Author: M.J. Flowerdew
Publisher:
ISBN:
Category :
Languages : en
Pages :

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Author: M. Satish-Kumar
Publisher: Geological Society of London
ISBN: 9781862392687
Category : Science
Languages : en
Pages : 472

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Geological correlations of East Antarctica with adjoining continents have been puzzling geologists ever since the concept of a Gondwana supercontinent surfaced. Despite the paucity of outcrops because of ice cover, difficulty of access and extreme weather, the past 50 years of Japanese Antarctic Research Expeditions (JARE) has successfully revealed vital elements of the geology of East Antarctica. This volume presents reviews and new research from localities across East Antarctica, especially from Dronning Maud Land to Enderby Land, where the geological record preserves a history that spans the Archaean and Proterozoic. The reviews include extensive bibliographies of results obtained by geologists who participated in the JARE. Comprehensive geological, petrological and geochemical studies, form a platform for future research on the formation and dispersion of Rodinia in the Mesoproterozoic and subsequent assembly of Gondwana in the Neoproterozoic to Early Palaeozoic.

Author: S.L. Harley
Publisher: Geological Society of London
ISBN: 1862393672
Category : Science
Languages : en
Pages : 241

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Antarctica preserves a rock record that spans three and a half billion years of history and has a remarkable story to tell about the evolution of our Earth, from the hottest crustal rocks yet found in an orogenic system, to the assembly and breakup of Gondwana in the Phanerozoic. This volume highlights our improved understanding of the tectonic events that have shaped Antarctica and how these potentially relate to supercontinent assembly and fragmentation. The internal constitution of the East Antarctic Shield is assessed using information available from the basement geology and from detritus preserved as Mesozoic sediments in the Trans Antarctic Mountains. Accretionary orogenesis along the proto-Pacific margin of Antarctica is examined and the volumes of intracrustal melting compared with juvenile magma additions in these complex orogenic systems assessed. This special volume demonstrates the diversity of approaches required to elucidate and understand crustal evolution and evaluate the supercontinent concept.

Author: Cathy Busby
Publisher: John Wiley & Sons
ISBN: 1444347144
Category : Science
Languages : en
Pages : 1034

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Investigating the complex interplay between tectonics and sedimentation is a key endeavor in modern earth science. Many of the world's leading researchers in this field have been brought together in this volume to provide concise overviews of the current state of the subject. The plate tectonic revolution of the 1960's provided the framework for detailed models on the structure of orogens and basins, summarized in a 1995 textbook edited by Busby and Ingersoll. Tectonics of Sedimentary Basins: Recent Advances focuses on key topics or areas where the greatest strides forward have been made, while also providing on-line access to the comprehensive 1995 book. Breakthroughs in new techniques are described in Section 1, including detrital zircon geochronology, cosmogenic nuclide dating, magnetostratigraphy, 3-D seismic, and basin modelling. Section 2 presents the new models for rift, post-rift, transtensional and strike slip basin settings. Section 3 addresses the latest ideas in convergent margin tectonics, including the sedimentary record of subduction intiation and subduction, flat-slab subduction, and arc-continent collision; it then moves inboard to forearc basins and intra-arc basins, and ends with a series of papers formed under compessional strain regimes, as well as post-orogenic intramontane basins. Section 4 examines the origin of plate interior basins, and the sedimentary record of supercontinent formation. This book is required reading for any advanced student or professional interested in sedimentology, plate tectonics, or petroleum geoscience. Additional resources for this book can be found at: www.wiley.com/go/busby/sedimentarybasins.

Author: John M. Hanchar
Publisher: Walter de Gruyter GmbH & Co KG
ISBN: 1501509322
Category : Science
Languages : en
Pages : 520

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Volume 53 of Reviews in Mineralogy and Geochemistry covers the most important aspects of zircon-related research over the past twenty-years and highlight possible future research avenues. The chapters review the structure of zircon and other mineral (and synthetic) phases with the zircon structure; the minor and trace element compositions of igneous, metamorphic and hydrothermal zircons; the study of melt inclusions in zircon; experimental and natural studies of zircon saturation and the use of zircon saturation thermometry for natural rocks; cation diffusion and oxygen diffusion in zircon; the historical development of zircon geochronology from the mid-1950s to the present; ID-TIMS, SIMS and ICP-MS; the application of zircon chronology in constraining sediment provenance and the calibration ofthe geologic time-scale; other isotopic systematics; the spectroscopy of zircon, both crystalline and metamict and an atlas of internal textures of zircon.

