7,758 research outputs found
Sulphur, sulphate oxygen and strontium isotopic composition of Cenozoic Turkish evaporates
No full textSulphur (δ34S) and strontium isotope (87Sr/86Sr) ratios have been measured in 37 sulphate minerals (gypsum, celestite and thenardite) and 4 sulphide samples (δ34S only) from 9 Cenozoic marine and nonmarine evaporites located in Anatolia, Turkey. Oxygen isotope (δ18Osulphate) ratios were also measured in 25 gypsum and 1 anhydrite sample from these deposits. These data have been used to determine the origin of dissolved sulphate in the brines that precipitated these minerals. They show that seawater was the dominant source of sulphate and Sr in the marine evaporites, but that perturbations from contemporaneous seawater Sr and sulphur isotope compositions result from recycling of older evaporites and sulphate reduction. Although continental geothermal fluids played an important role in supplying the dissolved salts that formed the nonmarine evaporites, the δ18Osulphate, δ34S and Sr isotope compositions of many of these nonmarine evaporites are indistinguishable from the marine evaporites. As well as suggesting that recycling of marine evaporites was important for controlling the composition of the nonmarine evaporites, it also suggests that δ18Osulphate, δ34S and Sr isotope compositions are not unequivocal tracers in distinguishing between these two types of evaporite. For the Turkish evaporites considered here, the major difference between marine and nonmarine evaporites that contain similar δ34S – δ18Osulphate – 87Sr/86Sr relationships is that the latter contain high concentrations of boron that reflect a geothermal contribution to the deposits
Fluids in early stage hydrothermal alteration of high-sulfidation epithermal systems: A view from the Vulcano active hydrothermal system (Aeolian Island, Italy)
No full textHigh-sulfidation (HS) epithermal systems have elements in common with passively degassing volcanoes associated with high T,
acid fumarole fields or acid crater lakes. They are considered to form in two stages, the first of which involves advanced argillic
alteration resulting from intense, strongly acidic fluid–rock interaction. The La Fossa hydrothermal system (Vulcano Island)
represents a classic example of such an active HS system and can be considered as a modern analogue of this early stage of
alteration, resulting in a core of intense silicic (90–95% pure SiO2) alteration surrounded by alunitic alteration zones.
This paper focuses on a geochemical and stable isotope study of the surficial alteration facies of Vulcano – particularly the horizon
characterized by strong silicic alteration – and on deep seated xenoliths ejected during the last eruption of La Fossa volcano (1888–90)
that can be considered as representative of fragments of the deep conduit system of La Fossa volcano. Using directly measured
temperatures at the sites of sampling, we have calculated fluid composition in isotopic equilibrium with the alteration products. The
large range of measured silica δ18O (12.3 to 29‰) reflects the wide range of formation temperatures (80–240 °C). The fluid
compositions calculated for intense silicic alteration vary from −0.9 to +6.5‰. These are significantly heavier than local meteoric
water (−6‰), and are consistent with derivation from the condensation of high-temperature fumarolic gases, dominated by magmatic
fluids and rich in acid gases (SO2, H2S, HCl, HF), into shallow groundwaters of meteoric origin, with dynamically variable ratios of
fumarolic steam/meteoric water. The calculated δ18O and δD of water in equilibrium with alunite also suggest the mixing of magmatic
and meteoric waters for the fluids involved in the genesis of advanced argillic alteration facies.
The calculated δ18Oofwater in equilibrium with hedenbergitic clinopyroxene, found in a veinlet in ametasomatized xenolith is +8.9‰.
This value cannot reasonably result from water–rock interaction between the host volcanic rocks and surface water. Instead, it most likely
represents a fluid (brine) exsolved from magma, which was responsible for high temperature metasomatism in the deep conduit system.
