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Late Neogene stratigraphy and sedimentation across the Murray Basin, southeastern AustraliaMiranda, J. A. January 2007 (has links)
The Late Neogene sedimentary sequence of the Murray Basin provides an excellent opportunity to examine paleoenvironmental change across southeastern Australia. A detailed stratigraphic analysis of sediments deposited within the basin in the last 10 Ma was undertaken to assess the influence of tectonic and eustatic processes on deposition. / Stratigraphic observations and radiogenic isotope analysis reveals the onset of deposition by 7.2 Ma with a transgressive episode that deposited the marine marls of the Bookpurnong Beds. Deposition was restricted to the central and eastern parts of the basin due to the Hamley Fault. In the west, subsurface elevation contours indicate the presence of incised paleodrainage channels above Miocene limestones, which facilitated the formation of a large estuary system at 5.3 Ma. The sediments of the Norwest Bend Formation were deposited within this western region, while further east, the Loxton-Parilla Sands strandplain deposited over 214 coastal ridges. The basal parts of this unit occur as lateral equivalents to the sediments of the Lower Norwest Bend Formation (in the west). Topographic and magnetic data reveal that tectonism was active during this period and resulted in the erosion and truncation of strandlines. / Tectonic evidence and an estimated minimum 28,037 year cyclicity between strandline sets, suggests that the Loxton-Parilla Sands strandlines do not represent an unbroken record of glacioeustatic change. The subaerial exposure of these sediments at approximately 3.0 Ma caused the formation of a calcareous karst above the Norwest Bend Formation and a ferruginous and/or silicious cap (the Karoonda Surface) above the Loxton-Parilla Sands. The stratigraphic position of these surfaces are indicative of a regional widespread unconformity. / The Douglas-Blackburn paleodrainage system in western Victoria was dammed during the Mid-Late Pliocene by uplift associated with the Padthaway High, which caused the formation of a 400,000 km2 lacustrine system, known as Lake Bungunnia. Topographic analysis indicates that Lake Bungunnia comprised at least four distinct sub-basins with water depths of up to 30 metres, with lake shorelines indicating that active tectonism occurred during this period. The resulting lack of sediment input to the coast caused the formation of the Kanawinka Escarpment, a large erosional scarp along the southern margin of the Padthaway High. / The geomorphology of the modern Murray Basin can be directly attributed to the demise of the Lake Bungunnia system. Movement along the Morgan Fault in the west at approximately 700 Ka, resulted in the draining and progressive drying of Lake Bungunnia as a breach was created along the Padthaway High. The Murray River gorge as observed today was incised following this episode. The modern Murray River (and playa lakes such as Lake Tyrell) occupy the lowest elevations along the former sub-basins of Lake Bungunnia. / The Late Neogene sedimentary sequence across the Murray Basin illustrates a complex interaction of eustatic and tectonic processes on deposition. Sedimentation within strandline, estuarine and lacustrine systems, particularly in the western Murray Basin, display evidence of significant tectonic control. This highlights the important role that neotectonic processes have played in shaping southeastern Australia.
