Residual Character Research Articles

Rare earth abundances and distribution in some spinel peridotite xenoliths from Assab (Ethiopia)

REE partition data between solid phases in nine spinel peridotite xenoliths from Assab (Ethiopia) are presented together with bulk-rock REE composition. REE partitioning between clinopyroxene and other coexisting solid phases varies over a relatively wide range. The largest ranges are for LREE in clinopyroxene/orthopyroxene and clinopyroxene/olivine pairs, while clinopyroxene/spinel partitioning of REE is more restricted. The range of REE partition values between coexisting phases is due to compositional dependency effects and is correlated with systematic variations in major element composition of the bulk rocks. The measured REE concentration in the Assab mantle harzburgites do not match with the compositions calculated by mass balance from the modal proportions and REE analyses in individual phases. Inconsistencies for HREE may be due to variable HREE amounts in the clinopyroxene, orthopyroxene phases within a single specimen, while the high LREE contents in the whole rocks are due to contamination during transport to the surface. A geochemical model based on theoretical treatment of the REE partition data suggests that the Assab harzburgites acquired their residual character during a batch melting episode in the upper mantle under the Afar region.

Orogenic lherzolite complexes studied by 87Rb- 87Sr: A clue to understand the mantle convection processes?

Ultramafic materials such as lherzolites found in orogenic lherzolite bodies are suitable materials to investigate mantle processes. We present here an extensive K, Rb, Sr and Sr isotopic study on 70 samples, whole rocks and diopsides, for lherzolites and pyroxenites from four bodies of orogenic lherzolites in the Western Mediterranean: Lherz, Freychinède, Lanzo, Beni Bousera. The more striking feature is the complexity of the data which cannot be explained by simple models of partial melting and (or) contamination of homogenous mantle. The scatter of the results of whole rocks may partly be due to further contamination, especially in some pyroxenites. Lherzolite diopsides show great heterogeneities on a small scale. At least two partial melting events separated by about 109 years are required to create these heterogeneities. K, Rb, Sr concentrations and Rb/Sr ratios confirm the residual character of the lherzolites and show that pyroxenites also often have a residual (or cumulate) character, and cannot be direct partial melting products of the lherzolites. Orogenic lherzolites bodies are interpreted as “sandwiches” of slightly depleted mantle parts of different origins coupled together as sheets by mechanical stirring in the convective cell and layered by injected partial melting liquids. In this model, pyroxenitees may have had different histories, for example some may have suffered selective partial melting whereas others have not. This model implies that the oceanic mantle is progressively more and more depleted and that it is mixed, and recycled. It is opposed to models of irreversible differentiation of the mantle, without any recycling of the differentiated oceanic crust, and to models of “catastrophic” event of differentiation. This model also implies that dating such orogenic lherzolite bodies is meaningless.

The lower continental crust of the Massif Central (Bournac, France)—with special references to REE, U and Th composition, evolution, heat-flow production

From the analyses of xenoliths scavenged by the Bournac pipe (Massif Central) an estimated average composition of the lower crust is presented for major and twenty-four trace elements. This composition, relatively basic and close to the average of some andesites, suggests that the lower crust is not always depleted in LILE; if a residual character may be attributed to some rocks, it seems unlikely to consider all the lower crust as a restite. The heat-flow production (1.6–1.7 H.P.U.) is relatively high for lower crustal granulite facies rocks.

Thermal history of excavation of Archaean gneisses from the base of the continental crust

General considerations of the mineral assemblages likely to be developed at the crust-mantle boundary, the manner in which such rocks are brought to the surface and the criteria for identifying them are followed by a specific model of events in the Scourie gneiss complex. The Scourie gneisses equilibrated their strontium isotopes to upper mantle ratios 2.8 Ga (1 Ga = 10 9 years) ago at the base of a c. 50 km thick crust. Conditions of 15 kbar, 1250°C with low water fugacity, imply thick crust (c. 50 kin) very high crustal geothermal gradient (c. 25°C/km over 50 km) and probable residual character of the entire complex due to loss of granitic fractions. Recovery history was marked by (i) rapid reduction in pressure to c. 11 kbar at high temperature (consistent with near adiabatic uplift) followed by (ii) rapid fall in temperature to c. 450°C at pressures of 11–7 kbar (consistent with rapid cooling of the outer parts of the earth in the late Archaean) prior to dyke intrusions at 2.2–2.4 Ga. Subsequent thermal history until surface exposure 10 Ga ago is poorly marked by mineralogical events. Closure of different mineral systems to chemical change at several stages allows the thermal history of excavation to be unravelled.

