Дисертації з теми "Glauconites"

Uma característica de destaque da Nhecolândia, uma sub-região do Pantanal Sul-Mato- Grossense, é a presença de lagoas doces (baías) e salgadas (salinas) com uma grande variabilidade química entre si. Apesar da presença de sal nas salinas ser historicamente atribuída a processos passados, estudos recentes sugerem que as águas salgadas estão sendo originadas atualmente devido à concentração por evaporação. O perfil químico das águas salinas estaria sendo originado principalmente pelo controle de elementos (Ca2+, Mg2+ e Si(OH)4) durante a concentração das águas, com o conseqüente envolvimento destes íons em dois processos: a formação de carbonatos e de silicatos magnesianos. Estudos preliminares em solos de salinas sugerem que a ocorrência de nódulos esbranquiçados e a presença de um horizonte enriquecido em argila podem evidenciar estes dois processos. Neste tipo de ambiente, carbonatos como calcita e dolomita são comumente neoformados, mas há divergências na literatura quanto ao mecanismo de origem autigênica dos silicatos magnesianos. Baseando-se no exposto acima, foram definidos os seguintes objetivos para a presente pesquisa: 1) ampliar o conhecimento sobre os solos associados às salinas através de uma caracterização baseada em dados de campo e laboratório dos solos presentes no entorno de uma lagoa salina representativa da Nhecolândia (lagoa do Meio); 2) identificar os processos envolvidos no controle do Ca2+, Mg2+ e Si(OH)4 nas águas salinas, através do estudo das relações entre as fases líquidas (águas superficiais e subsuperficiais) e sólidas (minerais) presentes nos solos do entorno da lagoa do Meio; e 3) identificar os mecanismos específicos de gênese dos minerais autigênicos possivelmente presentes nos solos do entorno da lagoa do Meio. As amostras de solo foram coletadas ao longo de uma topossequência nos arredores da lagoa do Meio e submetidas à análise granulométrica, análises químicas (ICP-MS, pH, CE, carbono total, carbonato de cálcio equivalente, bases trocáveis e testes de imersão em água, ácido e bases) e análises mineralógicas (DRX, MET-EDS). Amostras de água superficiais e subsuperficiais foram coletadas em um transecto que abarca a topossequência estudada e então encaminhadas às análises de pH, Eh, CE, temperatura, titulação com HCl, cromatografia de íons, EAA e ICP-MS. Os solos dos arredores da salina do Meio caracterizam-se pela textura areia a franco-arenosa, pela ausência de estrutura e, de maneira geral, por altos valores de pH, CE, CTC e saturação em Na+. O pH fortemente alcalino e o domínio de Na+ no complexo de troca desencadeiam a atuação do processo de solonização e dos seguintes processos específicos associados: migração de matéria orgânica perfil abaixo, precipitação de carbonatos (calcita, dolomita e nahcolita) em nódulos, solubilização/precipitação de sílica amorfa e formação autigênica de minerais de argila do grupo das esmectitas e micas. Diferentes esmectitas estão presentes ao longo da topossequência: a) na zona raramente atingida pelas variações sazonais do nível d\'água da salina, a esmectita é do tipo ferribeidelita, possui um grau de interestratificação com mica e vermiculita e apresenta teores de Fe3+ similares às micas identificadas no mesmo solo. Estas características sugerem que o mineral do tipo ferribeidelita é originado pela transformação de micas enriquecidas em Fe3+, sendo a vermiculita provavelmente uma fase intermediária nesta transformação; b) na zona de maior variação sazonal do nível d\'água da salina, as esmectitas são classificadas como do tipo saponita e estevensita. Os baixos teores de elementos terras-raras nas amostras enriquecidas nestes minerais, o controle do Mg2+ e do Si(OH)4 nas águas próximas à lagoa do Meio, a saturação das águas do entorno da lagoa em relação a saponita e estevensita e a presença destas esmectitas magnesianas nos locais onde são esperadas máximas taxas de evaporação, provam que estes minerais estão se originando por precipitação química diretamente da coluna d\'água da lagoa salina. Já as micas presentes nos solos estudados são do tipo ilita, glauconita e mica glauconítica, possuem interestratificação com camadas de esmectitas e parecem estar associadas a materiais amorfos. Experimentos de síntese disponíveis na literatura mostram que águas semelhantes às associadas à lagoa do Meio são ideais para a cristalização de micas a partir da precipitação inicial de hidróxidos amorfos. Desta forma, as evidências obtidas sugerem que estas micas são neoformadas a partir da precipitação inicial de amorfos e posterior cristalização. Os resultados obtidos certamente ampliaram o conhecimento sobre os solos presentes no entorno de lagoas salinas, uma vez os estudos disponíveis na literatura são baseados quase que exclusivamente em dados de campo. Mostrou-se que o controle do Ca2+ das águas mais salinas está sendo realizado pela formação de calcita e dolomita em nódulos, enquanto o controle do Mg2+ e do Si(OH)4 está ocorrendo pela formação de esmectitas magnesianas do tipo saponita e estevensita. Estes processos são provavelmente os responsáveis pela alta variabilidade entre as águas doces das baías/vazantes e as salgadas das salinas/arredores, conforme hipótese lançada em literatura. Assim, o presente trabalho fornece fortes evidências de que a presença de sal nas águas das lagoas salinas da Nhecolândia é atual ou, ao menos, tem contribuição de processos atuais. Por fim, mostrou-se ser possível a formação conjunta de ilita, glauconita e mica glauconítica e de esmectitas do tipo saponita e estevensita pelo mecanismo de precipitação diretamente das águas ou soluções em ambientes sujeitos a concentração evaporativa.
