, including X-ray diffraction, stable carbon and oxygen isotope analysis, and statistical algorithms. Nine lithofacies, representing a series of shallowing events, and environmentally significant subaerial exposure surfaces, were identified. The distribution and relative abundance of identified fossils were used to delineate faunal associations, which were examined in the context of the impending end-Ordovician mass extinction. Historically, the stratigraphy of the latest Ordovician has been problematic. Therefore, detailed examination of this succession aided in clarifying unit boundaries in the Stony Mountain and Stonewall formations. Study of this new succession contributed a wealth of information to the understanding of the uppermost Ordovician of Manitoba.

North of Grand Rapids, Manitoba, new exposures of a carbonate succession prompted study of the lithology and paleontology of the uppermost Ordovician along the northern edge of the Williston Basin in Manitoba. Modern concepts and approaches were applied in examining the sedimentary rocks and fossils, including X-ray diffraction, stable carbon and oxygen isotope analysis, and statistical algorithms. Nine lithofacies, representing a series of shallowing events, and environmentally significant subaerial exposure surfaces, were identified. The distribution and relative abundance of identified fossils were used to delineate faunal associations, which were examined in the context of the impending end-Ordovician mass extinction. Historically, the stratigraphy of the latest Ordovician has been problematic. Therefore, detailed examination of this succession aided in clarifying unit boundaries in the Stony Mountain and Stonewall formations. Study of this new succession contributed a wealth of information to the understanding of the uppermost Ordovician of Manitoba.

The early Pliocene age Gray Fossil Site (GFS) was relatively recently found, with much still to be discovered and examined, and represents one of only a few sites of its age in eastern North America. It has been noted that the diverse faunal remains found at GFS are unique compared to what have been found at other fossil sites in North America from the same time period. Studying mammalian community structures at fossil sites can provide an abundance of information about the past environment and species adaptations to it, such as niche occupation of species, resource partitioning, and interactions between organisms and their environment. The main questions being asked in this study are: 1) what is the mammal community structure like at GFS?, and 2) how does the community structure at GFS compare to other contemporaneous sites? While studies of the fauna and flora have helped us to understand the ecosystem at GFS, detailed study of the mammal community will help us better understand this unique site. It is expected that the community structure and niche occupation of the mammals at GFS will be different from other contemporaneous sites, dominated by mammals adapted for life in the warm oak, hickory forest present at the site. A taxon-free approach to analysis will be used so that environments not sharing the same taxa or of different ages can be compared to one another. Each mammal species from GFS (48 total) and five well-known contemporaneous sites are categorized by body size, locomotor mode, and dietary preference to characterize the niches occupied by each species. Categorizations for each species will come from published works and measurements / ecomorphological analysis of specimens. Preliminary results show that GFS is different from other sites in that there are more brachyodont and tree dwelling/climbing adapted species present, and there are fewer running species present. The initial findings are likely associated with the site being a closed, forested ecosystem, compared to the more open environments of the other sites. Moving forward, descriptions pertaining to specifically how GFS and its mammal community structure compare to the niche occupation of similar species at other sites will be discussed. This project will also examine what more this analysis can reveal about the ecosystem at GFS, particularly how the herbivorous mammals can provide greater insight into what environmental conditions were like, including what vegetation was predominant at GFS.

The early Pliocene age Gray Fossil Site (GFS) is a fossil site that preserves diverse fauna and flora and represents one of only a few sites of its age in eastern North America. The assemblage of fauna found at GFS is unique compared to what has been found at other contemporaneous fossil sites across the continent. While studies of the fauna and flora have helped us to understand the ecosystem at GFS, detailed study of the diverse mammal community will help us better understand this unique site. Studying mammalian community structures at fossil sites can provide an abundance of information about the past such as, ecological inferences and climate conditions. To understand the paleoenvironment at GFS, I have gathered data from twenty modern communities and five well-known contemporaneous sites. Mammal species from each of these 26 sites have been categorized by body size, locomotor mode, and cheek tooth crown height to characterize the niches occupied by each species. Proportions of species within categories have been compared and analyzed across modern and fossil sites using discriminant function analysis (DFA). Results of the DFA demonstrate that modern communities with different climates and habitats can be distinguished based on the body size, locomotion, and cheek tooth crown heights of mammals living there. Moreover, functions can be used to infer conditions of past sites. Species diversity within categories was also compared across all sites. Results show that GFS has more brachydont and scansorial species present, and fewer cursorial species than occur at other contemporaneous sites. The results of the discriminant functional analysis indicate that the GFS community structure is most similar to modern temperate forest regions of the Himalayan Mountains in China and modern Washington Co., TN. Proportions of brachydont, gliding, and scansorial species appear to be driving variables behind these results.

