Thesis (M.S.)--Ohio University, August, 2004. / Includes bibliographical references (leaves 187-219).

Thesis (M.S.)--Ohio University, August, 2004. / Title from PDF t.p. Includes bibliographical references (leaves 187-219)

Les cherts archéens permettent de contraindre les environnements primitifs qui ont vu l’apparition de la vie sur Terre. Ces roches siliceuses se forment selon trois processus : les C-cherts (cherts primaires) se forment par précipitation chimique de silice océanique sur le plancher, sous la forme d’une boue siliceuse ou en tant que ciment dans les sédiments de surface; les F-cherts (cherts de fracture) précipitent dans les fractures de la crôute depuis les fluides circulant; les S-cherts (cherts secondaires) sont issus de la silicification de roches préexistantes lors de la percolation de fluides enrichis en silice. Ces processus sont largement acceptés mais des questions majeures subsistent : comment reconnaître ces différents types de chert ? Quelle est l’origine de la silice et sous quelle forme a-t-elle précipité ? Quel signal chimique est porté par les cherts et comment s’en servir pour les reconstructions paléo-environnementales ? Ces questions sont abordées à travers trois sites de la ceinture de roches vertes de Barberton, en Afrique du Sud. L’approche adoptée combine l’analyse des structures sédimentaires et de déformation, de la pétrologie et de la composition chimique et isotopique de ces unités. Dans ces sites, la formation des cherts est étroitement liée à l’environnement de mise en place. La sédimentation clastique (turbidites) est à l’origine des C-cherts de Komati River, déposés sous la forme d’une boue siliceuse par adsorption de silice sur les particules argileuses en suspension. En absence de contribution continentale, les alternances de cherts noirs et blancs de Buck Reef sont interprétées comme issues de variations climatiques à l’échelle saisonnières (chert noir), voire glaciaires/inter-glaciaires (chert blanc). Les cherts de fracture de Barite Valley sont liés à la précipitation de silice depuis une suspension colloïdale thixotrope remontant à travers la croûte. La composition chimique des cherts est contrôlée par leur environnement de mise en place, et représente un mélange entre une phase siliceuse et une phase contaminante, indépendamment des processus qui ont précipité la silice. Les cherts de Komati River et de Barite Valley sont enrichis en Al, K, Ti, HFSE et en REE, ce qui est attribué à la contamination de la matrice siliceuse par la présence de phyllosilicate. Une telle contribution clastique peut expliquer les larges gammes de δ30Si dans les cherts de Komati River (-0.69‰à +3.89‰), et la majorité des valeurs positives est probablement liée à la contribution de l’eau de mer. Dans les dykes de Barite Valley, les δ30Si très négatifs (-4.5‰ à +0.22‰) sont cohérents avec l’origine hydrothermale basse température des fluides initiaux. A Buck Reef, l’absence de contribution continentale s’exprime dans les cherts blancs par une minéralogie exclusivement microquartzitique et par des concentrations extrêmement faibles en éléments traces (i.e. ΣHFSE et ΣREE<1ppm). 2% de carbonates et 3-4% de matériel continental (e.g. argiles) suffisent à masquer le signal siliceux dans ces cherts purs. Nous ne pouvons conclure sur la présence d’un signal océanique dans ces cherts par manque de fiabilité des proxys océaniques modernes (appauvrissement en LREE, enrichissement en La et Y). Reconnus à la fois dans des quartz océaniques, hydrothermaux, magmatiques et pegmatitiques, ils ne permettent pas d’identifier un signal d’eau de mer dans les cherts archéens. Les δ 18O de ces cherts indiquent la présence de circulations fluides secondaires à moins de 100°C, et leurs δ 30Si négatifs ou positifs (-2.23‰ et +1.13‰ en moyenne) montrent la contribution de fluides différents au moment de leur formation. Le couplage des observations pétrologiques et de terrain est la seule approche fiable pour reconnaître le mode de mise en place des cherts. Leur