435 research outputs found

    Project Echo: System Calculations

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    The primary experimental objective of Project Echo was the transmission of radio communications between points on the earth by reflection from the balloon satellite. This paper describes system calculations made in preparation for the experiment and their adaptation to the problem of interpreting the results. The calculations include path loss computations, expected audio signal-to-noise ratios, and received signal strength based on orbital parameters

    Rock magnetic and geochemical evidence for authigenic magnetite formation via iron reduction in coal-bearing sediments offshore Shimokita Peninsula, Japan (IODP Site C0020)

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    Sediments recovered at Integrated Ocean Drilling Program (IODP) Site C0020, in a fore‐arc basin offshore Shimokita Peninsula, Japan, include numerous coal beds (0.3–7 m thick) that are associated with a transition from a terrestrial to marine depositional environment. Within the primary coal‐bearing unit (∌2 km depth below seafloor) there are sharp increases in magnetic susceptibility in close proximity to the coal beds, superimposed on a background of consistently low magnetic susceptibility throughout the remainder of the recovered stratigraphic sequence. We investigate the source of the magnetic susceptibility variability and characterize the dominant magnetic assemblage throughout the entire cored record, using isothermal remanent magnetization (IRM), thermal demagnetization, anhysteretic remanent magnetization (ARM), iron speciation, and iron isotopes. Magnetic mineral assemblages in all samples are dominated by very low‐coercivity minerals with unblocking temperatures between 350 and 580°C that are interpreted to be magnetite. Samples with lower unblocking temperatures (300–400°C), higher ARM, higher‐frequency dependence, and isotopically heavy ÎŽ56Fe across a range of lithologies in the coal‐bearing unit (between 1925 and 1995 mbsf) indicate the presence of fine‐grained authigenic magnetite. We suggest that iron‐reducing bacteria facilitated the production of fine‐grained magnetite within the coal‐bearing unit during burial and interaction with pore waters. The coal/peat acted as a source of electron donors during burial, mediated by humic acids, to supply iron‐reducing bacteria in the surrounding siliciclastic sediments. These results indicate that coal‐bearing sediments may play an important role in iron cycling in subsiding peat environments and if buried deeply through time, within the subsequent deep biosphere

    Isolating detrital and diagenetic signals in magnetic susceptibility records from methane-bearing marine sediments

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    © The Author(s), 2021. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Johnson, J. E., Phillips, S. C., Clyde, W. C., Giosan, L., & Torres, M. E. Isolating detrital and diagenetic signals in magnetic susceptibility records from methane-bearing marine sediments. Geochemistry Geophysics Geosystems, 22(9), (2021): e2021GC009867, https://doi.org/10.1029/2021GC009867.Volume-dependent magnetic susceptibility (Îș) is commonly used for paleoenvironmental reconstructions in both terrestrial and marine sedimentary environments where it reflects a mixed signal between primary deposition and secondary diagenesis. In the marine environment, Îș is strongly influenced by the abundance of ferrimagnetic minerals regulated by sediment transport processes. Post-depositional alteration by H2S, however, can dissolve titanomagnetite, releasing reactive Fe that promotes pyritization and subsequently decreases Îș. Here, we provide a new approach for isolating the detrital signal in Îș and identifying intervals of diagenetic alteration of Îș driven by organoclastic sulfate reduction (OSR) and the anaerobic oxidation of methane (AOM) in methane-bearing marine sediments offshore India. Using the correlation of a heavy mineral proxy from X-ray fluorescence data (Zr/Rb) and Îș in unaltered sediments, we predict the primary detrital Îș signal and identify intervals of decreased Îș, which correspond to increased total sulfur content. Our approach is a rapid, high-resolution method that can identify overprinted Îș resulting from pyritization of titanomagnetite due to H2S production in marine sediments. In addition, total organic carbon, total sulfur, and authigenic carbonate ÎŽ13C measurements indicate that both OSR and AOM can drive the observed Îș loss, but AOM drives the greatest decreases in Îș. Overall, our approach can enhance paleoenvironmental reconstructions and provide insight into paleo-positions of the sulfate-methane transition zone, past enhancements of OSR or paleo-methane seepage, and the role of detrital iron oxide minerals on the marine sediment sulfur sink, with consequences influencing the development of chemosynthetic biological communities at methane seeps.This research was supported by the American Chemical Society-Petroleum Research Fund Award #53006-ND8 and U.S. Department of Energy Grant #DE-FE0010120