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Palinologia de seções selecionadas do neógeno da Bacia de Pelotas, RS, BrasilSilva, Wagner Guimarães da January 2011 (has links)
As informações palinológicas da Bacia do Pelotas são relativamente escassas para a seção pré-quaternária, ensejando estudos sistematizados, iniciados nos últimos anos. Com base na análise bioestratigráfica e a técnica de palinofácies, este trabalho apresenta resultados palinológicos obtidos de testemunhos de sondagem de três poços selecionados da bacia: 2-CA-1-RS, 2-TG-96-RS e BP-01 para investigar as variações paleoambientais preservadas nos depósitos neogenos e obtenção de datações relativas. Condições de deposição em ambiente marinho foram registradas para os três poços, com variações significativas entre eles. No poço 2-CA-1-RS, as formas registradas de dinoflagelados nas amostras basais caracterizam ambiente plataformal de nerítico médio a profundo, enquanto os níveis superiores são interpretados como nerítico interno. Para o poço 2-TG-96-RS, o padrão de distribuição da matéria orgânica particulada (mop) e as espécies de dinoflagelados registradas sugerem deposição em condições de ambiente nerítico interno, em todas as amostras. Entretanto, a maior representatividade da mop continental, nos níveis de topo, caracteriza certa proximidade com o continente. De maneira geral, é verificada uma tendência regressiva para os poços 2-CA-1-RS e 2-TG-96-RS. A distribuição da mop ao longo da seção estudada do poço BP-01 indicam condições marinhas distais. Esses resultados são distintos dos dois outros poços. As associações de dinoflagelados somadas aos demais palinomorfos registrados sugerem condições de deposição da seção, entre o ambiente nerítico externo a oceânico. Os resultados encontram apoio na literatura disponível sobre os mesmos poços assim como em outros trabalhos sobre a evolução geológica geral da bacia, durante o Neógeno. Espécies-índices foram identificadas nas associações palinológicas; dinoflagelados foram mais úteis para o posicionamento bioestratigráfico das seções. A seção estudada do poço 2-CA-1-RS é datada entre o Mioceno inferior–Pleistoceno inferior; do poço 2-TG-96-RS entre o Mioceno superior–Plioceno inferior; e do poço BP-01 no Mioceno inferior. Esses resultados demonstram o potencial de aplicação da palinologia para a interpretação paleoambiental e bioestratigráfica da Bacia de Pelotas. / Palynological data for the pre-Quaternary section from the Pelotas Basin are relatively scarce; in this way, systematic studies have been started in this theme from the last years. This work presents palynological results obtained from core samples collected in three selected wells: 2-CA-1-RS, 2-TG-96-RS and BP-01, based on biostratigraphy and palynofacies analyses, to offer their relative ages and paleoenvironmental changes. Marine environment depositional conditions were recorded for the three wells, with significant changes among them. For the 2-CA-1-RS well, assemblages from the basal samples characterize neritic to distal shelfl marine environments, while associations recorded from upper samples suggest proximal marine environment. The particulate organic matter (mop) distribution pattern and the dinoflagellate cysts species registered from the well 2-TG-96-RS suggest a depositional inner neritic environment, for all samples. However, the great representation of continental mop in the upper section of this well allows to indicate a closeness to the continental environment. In general terms, a regressive trend for the 2-CA-1-RS and 2- TG-96-RS wells is recognized. The distribution of mop along the BP-01 well samples suggest distal marine conditions. These results are different from the other two wells. The dinoflagellate associations, along with the other recorded palynomorphs, suggest that this section developed between the outer neritic and oceanic environments. These results are in accordance with the available literature from the same well as well as other studies on the general geological succession of the basin, during the Neogene. Index species were identified among the palynologic associations; dinoflagellates were more useful for biostratigraphic positioning of the sections. The study section of the 2- CA-1-RS is dated between the lower Miocene and the lower Pleistocene; samples from the 2-TG-96-RS are regarded as upper Miocene to Lower Pliocene; section of the BP- 01 is dated as lower Miocene. These results demonstrate the application potential of palynology to interpret the paleoenvironment and biostratigraphy of the Pelotas Basin.
