Comment on “The Fossil Coleoptera of the Two Creeks Forest Bed, Wisconsin”, by Alan V. Morgan and Anne Morgan     

Edward B. Evenson  Donald F. Eschman  William R. Farrand  Louis J. Maher  David M. Mickelson  Alan V. Morgan  Anne Morgan   《Quaternary Research》1980,14(3):377-378

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Stability of titanian clinohumite: Experiments and thermodynamic analysis   总被引：2，自引：0，他引：2  

Martin Engi  Donald H. Lindsley 《Contributions to Mineralogy and Petrology》1980,72(4):415-424

Reversed hydrothermal experiments on a natural titanoclinohumite [Ti-Cl; approximate formula Mg_7.5FeTi_0.5O₁₆(OH)] show that it breaks down at 475°±11° C (3.5 kbar), 620°±11° C (14 kbar) and 675°±8° C (21 kbar) to the assemblage olivine +ilmenite+vapor. An internal-consistency analysis of the data yields _r G _s ^/0 (298 K, 1 bar)=36,760±3,326 cal (mole Ti-Cl)^–1. _r S _s ^/0 (298 K, 1 bar)=34.14±5.91 cal deg^–1(mole Ti-Cl)^–1. Linear correlation coefficient r _G–S 1.0. A solution model that accounts for TiO₂-M(OH)₂ and F-OH substitution shows that the results for our nearly F-free Ti-Cl are in reasonable agreement with the unreversed breakdown experiments of Mer-rill et al. (1972) on a F-bearing Ti-Cl.Because fluorine is necessary to stabilize Ti-Cl under mantle conditions, we suggest that Ti-Cl is much more likely to be a storage device for fluorine than for water in the mantle.  相似文献   

Changing trade patterns of the West Pacific   总被引：1，自引：0，他引：1  

Donald W. Fryer 《GeoJournal》1980,4(5):479-484

In the enormous expansion of world trade in the quarter century after 1950, the share generated by countries of the Western Pacific remained remarkably constant. This relationship primarily reflected the rise of Japan as a major force in the international economy. Whereas Japan's own trade grew more widely oriented and the Western Pacific margins relatively less important as trading partners than before WW II, to the states of the Western Pacific Japan's status both as a supplier of imports and as an export market greatly enlarged —only rarely is Japan not the leading trading partner. The Japanese strategy of export-led growth has been replicated by South Korea, Taiwan, Hong Kong, and Singapore. All of these countries, as well as Japan itself, depend overwhelmingly on imports for their raw materials and energy supplies. Elsewhere trade patterns have been greatly modified by a rising spirit of nationalism that has emphasized development of manufacturing industries in Australia and New Zealand no less than in the states of SE Asia.  相似文献   

Process geomorphology,Leo F. Ritter,William C. Brown Company Publishers,Dubuque, Iowa,U.S.A. 1978. No. of pages: 603. Price: U.S. $22.95. ISBN 0 697 05035 1     

Donald Jakes 《地球表面变化过程与地形》1980,5(2):203-204

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Surface and complexation effects on the rate of Mn(II) oxidation in natural waters     

Donald E. Wilson 《Geochimica et cosmochimica acta》1980,44(9):1311-1317

Montmorillonite, kaolinite, goethite, and particulate and soluble natural organic materials influence the rate of Mn(II) oxidation. While surfaces accelerate the reaction, apparently by bonding Mn²⁺ in a manner which fulfills the requirements of the transition state, soluble organic materials retard the reaction by complexing the oxidizable species. It is doubtful whether particulate matter would influence the oxidation process under natural loading conditions since 50–500 mg l^?1quantities are required to produce measurable changes in the reaction rate. Complexation by humic materials, however, might be expected to reduce the rate of oxidation by an amount proportional to the dissolved organic carbon concentration. Oxidation followed by precipitation is predicted to be an important mechanism for Mn²⁺ removal in oceanic waters. The situation is less predictable in lake waters.  相似文献   

Uses of Chloride/Bromide Ratios in Studies of Potable Water   总被引：20，自引：0，他引：20  

Stanley N. Davis  Donald O. Whittemore  June Fabryka-Martin 《Ground water》1998,36(2):338-350

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Amphibole pyroxenite xenoliths: Cumulate or replacement phenomena from the upper mantle,Nunivak Island,Alaska     

Donald M. Francis 《Contributions to Mineralogy and Petrology》1976,58(1):51-61

Interstitial to poikilitic amphibole found in garnet pyroxenite xenoliths has been interpreted, in the past, to represent a critically silica undersaturated, residual intercumulus melt trapped by its cumulate assemblage of anhydrous phases. The textural features of such amphibole in pyroxenite xenoliths from Nunivak Island, Alaska, however, are more compatible with an origin by replacement of the anhydrous phases of the pyroxenite, following a period of cooling and sub-solidus recrystallization in the upper mantle. The reaction of amphibole and olivine to give orthopyroxene, observed in two specimens, requires that the associated fluid phase was not critically silica undersaturated. The amphibole is therefore thought to reflect the interaction of an alkali-bearing, migratory, aqueous fluid and an upper mantle consisting of spinel lherzolite cut by veins of spinel and garnet pyroxenite.  相似文献   