    Isolating Detrital and Diagenetic Signals in Magnetic Susceptibility Records From Methane-Bearing Marine Sediments

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    Volume-dependent magnetic susceptibility (Îș) is commonly used for paleoenvironmental reconstructions in both terrestrial and marine sedimentary environments where it reflects a mixed signal between primary deposition and secondary diagenesis. In the marine environment, Îș is strongly influenced by the abundance of ferrimagnetic minerals regulated by sediment transport processes. Post-depositional alteration by H2S, however, can dissolve titanomagnetite, releasing reactive Fe that promotes pyritization and subsequently decreases Îș. Here, we provide a new approach for isolating the detrital signal in Îș and identifying intervals of diagenetic alteration of Îș driven by organoclastic sulfate reduction (OSR) and the anaerobic oxidation of methane (AOM) in methane-bearing marine sediments offshore India. Using the correlation of a heavy mineral proxy from X-ray fluorescence data (Zr/Rb) and Îș in unaltered sediments, we predict the primary detrital Îș signal and identify intervals of decreased Îș, which correspond to increased total sulfur content. Our approach is a rapid, high-resolution method that can identify overprinted Îș resulting from pyritization of titanomagnetite due to H2S production in marine sediments. In addition, total organic carbon, total sulfur, and authigenic carbonate ÎŽ13C measurements indicate that both OSR and AOM can drive the observed Îș loss, but AOM drives the greatest decreases in Îș. Overall, our approach can enhance paleoenvironmental reconstructions and provide insight into paleo-positions of the sulfate-methane transition zone, past enhancements of OSR or paleo-methane seepage, and the role of detrital iron oxide minerals on the marine sediment sulfur sink, with consequences influencing the development of chemosynthetic biological communities at methane seeps

    Ozonation process analysis. Project 2697-3, report three : a progress report to the Fourdrinier Kraft Board Group of the American Paper Institute

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    "August 29, 1980.""The Institute of Paper Chemistry, William C. Krueger ... William J. Whitsitt ... Clyde H. Sprague.

    New Archaeocetes (Mammalia, Cetacea) from the Middle Eocene Domanda Formation of Sulaiman Range, Punjab (Pakistan)

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    291-330http://deepblue.lib.umich.edu/bitstream/2027.42/48650/2/ID517.pd

    Note and Comment

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    The Basis of Relief from Penalties and Forfeitures - The equitable principle of relief from penalties and forfeitures is so far elementary as almost to defy analysis. Many, perhaps most, of the judicial explanations of the principle have based it upon interpretation or construction, appealing to the doctrine that equity regards intent rather than form. Yet a logical application of this doctrine would lead to results very different from those which have actually been arrived at in the decisions. Thus, a stipulation in a mortgage that the mortgagor waives his equity of redemption can hardly be interpreted as meaning that he does not waive it, yet all such stipulations are ignored and redemption granted, nevertheless. Again, a penalty for breach of contract cannot be saved by the most solemn declaration that it is intended as liquidated damages. It must be conceded that many cases have actually been, decided on the interpretation theory, producing such enormities as Iowa Land Co. v. Mickel, 41 Ia. 4o2 (sale of land, 15aoutof15a out of 6oo paid, 4oooinimprovements,secondinstalmentof4ooo in improvements, second instalment of 150 one day late due to a misunderstanding; held forfeited), and Doctornan v. Schroeder, 114 AUt. 8io (N. J., 1921; sale of land, IOOOpaid,lastinstalmentofIOOO paid, last instalment of iooo thirty minutes late; held forfeited). But such cases represent the minority view, and one applicable only to instalment sales, no court pursuing this course in mortgage or liquidated damage cases
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