Deformation substructures and terminal properties of explosively-loaded thin-walled stainless-steel cylinders

Abstract Thin-walled cylinders of 304 stainless steel were explosively expanded in a constrained system to produce strains ranging from 0.5 to 62%. A flash x-ray technique was employed to measure the strain rates from freely expanding cylinders where the limits of strain rates in this investigation were established as 1.6-4.4 × 104 sec−1. Fracture of the expanded cylinders was detected for strains in excess of 25%, and the number of cracks per unit circumferential length was observed to be roughly proportional to the expansion velocity as predicted by Mott. Scanning electron microscope observations established that a predominant tensile fracture character existed at the outer cylinder wall, in support of the cylindrical stress conditions derived based on the Tresca yield criterion. Direct observations of the terminal substructures in the cylinder walls using transmission electron microscopy showed that a high density of deformation twins and dislocations contributed to the residual hardening. A comparison of the residual defect character and density in the explosively formed 304 stainless-steel cylinders with that previously observed for plane-wave shock-loaded 304 stainless steel at equivalent terminal hardnesses suggests a significant contribution to hardening at high strains in explosively formed stainless steel may arise from an appreciable point defect concentration.

Evidence for the residual character of two soils, one on granite, the other on limestone in Peterborough County, Ontario

The morphology, particle size distribution, and clay mineralogy data of a Methuen soil derived from a granite and a Tweed soil derived from a crystalline limestone are interpreted as supporting the concept that these two soils are residual. Sand mineralogy and elemental analysis of mica support the residual hypothesis.

The gas phase autophobicity of alcohols adsorbed on alumina

The adsorption isotherms for n-aliphatic alcohols (C 1C 4) have been obtained on two alumina surfaces of widely different surface area. The isotherms exhibit strong monolayer binding with little tendency toward multilayer formation. However, attempts to ascribe all multilayer adsorption to pendular ring condensate were not successful, and some multilayer contribution remains at high relative pressures. The residual multilayer character is higher for the low specific surface area alumina and decreases for both surfaces in going from C 1 to C 4. The enhanced multilayer character for the low area alumina is understandable in terms of its supposedly higher electrostatic field strength. The variation with hydrocarbon chain length is due to a gradual isolation of the surface from any multilayer adsorption in the context of previously developed autophobicity concepts presuming strongly oriented first-layer adsorption.

Remarks On the Egyptian Ritual of Opening the Mouth' and Its Interpretation

Egyptian religion. Parts of the textual material relevant to the ritual of 'Opening the Mouth' have been known for many years from notes taken by Champollion and Rosellini. In I88I and I890 a collection of these texts was published by Schiaparelli and some years later, in I906, they were republished by Wallis Budge. The latest edition was made by Eberhard Otto in I960, thereby incorporating some new material previously unknown. The body of texts included in these publications will in this paper be called 'the Theban texts'. This will make it easier to separate the ritual they represent from those hinted at in another body of texts of a more residual character. This latter category will be treated later on.

Extreme ultraviolet absorption spectra of various polymers

AbstractThe extreme ultraviolet absorption spectra between 1700–3000 A of a series of monomers and polymers show that, in addition to absorption due to the presence of chromophores such as phenyl rings and residual double bonds, other factors such as light scattering, orientation or polarization effects, and interaction, both intermolecular and intramolecular, are important in the observed spectra. In polymers such as polystyrene and polybutadiene, the effect due to scattering becomes appreciable (about 20–30%) at about 1700 A but the other factors do not appear to be important. In proteins, the absorption at short wavelengths is seen to be a function of absorbing chromophores as well as of residual double bond character of the polypeptide chain, of light scattering, and orientation or polarization and intramolecular effects. In other polyelectrolytes, such as polyvinylpyridinium chloride, changes in the 2000 A transition indicate that there is a degree of orientation and/or molecular interaction of the aromatic groups in these polymers.

The Post-Glacial Erosion Theory of Drumlins

In recent years Professor J. W. Gregory has challenged, one after the other, our most cherished beliefs and creeds in the field of glacial geology, fearlessly raising again the discarded standards, dust-laden these many years; the gaping fissures of the fjords, the glacial submergence, the residual character of many moraines, eskers, and kames, including the beautiful York moraines, and now —the post-glacial origin of drumlins.