A distinctive feature of Nhecolândia, a sub-region of the Pantanal wetland, is the presence in close proximity of freshwater and saline lakes with a huge chemical variability. The salt has been generally attributed to Pleistocene processes, but recent studies have suggested that saline waters arise from present-day concentration of freshwater by evaporation. The chemical profile of saline waters would be originated by chemical control of Ca2+, Mg2+, and Si(OH)4 as the water becomes more saline. Two processes would be responsible for this control: formation of carbonates and formation of Mg-silicates. The presence of whitish nodules and clayey horizons in soils associated to the saline lakes would be evidences of these processes. In saline-alkaline environments, carbonates such as calcite and dolomite are commonly formed by chemical precipitation, but the mechanisms responsible for Mgsilicates genesis are still under debate. The objectives of this research are: a) increasing the general knowledge about soils associated to Pantanal saline lakes through a detailed characterization of the soils located around a representative saline lake of Nhecolândia (\"Salina do Meio\"); b) identifying the processes involved in Ca2+, Mg2+ and Si(OH)4 control from saline waters, through the study of relationships between waters and minerals present in the soils around \"Salina do Meio\"; c) identifying the specific mechanisms of authigenic genesis of the minerals possibly found around \"Salina do Meio\". Soils were sampling along a toposequence and submitted to physical (particle-size), chemical (ICP-MS, pH, EC, total carbon, inorganic carbonate, exchangeable bases, and soaking in H2O, HCl 1N, and NaOH 4M), and mineralogical analyses (XRD and TEM-EDS). Water was collected along a transect involving the lake and submitted to pH, Eh, EC, temperature, titration with HCl, ion chromatography, and ICP-MS analyses. The studied soils are sandy, structureless, and present, in general, high values of pH, CE, CEC, and Na+ saturation. Prevailing of Na+ in the waters and exchangeable sites and dominance of extremely high pH strongly suggest the general action of solonization in these soils and its influence on the following processes: organic matter translocation toward deeper horizons, precipitation of carbonates (calcite, dolomite, and nahcolite) in nodules, precipitation of amorphous silica, and authigenic formation of smectites and micas. Different authigenic smectites occur along the toposequence: a) in the zone hardly reached by the lake level variation, the smectite is classified as ferribeidellite-type, present an interstratification with mica and vermiculite, and has similar amounts of Fe3+ than the Fe-mica present in the soils. These characteristics suggest that this ferribeidellite-type mineral originates from transformation of Fe-mica and that vermiculite may be an intermediate phase in this transformation; b) in the zone of seasonal lake level variation, the smectites are classified as saponite- and stevensite-type minerals. Low REE amounts in the samples enriched in saponite and stevensite, geochemical control of Mg2+ and Si(OH)4, saturation with respect to Mg smectite in the more saline waters, and presence of Mg-smectite where the maximum of evaporation is expected, prove that saponite- and stevensite-like minerals originate by chemical precipitation from the water column of the saline lake. The micas present in the studied soils are classified as illite-, glauconite- and glauconitic mica-type minerals. They present 20% or less smectite layers and seem to be associated to amorphous materials. Synthesis of micas available in the literature shows that water conditions similar to the study area allow for dioctahedral mica crystallization from initial precipitation of amorphous hydroxides. Therefore, it suggests that micas of study area are neoformed. The results of this dissertation contributed to a better understanding about the soils associated to Nhecolândia saline lakes, since most of the published researches are based on field data. The control of Ca2+ from more saline waters occurs by formation of calcite and dolomite in nodules, while the control of Mg2+ and Si(OH)4 occur by formation of Mg-smectites classified as saponite- and stevensite-type. These processes are probably responsible for the chemical variability between freshwater and saline lakes, as supposed in a previous research. Therefore, the present work gives strong evidences about the current origin of Nhecolândia salt water. Also, it showed the possibility of genesis of illite, glauconita, glauconitic mica, saponite, and stevensite minerals through direct precipitation of waters or soil solutions under concentration by evaporation.

