The Lake Heron basin is an intermontane basin located approximately 30 kms west of Mount Hutt. Sediments within the basin are derived from a glacier that passed through the Lake Stream Valley from the upper Rakaia Valley. The lack of major drainage in the south part of the basin has increased the preservation potential of glacial phenomena. The area provides opportunities for detailed glacial geomorphology, sedimentology and micropaleontogical work, from which a very high-resolution study on climate change spanning the Last Glacial Maximum (LGM) through to the present was able to be reconstructed. The geomorphology reveals a complex glacial history spanning multiple glaciations. The Pyramid and Dogs Hill Advance are undated but possibly relate to the Waimaungan and Waimean glaciations. The Emily Formation (EM), previously thought to be MIS 4 (Mabin, 1984), was dated using Be10 to c. 25 ka B.P. The EM was largest advance of the Last Glacial Maximum (LGM). Ice during the LGM was at least 150m thicker than previously thought, as indicated by relatively young ages of high elevation moraines. Numerous moraine ridges and kame terraces show a continuous recession from LGM limits, and, supported by decreasing Be10 ages for other LGM moraines, it seems ice retreat was punctuated by minor glacial readvances and still-stands. These may be associated with decadal-scale climate variations, such as the PDO or early ENSO-like systems. There are relatively little sedimentological exposures in the area other than those on the shores of Lake Heron. The sediment at this location demonstrates the nature of glacial and paraglacial sedimentation during the later stages of ice retreat. They show that ice fronts oscillated across several hundred metres before retreating into Lake Heron proper. Vegetation change at Staces Tarn (1200m asl) indicates climate amelioration in the early Holocene. The late glacial vegetation cover of herb and small shrubs was replaced by a low, montane forest about 7,000 yrs B.P, approximately at the time of the regional thermal maxima. From 7,000 and 1,400 yrs B.P, temperatures slowly declined, and grasses slowly moved back onto the site, although the montane forest was still the dominant vegetation. Fires were frequent in the area extending back at least 6,000 years B.P. The largest fire, about 5,300 yrs B.P, caused major forest disruption. But full recovered occurred within about 500 years. Beech forest appears at the site about 3,300 yrs B.P and becomes the dominant forest cover about 1,400 yrs B.P. Cooler, cloudier winters and disturbance by fire promoted the expansion of beech forest at the expense of the previous low, montane forest. Both the increased frequency of fire events and late Holocene beech spread may be linked to ENSO-related variations in rainfall. The youngest zone is characterised by both a dramatic decline in beech forest and an increase in grasses, possibly representing human activity in the area.

Thesis (M.S.)--Oregon State University, 2004. / Includes maps in pocket. Typescript (photocopy). Includes bibliographical references (leaves 306-314). Also available online.

Thesis (Ph. D.)--University of Texas at Austin, 2004. / Supervisor: William L. Fisher. Vita. Includes bibliographical references.

No description available.

Στην εργασία επιδιώκεται η ποιοτική και ποσοτική ανάλυση των ιζημάτων της βόρειας περιοχής του άνω ρου του Βοιωτικού Κηφισού ποταμού, από δειγματοληψία που προέκυψε σε μια στρωματογραφική τομή παρακείμενη του οικισμού Μπράλος του νομού Φθοιώτιδας. Σκοπός της έρευνας αυτής είναι ο προσδιορισμός των περιβαλλόντων ιζηματογένεσης στην ευρύτερη περιοχή που απαντά η μελετηθείσα τομή. / -

No description available.