Author: M.J. Flowerdew
Publisher:
ISBN:
Category :
Languages : en
Pages :

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Author: Gwen Margaret Linde
Publisher:
ISBN:
Category : Electronic books
Languages : en
Pages : 360

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This dissertation investigated Neoproterozoic–Devonian units of the western Laurentian passive margin and Roberts Mountains allochthon (RMA) and determined U-Pb detrital ages and Hf isotope zircon analyses that provide new insights into the early Paleozoic tectonics of western Laurentia. The three chapters investigate several difficult questions and contradictions in the understanding of early Paleozoic tectonism in western Laurentia through analysis of sedimentary units. The provenance, depositional histories, and tectonic evolution of the lower Paleozoic sedimentary strata of north-central Nevada have long been subjects of speculation and debate. Detrital zircon U-Pb geochronology and Hf-isotope analyses indicate the provenance, sedimentary distribution patterns, and tectonic evolution of Upper Neoproterozoic–Cambrian passive margin strata and Ordovician–Devonian strata of the RMA, with a special emphasis on the enigmatic Harmony Formation. The study reported in Chapter 1 uses detrital zircon U-Pb geochronology to determine whether or not the Upper Neoproterozoic–Lower Cambrian Osgood Mountain Quartzite and the Upper Cambrian–Lower Ordovician Preble Formation in the Osgood Mountains of northern Nevada were units of the western Laurentian passive margin. Within the Osgood Mountain Quartzite, U-Pb age populations of the detrital zircons shift with stratal age. This shift indicates that the zircons were shed in different proportions from the source terranes, which suggests a change in provenance within the Osgood Mountain Quartzite. These changes are consistent across a Great Basin transect of coeval passive margin strata. The change in provenance is due to a shift in sedimentary transport patterns, which was caused by the Late Neoproterozoic-Early Cambrian uplift of the Transcontinental Arch. This study provided independent corroboration of the existence of the Transcontinental Arch and better precision for the timing at which the Arch uplifted. The study also recorded the impact of the uplifted Arch on continent-wide sediment dispersal patterns—the change in predominant source terranes—and confirmed the Arch as a sediment source for passive-margin strata. Regional coeval changes in detrital zircon U-Pb age patterns provide a correlative tool in unfossiliferous sediments and could be useful in future studies. Chapter 2 describes how detrital zircon U-Pb geochronology and Hf-isotope analyses were used to determine the provenance, sedimentary transport, and tectonic evolution of RMA strata. Workers have speculated for decades, with little agreement, on the origin, depositional basin(s), and subsequent tectonic transport of the RMA. Zircon grains from six Ordovician to Devonian arenite samples were analyzed for U-Pb ages; approximately one-quarter of these grains were further analyzed for Hf isotope ratios. Five of the studied units have similar U-Pb age populations and Hf-isotope ratios, while the U-Pb ages and Hf-ratios of the Ordovician lower Vinini Formation are significantly different. Comparison of these data with known analyses of igneous basement rocks and other sedimentary units of Laurentia reveals that the lower Vinini Formation originated in the north-central Laurentian craton. The other five units, as well as Ordovician passive margin sandstones of the western Laurentian margin, had a common source in the Peace River Arch region of western Canada. All of the RMA strata were deposited near the Peace River Arch region and subsequently tectonically transported south along the Laurentian margin, from where they were emplaced onto the craton during the Antler orogeny. This study determined the origin, location of the depositional basin, and proposed a subsequent tectonic evolution that accounts for origin, deposition, and current location of the RMA strata. Chapter 3 describes the origin, age, and tectonic development of the Harmony Formation. The Harmony Formation has always been difficult to explain—it is mostly an immature feldspathic arenite, which would argue for minimal transport from origin to deposition. However, its general position as the top thrust plate in the RMA stack argues for deposition oceanward of other more texturally mature RMA strata. The age of the Harmony Formation is equally contentious—published age determinations range from Cambrian to Mississippian. Zircon grains from ten arenite samples were analyzed for U-Pb ages; grains from eight of these samples were further analyzed for Hf-isotope ratios. Seven of the arenite units have similar U-Pb age peaks and Hf isotope ratios, whereas three differ significantly. The data confirmed the subdivision of the Harmony Formation into two petrofacies, quartzose (Harmony A) and feldspathic (Harmony B). Harmony A originated in the central Laurentian craton. Harmony B had a common source in eastern Alberta–western Saskatchewan, north of the source of the Harmony A. All of the Harmony Formation strata were deposited near eastern Alberta in Late Neoproterozoic through Cambrian time and subsequently tectonically interleaved with the Roberts Mountains allochthon strata. The entire package was tectonically transported south along the Laurentian margin. Subsequently, it was emplaced eastward onto the craton during the Late Devonian to Early Mississippian Antler orogeny. This study proposed a reasonable solution to one of the longest enduring and most puzzling conundrums of the western Cordillera—the origin, age, and transport of the Harmony Formation. These three studies demonstrated the utility of detrital zircon U-Pb geochronology and Hf-isotope analyses in better understanding difficult sedimentary and tectonic problems. The studies also provided new insights into the Early Paleozoic tectonic evolution of western Laurentian.