composition chimique dépend plus des conditions environnementales que des caractéristiques du fluide initial. / Archean cherts potentially constrain the primitive environment in which life emerged and evolved. These siliceous rocks formed by three processes : C-cherts (primary cherts) formed by the chemical precipitation of oceanic silica, either as a siliceous ooze (or silica gel) on the seabed, or as cement within still soft sediments at the surface ; F-cherts (fracturefilling cherts) precipitated from circulating fluids in concordant or crosscutting veins in the shallow crust ; S-cherts (secondary cherts) are the result of the metasomatism (silicification) of preexisting rocks during the percolation of silica-rich fluids. These processes are generally accepted but major questions remain unsolved : how to recognize various chert types ? Where does the silica come from and how did it precipitate ? What chemical signal is hosted in cherts and how can it be used for paleo environmental reconstructions ? These questions are addressed here using three sites in the Barberton Greenstone Belt, South Africa, which contain a variety of cherts deposited in very different environments. The approach combines field description of sedimentary and deformation structures, the characterization of various chert petrologies, and the study of their chemical and isotopic composition. In these three sites, chert formation strongly depends on the environmental setting. Clastic sedimentation is directly linked to C-chert formation at Komati River, where the silica was deposited as a viscous, siliceous ooze by sorption process onto suspended clay particles. A continental contribution is absent at Buck Reef, and the black and white banded cherts (C-cherts) are interpreted to have formed by chemical precipitation of oceanic silica during seasonal (black chert) and maybe glacial/inter-glacial (white chert) climatic variations. The fracture-filling cherts from Barite Valley precipitated from a thixotropic colloidal suspension that migrated upward through the crust. The chemical compositions of cherts from these three sites are essentially controlled by the environment of deposition, and represent mixtures of a siliceous and contaminant phases, independent from the silica precipitation mode. Komati River C-cherts and Barite Valley F-cherts are both enriched in Al, K, Ti, HFSE and REE, which represents the contamination by phyllosilicates of the microquartzitic fabrics. Such a clastic contribution may account for the wide range of δ30Si in Komati River cherts (-0.69‰ to +3.89‰) although the majority of positive values is attributed to seawater involvement. In the dykes, δ30Si is strongly negative (-4.5‰to +0.22‰) and is consistent with the low-temperature hydrothermal nature of these fluids. At Buck Reef, the lack of continental contribution is expressed in the white cherts, by a mineralogy exclusively composed of microquartz, and by extremely low trace element contents, i.e. HFSE and REE below 1ppm. We calculate that 2% of carbonates and 3-4% of clastic particles (i.e. clay, feldspar) would be enough to mask the silica composition in these high purity cherts. A marine signature was not recognized in their geochemistry because of the unreliability of commonly used modern proxys (i.e. LREE depletion, La and Y enrichment). These features were identified in oceanic, hydrothermal, magmatic and pegmatitic quartz and thus do not reliably identify an oceanic signal in Archean cherts. Because the δ 18O values in these white cherts indicates secondary fluid circulations at <100°C, their negative or positive δ30Si values (-2.23‰ and +1.13‰ in average) most probably represent different fluid contributions at the time they formed. The combination of field and petrological observations appears to be the most reliable approach to classify cherts and to deduce their origin, and we show here that their chemical composition depends more on the environmental conditions than on the primary fluid characteristics.