The reconstruction of marine-based paleo ice sheet dynamics can reveal long-term ice sheet activity, and in turn provide constraints on the response of modern marine ice sheets (e.g. the West Antarctica Ice Sheet) to climate change. The marine-terminating Hebrides Ice Stream (HIS) flowed across the western Scottish shelf during the last glacial maximum (3024 ka) and drained a large portion of the northern sector of the British Irish-Ice Sheet (BIIS), affecting its stability. This thesis aims to examine how the HIS evolved and interacted with the changing climate and the underlying landscape after 27 ka. The work is subdivided into: a) an investigation of modern high-resolution bathymetry data coupled with seismic data with the aim of reconstructing deglacial dynamics; b) the analysis of Pb isotopic composition in sediment cores on the shelf in order to locate glacial sediment provenance; c) a study of Hebrides shelf core sedimentology and microfaunal assemblage to reconstruct Lateglacial paleoenvironmental changes. A three-stage deglacial pattern, where topography played a critical role, is defined: i) ice stream margin retreat punctuated by standstills, ii) topography-controlled fjordic retreat, with evolution from a coherent ice-sheet to separate fjord tidewater glaciers, and iii) a stabilisation at the transition from tidewater to land-based ice margins. Between 21 and 15 ka, fine-grained sediments transported by meltwater plumes were the product of erosion of Neoproterozoic basement, while the coarse-grained sediments were instead sourced from island igneous rocks. These results indicate prevailing sediment input from NW Scotland. Lateglacial sediment deposition was strongly influenced by shelf currents and shows wide variation. Therefore, the seismic and sedimentological interpretations need to be considered only on a local scale. Glacimarine sandy deposits in the Muck Deep region support a prolonged glacial occupancy until the latest stages of GS-1 (12.8-11.7 ka), and are at odds with recent studies indicating earlier glacial retreat. The thesis demonstrates the complex interactions between BIIS evolution, subglacial landscape and ocean dynamics. The outcome of this research can be useful to inform future numerical reconstructions.

The Msikaba Formation is a Late Devonian fluvial and marine succession which outcrops from Hibberdene to Port Edward along the south coast of KwaZulu-Natal Province, South Africa. The Formation is composed of brownish conglomerate at the bottom and white-greyish quartz arenite sequence in the middle and mixed quartz-arenite with feldspathic sandstone in the upper sequence. Previous studies put more emphasis on the correlation of Msikaba Formation with the Natal Group and Cape Supergroup, whereas this study revised the stratigraphy, and also put new insight on the petrography, sedimentary facies, depositional environments and diagenesis of the Formation. The total stratigraphic section attains a thickness of 184 m at Margate area and 186 m at Port Edward area. The stratigraphy of Msikaba Formation is well exposed on the outcrops along the KwaZulu-Natal coastline. The stratigraphy is subdivided into 4 new members along Margate to Shelly beach section; namely Manaba Member, Uvongo Member, Mhlangeni Member and Shelly Beach Member from bottom upward. Twelve sedimentary facies were