Η παρούσα εργασία εκπονήθηκε στο πλαίσιο του Διατμηματικού Προγράμματος Μεταπτυχιακών Σπουδών στις Περιβαλλοντικές Επιστήμες. Το θέμα της είναι η Παλαιοπεριβαλλοντική Εξέλιξη στον Αμβρακικό Κόλπο. Σκοπός της εργασίας είναι η διερεύνηση των περιβαλλοντικών συνθηκών που επικρατούσαν στην περιοχή του Αμβρακικού κόλπου στο βάθος των χρόνων. Αυτό πραγματοποιήθηκε μέσω της μελέτης σε ιζήματα που συλλέχθηκαν από το ανατολικό τμήμα του κόλπου και στα οποία πραγματοποιήθηκαν κοκκομετρικές και γεωχημικές αναλύσεις. Η εργασία αποτελείται από 6 κεφάλαια. Στο πρώτο κεφάλαιο, την εισαγωγή, αναφέρονται κάποια γενικά στοιχεία για τις παλαιοπεριβαλλοντικές έρευνες σε θαλάσσια και λιμναία περιβάλλοντα και για τις κλιματικές αλλαγές και τις αιτίες δημιουργίας τους. Στη συνέχεια αναφέρονται κάποια γενικά στοιχεία για τους παλαιοπεριβαλλοντικούς δείκτες αλλά και πιο συγκεκριμένα για αυτούς που χρησιμοποιήθηκαν στο πλαίσιο της παρούσας εργασίας. Τέλος αναφέρονται κάποια στοιχεία για το περιβάλλον των ημίκλειστων λεκανών, όπως αυτό του Αμβρακικού κόλπου, και στο τέλος του κεφαλαίου αναλύεται ο σκοπός της εργασίας. Το δεύτερο κεφάλαιο περιέχει κάποιες γενικές πληροφορίες για τον Αμβρακικό κόλπο. Συγκεκριμένα αναφέρονται στοιχεία για τη θέση του κόλπου, για τη μορφολογία των ακτών του, για τους ποταμούς που τον τροφοδοτούν και κάποια χαρακτηριστικά για την υδάτινη στήλη και τα ιζήματα από τα οποία αποτελείται ο πυθμένας του. Τέλος γίνεται αναφορά στη γεωλογία και την τεκτονική της ευρύτερης του Αμβρακικού κόλπου περιοχής. Στο τρίτο κεφάλαιο βρίσκεται η μεθοδολογία η οποία χρησιμοποιήθηκε κατά τη διάρκεια της μελέτης. Αρχικά αναφέρονται και αναλύονται οι εργασίες πεδίου, δηλαδή η πυρηνοληψία και ο τρόπος με τον οποίο έγινε. Στη συνέχεια παρουσιάζονται οι εργαστηριακές αναλύσεις οι οποίες είναι η μακροσκοπική περιγραφή του πυρήνα, οι κοκκομετρικές αναλύσεις, η φθορισμομετρία και η πολυδιάστατη στατιστική ανάλυση. Όσον αφορά στις κοκκομετρικές αναλύσεις και τη φθορισμομετρία γίνεται λεπτομερής ανάλυση τόσο του τρόπου με τον οποίο έγιναν όσο και των οργάνων που χρησιμοποιήθηκαν. Στο τέταρτο κεφάλαιο γίνεται η παρουσίαση των αποτελεσμάτων από όλες τις αναλύσεις που παρουσιάστηκαν στο κεφάλαιο της μεθοδολογίας. Στη συνέχεια ακολουθεί το πέμπτο κεφάλαιο στο οποίο βρίσκονται τα συμπεράσματα και τα κύρια ευρήματα που προέκυψαν από την έρευνα. Η εργασία ολοκληρώνεται με το έκτο κεφάλαιο στο οποίο παρατίθεται η βιβλιογραφία η οποία χρησιμοποιήθηκε. / This work was under the Interdepartmental Post-Graduate Program in Environmental Sciences. The thesis is the Palaioenvironmental Evolution Amvrakikos Gulf. The purpose of this study is to investigate the environmental conditions prevailing in the area of Amvrakikos Gulf in the background of years. This was done by studying sediments collected from the eastern part of the bay. The study consists of six chapters. The first chapter, the introduction, includes some general information on paleoenvironmental research in marine and lacustrine environments and climate changes and their causes creation. Mentioned below are some general elements for paleoenvironmental indicators and more specifically to those used in the present work. Finally some comments on the environment of semi-enclosed basins such as the Amvrakikos Gulf, and at the end of the chapter is the purpose of the work. The second section contains some general information about the Amvrakikos Gulf. Specific details refer to the position of the gulf, on the morphology of the coast, the rivers that feed the gulf, the water column and the sediments that make up the bottom of the gulf. Finally reference is made to the geology and tectonics of the wider Amvrakikos gulf region. In the third chapter is the methodology that was used during the study. Fisrt the field work is listed and analyzed, ie the coring and the way that it was made. Then presented laboratory analyzes which are the macroscopic description of the core, the grain size analysis, the X-ray fluorescence and the multidimensional statistical analysis. In the fourth section are presented the results of all the analyzes that were presented in the chapter of the methodology. Then follows the fifth chapter in which are the conclusions and key findings that emerged from the research. The work concludes with the sixth chapter which presents the literature being used.