Ethnographers in the early 20th century compiled notes and published reports and books concerning the cultures and life-ways of the California Indians. Among these are the Juaneño (Acjachemen) and Gabrielino (Tongva) peoples. This study aimed to correlate ethnographic data with methods of spatial archaeology and GIS analysis to test if the privately owned resource collecting areas and tribal boundaries described in the ethnographies could be seen archaeologically. Centered on CA-ORA-507 (an ancient chert quarry), the study shows that the boundaries between these resource areas are culturally derived as well as a part of the greater pattern of sites on the landscape and that the pattern of sites on the landscape conform to descriptions of the practices written at the turn of the last century.

The Consort Pebble Chert Quarry site (EkOr-8) is a Pre-Contact quarry site located south of the Village of Consort, Alberta. Despite knowledge of the site's existence by local area farmers, it was only in 1999 that it was first recorded as an archaeological site. It is described as a large area dominated by the presence of marked depressions that vary in size from less than a metre in depth and diameter to well over three metres in depth and diameter as well as an abundance of chert pebbles on the ground surface. Originally believed to be an example of meteorite impacts, the site was explored by geologists from the University of Calgary. Further visits by provincial archaeologists resulted in numerous theories as to the cause of the depression features and the purpose of the site. No archaeological investigation was undertaken prior to the summer of 2006.<p>No diagnostic artifacts were recovered from within the site area; however, a possible temporal indicator to site usage may be indicated based on the discovery of a Duncan projectile point in a site immediately to the south of the Consort Pebble Chert Quarry. An abundance of lithic artifacts were uncovered as results of the shovel test program undertaken by the author during the summer of 2006. The majority of these lithic artifacts were derived from the abundant lithic material within the site area known as pebble chert. No other non-lithic artifacts were found during the course of this excavation. <p>Shovel tests were used to provide an indication of the subsurface stratigraphy at the site. No evidence of cultural strata was found and the subsurface deposits present reflect a history of glacial landscapes. A number of glacial phenomena are the likely causes of the depression features. The presence of pebble chert on the ground surface; however, did make this area an attractive location for collecting unmodified lithic material in order to fashion stone tools. The existence of numerous artifacts made from pebble chert at the site indicates that past cultural groups had visited and collected from the area. An overview of archaeological sites on the Canadian Plains demonstrates that pebble chert is a valuable lithic material that was used in a wide variety of archaeological sites throughout the Pre-Contact era.

The Consort Pebble Chert Quarry site (EkOr-8) is a Pre-Contact quarry site located south of the Village of Consort, Alberta. Despite knowledge of the site's existence by local area farmers, it was only in 1999 that it was first recorded as an archaeological site. It is described as a large area dominated by the presence of marked depressions that vary in size from less than a metre in depth and diameter to well over three metres in depth and diameter as well as an abundance of chert pebbles on the ground surface. Originally believed to be an example of meteorite impacts, the site was explored by geologists from the University of Calgary. Further visits by provincial archaeologists resulted in numerous theories as to the cause of the depression features and the purpose of the site. No archaeological investigation was undertaken prior to the summer of 2006.<p>No diagnostic artifacts were recovered from within the site area; however, a possible temporal indicator to site usage may be indicated based on the discovery of a Duncan projectile point in a site immediately to the south of the Consort Pebble Chert Quarry. An abundance of lithic artifacts were uncovered as results of the shovel test program undertaken by the author during the summer of 2006. The majority of these lithic artifacts were derived from the abundant lithic material within the site area known as pebble chert. No other non-lithic artifacts were found during the course of this excavation. <p>Shovel tests were used to provide an indication of the subsurface stratigraphy at the site. No evidence of cultural strata was found and the subsurface deposits present reflect a history of glacial landscapes. A number of glacial phenomena are the likely causes of the depression features. The presence of pebble chert on the ground surface; however, did make this area an attractive location for collecting unmodified lithic material in order to fashion stone tools. The existence of numerous artifacts made from pebble chert at the site indicates that past cultural groups had visited and collected from the area. An overview of archaeological sites on the Canadian Plains demonstrates that pebble chert is a valuable lithic material that was used in a wide variety of archaeological sites throughout the Pre-Contact era.

Thesis (B.S.)--University of Wisconsin -- La Crosse, 2008. / Also available online. Includes bibliographical references (leaf [41]).