identified and the sedimentary facies were integrated into 4 facies association: Facies association 1 (Gmm+Sm) represents braided fluvial deposits, Facies association 2 (Gcm+St+Sp+Sl+Shb) represents tidal channel and tidal flat deposit, Facies association 3 (St+Sp+Sr+Sl) is result of shallow marine deposit and Facies association 4 (Sp+Sl+St+Sm) is a mixed marine and fluvial deposit. Each facies association represents a specific stratigraphic unit and were deposited in a specific sedimentary environment. Grain size analysis was conducted on seventeen thin sections and 500 grains were counted from each thin section. The sandstone grain size parameters of mean, sorting, skewness and kurtosis fell under the average of 0.75, 0.78, 0.4 and 1.2φ respectively. The results show that most of the grain size are coarse to medium grained throughout the study areas and sorting of the sandstones are moderate to poorly sorted. The cumulative frequency diagrams and bivariate plots show positive skewness and negative kurtosis, which indicate a high hydrodynamic environment. Modal composition analysis and petrography studies show that detrital components of the Msikaba Formation are dominated by monocrystalline quartz, feldspar (mostly K-feldspar) and lithic fragments of igneous and metamorphic rocks. The sandstones could be classified as quartz arenite, sub-arkosic sandstone and feldspathic litharenite; and the provenance analysis indicates that the sandstones were derived from craton interior, recycled or quartzose recycled sources which may derived from weathering and erosion of igneous and metamorphic rocks. Diagenetic processes of the Msikaba Formation have been passed through early, mid- and late diagenetic stages. Cementation, mineral conversion and compaction affect early diagenetic stage; authigenic minerals, quartz and feldspar overgrowth are presented in mid-diagenetic stage, whereas recrystallization, replacement, deformation and dissolution have been strongly affected late diagenetic stage. Microscopy, XRD and SEM-EDX studies have identified five types of cements including smectite clay, kaolinite, hematite, quartz and feldspar cements. Quartz cement, pore-filling and pore-lining clay are the major type of cements in the Msikaba Formation. Based on the lithology, sedimentary structure and facies variations, the Manaba Member was most probably deposited in a braided fluvial environment, the Uvongo Member was deposited in a tidal channel environment, the Mhlangeni Member was formed in shallow marine storm-influenced environment, whereas the Shelly Beach Member was represented mixed marine and fluvial environment. The sequence stratigraphy of Msikaba Formation constitutes a transgressive sequence from Manaba Member to Uvongo Member, whereas it ended as a regressive sequence from Mhlangeni Member to Shelly beach Member. The Msikaba Formation shows major differences with the Natal Group and Table Mountain Group (Cape Supergroup) in the lithology, stratigraphic sequence, sedimentary structures, facies system, palaeocurrent styles, fossil contents and depositional environments, which demonstrate that they are not the equivalent stratigraphic unit. Therefore, the Msikaba Formation is a separate, younger stratigraphic unit, and cannot correlate with the Natal Group and Table Mountain Group as suggested by previous researchers.