© 2007 Elsevier B.V. All rights reserved
Interview with Anthony F. Janson
No full textAnthony F. Janson is a retired professor and former Department Chair for the UNCW Department of Art and Theatre [retired December 2002]. This interview covers his complete life and career. He discusses his relationship with his art historian father, H.W. Janson, including his relationship as son and co-author and editor of the Janson texts on art history. The interview covers Tony's career as a scholar, book editor, author, art museum curator [at Indianapolis Art Museum and North Carolina Art Museum], and as a professor. Throughout, he comments on important artists in history and his philosophy of art history. He also includes stories of his time in the Vietnam War
Interview with Anthony F. Janson
No full textAnthony F. Janson is a retired professor and former Department Chair for the UNCW Department of Art and Theatre [retired December 2002]. This interview covers his complete life and career. He discusses his relationship with his art historian father, H.W. Janson, including his relationship as son and co-author and editor of the Janson texts on art history. The interview covers Tony's career as a scholar, book editor, author, art museum curator [at Indianapolis Art Museum and North Carolina Art Museum], and as a professor. Throughout, he comments on important artists in history and his philosophy of art history. He also includes stories of his time in the Vietnam War
Letter from Anthony Brummelkamp to Mrs. G. Groen van Prinsterer
No full textIn a letter to Mrs. G. Groen van Prinsterer from Rev. Anthony Brummelkamp, the author is clearing up some statements of Rev. Budding and chiding Rev. Hendrik Scholte for having an arrogant and sharp tone. A foonote to the letter mentions the school operated by Rev. Brummelkamp and Rev. Albertus C. Van Raalte in Arnhem.https://digitalcommons.hope.edu/vrp_1840s/1193/thumbnail.jp
Stable isotopes reveal Holocene changes in the diet of Adélie penguins in Northern Victoria Land (Ross Sea, Antarctica)
No full textAdélie penguin (Pygoscelis adeliae) modern and fossil eggshells and guano samples collected from ornithogenic soils in Terra Nova Bay (Victoria Land, Ross Sea) were processed for carbon and nitrogen isotopic ratios with the aim of detecting past penguin dietary changes. A detailed and greatly expanded Adélie penguin dietary record dated back to 7,200 years BP has been reconstructed for the investigated area. Our data indicate a significant dietary shift between fish and krill, with a gradual decrease from past to present time in the proportion of fish compared to krill in Adélie penguin diet. From 7,200 to 2,000 years BP, δ13C and δ15N values indicate fish as the most eaten prey. The dietary contribution of lower-trophic prey in penguin diet started becoming evident not earlier than 2,000 years BP, when the δ13C values reveal a change in the penguin feeding behavior. Modern eggshell and guano samples reveal a major dietary contribution of krill but not a krill-dominated diet, since δ13C values remain much too high if krill prevail in the diet. According to the Holocene environmental background attested for Victoria Land, Adélie penguin dietary shifts between fish and krill seem to reflect penguin paleoecological responses to different paleoenvironmental settings with different conditions of sea-ice extension and persistence. Furthermore, Adélie penguin diet appears to be particularly affected by environmental changes in a very specific period within the breeding season, namely the egg-laying period when penguin dietary and feeding habit shifts are clearly documented by the δ13C of eggshell carbonate
Boron, carbonate carbon and oxygen isotope data of all analyzed sections from the Marinoan glaciation
No full textUncertainty for Namibian B isotope data is d11B: ±1per mil 2 Sigma f. A, B, C are pH estimations based on different d11Bseawater assumptions: pKB of 8.579 (Dickson, 1990), a fractionation factor alpha of 1.0272 (Klochko et al., 2006) and a seawater d11B composition of A=20.5 per mil, B=21.5 per mil and C=22.5 per mil (same as Kasemann et al. (2010)) are used
Major and trace elements for the Chinese Xiaofenghe Section (NXF)
No full textMajor and trace elements for the Chinese Xiaofenghe Section (NXF
Fr. Anthony J. Gittins, C.S.Sp.
No full textFr. Anthony J. Gittins, C.S.Sp. [b. 1943] was ordained in 1967. He attended the University of Edinburgh from 1968-72 and received a doctorate in Social Anthropology in 1977. Fr. Gittins was a missionary to the Mende people in Sierra Leone from 1972-80. He went on to serve as a professor at the Missionary Institute and as Formation Director in London from 1980-84. He is the Emeritus Professor of Theology and Culture at the Catholic Theological Union in Chicago, Illinois, where he began teaching in 1984. Fr. Gittins has spent over thirty years ministering to homeless women and those leaving prostitution in Chicago, and is the author of several books.https://dsc.duq.edu/sohp/1000/thumbnail.jp
Anthony Grooms, 21st Annual ODU Literary Festival
No full textAnthony Grooms is the author of Ice Poems (Poetry Atlanta Press) and Trouble No More: Stories (LaQuesta Press). Shorter works have appeared in Callaloo, African American Review, and other journals. He has received awards from the City of Atlanta, the State of Georgia, Breadloaf Writers Workshop and the National Endowment for the Arts. In 1996, Trouble No More won the Lillian Smith Award from the Southern Regional Council. Novelist Marita Golden noted that “Grooms writes about the South, civil rights, home folks, black and white people and anything he wants to with more love, humor and finely-honed skill than I have seen in a long time.” The Atlanta Journal-Constitution said, “Groom’s stories take us to the center of the phenomenon (civil rights movement) with an honesty and courage long overdue.” Grooms is an Associate Professor of Creative Writing at Kennesaw State University in Georgia
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