No description available.

No description available.

The rocks of the Carboniferous to Jurassic aged main Karoo Supergroup of South Africa preserve an internationally significant and stratigraphically continuous retro-arc foreland depositional sequence. This succession documents environmental change from glacial-marine, through fluvio-deltaic to continental fluvial and aeolian, culminating in rift associated continental flood basalt extrusions. The fluvio-deltaic transition from marine to continental deposition has been the subject of much recent research and corresponds with the position of the Ecca-Beaufort contact. Over the entire basin this transition comprises three separate lithofacies associations deposited in the prodelta, deltafront and delta plain environments. Anomolously the southeastern contact is currently mapped as reflecting fluvial deposits of the Koonap Formation lying unconformably on prodelta deposits of the Fort Brown Formation. Detailed study across the Ecca-Beaufort contact in this part of the basin now reveals the same lithological transition as is present in the rest of the basin. Contrary to previuos work, this has shown that the Waterford Formation is indeed present in this part of the basin. This in effect means that the Grahamstown map sheet (1:250 000, Map 3326) requires modification to include this Formation and the new contact placement of the Ecca-Beaufort contact occurs some 70 to 120m above the presently mapped contact. Fossils collected during this and previous studies show that biostratigraphically Tapinocephalus Assemblage Zone fauna occurs in the rocks of the Koonap Formation in this part of the basin, indicating that the Ecca-Beaufort contact in the southern part of the basin youngs towards the east. This supports the prograding shoreline deposition model that has been previously proposed for the Ecca-Beaufort contact.

No description available.

The study area encompasses a region of about 80 square kilometers, centered about Corbett, Oregon. Sieve analyses suggest that the Troutdale Formation is composed of a conglomerate, a coarse-grained sandstone, and a siltstone lithofacies. Measured sections data show that 56 to 60 percent of the Troutdale Formation's exposures are composed of the conglomerate lithofacies. The coarsegrained sandstone lithofacies makes up 34 to 38 percent, while the siltstone lithofacies makes up only 4 to 8 percent. Pebble count data show that the representation of basalt varies from 69 to 100 percent, with an average of 85 percent, while quartzite varies from 0 to 25 percent, with an average of 9 percent. Geochemical data show that at least one formal member and two informal members of the Columbia River Basalt Group (Frenchman Springs, Grande Ronde High Mg, and Grande Ronde Low Mg) compose part of the detritus. The geochemical data also show that rocks of the Boring Lavas or similar lavas are intercalated with the Troutdale Formation, high in the section. Grain mount petrographic data show that volcanic rock fragments are the dominant component in the coarse sand fraction of the Troutdale Formation. Many of the volcanic rock fragments contain brown glass with an index of refraction of 1.583 +/- 0.001, which indicates a mafic composition {silica content of 50 +/- 1 percent). The representation of volcanic rock fragments varies from 29 to 98 percent, with an average of 75 percent. Sedimentary rock fragments, such as chert, vary from 0 to 17 percent, with an average of 5 percent. Biotite ranges from 0 to 12 percent, with an average of 2 percent. Two-thirds of the samples which contain sedimentary rock fragments also contain biotite. Orthopyroxene varies from 0 to 18 percent, with an average of 5 percent. 2 The samples with the three greatest amounts of orthopyroxene do not contain sedimentary rock fragments or biotite.

