78 research outputs found
Clay Neomineralization and the Timing, Thermal Conditions and Geofluid History of Upper Crustal Deformation Zones
Corrigendum notice for Chapter VI follows the title page.The various occurrences of clay neomineralization often coincide with zones of crustal deformation, making this family of minerals uniquely suited to record and retain the temperature, timing, and chemical conditions of upper crustal deformation. This dissertation comprises a suite of studies that employ various aspects of clay mineralogy, crystallography and clay chemistry to answer major questions in regional structural geology. These studies are diverse in their geography, timing and structural/tectonic setting, while united in their utilization of applied clay science. A key methodological tool used in these investigations is the illite polytype analysis method. An important contribution is the refinement of this method, both improving its accuracy by using state-of-the-art, Rietveld-type quantitative X-ray powder diffraction techniques, as well as broadening its application to include H isotopic analysis.
Chapter I serves to preface the dissertation and includes an introduction to practical aspects of clay mineralogy that distinguish them as geochronometers, geothermometers, and stable isotopic recorders. It outlines how the 3-dimensional arrangement of mineral populations and the properties of clays can be useful in understanding the structural history and mechanical behavior of deformed rock. Chapter II presents a new illite polytype analysis technique that represents significant advances on prior approaches, which is further utilized in subsequent chapters. Chapter III constrains the timing, temperatures, and mineralizing fluid characteristics of clays present in principal slip zone gouges from the Alpine Fault Zone (New Zealand), and concludes that both illitic and chloritic material in the fault zone are recent, surface-localized alteration. Chapter IV is an experimental study of temperature-dependent hydration behavior of natural smectite from the borehole of the Japan Trench Fast Drilling Project, which provides physical limits for estimates of coseismic heating during the 2011 Tohoku earthquake of 5 km in the upper crust. Chapter VI is a study of diagenetic illite in mudstones of the Appalachian Plateau. The study presents evidence that mineralization timing (Early-Mid Triassic) coincides with the timing of maximum burial, and, therefore, hottest basinal temperatures, and that the fluid was surface-derived at spatial scales small enough to preserve a rain shadow effect from the nearby Appalachian orogen. This study challenges reigning views on tectonically-mobilized, older fluid flow for associated geologic processes. Chapter VII offers concluding remarks that highlight the main themes of this dissertation. Three appendices are included, presenting data tables and preliminary results of ongoing research efforts on pseudotachylytes from gneiss-dome bounding faults (Papua New Guinea), a fault dating campaign in the Istanbul Zone of northwest Turkey, and isotopic work on clay minerals recovered from principal slip zones in the San Andreas Fault Observatory at Depth borehole.
The overarching themes of the dissertation are the fingerprinting and timing of surface-derived (meteoric) signals in authigenic clay phases that formed at shallow to mid-crustal depths in major fault zones. This requires significant down-dip fluid flow. Emphasis is placed on how pre-existing, deep-seated weaknesses in the crust control deformation styles and facilitate fluid flow and mineralization, and on insights into the nature of deformation-related fluid flow and clay authigenesis.PHDEarth and Environmental SciencesUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttps://deepblue.lib.umich.edu/bitstream/2027.42/136996/4/aboles_1.pd
[Study Protocol] Palliative long-term abdominal drains versus repeated drainage in individuals with untreatable ascites due to advanced cirrhosis: study protocol for a feasibility randomised controlled trial
Background: UK deaths due to chronic liver diseases such as cirrhosis have quadrupled over the last 40 years, making this condition now the third most common cause of premature death. Most patients with advanced cirrhosis (end–stage liver disease, [ESLD]) develop ascites. This is often managed with diuretics, but if refractory then the fluid is drained from the peritoneal cavity every 10-14 days by large volume paracentesis (LVP), a procedure requiring hospital admissions. As the life expectancy of patients with ESLD and refractory ascites (if ineligible for liver transplantation) is on average ≤ 6 months, frequent hospital visits are inappropriate from a palliative perspective. One alternative is long-term abdominal drains (LTAD), used successfully in patients whose ascites is due to malignancy. Although inserted in hospital, these drains allow ascites management outside of a hospital setting. LTAD have not been formally evaluated in patients with refractory ascites due to ESLD.