The middle Miocene thermal maximum (~16 Ma) was a period of global climate unusually warm and wet for the Neogene and is of interest as a paleo-analog for future climate change from anthropogenic global warming. In Australia, paleosols of the Oligocene-Miocene Etadunna and Pliocene Tirari Formations formed in arid palaeoclimates and include pedogenic gypsum. The Middle Miocene paleosol has shallow calcareous nodules and stout root traces suggesting vegetation like dry woodland. Comparable mallee vegetation now grows no closer than 1200 km to the southwest, so middle Miocene warm-wet climate enabled range extension of mallee and woody thickening of plants in the Australia outback. There is no evidence in the outback of middle Miocene rain forest, which may have expanded its range to form kaolinitic Ultisols near Sydney, Mudgee, and Gulgong, in New South Wales. Nor is there evidence so far inland of swamp woodlands and heaths like those producing brown coals in the Latrobe Valley, Victoria. In Argentina, the Santa Cruz Formation, in addition to its rich fossil vertebrate assemblages, contains a similar paleosol record of middle Miocene climate change. The early Miocene in the Santa Cruz Formation is characterized by a thick sequence of weakly to strongly developed grassland paleosols (Orthents and Ustolls) as well as paleosols with root traces and profile forms of open shrubland vegetation (Cambid). The middle Miocene thermal maximum is characterized by paleosols (Udepts, Udalfs) developed under open woodland-shrubland vegetation, during a period of climatic warmth and humidity. The late middle Miocene is characterized by a greater diversity of pedotypes, all suggestive of an arid and cooler environment (Argids, Cambids, and Ustepts). Middle Miocene soil maps compiled for this study show extension of tropical soils (Oxisols, Ultisols) into northern and southern mid-latitudes, accompanied by thermophilic flora and fauna. Peats, lignites, and Histosols of wetlands are also more abundant at higher latitudes, especially in the northern hemisphere, during the middle Miocene. The expansion of such soils is an expected result of greater precipitation associated with higher water vapor content of a warmer atmosphere during the Middle Miocene. This dissertation includes previously published co-authored material in chapter II.

Elemental proxy models for temperature and seawater chemistry begin by assuming compositional signatures reflect environmental conditions of formation. The Mg/Ca ratio in marine cements and calcified skeletal structures is a widely used proxy for reconstructing past earth environments. Many studies have positively correlated Mg content in biogenic carbonates with temperature, but it is difficult to differentiate the effect of temperature from other environmental factors. Supersaturation, precipitation rate, salinity, pH, and ion concentration have also been proposed as drivers of Mg/Ca. Furthermore, it is difficult to distinguish environmental signatures from the “vital effect,” or the influences superimposed by the growth needs and metabolic activities of the organism. To construct viable paleoenvironmental proxies from biomineral compositions, we must resolve the effects of environmental conditions from the vital effects of the organism by first understanding the underlying thermodynamic and kinetic mechanisms for incorporating minor and trace elements. Using in situ Atomic Force Microscopy, controlled solution chemistries, and different ion microprobe techniques, this dissertation investigates the kinetics and thermodynamics of calcite growth to establish an inorganic baseline for uptake of Mg. I use this information to quantify the enhancement in Mg/Ca due to the presence of hydrophilic 27-mer peptides, demonstrating a possible origin of vital effects. Likewise I measure the effect of ionic strength on signatures and find that growth rate and background electrolyte proved more important than salinity in determining Mg contents. The findings contribute to the ongoing discussion regarding the relative importance of unique seawater parameters in determining Mg/Ca in calcite. Mg contents are significantly enhanced by biomolecules relative to the amounts attributed to temperature differences, while Mg content is less influenced by salinity variation than by changing supersaturation or driving force. In addition to sorting out the relative importance of environmental factors, our results begin to address the interplay of these different parameters in concert, and at different scales. At sites of calcification, the local biochemistry within an organism may shift in response to more saline waters. At a geological scale, interpreting past temperatures and particularly those of the Last Glacial Maximum depends on our ability to sort out and account for this interplay of salinity and temperature on Mg/Ca. Processes underlying inorganic and biogenic carbonate mineralization and interpretations of their formation environments are better understood by examining the influence of environmental parameters and biomolecular chemistry on kinetics and thermodynamics of calcite growth and stability. / Ph. D.