Os sambaquis do litoral sul brasileiro são marcos paisagísticos, com valor histórico e científico. Constituem-se, predominantemente, de conchas de moluscos e sedimentos com marcante presença de matéria orgânica, empilhados em conformações estratigráficas variadas. Neste trabalho, elegeram-se como objetos de estudo três sambaquis da costa centro-sul de Santa Catarina, com dois tipos de conformações distintas: de um lado, os sambaquis Carniça III e Encantadas III, e, de outro, o Jabuticabeira II, maior e estratigraficamente mais complexo. A proposta é auxiliar na reconstrução dos hábitos e costumes dos povos que viveram nesta área litorânea durante grande parte do Holoceno pré-descobrimento, e inferir suas relações com a evolução do ambiente geológico que os cercava. Para isso, foca-se em duas metas ou objetivos maiores: a aplicação de análise de fácies e de arquitetura deposicional nos sambaquis selecionados; e a investigação do uso de sedimentos paleolagunares como seu material construtivo. Para buscar estes objetivos, utilizou-se uma abordagem multi-analítica, que compreendeu: análise de fácies; determinação dos teores de matéria orgânica e carbonatos mais fosfatos; caracterização da fração grossa por lupa; granulometria; mineralogia de grãos pesados; estudo petrográfico e micromorfológico em seção delgada; microscopia eletrônica de varredura; e geoquímica e isotopia de carbono e nitrogênio. A estratigrafia dos sambaquis Carniça III e Encantada III é composta por um núcleo arenoso sobreposto por camada preta orgânica rica em conchas e artefatos antrópicos (terra preta, codificada como fácies LA). Em contraste, o sambaqui Jabuticabeira II caracteriza-se pela intercalação entre camadas conchíferas e lâminas pretas contendo sepultamentos (fácies funerária, codificada como Lc), capeada por camada de terra preta, rica em artefatos e sepultamentos. Por meio da análise de fácies, foi possível distinguir neste sambaqui três associações, da base para o topo: cascalho-lamosa, areno-lamosa e cascalho-arenosa. A sucessão vertical destas associações reflete o assoreamento progressivo do sistema lagunar e configura assim a relação do sambaqui com o ambiente deposicional do entorno. As associações de fácies, de qualquer hierarquia, são delimitadas pelas lâminas da fácies Lc. As análises do material construtivo utilizado nos sambaquis indicaram proveniência a partir das feições deposicionais mais próximas aos sítios, representadas por fundo, margem e brejo lagunar, nos casos dos sambaquis Jabuticabeira II e Encantada III, e por cordões litorâneos lagunares e dunas eólicas superimpostas, no caso do sítio Carniça III. Os parâmetros granulométricos e os índices de minerais pesados revelaram controle sobretudo geográfico em sua distribuição. A análise de componentes fosfáticos aliados aos sinais isotópicos do carbono e nitrogênio indicam grande processamento antrópico no material constituinte das lâminas funerárias e da terra preta do sambaqui Jabuticabeira II, com características de matéria orgânica putrefata, provável refugo do processamento cotidiano dos sambaquieiros. Já para o Carniça III e Encantada III, este processamento teria sido muito menor. / The sambaquis (also known as shell mounds or shell middens) in the Brazilian southern coast are landscape references and bear historical and scientific value. They are predominantly constituted of mollusk shells and sediments and also hold a sound presence of organic matter, piled up in different stratigraphic configurations. In this work, three sambaquis in the central-southern coast of the Santa Catarina state have been chosen as objects of study. They present two distinct configuration types: on one hand, the Carniça III and the Encantadas III, and, on the other hand, the Jabuticabeira II, which is larger and stratigraphically more complex. The proposal is to assist on the reconstruction of habits and traditions of the people who lived in this coastal area during a great part of the Holocene period (before the Portuguese navigators arrived in Brazil in 1500), and to infer their relations with the evolution of the surrounding geological environment. Two main goals have been set for this purpose: the application of facies analysis and depositional architecture in the selected sambaquis; and the investigation of the use of sediments from paleo-lagoons as their construction material. In order to achieve these goals, a multi-analytical approach has been used comprising: facies analysis; quantity evaluation of organic matter and carbonates associated with phosphates; characterization of the thick fraction in stereomicroscope; granulometry; heavy grains mineralogy; petrographic and micromorphological study of the thin section; scanning electron microscopy (SEM); and both carbon and nitrogen geochemistry and isotopy. The stratigraphy of the Carniça III and Encantada III sambaquis is composed of a sandy nucleus covered with a black organic layer full of shells and anthropic artifacts (black soil, represented as LA facies). In contrast, the Jabuticabeira II sambaqui is characterized by an assorted sequence of shell layers and thin black layers containing burial remains (funerary facies, represented as Lc) covered by black soil, and full of artifacts and burials. According to the facies analysis results, three associations have been found in this sambaqui, from bottom to top: muddy-gravel, muddy-sand and sandy-gravel. The vertical sequence of these associations reflects the progressive aggradation of the lagoon system and it establishes, thus, the relation between the sambaqui and the surrounding depositional environment. The facies associations, in any hierarchy, are limited by the thin layers in the Lc facies. The analysis of the construction materials used in the sambaquis has set their provenance in the nearest depositional features to the sites, represented by the lagoon bottom, margin and swamp for the Jabuticabeira II and Encantada III sambaquis, and by coastal lagoon barriers and superimposed wind dunes for the Carniça III site. The granulometric parameters and the heavy minerals indexes have showed control, mainly geographic, in their distribution. The analysis of phosphate components associated with the carbon and nitrogen isotopic signals shows great anthropic processing in the material which constitutes the funerary and the black soil layers found in the Jabuticabeira II sambaqui, with putrid organic matter characteristics, a probable waste from the day-by-day processing of the people who built the sambaquis. On the contrary, this kind of processing is supposed to have been much lower in the Carniça III and the Encantada III sambaquis.

