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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

The Origin of the Gran Canarian Xenoliths / Ursprunget till Gran Canarias xenoliter

Jägerup, Beatrice January 2016 (has links)
Xenoliths are pieces from the surrounding bedrock, brought to the surface of the earth by host magma. On Gran Canaria, the largest island in the Canary Islands archipelago, strange xenoliths have been found. They are light in color, porous and very different from the basaltic magma carrying them. By studying petrological features and oxygen isotope content of the xenoliths, the focus of this report will be to investigate their origin. The minerals and texture of 14 samples were studied in thin section, and the δ18O–value was determined for 17 samples. The mineralogical composition of xenolith glass was examined by EPMa. The results show that the xenoliths are rich in silica rich glass, quartz and feldspars, but also have high calcium content. 9 of 14 xenoliths have textures and δ18O–values from 8.1 ‰ to 16.77 ‰, similar to sedimentary rocks. The remaining xenoliths are metamorphosed and exhibit altered phenocrysts, indicating they have been melted and recrystallized. The latter group also has extremely low δ18O–value, which could be explained by the effects of hydrothermal processes. Most likely all the xenoliths originate from the prevolcanic sedimentary deposits beneath Gran Canaria.
2

Ceramic thin-section analysis and Early Postclassic to Middle Postclassic discontinuity at Colha, Belize

Reid, Elizabeth Katherine 12 November 2013 (has links)
Petrographic and Type:variety analyses of Colha ceramics are used to investigate changes in ceramic production technology and organization during the Early and Middle Postclassic. Postclassic sherds from Colha are grouped by petrofabric, surface treatment, and modes. This dissertation focuses on the petrofabric analysis of the ceramic sherds. The groupings are then compared to locally available raw materials. Changes in technological homogeneity, production specialization, and origin will be examined and related to the general economy of Postclassic Colha. / text
3

Quantitative paleoenvironmental analysis of carbonate platform sediments on the Marion Plateau (NE Australia, ODP Leg 194)

Sheps, Kathryn 01 November 2004 (has links)
The Marion Plateau is a carbonate-platform complex on the passive northeast Australian margin. During ODP Leg 194, a series of eight sites, on two transects, were drilled through Oligocene to Holocene mixed carbonate and siliciclastic sediments that record the depositional history of the Marion Plateau. Major sediment constituents, including benthic foraminifers, were counted from thin sections made from samples taken from three drilling sites: bryozoan-dominated northern highstand platform site 1193 and northern lowstand ramp site 1194, and coralline red algae-dominated southern platform site 1196. Quantitative multivariate analysis of benthic foraminiferal assemblages revealed three paleoenvironmentally relevant groups of taxa. The first group, dominated by Amphistegina and Lepidocyclina, was found at all three sites and is interpreted to be representative of euphotic open-shelf deposition in less than 50 m water depth. The second group was dominated by Cycloclypeus, Operculina and planktonic foraminifers. This group was found at all three sites, but was more common from sites on the northern platform and is interpreted to represent deposition in deep, oligophotic water, in greater than 50 m water depth. The third group, consisting of soritids, alveolinids, Austrotrillina and Flosculinella, was found only in sediments from the southern platform and is interpreted to represent deposition in a restricted, shallow-marine environment, in less than 20 m water depth, consistent with a sea-grass meadow. These three groups of taxa record changing paleoenvironments on the Marion Plateau, and reveal the depositional histories of the Marion Plateau's carbonate platforms.
4

Lithic technologies of the Discovery Islands: materials, stone tool production, and communities of skilled practitioners

Abbott, Callum William Filan 26 April 2018 (has links)
This thesis explores the findings of a diachronic analysis of three lithic assemblages from Quadra Island, British Columbia. From this, insights flow about the genealogies of technological practice and communities of skilled practitioners who inhabited the study area throughout its deep history. I use qualitative and quantitative methods including macroscopic lithic analysis, thin section petrography, X-ray fluorescence spectrometry, and morphometrics to operationalize these theoretical foundations. This suite of complementary methods and theory weaves a narrative of technological change alongside simultaneous continuity for hundreds of generations of human life. I argue this is evidence of the dynamic, sophisticated, yet enduring knowledge and practice of the inhabitants of the Discovery Islands throughout their deep histories that persist in the present. / Graduate / 2019-04-16
5