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Palinologia de seções selecionadas do neógeno da Bacia de Pelotas, RS, BrasilSilva, Wagner Guimarães da January 2011 (has links)
As informações palinológicas da Bacia do Pelotas são relativamente escassas para a seção pré-quaternária, ensejando estudos sistematizados, iniciados nos últimos anos. Com base na análise bioestratigráfica e a técnica de palinofácies, este trabalho apresenta resultados palinológicos obtidos de testemunhos de sondagem de três poços selecionados da bacia: 2-CA-1-RS, 2-TG-96-RS e BP-01 para investigar as variações paleoambientais preservadas nos depósitos neogenos e obtenção de datações relativas. Condições de deposição em ambiente marinho foram registradas para os três poços, com variações significativas entre eles. No poço 2-CA-1-RS, as formas registradas de dinoflagelados nas amostras basais caracterizam ambiente plataformal de nerítico médio a profundo, enquanto os níveis superiores são interpretados como nerítico interno. Para o poço 2-TG-96-RS, o padrão de distribuição da matéria orgânica particulada (mop) e as espécies de dinoflagelados registradas sugerem deposição em condições de ambiente nerítico interno, em todas as amostras. Entretanto, a maior representatividade da mop continental, nos níveis de topo, caracteriza certa proximidade com o continente. De maneira geral, é verificada uma tendência regressiva para os poços 2-CA-1-RS e 2-TG-96-RS. A distribuição da mop ao longo da seção estudada do poço BP-01 indicam condições marinhas distais. Esses resultados são distintos dos dois outros poços. As associações de dinoflagelados somadas aos demais palinomorfos registrados sugerem condições de deposição da seção, entre o ambiente nerítico externo a oceânico. Os resultados encontram apoio na literatura disponível sobre os mesmos poços assim como em outros trabalhos sobre a evolução geológica geral da bacia, durante o Neógeno. Espécies-índices foram identificadas nas associações palinológicas; dinoflagelados foram mais úteis para o posicionamento bioestratigráfico das seções. A seção estudada do poço 2-CA-1-RS é datada entre o Mioceno inferior–Pleistoceno inferior; do poço 2-TG-96-RS entre o Mioceno superior–Plioceno inferior; e do poço BP-01 no Mioceno inferior. Esses resultados demonstram o potencial de aplicação da palinologia para a interpretação paleoambiental e bioestratigráfica da Bacia de Pelotas. / Palynological data for the pre-Quaternary section from the Pelotas Basin are relatively scarce; in this way, systematic studies have been started in this theme from the last years. This work presents palynological results obtained from core samples collected in three selected wells: 2-CA-1-RS, 2-TG-96-RS and BP-01, based on biostratigraphy and palynofacies analyses, to offer their relative ages and paleoenvironmental changes. Marine environment depositional conditions were recorded for the three wells, with significant changes among them. For the 2-CA-1-RS well, assemblages from the basal samples characterize neritic to distal shelfl marine environments, while associations recorded from upper samples suggest proximal marine environment. The particulate organic matter (mop) distribution pattern and the dinoflagellate cysts species registered from the well 2-TG-96-RS suggest a depositional inner neritic environment, for all samples. However, the great representation of continental mop in the upper section of this well allows to indicate a closeness to the continental environment. In general terms, a regressive trend for the 2-CA-1-RS and 2- TG-96-RS wells is recognized. The distribution of mop along the BP-01 well samples suggest distal marine conditions. These results are different from the other two wells. The dinoflagellate associations, along with the other recorded palynomorphs, suggest that this section developed between the outer neritic and oceanic environments. These results are in accordance with the available literature from the same well as well as other studies on the general geological succession of the basin, during the Neogene. Index species were identified among the palynologic associations; dinoflagellates were more useful for biostratigraphic positioning of the sections. The study section of the 2- CA-1-RS is dated between the lower Miocene and the lower Pleistocene; samples from the 2-TG-96-RS are regarded as upper Miocene to Lower Pliocene; section of the BP- 01 is dated as lower Miocene. These results demonstrate the application potential of palynology to interpret the paleoenvironment and biostratigraphy of the Pelotas Basin.