O Grupo Carrancas, neoproterozóico, é composto por uma pilha metassedimentar alóctone, com aproximadamente 400m de espessura, de quartzitos (metapsamitos) e xistos grafitosos (metapelitos), divididos em três formações: Fm. São Tomé das Letras, base da seqüência, composta por muscovita quartzitos, muscovita-quartzo xistos e subordinadamente muscovita xistos, ambos com muscovitas esverdeadas; Fm. Campestre, intermediária, caracterizada por uma intercalação de xistos grafitosos ± porfiroblásticos (Grt-St-Ky-Cld) e níveis expressivos de muscovita quartzitos com mica branca; Fm. Chapada das Perdizes, equivalente a Formação São Tomé das Letras, porém disposta no topo da sequência. A unidade do biotita xisto (metawacke), sempre com estrutura milonítica presente, se encontra tectonicamente sobre o Grupo Carrancas, dispondo-se no núcleo das estruturas sinformais D3, e sendo, portanto, uma unidade metassedimentar também alóctone.Os metassedimentos, assim como parte da infraestrutura gnáissica alóctone, estão estruturados em nappes sin-S2 com transporte tectônico para leste e sudeste, paralelo aos mullions e rods B2. Esse transporte, relacionado aos eventos contínuos progressivos D1 e D2, ocorreu a partir de zonas de cisalhamento ductil de baixo ângulo, sob regime de deformação não-coaxial, responsável pela geração de dobras isoclinais e intensa recristalização plano axial que constituí a foliação principal regional S2. O evento deformacional D3, produto da progressão da deformação em níveis crustais mais rasos, possuí caráter rúptil-ductil, onde foram geradas dobras assimétricas em diversas escalas, com espessamento de charneira, no geral homoaxiais a D2 (B2//B3). Também foram geradas em D3, importantes zonas de cisalhamento com movimentação lateral destral, como a Zona de Cisalhamento de Três Corações, de direção NE-SW e zonas de cisalhamento dispostas no norte da Serra da Estância. Nas proximidades dessas zonas de cisalhamento, a foliação se torna sub-vertical e as dobras D3 apertadas, ocorrendo transposição para S3 (S2//S3). Os dobramentos D4, com direção NE-SW e N-S, eixos com caimento para SW e S, e vergêntes para NW, foram responsáveis pela configuração da geometria em \"Z\" da Nappe Carrancas, redobrando e crenulando os elementos estruturais anteriormente formados. O metamorfismo registrado nos xistos grafitosos, aumenta de modo geral de NW para SE, com paragêneses que variam de Grt+Chl+Cld a Grt+Ky+St+Cld na Serra da Estância, Pombeiro e Galinheiro, evidenciando condições de fácie xisto verde na transição para o fácie anfibolito, considerando pressões intermediárias. Já para sul da Serra de Carrancas, a paragênese predominante é de Grt+St+Ky, típica da fácie anfibolito na zona da cianita. Contrastando com o Grupo Carrancas, a unidade do biotita xisto se encontra sempre em fácie xisto verde, marcada pela paragênese de Grt+Chl+Bt. / The Carrancas Group, Neoproterozoic, is composed by an allochthonous sedimentary pile, about 400m thick of quartzite (metapsamites) and graphitic schists (metapelites),divided into three formations: São Tomé das Letras Formation, the base of the sequence, composed of muscovite quartzite, quartz-muscovite schist and subordinate muscovite schists, both with greenish muscovites; Campestre Formation, intermediate, characterized by an intercalation of graphitic schists ± porfiroblastics (Grt-St-Cld-Ky) and significant levels of muscovite quartzites with white mica; Chapada das Perdizes Formation, equivalent to São Tomé das Letras Formation, but arranged on top of the sequence. The biotite schist, always with mylonitic structure present, is tectonically localized above of Carrancas Group, in the core of D3 sinformals structures, and is therefore also a sedimentary allochthonous unit. The metasediments, as part of the allochthonous gneiss infrastructure, are structured in sin-S2 nappes, with tectonic transport to the east and southeast, parallel to the mullions and rods B2. This transport, related to continuous and progressive events D1 and D2, occurred from ductile shear zones of low angle, under the regime of non-coaxial deformation, responsible for the generation of isoclinals folds and intense recrystallization axial plane that constitutes the main S2 regional foliation. The D3 deformational event, a product of progressive deformation in shallow crustal levels, possess character brittle-ductile, which were generated by asymmetric folds in several scales, with thickening of the hinge, usually homoaxials to D2 (B2 / / B3). Major shear zones with dextral lateral movement, such as the Três Corações Shear Zone, NE-SW direction and shear zones arranged in the northern Serra da Estância, were also generated in D3. Near these shear zone, the foliation becomes sub-vertical and D3 bends tight, occurring transposition to S3 (S2 / / S3). The D4 folds with NE-SW and N-S axis with trim to SW and NW vergence, were responsible for setting up the \"Z\" geometry of Carrancas Nappe, redoubling and crinkling structural elements previously formed. The metamorphism recorded in the graphitic schists, generally increases from NW to SE, which vary with paragenesis Grt + Chl + Cld the Grt + Ky + St + Cld at Serra da Estância, Galinheiro and Pombeiro, showing conditions of the greenschist facie transition to the amphibolite facie, considering intermediate pressures. As for the southern Serra das Carrancas, the predominant paragenesis of Grt + St + Ky, typical of amphibolite facie in the kyanite zone. In contrast to the Carrancas Group, a unit of biotite schist is always in greenschist facie, marked by the paragenesis of Grt + Chl + Bt.