The Zerrissene turbidite system of central-western Namibia is a late Proterozoic sequence which consists of dominantly siliciclastic turbidites interbedded with minor turbiditic and hemipelagic marbles. The basin in which these sediments were deposited is located at the junction of the coastal and intra-cratonic arms of the Pan-African Damara Orogen, and an understanding of the sedimentary evolution of this basin is therefore important to the understanding of the development of the orogen as a whole. One major and two minor phases of folding have deformed the sediments, but the grade of metamorphism is low and sedimentary structures are often well preserved. Further, the area lies entirely within the Namib Desert and the lack of vegetation cover results in good outcrops providing an unusual opportunity for examining a large Precambrian turbidite system. The system consists of five formations: three siliciclastic and two mixed carbonatesiliciclastic units. The floor of the system is not exposed, and the oldest sedimentary rocks which outcrop are siliciclastics of the Zebrapiits Formation. This is overlain successively by the Brandberg West Formation (dominantly calcareous), the Brak River Formation (siliciclastic), the Gemsbok River Formation (calcareous) and the Amis River Formation (siliciclastic). Nine silicilastic turbidite facies have been recognised in the basin. These are facies A₂ (disorganised onglomerates), B₁ (horizontally laminated to massive greyackes), C₂ ("classical" turbidites), Dl (sandstone-shale couplets with base cut-out Bouma sequences), D₂ (sandstone-shale couplets with less sand than shale and base cut-out Bouma sequences), E (coarse, discontinuous sandstone-shale couplets), F (slumped units), G (shale) and H (glacial dropstones). Four facies are associated with the carbonate horizons, and these carbonate facies are given the suffix c to distinguish them from similar siliciclastic facies. These are facies Ac (disorganised and graded marble breccias), facies Cc (graded carbonates), facies Gc (hemi-pelagic marbles) and facies G (pelagic shales). The basal Zebrapiits Formation is made up of relatively thin packages of thin- to thickbedded, laterally continuous facies D₁, D₂ and B₁ beds encased in thick envelopes of shale. This type of sequence is typical of a distal lobe-fringe, and requires an unconfined basin-floor on which it can develop. The overlying Brandberg West Formation consists of a basal portion of interbedded facies Cc and G, followed by a sequence dominanted by facies Gc. This sequence is interpreted as representing outer-apron carbonate turbidites, derived from multiple point sources (facies Cc), with background pelagic settling (facies G) overlain by hemi-pelagic deposits (facies Gc). A reversal back to siliciclastic turbidites followed with deposition of the Brak River Formation. This sequence comprises relatively thick packages of laterally continuous facies B₁, D₁, and D₂ beds sandwiched between facies G shales, a succession characteristic of a lobe to lobe-fringe environment with intermittent abandonment of lobes. An unconfined basin floor adjacent to a passive margin is required for the development of this type of sequence. Glacial dropstones (facies H) are found in the upper portions of this formation, and slumped beds are also present (facies F), but are uncommon. The facies F beds are only found in association with facies H and are therefore considered to be genetically related. Slumping of beds was possibly caused by an oversupply of sediment from ice-rafting which caused instability. The overlying Gemsbok River Formation has a sequence similar to the Brandberg West Formation in that the basal portion consists of interbedded facies Cc and G, which is overlain by a thick sequence of largely facies Gc beds. Minor facies Ac beds occur near the top of the overall sequence. This formation is interpreted as an outer-apron succession with the facies Ac beds representing distal inner-apron deposits, indicating progradation of the system. The youngest unit in the basin, the Amis River Formation, shows strong lateral variation from west to east. In the west the sequence comprises laterally continuous facies B₁, C₂, D₁ and D₂ with rare, discontinuous facies E beds. Facies G is relatively minor in the sequence. In the east the succession is dominated by facies D₁, D₂ and G, and this succession is interpreted as a sequence of distal turbidites which were deposited on a basin-plain. The system developed by aggradation rather than progradation as only minor cycles are developed. Geochemical and petrological features indicate that the entire siliciclastic system was derived from a granite-recycled orogen terrane. Palaeocurrent data are unreliable because of the deformation, but transport was initially from the south-west, moving later to the west and north-west. The provenance of the carbonates is uncertain as reliable palaeocurrent indicators are rare, but they could have been derived either from South America or from the extensive carbonate deposits developed on the north-western margins of the basin. The Zenissene siliciclastic turbidite system represents the distal portion of a major submarine turbidite system, the more proximal parts of which now lie west of the exposed basin, either under the Atlantic Ocean or in eastern South America. The calcareous deposits developed as an apron adjacent to a multiple point source, the position of which is at present unknown.