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Palinologia de seções selecionadas do neógeno da Bacia de Pelotas, RS, BrasilSilva, Wagner Guimarães da January 2011 (has links)
As informações palinológicas da Bacia do Pelotas são relativamente escassas para a seção pré-quaternária, ensejando estudos sistematizados, iniciados nos últimos anos. Com base na análise bioestratigráfica e a técnica de palinofácies, este trabalho apresenta resultados palinológicos obtidos de testemunhos de sondagem de três poços selecionados da bacia: 2-CA-1-RS, 2-TG-96-RS e BP-01 para investigar as variações paleoambientais preservadas nos depósitos neogenos e obtenção de datações relativas. Condições de deposição em ambiente marinho foram registradas para os três poços, com variações significativas entre eles. No poço 2-CA-1-RS, as formas registradas de dinoflagelados nas amostras basais caracterizam ambiente plataformal de nerítico médio a profundo, enquanto os níveis superiores são interpretados como nerítico interno. Para o poço 2-TG-96-RS, o padrão de distribuição da matéria orgânica particulada (mop) e as espécies de dinoflagelados registradas sugerem deposição em condições de ambiente nerítico interno, em todas as amostras. Entretanto, a maior representatividade da mop continental, nos níveis de topo, caracteriza certa proximidade com o continente. De maneira geral, é verificada uma tendência regressiva para os poços 2-CA-1-RS e 2-TG-96-RS. A distribuição da mop ao longo da seção estudada do poço BP-01 indicam condições marinhas distais. Esses resultados são distintos dos dois outros poços. As associações de dinoflagelados somadas aos demais palinomorfos registrados sugerem condições de deposição da seção, entre o ambiente nerítico externo a oceânico. Os resultados encontram apoio na literatura disponível sobre os mesmos poços assim como em outros trabalhos sobre a evolução geológica geral da bacia, durante o Neógeno. Espécies-índices foram identificadas nas associações palinológicas; dinoflagelados foram mais úteis para o posicionamento bioestratigráfico das seções. A seção estudada do poço 2-CA-1-RS é datada entre o Mioceno inferior–Pleistoceno inferior; do poço 2-TG-96-RS entre o Mioceno superior–Plioceno inferior; e do poço BP-01 no Mioceno inferior. Esses resultados demonstram o potencial de aplicação da palinologia para a interpretação paleoambiental e bioestratigráfica da Bacia de Pelotas. / Palynological data for the pre-Quaternary section from the Pelotas Basin are relatively scarce; in this way, systematic studies have been started in this theme from the last years. This work presents palynological results obtained from core samples collected in three selected wells: 2-CA-1-RS, 2-TG-96-RS and BP-01, based on biostratigraphy and palynofacies analyses, to offer their relative ages and paleoenvironmental changes. Marine environment depositional conditions were recorded for the three wells, with significant changes among them. For the 2-CA-1-RS well, assemblages from the basal samples characterize neritic to distal shelfl marine environments, while associations recorded from upper samples suggest proximal marine environment. The particulate organic matter (mop) distribution pattern and the dinoflagellate cysts species registered from the well 2-TG-96-RS suggest a depositional inner neritic environment, for all samples. However, the great representation of continental mop in the upper section of this well allows to indicate a closeness to the continental environment. In general terms, a regressive trend for the 2-CA-1-RS and 2- TG-96-RS wells is recognized. The distribution of mop along the BP-01 well samples suggest distal marine conditions. These results are different from the other two wells. The dinoflagellate associations, along with the other recorded palynomorphs, suggest that this section developed between the outer neritic and oceanic environments. These results are in accordance with the available literature from the same well as well as other studies on the general geological succession of the basin, during the Neogene. Index species were identified among the palynologic associations; dinoflagellates were more useful for biostratigraphic positioning of the sections. The study section of the 2- CA-1-RS is dated between the lower Miocene and the lower Pleistocene; samples from the 2-TG-96-RS are regarded as upper Miocene to Lower Pliocene; section of the BP- 01 is dated as lower Miocene. These results demonstrate the application potential of palynology to interpret the paleoenvironment and biostratigraphy of the Pelotas Basin.