Nutrients for plant growth are often limited in soil systems and additions are required in the form of fertiliser. Potassium is an essential macro-nutrient for plants and demands for K are expected to increase in the future. Glaucony is an abundant marine mineral which may provide an alternative K-rich fertiliser resource. The South Island of New Zealand contains deposits of glaucony-rich rocks which were deposited in the Early- to Mid-Cenozoic during periods of low sedimentation to the seafloor. Here, the geochemistry of glaucony from the Waitaki Basin (Otago), the Waipara Greensand (North Canterbury) and the Stoney Creek Limestone (Karamea) was examined using spatially resolved geochemical analysis and dissolution experiments. Grain-by-grain analysis using Laser Ablation Induction Coupled Plasma Mass Spectrscopy (LA-ICP-MS) and Scanning Electron Microscopy with Energy Dispersive Spectroscopy (SEM + EDS) revealed that glaucony from all deposits were of the mature type and were enriched in K. Glaucony derived from growth inside faecal pellets was found to contain elevated K and Fe concentrations compared to bioclast hosted glaucony. These variations can be explained by the physical properties of host grains and sea-floor redox conditions at the time of precipitation, both of which increased ionic mobility into the zone of glauconitisation. Solubility analysis showed that K^{+} was released from glaucony more rapidly than any other element. Additionally, decreasing the pH and introducing an oxidising agent (i.e, birnessite which is ubiquitous in soil environments) accelerated K^{+} release 13-fold. Trace metals including Cr, Zn, Cu and Ni were present in the solid phase analysis, however further investigation revealed that these elements were released into solution in low concentrations and may present a source of micro-nutrients, not a soil contaminant. These results suggest that glaucony may offer a source of slow releasing K fertiliser, and the South Island of New Zealand is ideally situated as a place to consider using glaucony as a locally sourced, environmentally sustainable K resource for agriculture.

Le plateau de Demerara est un plateau marginal situé le long de la marge de la Guyane française et du Surinam. Grâce aux données récentes acquises lors de la campagne IGUANES, avec des données géophysiques et des carottes sédimentaires, certaines structures sédimentaires illustrent une forte influence du courant sur la construction récente de cette marge.Les géométries sédimentaires suggèrent la présence d'un Système de Dépôt contouritique (CDS) sur ce plateau. Le fond marin est marqué par la présence de structures longitudinales formées par l'activité actuelle: « giant flute casts » ou queues de comètes et des « longitudinal waves ». Sur la base de l'analyse des données chirp et des carottes, la présence de processus contouritiques a été identifiée sur les plateaux marginaux intermédiaires et inférieurs. Cette contourite est probablement induite par la circulation de la NADW. Des structures sédimentaires sont présentes et enregistrées après cet événement : des « comet marks » et des « longitudinal waves ».Le contourite sur ce plateau est constitué de sédiments riches en illustrant le vannage induit par les courants de fond. L'étude des carottes sédimentaires associées à un cadre chrono-stratigraphique permet d'identifier les caractéristiques sédimentaires en fonction de l'intensité du courant. La glauconite, minéral authigénique, est utilisé comme un nouvel outil qui, couplé à des analyses granulométriques et de faciès, permet d’enregistrer les variations du vannage. Sur le plateau de Demerara, la sédimentation indiquent des taux d'accumulation sédimentaire faibles et des courants de fond intenses pendant les périodes glaciaires.La présence de contourites le long du plateau de Demerara et le long d'autres plateaux marginaux montre l'impact fort de tels reliefs bathymétriques sur la circulation océanique
