Stromatolites (Developments in Sedimentology, 20): M.R. Walter (Editor). Elsevier,Amsterdam, 1796, 790 pp., U.S. $99.95 or Dfl. 259.00     

J.William Schopf 《Sedimentary Geology》1978,21(4):316-318

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A numerical study of damping     

William T. Thomson  Tom Calkins  Paolo Caravani 《地震工程与结构动力学》1974,3(1):97-103

Diagonal damping matrices were computed for three systems which have non-proportional damping matrices. These diagonal damping matrices were computed on three bases, as follows: 1. After normalizing the equations of motion by the modal matrix, the diagonal terms are retained ignoring the non-diagonal terms. 2. Diagonal damping matrix is established by the optimization algorithm which minimizes the mean square error of the frequency response. 3. Diagonal damping is determined from the normalized differential equation by matching the peaks of the coupled and uncoupled system. The frequency responses for the three cases of one of the three systems are presented together with a comparison of the energy dissipation.  相似文献   

The formation of pyrite from hydrated iron oxide in aqueous solution at 20°C     

William M. B. Roberts 《Mineralium Deposita》1968,3(4):364-367

Experiments are described in which pyrite is synthesized at room temperature and atmospheric pressure from hydrated iron oxides and hydrogen sulphide under conditions similar to those expected in the natural environment. This synthesis differs from earlier work in that oxygen was rigorously excluded from the system and the pH was 5.6. During a later ageing period a reaction appears to take place in which iron monosulphide is converted to pyrite at pH 5.85.

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Zusammenfassung Versuche zur Synthese von Pyrit bei Raumtemperatur unter atmosphärischem Druck, ausgehend von Eisenhydroxiden und Schwefelwasserstoff und somit unter gleichen Verhältnissen, wie in natürlicher Umgebung, werden beschrieben.Die Synthese unterscheidet sich von früheren Arbeiten durch den strengen Ausschluß von Sauerstoff und den pH-Wert von 5.6. In einer darauffolgenden Alterungsperiode scheint eine Reaktion einzusetzen, in der Eisenmonosulfid bei pH 5.85 zu Pyrit umgewandelt wird.

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Published with the approval of the Director; Bureau of Mineral Resources, Geology and Geophysics.  相似文献   

A note on the historical industrial production of carbon dioxide     

William P. Elliott 《Climatic change》1983,5(2):141-144

The historical record of CO₂ emissions from industrial activity is reexamined. The overall annual growth rate has been about 3.5% but with wide variations due to economic fluctuations. It is unlikely that the total CO₂ production would have been greatly different had the major wars of the Twentieth Century been avoided.  相似文献   

The carbon dioxide review     

William C. Clark 《Climatic change》1983,5(1):3-5

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Sterane distribution of solid bitumen pyrolyzates. Changes with biodegradation of crude oil in the Ouachita Mountains,Oklahoma     

Joseph A Curiale  William E. Harrison  Garmon Smith 《Geochimica et cosmochimica acta》1983,47(3):517-523

Solid bitumens (grahamite and impsonite) of southeastern Oklahoma have been shown to originate from near-surface alteration of crude oil (Curiale, 1981; Curiale and Harrison, 1981). Pyrolysis of these solids has been employed to compare the sterane distribution of geographically proximate oils to that of the bitumens. The ratio of rearranged to regular steranes is higher in the pyrolyzates than in the oils, a finding consistent with a bitumen origin due to biodegradation of oil. The remaining presence of steranes, particularly regular steranes, in the bitumens suggests that sterane occlusion may have occurred prior to or during the alteration process, thus removing tetracyclic compounds from the influence of microbial attack. These data suggest that pyrolysis-$\text{GC}\text{MS}$ offers a viable approach to correlation problems involving solid bitumens.  相似文献   

Geotechnical properties of lower trench inner-slope sediments     

L.E. Shephard  William R. Bryant 《Tectonophysics》1983,99(2-4)

Geotechnical property analyses on sediments recovered by DSDP drilling within select convergent margins were integrated to determine the variability in these properties along the trench inner-slope and to delineate the effects of convergence on these properties. Consolidation states range from very underconsolidated to highly overconsolidated, with preconsolidation pressures exceeding 46,000 kPa in Quaternary sediments. Underconsolidated sediments are attributed to:

1. (1) high sedimentation rates.

2. (2) low sediment permeability relative to the length of the drainage path; (3) laterally applied stresses; and (4) induced pore water pressures resulting from the subduction of pelagic sediments with high water content. Factors contributing to the state of overconsolidation include: (1) tectonically induced overpressures; (2) removal of overburden by mass movement processes.

3. (3) low sediment accumulation rates.

4. (4) age.