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Paleohydrology and Paleoecology of the Neogene Siwalik rocks, Nepalese Himalaya using multi-proxy lipid biomarker isotopic studyNeupane, Prabhat Chandra 19 May 2017 (has links)
This study deploys compound-specific multi-proxy isotopic study of lipid biomarkers to understand Neogene climatic and ecological variabilities in the Himalayan foreland. The investigation of compound-specific carbon and hydrogen isotopes along with glycerol dialkyl glycerol tetraether (GDGT) is the first of its kind for the Nepalese Siwalik. A total of 49 mudstone (and some paleosol) samples were collected from the paleomagnetically age-constrained Siwalik strata in the Surai Khola and Karnali River sections.
δ13C results suggest a domination of C3 trees between 12 and 8.5 Ma, and a stepwise expansion of C4 grasses starting gradually at 8.5 Ma and culminating rapidly around 5.5 Ma. δD results show an overall gradual increase in rainfall since 12 Ma, with a rapid intensification around 5.5 Ma. The negative correlation between rainfall and GDGT-derived paleotemperature prior to 5.5 Ma indicates that the region experienced higher rainfalls during colder periods and vice versa. We propose that this negative correlation could be related to the strong presence of mid-latitude westerlies in the region because of the subdued Himalayas, when summer monsoon winds were weaker, that brought enhanced winter-precipitation particularly during colder periods. After 5.5 Ma, our data show a conspicuous positive correlation between rainfall and annual temperature, indicating the onset of modern-style seasonality in rainfall in the Indian subcontinent, which generates more rainfall during summer than during winter. Notably, this initiation of the Indian monsoon around 5.5 Ma favored the dominance of C4 grasses over C3 trees that is reflected in our δ13C data.
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The Mammalian Geochronology and Biogeography of Paşalar (Middle Miocene, Turkey)Bernor, Raymond L., Tobien, Heinz 01 January 1990 (has links)
The Paşalar fauna includes 56 mammalian species of European. Asian, African and North American origin. Evidence provided on the stage-of-evolution of the primates Sivapithecus darwini and cf. Kenyapithecus, the rodent Turkomys pasalarensis, insectivores, carnivores, rhinos, suids and ruminants suggests that Paşalar is correlative with the Late Langhian marine stage and European Mammal Neogene Zone 6., circa 15 Ma (million years ago). A review of the Paşalar fauna's biogeographic history suggests that it was aggregated by a succession of pulsed intercontinental geographic extensions tied to global sea-level lowering events during the earlier half of the Miocene.
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Palaeoenvironment of Late Neogene Lacustrine Sediments at the Gray Fossil Site, Tennessee, USAWorobiec, Elzbieta, Liu, Yu Sheng Christopher, Zavada, Michael S. 31 July 2013 (has links)
A new palaeopalynological investigation was conducted on 15 samples from four test-pits at the Gray Fossil Site (Bear Pit, Elephant Pit, Test Pit 2-2010, and Rhino Pit). In total, 50 morpho-species of miospores (including five species of spores, eight species of gymnosperm pollen, and 37 species of angiosperm pollen) and 18 morpho-species of freshwater algal micro-remains were identified. One new morphological species, related to zygospores of the Zygnemataceae, Stigmozygodites grayensis sp. nov., is proposed. The assemblage of fossil algae recovered provides insights into the palaeoenvironmental conditions of the uppermost (125 cm) part of the Gray Fossil Site sedimentary cover, deposited after the formation of a number of sinkholes, and the fill of the palaeosinkholes. Most of the algae identified prefer meso-to eutrophic conditions and are characteristic of stagnant to slowly flowing shallow fresh water. Therefore, the lacustrine fossiliferous sediments at the Gray Fossil Site represent pond deposits. The palaeopalynological analysis revealed differences in the composition of the miospore and algal assemblages of the pits studied, suggesting that the Test Pit 2-2010, Bear, and Elephant pits are similar and may have been formed in the same pond, while the presence of a higher percentage of algae in the Rhino Pit may indicate sedimentation in a separate water body.