Ceramic production in a Roman frontier zone : a comparative Neutron Activation and Petro-Textural analysis of Roman coarse pottery from selected sites on and around the Antonine wall, Scotland

Gillings, Mark January 2009 (has links)
A series of recent excavations on the 2nd Century AD Antonine frontier forts of the Midland Scottish valley, have produced results which suggest that the army was making its own pottery on an appreciable scale. This was at a time when pottery production was thought to have moved almost exclusively into civilian hands. The possible local ware groups identified by the excavations were largely independent of firm source indicators such as kiln and waster material and the number of available samples was often-small. A program of Neutron Activation and Thin Section petrological analyses was undertaken along with an investigation into Textural Analysis, a facet of the Petrological toolkit. The aim was both to define the site ware groups and a group of specialist vessels thought to be local to Scotland, the Mortaria, and to make statements as to their provenance. Although the Mortaria analysis was limited by problems of sample group size and availability, by improving the objectivity of the statistical handling of the derived data sets and developing methods for the high level study of textural data, the site ware groups were defined successfully at both the "intrall and "inter" site levels. The analyses also furnished interpretations as to the mode and nature of the site production schemes. Through the full analysis of' site Daub samples linked to more traditional provenancing techniques, in all but one case the ware groups could be assigned to the source sites, where contrasting production modes could be identified with military as opposed to civilian production.
6

Comparing the Feasibility of Cutting Thin-Walled Sections from Five Commonly Used Metals Utilizing Wire Electric Discharge Machining

Stephenson, Richard C. 11 July 2007 (has links) (PDF)
Wire Electric Discharge Machining (wire-EDM) is a non-traditional machining process. Controlled electric sparks are successively used to vaporize part of a workpiece along a programmed path in order to machine a desired part. Because there is no tool that comes in direct contact with the workpiece, it is possible to machine thin, delicate parts. This thesis was designed to observe and analyze the differences in cutting capabilities for a conventional wire-EDM machine when cutting thin-walled sections from five commonly used metals utilizing a variation of roughing and finishing passes. The five metals that were used in this study are: Aluminum 6061 T6, Yellow Brass SS360, 420 Stainless Steel, D2 Tool Steel at 25 to 30 RC, and D2 Tool Steel at 60 to 65 RC. The thin-walled sections were constrained on each end by the parent material to which they remained attached, and they ranged in thickness from 0.05 millimeters (0.002 inches) increasing incrementally by 0.05 millimeters (0.002 inches) until they reached a thickness of 0.30 millimeters (0.012 inches). A Sodick AQ325L wire-EDM machine was employed to perform the machining. It was observed that differences exist in the capabilities of cutting thin-walled sections from the five different metals. This could be both observed visually through inspection and statistically through the analysis of each data set obtained by measuring the resultant thickness of each section. It was also observed that differences exist for the same material while utilizing the variations of cutting parameters: a roughing with no finishing passes, a roughing with one finishing pass, and a roughing with three finishing passes. Thus both the material properties and the cutting parameters play a significant role in determining the capability of cutting thin-walled sections with a wire-EDM machine.
7

Ceramic production in a Roman frontier zone: A comparative Neutron Activation and Petro-Textural analysis of Roman coarse pottery from selected sites on and around the Antonine wall, Scotland.

Gillings, Mark January 1991 (has links)
A series of recent excavations on the 2nd Century AD Antonine frontier forts of the Midland Scottish valley, have produced results which suggest that the army was making its own pottery on an appreciable scale. This was at a time when pottery production was thought to have moved almost exclusively into civilian hands. The possible local ware groups identified by the excavations were largely independent of firm source indicators such as kiln and waster material and the number of available samples was often-small. A program of Neutron Activation and Thin Section petrological analyses was undertaken along with an investigation into Textural Analysis, a facet of the Petrological toolkit. The aim was both to define the site ware groups and a group of specialist vessels thought to be local to Scotland, the Mortaria, and to make statements as to their provenance. Although the Mortaria analysis was limited by problems of sample group size and availability, by improving the objectivity of the statistical handling of the derived data sets and developing methods for the high level study of textural data, the site ware groups were defined successfully at both the "intrall and "inter" site levels. The analyses also furnished interpretations as to the mode and nature of the site production schemes. Through the full analysis of' site Daub samples linked to more traditional provenancing techniques, in all but one case the ware groups could be assigned to the source sites, where contrasting production modes could be identified with military as opposed to civilian production. / SERC
8