Master of Science / Geology / Matthew W. Totten / Mississippian chert reservoirs, also known as chat reservoirs among the mid-continent in Kansas and northern Oklahoma, produce an abundant amount of hydrocarbons. Since the 1920s, chat reservoirs in Kansas have yielded over 380 million bbl of oil and 2.3 tcf of natural gas. The largest Mississippian field in south-central Kansas is the Spivey-Grabs, which spans Kingman and Harper Counties. Development of the Spivey-Grabs Mississippian reservoir, and continued production within the field, has been compromised by compartmentalization within the field, resulting in unpredictable producing rates. Previous research has investigated the differences of the fluids within the separate compartments (Evans, 2011; Kwasny, 2015), and identified the existence of at least two oil types of differing viscosity (Kwasny, 2015). The objective of this research was to determine whether the compartmentalization of the reservoir is controlled by the different lithologic characteristics between the various compartments. This was accomplished by examining drill cuttings under binocular microscope, under a petrographic microscope using digital imaging software, and under the high magnification of a scanning electron microscope. Calculated rock porosity from ImageJ software showed variation among the wells selected for this study; but the porosity variation does not correlate with differences in fluid viscosity that was previously observed, i.e. heavy and light viscosity oils (Kwasny, 2015). Heavy oils were seen in wells that had both higher and lower porosity values, and the same is true for the distribution of light oils. This suggested that fluid viscosity is the major controlling factor in compartmentalization in the Spivey-Grabs and not rock properties.

Lithic source analysis, or “sourcing,” is a geochemical compositional analysis of lithic materials for both major and trace elements. Sourcing analysis assigns lithic sources to geochemical groups according to distinct geochemical compositions, where unique elemental signatures represent separate lithic sources. In archaeological research, sourcing informs upon mobility strategies, trade and exchange networks, and lithic conveyance studies. While obsidian sourcing is a relatively reliable and popular technique, chert sourcing is more difficult and historically less successful largely due to variability in chert formation processes. X-ray fluorescence spectrometry (XRF) offers a possible sourcing technique, and is non-destructive, as well as time and cost-effective. In this thesis, I test the reliability of XRF in determining the geochemical characterization of Tosawihi Quarries chert, a unique chert source located in the Humboldt River Basin of north-central Nevada. The Tosawihi Quarries archaeological district (26EK6624) is a significant lithic resource that has hosted human occupation and activity for millennia. The Tosawihi Quarries offers a high quality toolstone that was intensely used, as indicated by numerous quarry locales and biface tool caches. Additionally, the Tosawihi Quarries is a social identity marker for the Tosawihi band of Western Shoshone, also serving as a source of spirituality and medicine. Tosawihi chert is a distinct, white lithic material type that also has a characteristic fluorescence pattern when exposed to ultraviolet light. While these are defining attributes, they are not unique to Tosawihi chert, as they occur in other Great Basin white chert sources. Identifying Tosawihi chert has been problematic, and misidentifications may have led to erroneous interpretations of the archaeological and ethnographic records. If successful, a geochemical characterization by XRF would provide an elemental signature specific to Tosawihi chert, thus eliminating discrepancies in visual and ultraviolet fluorescence readings and permitting archaeologists to accurately asses the distribution and use of this sacred material. In this thesis research, I first conducted an XRF analysis of a source standard collection of Tosawihi Quarries chert, which yielded a preliminary methodology for identifying Tosawihi chert. This protocol was tested against two comparative collections of other Great Basin white cherts: Mono Lake Spillway located in western Nevada and Pahute Mesa (26NY1408) located in southern Nevada. The methodology, now refined, was then run against the archaeological collection, where five collections of white chert artifacts were tested for the presence of Tosawihi chert. Incorporating both the qualitative and quantitative data from XRF analysis, the results show that this proposed methodology can successfully discriminate between Tosawihi chert and other Great Basin white cherts based on its XRF signature.

One of the most significant finds at the site of Blackman Eddy, Belize, is a series of superimposed structures that date between 1200 B.C.-A.D. 600 (calibrated). Because it was continuously occupied for over 1800 years, this site provides a unique opportunity to examine long-term socio-economic changes in the eastern Maya lowlands. This thesis is a diachronic study of the chipped stone tool artifacts of Blackman Eddy using technological, attribute, and use-wear analysis. The data collected for this study were examined to see what types of raw materials were used in tool production, what types of tools were produced, how they were produced, and what they were used for during the Middle Preclassic, Late Preclassic, and Classic periods. Each of the attributes studied in this thesis creates different opportunities and constraints for the various chipped stone tool industries of Blackman Eddy, and changes in chipped stone artifact attributes between the different structures may be indicative of socio-economic change over time.