Methods: Due to uncertainty about appropriate outcome measures and whether patients with ESLD would wish or be able to participate in a study, a feasibility randomised controlled trial (RCT) was designed. Patients were consulted on trial design. We plan to recruit 48 patients with refractory ascites and randomise them (1:1) to either a) LTAD or b) current standard of care (LVP) for 12 weeks. Outcomes of interest include acceptability of LTAD to patients, carers and healthcare professionals as well as recruitment and retention rates. Palliative care Outcome Scale (IPOS), the Short Form Liver Disease Quality of Life (SF-LDQOL), the EuroQol (EQ-5D) and carer (Zarit Burden Interview [ZBI-12]) reported outcomes will also be assessed. Preliminary data on cost effectiveness will be collected and patients and healthcare professionals will be interviewed about their experience of the trial with a view to identifying barriers to recruitment.
Discussion: LTAD could potentially improve end-of-life care in patients with refractory ascites due to ESLD by improving symptom control, reducing hospital visits and enabling some self-management. Our trial is designed to see if such patients can be recruited, as well as informing the design of a subsequent definitive trial.
Trial registration: ISRCTN30697116, date assigned: 07/10/201
Hydrogen and 40Ar/39Ar isotope evidence for multiple and protracted paleofluid flow events within the long‐lived North Anatolian Keirogen (Turkey)
We present a new approach to identifying the source and age of paleofluids associated with low‐temperature deformation in the brittle crust, using hydrogen isotopic compositions (δD) and 40Ar/39Ar geochronology of authigenic illite in clay gouge‐bearing fault zones. The procedure involves grain‐size separation, polytype modeling, and isotopic analysis, creating a mixing line that is used to extrapolate to δD and age of pure authigenic and detrital material. We use this method on samples collected along the surface trace of today's North Anatolian Fault (NAF). δD values of the authigenic illite population, obtained by extrapolation, are −89 ± 3‰, −90 ± 2‰, and −97 ± 2‰ (VSMOW) for samples KSL, RES4‐1, and G1G2, respectively. These correspond to δD fluid values of −62‰ to −85‰ for the temperature range of 125°C ± 25°, indistinguishable from present‐day precipitation values. δD values of the detrital illite population are −45 ± 13‰, −60 ± 6‰, and −64 ± 6‰ for samples KSL, G1G2, and RES4‐1, respectively. Corresponding δD fluid values at 300°C are −26‰ to −45‰ and match values from adjacent metamorphic terranes. Corresponding clay gouge ages are 41.4 ± 3.4 Ma (authigenic) and 95.8 ± 7.7 Ma (detrital) for sample G2 and 24.6 ± 1.6 Ma (authigenic) and 96.5 ± 3.8 Ma (detrital) for sample RES4‐1, demonstrating a long history of meteoric fluid infiltration in the area. We conclude that today's NAF incorporated preexisting, weak clay‐rich rocks that represent earlier mineralizing fluid events. The samples preserve at least three fluid flow pulses since the Eocene and indicate that meteoric fluid has been circulating in the upper crust in the North Anatolian Keirogen since that time.Key Points:Illite preserves the hydrogen isotopic signature and age of paleofluids in the earth's upper crustThree fluid events are pinpointed in the NAKThe NAF exploited zones of preexisting weak clay material during its formationPeer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/112210/1/ggge20754.pd
Mapping past human land use using archaeological data: A new classification for global land use synthesis and data harmonization
In the 12,000 years preceding the Industrial Revolution, human activities led to significant changes in land cover, plant and animal distributions, surface hydrology, and biochemical cycles. Earth system models suggest that this anthropogenic land cover change influenced regional and global climate. However, the representation of past land use in earth system models is currently oversimplified. As a result, there are large uncertainties in the current understanding of the past and current state of the earth system. In order to improve repre- sentation of the variety and scale of impacts that past land use had on the earth system, a global effort is underway to aggregate and synthesize archaeological and historical evi- dence of land use systems. Here we present a simple, hierarchical classification of land use systems designed to be used with archaeological and historical data at a global scale and a schema of codes that identify land use practices common to a range of systems, both imple- mented in a geospatial database. The classification scheme and database resulted from an extensive process of consultation with researchers worldwide. Our scheme is designed to deliver consistent, empirically robust data for the improvement of land use models, while simultaneously allowing for a comparative, detailed mapping of land use relevant to the needs of historical scholars. To illustrate the benefits of the classification scheme and meth- ods for mapping historical land use, we apply it to Mesopotamia and Arabia at 6 kya (c. 4000 BCE). The scheme will be used to describe land use by the Past Global Changes (PAGES) LandCover6k working group, an international project comprised of archaeologists, historians, geographers, paleoecologists, and modelers. Beyond this, the scheme has a wide utility for creating a common language between research and policy communities, link- ing archaeologists with climate modelers, biodiversity conservation workers and initiatives.publishedVersio
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Mapping past human land use using archaeological data: A new classification for global land use synthesis and data harmonization.