Author:
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Category :
Languages : en
Pages : 0

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Provenance study is a fundamental element of basin analysis, where understanding of sedimentation patterns and their driving mechanisms often requires information about the source of basin sediments. Many recent studies have turned to the geochronology (particularly single detrital zircon ages) and isotope geochemistry in sedimentary rocks to derive detailed information about sediment sources. This dissertation applies geochronology and isotope geochemistry to provenance questions in different settings, utilizing zircon U/Pb ages, feldspar common Pb isotope ratios, and carbonate 87Sr/86Sr ratios to gain new insights into provenance in three well-studied sedimentary systems. The first chapter, set in the Gualala Basin of northern California, provides an example of how conventional provenance indicators, detailed study of conglomerate clasts, U/Pb zircon ages, and common Pb isotope ratios of feldspar from the sand-sized fraction can all provide useful information. Combined, these different data types can produce a more complete picture of sedimentary source areas than any of them would be able to alone. In a continued investigation of applications for detrital zircon ages in provenance study, the second chapter develops a new "Confidence Envelope" method for comparing age distributions. The method developed here is based on characterizing the expected range of variability in samples drawn from the age distribution of a proposed sediment source area, and testing whether a sample of unknown provenance falls within that range. Using the uniquely well-constrained setting of the Green River Formation in Wyoming, the last two chapters investigate paleo-water provenance using an unprecedented dataset of 87Sr/86Sr ratios and Sr concentrations, compiled from both new data and data collected from previous studies. These data demonstrate that isotopic ratios in the Green River Formation lacustrine system changed rapidly, therefore lacustrine sediments were an extremely high-resolution recorder of lacustrine Sr evolution

Author: Yan Luo
Publisher:
ISBN: 9781361438718
Category :
Languages : en
Pages :

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This dissertation, "U-Pb Age and Hf Isotopic Study of Detrital Zircons From the Liaohe Group: Constraints on the Evolution of the Jiao-Liao-Ji Belt, North China Craton" by Yan, Luo, 羅彥, was obtained from The University of Hong Kong (Pokfulam, Hong Kong) and is being sold pursuant to Creative Commons: Attribution 3.0 Hong Kong License. The content of this dissertation has not been altered in any way. We have altered the formatting in order to facilitate the ease of printing and reading of the dissertation. All rights not granted by the above license are retained by the author. Abstract: Abstract of thesis entitled U-Pb AGE AND Hf ISOTOPIC STUDY OF DETRITAL ZIRCONS FROM THE LIAOHE GROUP: CONSTRAINTS ON THE EVOLUTION OF THE JIAO-LIAO- JI BELT, NORTH CHINA CRATON Submitted by Luo Yan for the degree of Doctor of Philosophy at The University of Hong Kong in December 2005 The North China Craton (NCC) is the largest and oldest known continental block in China. The Jiao-Liao-Ji mobile belt along the eastern margin of the NCC is one of the rarely preserved Paleoproterozoic integrities in the world. As an important Paleoproterozoic sedimentary sequence of this belt, the Liaohe Group consists of an assemblage that includes a lower arkose- and volcanic-rich sequence (Langzishan, Li'eryu /Gaojiayu Formations), through a middle carbonate-rich sequence (Dashiqiao Formation) to an upper argillaceous sequence (Gaixian Formation). Traditionally, this group was subdivided into the North and South Liaohe Groups. Associated with the Liaohe Group are large volumes of granitoid rocks (Liaoji Granite), whose emplacement age has been dated at 2.1-2.2 Ga. Regionally, the Liaohe Group and the associated Liaoji Granite extend along a NEE-trending belt that is flanked by 2.45-2.55 Ga basement gneisses. Because of the lack of knowledge about the timing of deposition and metamorphism, nature of the sedimentary provenance and the basement, controversy exists on several issues including the depositional environment and tectonic significance of these rocks. The present work aims to constrain key issues by studying U-Pb, Hf isotopic and trace elemental compositions of detrital zircons from the Liaohe Group. Modern analytical technology such as cathodoluminescence (CL) imaging, laser ablation inductively coupled plasma mass spectrometry and laser ablation multiple collector inductively coupled plasma mass spectrometry were employed. CL images reveal that most detrital zircon grains from the Liaohe Group are characterized by concentric oscillatory zoning, suggesting magmatic origin. However, a small number of zircon grains have structureless recrystallization rims, indicating metamorphic origin. Results of this study show that the zoned zircon grains of the Langzishan Formation, the lowest sequence of the Liaohe Group, have concordant U-Pb ages ranging from 2.24-2.05 Ga, suggesting that the minimum depositional time of the Liaohe Group is at 0.2815 and 0.2813), similar Hf model ages (T, peaks at 2.66 Ga 2.75 DM Ga, and 2.8 3.0 Ga) and similar εHf values ( -5 +9 and -7 +5). Data of this study suggest that the metasedimentary rocks of the Liaohe Group were deposited between 2.05 and 1.93 Ga, a short time after emplacement of the Liaoji Granite. The provenance of the Langzishan, Li'eryu and Gaixian Formations, is particularly dominated by the Liaoji Granite. Furthermore, the protoliths of the North and South groups may have formed simultaneously and could have developed on a single late Archean basement rather than two different blocks. This