The Demerara Plateau is a marginal plateau located along the French Guyana and Surinam margin. Thanks to the recent data acquired during the IGUANES cruise, with geophysical data and sedimentary cores, some sedimentary structures illustrate a strong current influence on the recent building of this margin. The sedimentary geometries suggest the presence of a Contourite Depositional System (CDS). The seafloor is marked by the presence of longitudinal structures formed by the current activity: giant flute clasts or comet marks, and longitudinal waves. Based on the chirp data analysis and on cores, some sedimentary domains are identified on the Demerara marginal plateau. The intermediate and the lower marginal plateaus are affected by contouritic process with two moats and a mounded elongated drift. This contourite is likely induced by the NADW circulation. The contourite on this plateau is made of glauconitic rich sediments inside the moat showing the winnowing effect induced by the bottom currents. The detailed study of sedimentary cores associated with a chronostratigraphic framework allows identifying the sedimentation features depending on current intensity through time. The glaucony authigenic mineral is used as a main proxy, coupled with grain-size and facies analyses, for inferring the degree of winnowing at the sediment-water interface. On the Demerara plateau, the sedimentation suggests low sediment accumulation rates and quite energetic bottom currents during ice periods.The presence of contourites along the Demerara Plateau and along other marginal plateaus shows the strong impact of such deep-sea marginal bathymetric reliefs on the oceanic circulation

The Lower Cretaceous (Albian) Glauconitic Sandstone is the lowermost stratigraphic unit of the Upper Mannville interval in southern Alberta. It overlies calcareous and fossiliferous strata of the Ostracode Limestone and is unconformably overlain by feldspathic and lithic-rich fluvial sandstone of the undifferentiated Upper Mannville. In the study area, Glauconitic Sandstone strata comprise three facies associations consisting of prograding shoreface to shallow shelf (FA1I), upper estuary channel fill (FA2) and tidally-influenced abandoned channel fill/interchannel (FA3) deposits. The Jenner Upper Mannville E Pool is a 10 km long by 2 km wide north-south trending conventional oil pool located in Townships 19--20, Range 9W4 in southeastern Alberta. Since its discovery in 1963, the pool has produced 7.3 million barrels of 21.1° API oil and 6.7 billion cubic feet of gas from the Glauconitic Sandstone. The original oil in place is 28.6 mmbbl and estimated remaining reserves are of the order of 700 mbbl.

In the mid-Cenozoic, New Zealand underwent slow subsidence interspersed with unconformity development, however significant controversy exists around both the extent of submergence below sea level during this period of maximum drowning, as well as the causes of these unconformities. Detailed field observations, combined with extensive petrographic analyses, stable isotopes, cathodoluminescence, and thin section staining were used to develop lithofacies, depositional, and sequence stratigraphic models of the mid-Cenozoic succession in the Waitaki region, South Island, to address these controversies. Twelve facies types have been described for Late Eocene-Early Miocene sedimentary rocks, leading to the identification of two major (Mid Oligocene & Early Miocene) and one minor (Late Oligocene) sequence boundaries. Surtseyan volcanism in the east produced a palaeohigh, resulting in a submerged rimmed cool-water carbonate platform, with low-lying land to the west. This eastern palaeohigh developed karst during sea-level lowstands, which correlate with silty submarine bored hardgrounds in the west. Glauconitic and phosphatic facies deposited during early marine transgression suggest an authigenic factory supplied by terrigenous clays existed during lowered sea level that was progressively shut down in favour of a carbonate factory as sea level rose and terrigenous supply decreased. The eastern palaeohigh served to nucleate this carbonate factory by raising the sea floor above the influence of siliciclastic sediment supply and providing a shallow substrate for marine colonisation. The higher energy eastern facies display dissolution of aragonitic taxa, while deeper western facies retained an aragonitic assemblage. This early bathymetric high created a barrier to submarine currents, but was gradually reduced by erosion during subsequent lowstands. Calcareous facies were often subjected to minor seafloor cement precipitation to shallow burial diagenesis, while eastern facies developed some meteoric cement during subaerial exposure. Comparisons between sea-level change in the study area and the New Zealand megasequence indicate eustatic changes as the primary driver of water depth in the Waitaki region until the development of the modern plate boundary in the Early Miocene.