Vertical gradients of index properties also vary greatly with the maximum gradient associated with overconsolidated sediments. Values of porosity generally exceed 30% at all margins studied, suggesting this porosity represents the minimum attainable solely by the effects of convergence.Geotechnical property results and site-specific parameters suggest two end members should be considered in the general geotechnical property model for convergent margin sediments. Clastic dominated margins form the basis for the initial geotechnical property model. These margins are characterized by thick trench sediment sequences which are folded and faulted and become progressively more deformed upslope. Convergence rates are low, and no well-developed faults or hrst and graben structures are evident on the downbending oceanic plate. Highly overconsolidated sediments and index property values which change rapidly with depth result from the slow progressive deformation of trench and lower slope sediments. Examples of clastic-dominated margins include the Nankai Trough, Aleutian Trench, and Washington continental margin.Pelagic-dominated margins have significantly different geotechnical properties and site-specific parameters. These margins are characterized by thin clastic trench sediment sequences overlying pelagic sediments on a rapidly converging oceanic plate. Well-developed faults and/or hrst and graben structures are evident on the downbending oceanic plate. Sediment deformation along the trench and lower slope appears limited. These sediments are underconsolidated and index property values change gradually but often irregularly with depth. Japan Trench and Middle America Trench-Guatemala margins are considered pelagic-dominated. Middle America Trench-Mexico appears to represent an intermediate case having characteristics of both margin types.  相似文献   

Structural features of the bonin arc: Implications for its tectonic history     

William L. Bandy  Thomas W.C. Hilde   《Tectonophysics》1983,99(2-4)

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Nucleation on perthite-perthite boundaries and exsolution mechanisms in alkali feldspars     

William L. Brown  Ian Parsons 《Physics and Chemistry of Minerals》1983,10(2):55-61

A transmission electron microscope study of intracrystalline boundaries between two perthites of markedly different composition in composite crystals, one a tenary mesoperthite (Or₂₆Ab₅₂An₂₂, initially a homogeneous potassian monalbite) the other a more potassic cryptoperthite (Or₆₁Ab₃₃An₆, initially a homogeneous sodian sanidine), shows that the two perthites are in nearly parallel intergrowth. Most boundaries examined were of (hkO) type; (010) boundaries are straight, whereas other (hkO) boundaries are curved or stepped. Exsolution occurred first in the potassian monalbite (mesoperthite) and was unaffected by the boundary. Subsequent exsolution in the sodian sanidine (cryptoperthite) was affected by the boundary, but for up to only a few micrometers. Exsolution occurred by heterogeneous nucleation and growth of oligoclase on and from the intracrystalline boundary. At almost the same time the rest of the volume of sanidine exsolved by spinodal decomposition. 1–2 μm from the boundary in the intervening K-rich matrix of the sodian sanidine, further exsolution occurred by homogeneous nucleation. Time — temperature — transition curves for continuous cooling have been devised to account for the unusual complexity of the exsolution texture. Except in such exceptional circumstances as the example studied, the initial exsolution in high-temperature alkali feldspars of intermediate composition, unlike other minerals, probably does not occur by nucleation, but only by spinodal decomposition.  相似文献   

<Superscript>40</Superscript>Ar/<Superscript>39</Superscript>Ar dating of the eruptive history of Mount Erebus,Antarctica: volcano evolution     

Richard?P.?EsserEmail author  Philip?R.?Kyle  William?C.?McIntosh 《Bulletin of Volcanology》2004,66(8):671-686

Mt. Erebus, a 3,794-meter-high active polygenetic stratovolcano, is composed of voluminous anorthoclase-phyric tephriphonolite and phonolite lavas overlying unknown volumes of poorly exposed, less differentiated lavas. The older basanite to phonotephrite lavas crop out on Fang Ridge, an eroded remnant of a proto-Erebus volcano and at other isolated locations on the flanks of the Mt. Erebus edifice. Anorthoclase feldspars in the phonolitic lavas are large (~10 cm), abundant (~30–40%) and contain numerous melt inclusions. Although excess argon is known to exist within the melt inclusions, rigorous sample preparation was used to remove the majority of the contaminant. Twenty-five sample sites were dated by the ⁴⁰Ar/³⁹Ar method (using 20 anorthoclase, 5 plagioclase and 9 groundmass concentrates) to examine the eruptive history of the volcano. Cape Barne, the oldest site, is 1,311±16 ka and represents the first of three stages of eruptive activity on the Mt. Erebus edifice. It shows a transition from sub-aqueous to sub-aerial volcanism that may mark the initiation of proto-Erebus eruptive activity. It is inferred that a further ~300 ky of basanitic/phonotephritic volcanism built a low, broad platform shield volcano. Cessation of the shield-building phase is marked by eruptions at Fang Ridge at ~1,000 ka. The termination of proto-Erebus eruptive activity is marked by the stratigraphically highest flow at Fang Ridge (758±20 ka). Younger lavas (~550–250 ka) on a modern-Erebus edifice are characterized by phonotephrites, tephriphonolites and trachytes. Plagioclase-phyric phonotephrite from coastal and flank flows yield ages between 531±38 and 368±18 ka. The initiation of anorthoclase tephriphonolite occurred in the southwest sector of the volcano at and around Turks Head (243±10 ka). A short pulse of effusive activity marked by crustal contamination occurred ~160 ka as indicated by at least two trachytic flows (157±6 and 166±10 ka). Most anorthoclase-phyric lavas, characteristic of Mt. Erebus, are less than 250 ka. All Mt. Erebus flows between about 250 and 90 ka are anorthoclase tephriphonolite in composition.Editorial responsibility: J. Donelly-Nolan  相似文献