Využití půdní mikrostruktury pro sledování sukcesních změn v bioturbační činnosti půdní fauny na výsypkách po těžbě uhlí / Using of soil microstructure in study of soil fauna bioturbation in post mining sites

Suchá, Linda January 2014 (has links)
The paper follows up on previous analyses of changes in soil microstructure in the process of soil development on dumps around Sokolov, Czech Republic, using the soil thin section method. The distribution of structures in the topsoil of the profile was studied in two chronosequences, one overgrown with spontaneous vegetation and one reclaimed by alder planting. A comparison with historical data obtained at these locations 10 years ago was used, and, therefore, the same methods were also applied (Frouz et al., 2007b). The most distinct trend in the process of soil development over time, as observed through both a comparison of soil thin sections from various areas of chronosequence and changes in particular sites over time, is a gradual reduction of purely mineral structures and their replacement by organic matter - litter and its fragments, faecal pellets of arthropods, earthworms coprolites, and roots. This is illustrative of a high share of biogenic structures and a fundamental contribution of organisms to forming topsoil, a fact also pointed out by other authors. Keywords: Soil macrofauna; Soil microstructure; Soil thin section; Reclamation; Post-mining sites; Soil development; Earthworms
9

Sicilian amphorae (1st-6th centuries AD) : typology, production and trade

Franco, Carmela January 2014 (has links)
This thesis is a comprehensive investigation of the transport containers produced in Roman Sicily over a chronological period composed of five phases: Early Roman period (30 BC–AD 100); Middle Roman period (AD 100–300); Late Roman period (AD 300–440); Vandal Perios (AD 440/535) and Early Byzantine period (AD 536/600). The research investigates the production and transportation of Sicilian foodstuffs (especially wine) from the major ports of the island to Mediterranean ports and northern Europe. The results demonstrate the wide distribution of Sicilian amphorae and their important role within the wider economy of the Roman Empire. The importance of this research lies in the fact that, despite the agricultural prosperity of Sicily in the Roman Period and its strategic topographical position, transport amphorae remain understudied especially in economic terms. In regards to typology, chronology and distribution, our current knowledge of regional containers has not reached a level comparable to that of amphorae manufactured in other territories. The key discussion focuses on the commercial dynamics of Roman Sicilian amphorae from local, regional and Mediterranean-wide perspectives. The research aims to outline the distribution trends of Sicilian amphorae, looking at the different relative quantities of each amphora type and consequently the extent to which they are present in regions inside and outside Sicily, while considering presences and absences within the more general and homogeneous context of the Mediterranean basin. The organisation of Sicilian amphora production is also tackled through the presentation of probable production sites and excavated kilns. Using these examples, the study investigates the management of production of these containers on the island. The initial data obtained by this research represents a first step in determining differences between Sicilian amphorae workshops producing amphorae — therefore trading wine — for Mediterranean export and manufacturing sites specializing in local/regional trade. Other key achievements include the creation of a new illustrated typology with profile drawings of all the amphora forms and a summary and catalogue of Sicilian amphorae fabrics. In the thesis, the results of archaeometric analysis (thin-sections) carried out on more than 120 Sicilian amphora samples, provided by numerous institutions in Sicily and abroad, are presented. These results add significantly to our knowledge of the fabric composition, manufacture technology, origin and consequently movement of these amphorae around the Mediterranean over six centuries. More generally the research shows that the study of Sicilian material culture along with archaeological evidence is essential for recording the economic dynamics of Sicily, with the intent of dispelling the stereotype that Sicily's primary role was as a grain supplier to Rome. Besides grain — widely produced and exported throughout the imperial period, as attested by ancient sources and inscriptions — the archaeological evidence clearly indicates the export of foodstuffs, especially wine, at an inter-provincial level from the 1<sup>st</sup> until the second half of the 6<sup>th</sup> century AD.
10

Zum 175. Geburtstag Alfred Wilhelm Stelzners, eines verdienstvollen Wissenschaftlers auf dem Gebiet der Geologie und der Lagerstättenlehre

Grabow, Gerd 07 October 2016 (has links) (PDF)
Alfred Stelzner, ein Geologe, Petrograph und Vertreter der Stratigraphie und Lagerstättenlehre, war ein Meister der mechanischen Trennung von Materialien.

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