In the 12,000 years preceding the Industrial Revolution, human activities led to significant changes in land cover, plant and animal distributions, surface hydrology, and biochemical cycles. Earth system models suggest that this anthropogenic land cover change influenced regional and global climate. However, the representation of past land use in earth system models is currently oversimplified. As a result, there are large uncertainties in the current understanding of the past and current state of the earth system. In order to improve representation of the variety and scale of impacts that past land use had on the earth system, a global effort is underway to aggregate and synthesize archaeological and historical evidence of land use systems. Here we present a simple, hierarchical classification of land use systems designed to be used with archaeological and historical data at a global scale and a schema of codes that identify land use practices common to a range of systems, both implemented in a geospatial database. The classification scheme and database resulted from an extensive process of consultation with researchers worldwide. Our scheme is designed to deliver consistent, empirically robust data for the improvement of land use models, while simultaneously allowing for a comparative, detailed mapping of land use relevant to the needs of historical scholars. To illustrate the benefits of the classification scheme and methods for mapping historical land use, we apply it to Mesopotamia and Arabia at 6 kya (c. 4000 BCE). The scheme will be used to describe land use by the Past Global Changes (PAGES) LandCover6k working group, an international project comprised of archaeologists, historians, geographers, paleoecologists, and modelers. Beyond this, the scheme has a wide utility for creating a common language between research and policy communities, linking archaeologists with climate modelers, biodiversity conservation workers and initiatives
Mapping past human land use using archaeological data: A new classification for global land use synthesis and data harmonization
In the 12,000 years preceding the Industrial Revolution, human activities led to significant changes in land cover, plant and animal distributions, surface hydrology, and biochemical cycles. Earth system models suggest that this anthropogenic land cover change influenced regional and global climate. However, the representation of past land use in earth system models is currently oversimplified. As a result, there are large uncertainties in the current understanding of the past and current state of the earth system. In order to improve representation of the variety and scale of impacts that past land use had on the earth system, a global effort is underway to aggregate and synthesize archaeological and historical evidence of land use systems. Here we present a simple, hierarchical classification of land use systems designed to be used with archaeological and historical data at a global scale and a schema of codes that identify land use practices common to a range of systems, both implemented in a geospatial database. The classification scheme and database resulted from an extensive process of consultation with researchers worldwide. Our scheme is designed to deliver consistent, empirically robust data for the improvement of land use models, while simultaneously allowing for a comparative, detailed mapping of land use relevant to the needs of historical scholars. To illustrate the benefits of the classification scheme and methods for mapping historical land use, we apply it to Mesopotamia and Arabia at 6 kya (c. 4000 BCE). The scheme will be used to describe land use by the Past Global Changes (PAGES) LandCover6k working group, an international project comprised of archaeologists, historians, geographers, paleoecologists, and modelers. Beyond this, the scheme has a wide utility for creating a common language between research and policy communities, linking archaeologists with climate modelers, biodiversity conservation workers and initiatives
Productivity loss and indirect costs associated with cardiovascular events and related clinical procedures
Quorum sensing in veterinary pathogens: Mechanisms, clinical importance and future perspectives
Bedrock geology of DFDP-2B, central Alpine Fault, New Zealand
<p>During the second phase of the Alpine Fault, Deep Fault Drilling Project (DFDP) in the Whataroa River, South Westland, New Zealand, bedrock was encountered in the DFDP-2B borehole from 238.5–893.2 m Measured Depth (MD). Continuous sampling and meso- to microscale characterisation of whole rock cuttings established that, in sequence, the borehole sampled amphibolite facies, Torlesse Composite Terrane-derived schists, protomylonites and mylonites, terminating 200–400 m above an Alpine Fault Principal Slip Zone (PSZ) with a maximum dip of 62°. The most diagnostic structural features of increasing PSZ proximity were the occurrence of shear bands and reduction in mean quartz grain sizes. A change in composition to greater mica:quartz + feldspar, most markedly below c. 700 m MD, is inferred to result from either heterogeneous sampling or a change in lithology related to alteration. Major oxide variations suggest the fault-proximal Alpine Fault alteration zone, as previously defined in DFDP-1 core, was not sampled.</p
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