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Palaeoenvironment of Late Neogene Lacustrine Sediments at the Gray Fossil Site, Tennessee, USAWorobiec, Elzbieta, Liu, Yu Sheng Christopher, Zavada, Michael S. 31 July 2013 (has links)
A new palaeopalynological investigation was conducted on 15 samples from four test-pits at the Gray Fossil Site (Bear Pit, Elephant Pit, Test Pit 2-2010, and Rhino Pit). In total, 50 morpho-species of miospores (including five species of spores, eight species of gymnosperm pollen, and 37 species of angiosperm pollen) and 18 morpho-species of freshwater algal micro-remains were identified. One new morphological species, related to zygospores of the Zygnemataceae, Stigmozygodites grayensis sp. nov., is proposed. The assemblage of fossil algae recovered provides insights into the palaeoenvironmental conditions of the uppermost (125 cm) part of the Gray Fossil Site sedimentary cover, deposited after the formation of a number of sinkholes, and the fill of the palaeosinkholes. Most of the algae identified prefer meso-to eutrophic conditions and are characteristic of stagnant to slowly flowing shallow fresh water. Therefore, the lacustrine fossiliferous sediments at the Gray Fossil Site represent pond deposits. The palaeopalynological analysis revealed differences in the composition of the miospore and algal assemblages of the pits studied, suggesting that the Test Pit 2-2010, Bear, and Elephant pits are similar and may have been formed in the same pond, while the presence of a higher percentage of algae in the Rhino Pit may indicate sedimentation in a separate water body.
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Vitis Seeds (Vitaceae) From the Late Neogene Gray Fossil Site, Northeastern Tennessee, U.S.A.Gong, Fade, Karsai, Istvan, Liu, Yu Sheng C. 01 August 2010 (has links)
This study focuses on morphometric and systematic analyses of the fossil Vitis seeds, recovered from the Gray Fossil Site (7-4.5. Ma, latest Miocene-earliest Pliocene), northeastern Tennessee, U.S.A. A multivariate analysis based on eleven measured characters from 76 complete fossil seeds recognizes three morphotaxa. Further comparisons with both selected modern and fossil vitaceous specimens confirm that these morphotaxa represent three new species, viz. Vitis grayensis sp. nov., Vitis lanatoides sp. nov., and Vitis latisulcata sp. nov. Furthermore, the close resemblance of the first two fossil grapes (V. grayensis and V. lanatoides) with two East Asian Vitis species provides further support concerning a strong eastern Asian aspect of the Gray fossil biota in the late Neogene southeastern North America, as previously evidenced by both animals (e.g. Pristinailurus bristoli [red panda]) and other plants (e.g. Sinomenium and Sargentodoxa).
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<em>Vitis</em> Seeds (Vitaceae) from the Late Neogene Gray Fossil Site, Northeastern Tennessee, USA.Gong, Fade 19 December 2009 (has links) (PDF)
This study focuses on the morphometric and systematic studies of fossil vitaceous seeds recently recovered from the Gray Fossil Site (7-4.5 Ma, latest Miocene-earliest Pliocene) northeastern Tennessee. Morphologically, all fossil seeds correspond to the extant subgenus Vitis (genus Vitis) of the Vitaceae based on the smooth dorsal surface with a centrally positioned chalaza connected with a conspicuous chalaza-apex groove and short linear ventral infolds that are slightly diverged apically. A multivariate analysis based on 11 measured characters from 76 complete seeds identified three types of seeds, each representing a distinct morphotaxon. Based on comparison with modern and fossil vitaceous specimens, three new species were recognized: Vitis grayana sp. nov., Vitis lanatoides sp. nov., and Vitis latisulcata sp.nov. The close resemblance between the first two fossil grapes (Vitis grayana and Vitis lanatoides) with extant eastern Asian Vitis provides further evidence that the eastern Asian floristic elements existing in the southeastern North American flora continued to as late as late Neogene.
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