Author: Thomas R. Lovell
Publisher:
ISBN:
Category : Electronic dissertations
Languages : en
Pages : 178

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Detrital zircon U-Pb geochronology and thin-section petrology of core samples taken from onshore Alabama and offshore federal lease blocks, including Destin Dome, Pensacola, and Mobile, constrain sediment provenance for the Upper Jurassic Norphlet Formation in the eastern Gulf of Mexico. Previous research of the Norphlet Fm. in onshore Alabama suggests that sediments near onshore areas of Alabama originated from metamorphic rocks of the Talladega slate belt and Piedmont. This study provides evidence that the Gondwanan Suwannee terrane is another potential source for the Norphlet Fm. in the EGOM. This study determined U-Pb ages for 1111 detrital zircons from 13 Norphlet Fm. core and cutting samples were determined using LA-ICPMS. The Norphlet Fm. yields four major U-Pb age ranges: 197.9 - 350 Ma, 350 - 770 Ma, 800 - 1650 Ma, and 1650 - 3390 Ma. These ages correspond with known U-Pb ages of source terranes common to Laurentia, including the Grenville (950 - 1300 Ma), (Granite-Rhyolite (1350 - 1550 Ma), Yavapai-Matzatzal (1650 - 1750 Ma), Penokean (1800 - 1900 Ma), and Superior Provinces (>2500 Ma). U-Pb ages also reveal sourcing from the Gondwanan Suwannee Terrane (540 - 580 Ma and 2000 - 2200 Ma). This study establishes four geochronologic source terranes: the ancient Appalachian Mountains, the Appalachian foreland basin, Mesozoic rift basins, and the Suwannee Terrane. Ten samples from onshore Alabama yield detrital zircon U-Pb ages characteristic of Laurentian sources (Appalachian mountains and Appalachian foreland basin), whereas two offshore samples yield characteristic Gondwanan (Suwannee Terrane) ages. Four samples located adjacent to the Mesozoic rift basin reveal ages characteristic of both Laurentia and Gondwana - indicating an area of sediment mixing during the late Jurassic. Twelve thin-sections taken from 9 cores in the onshore and state waters areas were point counted for 400 grains each for compositional analysis. Petrolographic analyses reveal plagioclase and potassium feldspars, polycrystalline quartz, metamorphic and volcanic lithic fragments as dominant grain types. Petrologic data corroborate that onshore Alabama samples were sourced by recycled orogenic and cratonic rocks of Laurentia and southern samples were sourced by less mature sources characteristic of a rift basin (Mesozoic rift basins). A paleogeographic reconstruction illustrates sediment being distributed from Laurentian and Gondwanan sources via alluvial, fluvial, eolian, and marine depositional environments.