O Grupo Carrancas, neoproterozóico, é composto por uma pilha metassedimentar alóctone, com aproximadamente 400m de espessura, de quartzitos (metapsamitos) e xistos grafitosos (metapelitos), divididos em três formações: Fm. São Tomé das Letras, base da seqüência, composta por muscovita quartzitos, muscovita-quartzo xistos e subordinadamente muscovita xistos, ambos com muscovitas esverdeadas; Fm. Campestre, intermediária, caracterizada por uma intercalação de xistos grafitosos ± porfiroblásticos (Grt-St-Ky-Cld) e níveis expressivos de muscovita quartzitos com mica branca; Fm. Chapada das Perdizes, equivalente a Formação São Tomé das Letras, porém disposta no topo da sequência. A unidade do biotita xisto (metawacke), sempre com estrutura milonítica presente, se encontra tectonicamente sobre o Grupo Carrancas, dispondo-se no núcleo das estruturas sinformais D3, e sendo, portanto, uma unidade metassedimentar também alóctone.Os metassedimentos, assim como parte da infraestrutura gnáissica alóctone, estão estruturados em nappes sin-S2 com transporte tectônico para leste e sudeste, paralelo aos mullions e rods B2. Esse transporte, relacionado aos eventos contínuos progressivos D1 e D2, ocorreu a partir de zonas de cisalhamento ductil de baixo ângulo, sob regime de deformação não-coaxial, responsável pela geração de dobras isoclinais e intensa recristalização plano axial que constituí a foliação principal regional S2. O evento deformacional D3, produto da progressão da deformação em níveis crustais mais rasos, possuí caráter rúptil-ductil, onde foram geradas dobras assimétricas em diversas escalas, com espessamento de charneira, no geral homoaxiais a D2 (B2//B3). Também foram geradas em D3, importantes zonas de cisalhamento com movimentação lateral destral, como a Zona de Cisalhamento de Três Corações, de direção NE-SW e zonas de cisalhamento dispostas no norte da Serra da Estância. Nas proximidades dessas zonas de cisalhamento, a foliação se torna sub-vertical e as dobras D3 apertadas, ocorrendo transposição para S3 (S2//S3). Os dobramentos D4, com direção NE-SW e N-S, eixos com caimento para SW e S, e vergêntes para NW, foram responsáveis pela configuração da geometria em \"Z\" da Nappe Carrancas, redobrando e crenulando os elementos estruturais anteriormente formados. O metamorfismo registrado nos xistos grafitosos, aumenta de modo geral de NW para SE, com paragêneses que variam de Grt+Chl+Cld a Grt+Ky+St+Cld na Serra da Estância, Pombeiro e Galinheiro, evidenciando condições de fácie xisto verde na transição para o fácie anfibolito, considerando pressões intermediárias. Já para sul da Serra de Carrancas, a paragênese predominante é de Grt+St+Ky, típica da fácie anfibolito na zona da cianita. Contrastando com o Grupo Carrancas, a unidade do biotita xisto se encontra sempre em fácie xisto verde, marcada pela paragênese de Grt+Chl+Bt. / The Carrancas Group, Neoproterozoic, is composed by an allochthonous sedimentary pile, about 400m thick of quartzite (metapsamites) and graphitic schists (metapelites),divided into three formations: São Tomé das Letras Formation, the base of the sequence, composed of muscovite quartzite, quartz-muscovite schist and subordinate muscovite schists, both with greenish muscovites; Campestre Formation, intermediate, characterized by an intercalation of graphitic schists ± porfiroblastics (Grt-St-Cld-Ky) and significant levels of muscovite quartzites with white mica; Chapada das Perdizes Formation, equivalent to São Tomé das Letras Formation, but arranged on top of the sequence. The biotite schist, always with mylonitic structure present, is tectonically localized above of Carrancas Group, in the core of D3 sinformals structures, and is therefore also a sedimentary allochthonous unit. The metasediments, as part of the allochthonous gneiss infrastructure, are structured in sin-S2 nappes, with tectonic transport to the east and southeast, parallel to the mullions and rods B2. This transport, related to continuous and progressive events D1 and D2, occurred from ductile shear zones of low angle, under the regime of non-coaxial deformation, responsible for the generation of isoclinals folds and intense recrystallization axial plane that constitutes the main S2 regional foliation. The D3 deformational event, a product of progressive deformation in shallow crustal levels, possess character brittle-ductile, which were generated by asymmetric folds in several scales, with thickening of the hinge, usually homoaxials to D2 (B2 / / B3). Major shear zones with dextral lateral movement, such as the Três Corações Shear Zone, NE-SW direction and shear zones arranged in the northern Serra da Estância, were also generated in D3. Near these shear zone, the foliation becomes sub-vertical and D3 bends tight, occurring transposition to S3 (S2 / / S3). The D4 folds with NE-SW and N-S axis with trim to SW and NW vergence, were responsible for setting up the \"Z\" geometry of Carrancas Nappe, redoubling and crinkling structural elements previously formed. The metamorphism recorded in the graphitic schists, generally increases from NW to SE, which vary with paragenesis Grt + Chl + Cld the Grt + Ky + St + Cld at Serra da Estância, Galinheiro and Pombeiro, showing conditions of the greenschist facie transition to the amphibolite facie, considering intermediate pressures. As for the southern Serra das Carrancas, the predominant paragenesis of Grt + St + Ky, typical of amphibolite facie in the kyanite zone. In contrast to the Carrancas Group, a unit of biotite schist is always in greenschist facie, marked by the paragenesis of Grt + Chl + Bt.

