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Anhydrite deformation and microstructures in the oceanic lower crust: an insight from Samail ophiolite core, Wadi Gideah GT1 Borehole
No full textTethyan anhydrite preserved in the lower crust of the Samail ophiolite: Evidence from Oman Drilling Project Holes GT1A and 2A
No full textLow-Temperature Hydrogen Formation During Aqueous Alteration of Serpentinized Peridotite in the Samail Ophiolite
No full textSerpentinized peridotite is reacting with groundwater in the subsurface of the Samail ophiolite in Oman. Although these rocks are partially to completely serpentinized, they interact with a groundwater aquifer containing hyperalkaline fluids rich in H2 and CH4. Since the mechanisms by which H2 production may continue at low temperatures (<50°C) are not fully understood, core recovered during the Oman Drilling Project provides an excellent opportunity to study the mineralogy and Fe speciation in highly serpentinized harzburgite recording multiple stages of water/rock interaction. In Hole BA3A, early hydration of olivine and pyroxene, which likely occurred at temperatures of ∼100°C–200°C, produced serpentine, Fe-rich brucite, awaruite, and little magnetite. Notably, Fe-rich brucite is only preserved at >∼100 m depth in the core. Fe-rich brucite is nearly absent within two near-surface reaction zones where later stages of reaction are recorded, which include replacement of Fe-rich brucite by Fe(III)-bearing serpentine, and increases in the proportion of other Fe(III)-bearing phases such as magnetite and hydroandradite. Thus, Fe-rich brucite at depth represents substantial stored capacity for H2 production that can continue at low temperature, even after primary olivine and pyroxene are exhausted, thereby sustaining habitable conditions for microbial life
Oman Drilling Project Micro-Imaging Spectroscopy Data
No full textThis record will contain the imaging spectroscopy data of the archive halves of all core recovered by the International Continental Scientific Drilling Program (ICDP) Oman Drilling Project (OmanDP; Kelemen et al., 2020).
The dataset will eventually be available here through the CaltechDATA Large Data Pilot approved in June 2021. At this time, the pilot is not built and ready to accept data. We anticipate having the data here by the end of 2021.
In the meantime, the shortwave infrared dataset for OmanDP Holes GT1A, GT2A, and GT3A is available through OneDrive. Interested users should contact Rebecca Greenberger ([email protected]) to gain access to the OneDrive folder.
Available data include shortwave infrared data cubes as described in Kelemen et al. (2020) processed to reflectance with mineral occurrence maps (Greenberger et al., 2021, JGR Solid Earth). Data paired .img and .hdr files.
Greenberger, R. N., Harris, M., Ehlmann, B. L., Crotteau, M. A., Kelemen, P. B., Manning, C. E., et al. (2021). Hydrothermal alteration of the ocean crust and patterns in mineralization with depth as measured by micro-imaging infrared spectroscopy. Journal of Geophysical Research: Solid Earth, 126, e2021JB021976. https://doi.org/10.1029/2021JB021976Related Publication:
Proceedings of the Oman Drilling Project: Scientific Drilling in the Samail Ophiolite, Sultanate of Oman
Kelemen, P. B.
Matter, J. M.
Teagle, D. A. H.
Coggon, J. A.
Oman Drilling Project Science Team
International Ocean Discovery Program
2020
https://doi.org/10.14379/OmanDP.proc.2020
engContact person: Rebecca Greenberger [email protected]
Anhydrite microstructures as testimony of a paleo hydrothermal vent along an active normal fault in the oceanic crust
No full textSupplementary material for "Measurement of volume change and mass transfer during serpentinisation: insights from the Oman Drilling Project" (JGR Solid Earth)
No full textThe three supplementary files include one figure displaying the results of X-ray microtomography (File S1), two compilations of figures dealing with the volume change measurement (Files S2 and S3) and a table with the measured compositions in major and trace elements (Table S1).
File S1 (Malvoisin_ds01.pdf). Result of X-ray microtomography. Olivine and Fe-brucite have a similar attenuation. The grains segmented by selecting this attenuation are displayed with a circle with a size proportional to the radius of a sphere of equivalent volume. The color of each circle depends on e, the aspect ratio (ratio of the length of the minimum and maximum axes of an ellipsoid fitted to each grain). The white arrow indicates the location of the main central vein. Grains near the main central vein have a lower e attributed to the platy habitus of Fe-brucite. The other grains are considered as olivine and used for the calculation of the extent of reaction.
File S2 (Malvoisin_ds02.pdf). Optical photomicrographs used to calculate volume change during reaction (see main text for details about the calculation). Olivine grains (white) are surrounded by the serpentine + brucite mixture (light green to yellowish). The magnetite/clinopyroxene platelets are mapped in blue in olivine and in red in the serpentine + brucite mixture. The results of the model fitting the best the average orientation of the platelets in olivine are shown in green. The title of each photomicrograph provides the minimum and maximum estimates for volume change calculated with this model (see details about the calculation in the main text), and the size of the bottom right scale bar.
File S3 (Malvoisin_ds03.pdf). Histograms of magnetite/clinopyroxene platelet orientation (in degree). Each histogram corresponds to a photomicrograph of File S1. The order of the histograms and the photomicrographs is the same. The orientations in the olivine grains, the serpentine + brucite mixture and for the model fitting the best the average orientation in olivine are displayed in blue, red and green, respectively. The title of the histograms provides the standard deviation of the platelet orientation in the olivine grains (STDoli), the serpentine + brucite mixture (STDori) and calculated with the model fitting the best the orientation in olivine (STDcal).
Table S1 (Malvoisin_ds01.xlsx). Composition in major and trace elements measured with LA-ICPMS along five profiles perpendicular to the main vein. The composition as a function of the distance to the main vein is provided. The name of the tabs indicates if the profile was acquired in spot or in continuous mode (the two modes are described in the main text)
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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