On the calculation of cosmic-ray exposure ages of stone meteorites     

Philip J. Cressy  Donald D. Bogard 《Geochimica et cosmochimica acta》1976,40(7):749-762

Abundances of cosmic ray-produced noble gases and ²⁶Al, including some new measurements, have been compiled for some 23 stone meteorites with exposure ages of < 3 × 10⁶ yr. Concentrations of cosmogenic He, Ne, and Ar in these meteorites have been corrected for differences in target element abundances by normalization to L-chondrite chemistry. Combined noble gas measurements in depth samples of the Keyes and St. Séverin chondrites are utilized to derive equations for normalizing the production rates of cosmogenic ³He, ²¹Ne, and ³⁸Ar in chondrites to an adopted ‘average’ shielding: ${}^{22}\text{Ne}{}^{21}\text{Ne}\text{= 1.114.}$ The measured unsaturated ²⁶Al concentrations and the calculated equilibrium ²⁶Al for these meteorites are combined to estimate exposure ages. These exposure ages are statistically compared with chemistry- and shielding-corrected concentrations of cosmogenic He, Ne, and Ar to derive absolute production rates for these nuclides. For L-chondrites, at ‘average’ shielding, these production rates (in 10^?8 cm³/g 10⁶ yr) are: ³He = 2.45,²¹Ne = 0.47, and ³⁸Ar = 0.069, which are ~ 25% higher than production rates used in the past. From these production rates and relative chemical correction factors, production rates for other classes of stone meteorites are derived.  相似文献   

Greatlakean Substage: A replacement for Valderan Substage in the Lake Michigan basin     

Edward B. Evenson  William R. Farrand  Donald F. Eschman  David M. Mickelson  Louis J. Maher 《Quaternary Research》1976,6(3):411-424

New evidence from recent field and seismic investigations in the Lake Michigan basin and in the type areas of the Valders, Two Creeks and Two Rivers deposits necessitates revision of late-glacial ice-front positions, rock- and time-stratigraphic nomenclature and climatic interpretations and deglaciation patterns for the period ca. 14,000–7,000 radiocarbon years B.P. The previously reported and long accepted pattern of deglaciation for the Lake Michigan basin started with a regular retreat from the Lake Border Morainic System, with a minor oscillation marked by the Port Huron moraine(s) and then an extensive Twocreekan deglaciation followed by a major (320 km) post-Twocreekan advance (Valders). However, we now record a major retreat between the times of the Lake Border and Port Huron moraines, followed by a gradual retreat from the Port Huron limit and interrupted by a minor standstill (deposition of Manitowoc Till), a retreat (Twocreekan) and a readvance (Two Rivers Till). No Woodfordian or younger readvance was as extensive as had been the preceding one. This sequence argues for a normal, climatically controlled, progressive deglaciation rather than one interrupted by a major post-Twocreekan (formerly Valderan) surge. This revision appears finally to harmonize the geologic evidence and the palynological record for the Great Lakes region. Our investigations show that Valders Till from which the Valderan Substage was named is late-Woodfordian in age. We propose the term “Greatlakean” as a replacement for the now misleading time-stratigraphic term “Valderan”. The type section and the definition of the upper and lower boundaries of the Greatlakean Substage remain the same as those originally proposed for the Valderan Substage but the name is changed.  相似文献   

The relationship of elasticity and crystal structure in andalusite and sillimanite     

Michael T. Vaughan  Donald J. Weidner 《Physics and Chemistry of Minerals》1978,3(2):133-144

The nine elastic constants of andalusite and sillimanite have been determined, using the technique of Brillouin scattering. They are, in megabars, for andalusite: c ₁₁=2.334, c ₂₂=2.890, c ₃₃=3.801, c ₄₄=0.995, c ₅₅=0.878, c ₆₆=1.123, c ₂₃=0.977, c ₁₃=1.162, c ₁₂=0.814; for sillimanite: c ₁₁=2.873, c ₂₂=2.319, c ₃₃=3.884, c ₄₄=1.224, c ₅₅=0.807, c ₆₆=0.893, c ₂₃=1.586, c ₁₃=0.834, c ₁₂=0.947. Both structures are characterized by chains of edge-linked coordination octahedra extending parallel to the crystallographic c direction, cross-linked by polyhedra of lower coordination. In each structure the stiffness measured parallel to c is greater than that measured normal to c. The shear moduli can be directly correlated with the relative rigidity of the cross-linking structures.  相似文献