<p>The Middle Jurassic Tecocoyunca Group of northeastern Guerrero, Mexico is situated on the allochthonous Mixteca tectostratiqraphic terrane. This group represents an overall transgressive trend with a few minor fluctuations of base level. Foreshore, shoreface, barrier island, washover, and laqoonal facies are identified within five coarsening-upward sequence. Abundant hummocky cross stratification, low-angle inclined stratification, and swash cross stratification indicate dominance of wave processes. These nearshore sequences are overlain by offshore marine shales, which are thought to represent a major global eustatic sea-level rise in the latest Bathonian, continuing into the Early Callovian. During the transgression, deep portions of the basin developed anoxic bottom conditions, resulting in the deposition of bituminous black shales. The combined effects of basinal subsidence and eustatic sea-level rise resulted in a rapid rate of transgression which exceeded that of sedimentation; ca. 110 cm/Ka. </p> <p> Five ammonite associations date the Tecocoyunca Group as Upper Bathonian (Retrocostatum Zone) to Lower Callovian (Calloviense Zone). Biogeoqraphic affinity of the ammonite fauna is mostly Andean with signicant west-Tethyan/mediterranean elements and a few endemic species. The ammonite faunas show: 1) a rapid faunal replacement, 2) shell morphology trends, and 3 ) varying degrees of endemism/cosmopolitanism, all in relation to sea level variation. </p> <p>Biostratiqraphy and lithostratigraphy of the Tecocoyunca Group suggest that: 1) the Mixteca terrane had a paleoposition, during the Middle Jurassic, near the Pacific opening of the Hispanic Corridor (proto-AtlanticJ, 2) the Hispanic corridor provided marine connections between the eastern Pacific Ocean and the western Tethys Sea, and 3) preponderance near shore sediments suggests close proximity to the Andes of South America. </p> / Thesis / Master of Science (MS)