Thesis advisor: Paul Strother
The Rogersville Shale of the Middle to Late Cambrian Conasauga Group was deposited on the margins of Laurentia, in what is now eastern Tennessee. Based on 21 thin section samples from the ORNL-Joy2, core five distinct microlithofacies are described, trace fossils characterized, and palynological data interpreted. This investigation concluded that the Rogersville Shale was deposited in a shallow, restricted marine or possibly estuarine environment that would have been exposed to terrestrial runoff. Previous work on the Conasauga Group placed deposition of the Rogersville Shale within an intercratonic basin in approximately 250m of water, perhaps significantly deeper. This investigation found that the Rogersville Shale was likely deposited in a lagoonal setting or restricted estuarine environment that had freshwater input
Thesis (MS) — Boston College, 2008
Submitted to: Boston College. Graduate School of Arts and Sciences
Discipline: Geology and Geophysics

Detailed study of strata associated with the glauconite-rich Floyds Knob Bed in the western Appalachian and eastern Illinois basins have corroborated previous interpretations that the unit is a widespread, largely synchronous marker horizon. However, in some areas there are multiple glauconite beds; in others a distinct bed is lacking, but the glauconite is dispersed throughout many beds, forming an interval rather than a distinct bed. In Kentucky and adjacent states, the Floyds Knob interval, in upper parts of the Lower-Middle Mississippian Borden-Grainger delta sequence and in lower parts of the Fort Payne carbonate sequence, was deposited at the end of loading-type relaxation during a flexural cycle in the Neoacadian (final) tectophase of the Acadian Orogeny. Tectonic influence, combined with a major late Osagean sea-level lowstand, created conditions that generated sediment starvation and shallower seas across widespread parts of the western Appalachian and eastern Illinois basins. In the absence of major sediment influx, glauconite was deposited uniformly across many major depositional settings, ranging from delta-platform to basinal environments. Especially important, however, is the newly reported occurrence of the Floyds Knob interval in basinal Fort Payne environments from south-central Kentucky, where it is represented by a thick, pelletal, glauconite-rich horizon that separates clastics at the base of the Fort. Payne Formation from carbonates at top. The study also provides the first-ever radiometric dating of the Floyds Knob glauconites, which suggests a late Osagean origin. These results support the existing biostratigraphic studies that point to a late Osagean origin for the Floyds Knob interval.

Detailed provenance analysis and glauconite morphology of the Broken River and Iron CreeklWaipara Formations and other correlatives were conducted at 6 localities: the MandamusDove River area, Waipara River, Avoca-Iron Creek, Castle Hill Basin, Malvern and Mt Somers. The basal Broken River Formation is a fluvial boulder conglomerate interbedded with sandstones, mudstones and coal dated as Haumurian (Late Cretaceous) by pollen. The transgression is marked by a gradual drowning of the fluvial conglomerates with minor glauconite appearing in the beds immediately overlying the conglomerates in alllocali ties. The estuarine-marginal marine I lower shoreface succession of the Broken River Formation contains minor nascent micaceous glauconite. This increases in the overlying Iron Creek I Waipara Formations to 30-60% glauconite composed of nascent-micaceous to evolved/mature glauconity types characteristic oflower shoreface I foreshore to shallow shelf depositional setting. Up section, evolved mature glaucony dominates, in some beds formed in situ (autochthonous) and in other beds transported from nearby (parautochthonous) to line foresets. An extremely low sedimentation rate is necessary to form the evolved I mature type of glauconite. The age of the greensands is Teurian to Whaingaroan (Late Paleocene-Late Eocene). Overall the glauconite analysis indicates extremely low sedimentation rates with autochthonous I parautochthonous glaucony formation in nearshore marine settings, possibly even estuary environments. Clast counts from the basal conglomerates indicate derivation from local sources such as the underlying Torlesse greywackes (Pahau and Rakaia Terranes) and/or the Mandamus Igneous Complex. Sandstone composition indicates the addition of more distal sources. Quartzose sandstones plot in the interior craton province in QFL plots for both Broken River and Iron Creek/Waipara Greensand Formations. Sandstone lithics are probably derived from the underlying Torlesse greywacke. Alkali feldspar dominates over plagioclase indicating a probable plutonic felsic source. SEM-cathodoluminescence on quartz grains indicates a bimodal metamorphic to plutonic quartz grains with minor volcanic input. Plutonic grains are identified by healed microcracks, and are possibly derived from Western Province plutonic suites such as the Karamea and Separation Point Batholiths. Polycrystalline/dark CL quartz grains indicate a relatively high grade metamorphic source such as the OtagolHaast Schist while dark CL monocrystalline quartz grains indicate a low to medium metamorphic grade source such as the Alpine Schist. Volcanic quartz is zoned with straight extinction and was most likely derived from the Cretaceous Mount Somers Volcanics Group. Overall the provenance suggests local derivation of sediments when coarse fluvial deposition occurred followed by more distal derivation once transported in the nearshore marine setting.

Леськів Г.З. Очищення стічних вод від барвників шляхом адсорбції на природних дисперсних сорбентах.: дисертація на здобуття наукового ступеня кандидата технічних наук за спеціальністю 21.06.01 – екологічна безпека / Леськів Галина Зіновіївна. - Львів: Національний університет “Львівська політехніка”, 2008. - 123 с.
Дисертацію присвячено розробленню технології очищення стічних вод від органічних барвників шляхом їхньої адсорбції на природних дисперсних сорбентах – глауконіті та палигорськіті. Здійснено моніторинг забруднень поверхневих вод України органічними барвниками зважаючи на локалізацію підприємств, які виробляють і застосовують барвники у своїх технологіях. Виконано токсикологічну оцінку барвників, від яких досліджено очищення стоків, а саме – активного алого 4ЖТ та аніонного червоного 8С. На основі теоретичного аналізу розроблено методику опрацювання кінетичних рівнянь, яка ґрунтується на використанні інтегрального методу. Для аналізу досліджуваних процесів запропоновано найбільш використовувані теоретичні моделі адсорбції. Розробле-но принципову технологічну схему процесу очищення стічних вод від барвників шляхом застосування природних дисперсних сорбентів. Здійснено розрахунок еколого-економічного ефекту, який досягається у випадку впровадження розробленої технології для очищення стоків фарбувально-обробних підприємств України. The dissertation is devoted to developing of the technology of wastewater cleanout from organic pigments by adsorption them on the natural dispersive sorbents: glauconite and palygorskit. The monitoring the pollution of surface waters of Ukraine with organic pig-ments according to the location of the enterprises which produce pigments and which use them in their technologies was carried out. Toxicological evaluation of the pigments, wastewater cleanout from which is being researched: active scarlet 4GT and anion red 8C, was carried out. The methods of working–out kinetic equations which is grounded on using of the in-tegral method was developed on the base of the theoretical models of adsorption were offered for analysis of the researched process. The principle technological scheme of the process of wastewater cleanout from pigments by applying natural dispersive sorbents was developed. The calcu-lation of ecologic and economic effect which could be reached in case of inculca-tion of the developed technology for cleanout of wastewaters of dyeing and man-ufacturing enterprises of Ukraine.

Temperate mixed carbonate-siliciclastic sediments and authigenic minerals are the current surficial deposits at shelf and slope depths (30-1015 m water depth) on the north Kaipara continental margin (NKCM) in northern New Zealand. This is the first detailed study of these NKCM deposits which are described and mapped from the analysis of 54 surficial sediment samples collected along seven shorenormal transects and from three short piston cores. Five surficial sediment facies are defined from the textural and compositional characteristics of this sediment involving relict, modern or mixed relict-modern components. Facies 1 (siliciclastic sand) forms a modern sand prism that extends out to outer shelf depths and contains three subfacies. Subfacies 1a (quartzofeldspathic sand) is an extensive North Island volcanic and basement rock derived sand deposit that occurs at less than 100-200 m water depth across the entire NKCM. Subfacies 1b (heavy mineral sand) occurs at less than 50 m water depth along only two transects and consists of predominantly local basaltic to basaltic andesite derived heavy mineral rich (gt30%) deposits. Subfacies 1c (mica rich sand) occurs at one sample site at 300 m water depth and contains 20-30% mica grains, probably sourced from South Island schists and granites. Facies 2 (glauconitic sand) comprises medium to fine sand with over 30% and up to 95% authigenic glauconite grains occurring in areas of low sedimentation on the outer shelf and upper slope (150-400 m water depth) in central NKCM. Facies 3 (mixed bryozoan-siliciclastic sand) consists of greater than 40% bryozoan skeletal material and occurs only in the northern half of the NKCM. Facies 4 (pelletal mud) occurs on the mid shelf (100-150 m water depth) in northern NKCM and comprises muddy sediment dominated by greater than c. 30% mixed carbonatesiliciclastic pellets. Facies 5 (foraminiferal mud and sand) contains at least 30% foraminifera tests and comprises two subfacies. Subfacies 5a consists of at least 50% mud sized sediment and occurs at gt400 m water depth in southern NKCM while subfacies 5b comprises gt70% sand sized sediment and occurs at mid to outer shelf and slope depths in the northern NKCM. vi A number of environmental controls affect the composition and distribution of NKCM sediments and these include: (1) variable sediment inputs to the NKCM dominated by inshore bedload sources from the south; (2) northerly directed nearshore littoral and combined storm-current sediment transport on the beach and shelf, respectively; (3) offshore suspended sediment bypassing allowing deposition of authigenic minerals and skeletal grains; (4) exchange between the beach and shelf producing similar compositions and grain sizes at less than 150 m water depth; and (5) the episodic rise of sea level since the Last Glaciation maximum approximately 20 000 years ago which has resulted in much sediment being left stranded at greater depths than would otherwise be anticipated. Sedimentation models developed from other wave-dominated shelves generally do not appear to apply to the NKCM sediments due to their overall relative coarseness and their mosaic textural characteristics. In particular, the NKCM sediments do not show the expected fining offshore trends of most wavedominated shelf models. Consequently, sandy sediments (both siliciclastic and authigenic) are most typical with mud becoming a dominant component in southern NKCM sediments only at greater than 400 m water depth, over 350 m deeper than most models suggest, a situation accentuated by the very low mud sediment supply to the NKCM from the bordering Northland landmass.