<p>Frenchman's Bay is a shallow coastal lagoon (0.84 km2) located near the eastern limits of the Toronto urban area. Wholesale land clearance in the 1850's and subsequent industrialization and urbanization of the watershed have had severely impacted wetland habitats and degraded sediment and water quality. Prior to implementation of remediation work, a detailed sedimentologic and magnetic property study was conducted to determine the impacts of post-colonial land use changes in Frenchman's Bay. 11 vibrocores (2-4.5m length) were extracted from the lagoon and 3 5 magnetic susceptibility profiles were collected using a probe driven 1-2 m in the lagoon floor. The core lithofacies were logged in detail and magnetic susceptibility (K, x.) and remanence parameters (NRM, SIRM, Bcr) were measured at 2 cm intervals. Magnetic property and lithofacies data were integrated with geochemical analyses (TOC, C03) and 210Pb dating of core in order to reconstruct the lagoon lithostratigraphy and the thickness of the post-colonial 'anthropogenic layer'. </p> <p>The stratigraphic succession in the lagoon consists of a thick upper sequence of marly gyttja and peat-rich silty marls overlying Holocene laminated marls. The postcolonial layer (Unit 1) is recognized as an uppermost high magnetic susceptibility (x = ~200-300 xl0-8 m3/Kg) gyttja layer that extends to 1-1.5 m depth. The base of the unit has a 210Pb age of 1850 (±55.6), corresponding with the main phase of land clearance and onset of industrialization of the harbour. Titanomagnetite, maghemite and magnetite spherules are the primary magnetic minerals, indicating soil erosion and coal burning as the predominant sources of magnetic particles. The underlying Unit 2 consists of peaty marls with abundant plant fragments recording a more extensive marsh. Unit 3 consists of more carbonate-rich laminated sands (magnetic susceptibility x = 6000 x10-8 m3/Kg) deposited in a low energy oligotrophic lagoon. The basal layer (Unit 4) consists of high magnetic susceptibility massive pebbly muds, which record a pre-lagoon phase of higher water levels in post-glacial Lake Iroquois (ca. 13,500 Ka). </p> <p> Isopach mapping of the magnetostratigraphic units clearly identifies that the anthropogenic layer (Unit I; post-1850) is thickest within a central basin which has acted as trap for sediment carried into the lagoon by several streams. The total volume of impacted anthropogenic sediment is estimated at 4 x105 m3. Isopach maps also identify two thin(< 2 m) wedges of sand (9.6 x104 m3) near the north and southern shores of the bay that records periodic overwash and growth of the beach barrier. </p> <p>The major environmental changes in the lagoon since it inception (ca. 2. 7 Ka include: 1. The formation of a shallow coastal embayment following water level rise from a mid-Holocene low-stand in Lake Ontario (Unit 4); 2. Development of a spit and beach barrier by eastward longshore transport (Unit 3); 3. Closure of the lagoon and development of a stabilized marsh habitat with low sedimentation levels (Unit 2); 4. Destruction of marsh habitats and eutrophication of the lagoon coinciding with land clearance (post-1850's) and an increased in the influx of sediments eroded from the catchment area. </p> / Thesis / Master of Science (MS)

Title from PDF of title page. / Document formatted into pages; contains 113 pages. / Thesis (M.S.)--University of South Florida, 1983. / Includes bibliographical references. / Text (Electronic thesis) in PDF format. / ABSTRACT: Bunces Key, a narrow, linear, barrier island on the west-central coast of Florida, was formed in 1961. Its growth and development since that time is well documented by aerial photography. Cores taken from the Key and surrounding areas reveal a stratigraphic succession of facies reflecting rapid vertical aggradation. Sedimentation began on a gently sloping platform through the landward migration of large scale bedforms (sand waves) during fair weather periods. Migration of these bedforms ceased when emergence and lack of continued overwash precluded further movement. / Vertical accretion to supratidal levels resulted from the continued onshore transport of sediment and subsequent welding to the previously formed bars. Stratigraphically, the barrier exhibits a "layer-cake" type of stratigraphy, with nearshore sediments overlain by foreshore, backbeach, and dune deposits. The backbarrier generally exhibits muddy lagoon sediments intercalated with washover and channel margin sediments.Fining upward washover sequences reflect the unstable nature of the island. / Low pressure systems commonly cause overtopping of the barrier, with the subsequent formation of tidal inlets and washover fans. Aerial photographs document the formation of an initial barrier that was breached twice prior to 1973. A second barrier formed in late 1973 just seaward of the initial island and subsequently grew through littoral drift to a length of 1.8 km. A narrow inlet (30 m) formed through the northern end of the island in 1982. / System requirements: World Wide Web browser and PDF reader. / Mode of access: World Wide Web.