The Archean-Proterozoic transition is marked by globally synchronous changes in tectonothermal and climatic patterns along with development of widespread epicontinental seas, with extensive shelf-sedimentation. The Indian Shield hosts several Proterozoic sedimentary basins, popularly known as the Purana basins, with mostly undeformed and unmetamorphosed siliciclastic and carbonate sediments. The undeformed and unmetamorphosed nature of these sediments, along with their prolonged sedimentation, makes them excellent geological archives of past tectono-thermal and climatic events as well as paleo-depositional environments, and makes them suitable for geochemical and isotopic studies. In this study, sedimentary rocks were collected from the Paleo-Mesoproterozoic Cuddapah Basin and the Mesoproterozoic Chhattisgarh Basin from the Southern Indian Block (SIB), the Paleo-Mesoproterozoic Vindhyan Basin from the Northern Indian Block (NIB), and the Neoproterozoic Marwar Basin from the Western Indian Block (WIB) or the Marwar Block (MB). A geochemical and Nd isotope study of the siliciclastic sediments from the Cuddapah, Vindhyan, and Chhattisgarh basins show that during periods of tectonic stability in the Indian Craton, these basins derived detritus from evolved sources with unradiogenic Nd isotopic compositions. Periods of juvenile magmatism can be well-traced in the associated sediments across the basins. The volcanic tuffs from Cuddapah (1.86 Ga), Singhora (1.5 Ga), and Chhattisgarh basins (1.0 Ga) show similar geochemical compositions suggesting their derivation from ancient arcs. The Nd isotope evolution of these tuffs, with widely-varying eruption ages, suggest their derivation from a common mantle source. Chemically precipitated Precambrian sediments have been variably used to infer the redox condition of early Earth, to trace the fluxes of crustal and mantle derived cations and anions to the oceans, and to understand the paleo-habitat of ancient lifeforms. However, a significant portion of the preserved Precambrian carbonates are considered to have been deposited in epicontinental environments. To constrain the paleo-depositional environments of the extensive carbonate deposits in the Proterozoic sedimentary basins of India, the samples were first screened for diagenesis using Mn/Sr and Fe/Sr ratios followed by analyses of REY (REE+Y), radiogenic Sr, and stable Ca isotopic compositions. Paleo-Mesoproterozoic carbonates from Cuddapah, Vindhyan, and Chhattisgarh basins do not show prominent seawater-like geochemical signatures. These carbonates also record relatively radiogenic 87Sr/86Sr compositions, which suggests high freshwater input and possibly, deposition under epeiric settings. In contrast, geochemical and isotopic compositions of carbonates from the Neoproterozoic Marwar Basin suggest deposition in an open-ocean setting. Compared to the Paleo-Mesoproterozoic carbonates from Cuddapah, Vindhyan and Chhattisgarh basins, the Neoproterozoic Marwar carbonates record significantly higher δ44/40CaSRM915a values. These high values overlap with isotopic compositions of global Neoproterozoic post-glacial successions. Based on our inferences on provenance and paleo-environmental conditions of the Vindhyan Basin, correlation between the Chambal Valley and the Son Valley sub-basins were investigated based on Nd and Ca isotopic compositions of the Vindhyan carbonates. A significant shift in Nd isotopic composition towards radiogenic values around 1.6 Ga ago is observed in carbonates from both sub-basins, which is consistent with eruption of a juvenile Andean-type arc situated near the Son Valley sub-basin. Similar Ca isotopic composition of the limestone horizons in the two sub-basins suggest deposition from a single water-mass. This similarity in δ44/40CaSRM915a composition suggests that during the deposition of the Lower Vindhyan carbonates, the two sub-basins were connected. In contrast, Upper Vindhyan carbonates from two sub-basins show compositional differences, which suggests that during deposition of the Upper Vindhyan carbonates, the two sub-basins were disconnected. Glauconitic sandstones and limestones from the Semri Group of Son Valley Vindhyans were analysed for their geochemical and Sr isotope compositions. The REE+Y (REY) composition of these glauconites suggest their formation in an enclosed condition without significant interaction with the Proterozoic seawater, while their Sr isotopic compositions suggest that these minerals formed much after the deposition of the ~ 1.6 Ga old Semri Group of sediments. The latter observation is consistent with formation of Precambrian glauconies by pseudomorphic replacement of the substrates.

博士
國立成功大學
資源工程學系碩博士班
96
High-resolution transmission electron microscopy (TEM) accompanied with petrographic observation, X-ray diffraction (XRD) and electron probe microanalysis (EPMA) has been used to study the glauconitic pellets occurred in Tertiary sedimentary rocks from Kuohsing and Chungliao areas, central Taiwan; especially from Takeng Formation, Tsukeng Formation, and Shuichangliu Formation, respectively. The glauconitic pellets show two main types in morphology: ovoid pellets and vermicular pellets, with that the vermicular pellets is much well-crystallized than the ovoid pellets. The optical properties show that the ovoid glauconitic pellets consist of microcrystals of phyllosilicates in random orientation. Whereas, the vermicular glauconitic pellets occur like a single crystal. The vermicular glauconitic pellets has cleavages which are approximately perpendicular to the long axis of grain. The XRD results show that the glauconitic pellets contain glauconite, chlorite, and small amount of smectites. The TEM study has shown that the spheroidal pellets consist mainly of packets of glauconite and Fe-riched chlorite, muscovite, biotite. The packet size of glauconite are ranging from tens of Å to hundreds of Å (thickness in perpendicular to basal plane). There are also small amounts of submicroscopic quartz, apatite, and monazite in the pellets. The vermicular pellets consist of glauconite pellets with very little chlorite or no chlorite. The basal planes of glauconite packets are perpendicular approximately to the long axis of the vermicular pellets, whereas the glauconite and chlorite packets generally arrange in random in the spheroidal pellets. The EPMA results show vermicular glauconitic pellets has more K and Fe contents than the spheroidal or ovoid glauconitic pellets, and thus imply that spheroidal or ovoid glauconitic pellets have more glauconite/smectite mixed layers than vermicular glauconitic pellets. Based on the morphology, mineral constituents, mineral composition, and submicroscopic textures, it appears that the ovoid and vermicular glauconitic pellets have formed from precursors of faecal pellets, via glauconition and diagenesis.

碩士
國立中山大學
海洋資源研究所
86
High-resolution transmission electron microscopy (TEM) accompanied with petrographic observation, X-ray diffraction (XRD) and electron probe microanalysis (EPMA) has been used to study the glauconitic pellets occurred in Tertiary sedimentary rocks from Kuohsing and Chungliao areas, central Taiwan. The glauconitic pellets mainly occur in siltstones and mudstones that contain abundant shell fossils and trace fossils. The glauconitic pellets show two main types in morphology: spheroidal or ovoid pellets and vermicular pellets, with that the former is much abundant than the latter. The optical properties show that the spheroidal or ovoid glauconitic pellets consist of microcrystals of phyllosilicates in random orientation. Whereas, the vermicular glauconitic pellets occur like a single crystal. The vermicular glauconitic pellets has cleavages which are approximately perpendicular to the long axis of grain. The XRD results showthat the glauconitic pellets contain glauconite, chlorite, and small amount of smectites. The TEM study has shown that the spheroidal pellets consist mainly of packets of glauconite and Fe-riched chlorite, muscovite, biotite. The packet size of glauconite are ranging from tens of angstrom to hundreds of angstrom (thickness in perpendicular to basal plane). There are also small amounts of submicroscopic quartz, apatite, and monazite in the pellets. The vermicular pellets consist of glauconite pellets with very little chlorite or no chlorite. The basal planes of glauconite packets are perpendicular approximately to the long axis of the vermicular pellets, whereas the glauconite and chlorite packets generally arrange in random in the spheroidal pellets. The EPMA results show vermicular glauconitic pellets has more K and Fe contents than the spheroidal or ovoid glauconitic pellets, and thus imply that spheroidal or ovoid glauconitic pellets have more glauconite/smectite mixed layers than vermicular glauconitic pellets. Based on the morphology, mineral constituents, mineral composition, and submicroscopic textures, it appears that the spheroidal and vermicular glauconitic pellets have formed from precursors of faecal pellets, via glauconition and diagenesis.-1 -aA study of mineralogy and submicrostructures of glauconite pellets in Tertiary sedimentary rocks from central Taiwan