Carbon-14 production compared to oxygen isotope records from Camp Century,Greenland and Devon Island,Canada

Carbon-14 production rate variations that are not explainable by geomagnetic changes are thought to be in antiphase with solar activity and as such should be in antiphase with paleotemperature records or proxy temperature histories such as those obtainable from oxygen isotope analyses of ice cores. Oxygen isotope records from Camp Century, Greenland and Devon Island Ice Cap are in phase with each other over thousands of years and in antiphase to the ¹⁴C production rate residuals.     

An analysis of mesh sizes required for screening fishes at water intakes

Twenty-four species of marine and freshwater fish were examined to determine mesh size requirements for fish screens placed at water intakes. Curves relating fish length to the mesh size requirements are given for these species and a model for predicting mesh size requirements as a function of fish shape and size is presented. This is of superior accuracy in general application to a previous model given by Bell (1973) and appears to hold good for a wide range of fish species. Its practical application is discussed.     

The use of chi-square maps in the analysis of census data

This paper addresses itself to one of the problems inherent in any spatial analysis of census data, namely the variable size of the enumeration units. This variation renders some proportions unstable, due to the small numbers involved. Attempts to overcome this, using visual methods, can be unsatisfactory, whilst doing nothing to aid statistical analysis. Chi-square maps are suggested as a satisfactory alternative in both contexts, and data for Reading, Berkshire are displayed to illustrate this. These maps suggest that some inferences, based upon indicators derived from proportions, may be unsound.     

The geochemistry of basalts from a back-arc spreading centre in the East Scotia Sea

Rapid sea floor spreading has taken place over the last 8 Myr behind the South Sandwich island arc, producing a regular set of magnetic lineations. Suites of fresh basalts have been dredged from four widely separated localities along the spreading axis. Dredges 20 and 23 yielded sub-alkaline olivine tholeiites, dredge 22 recovered vesicular tholeiites with minor normative olivine, while dredge 24 contained a fractionated suite of highly vesicular quartz-normative basalts with higher $\text{Fe}\text{Mg}$. The concentrations of the incompatible elements Ti, P, Zr, Hf, Nb, Ta, Y and the REE increase systematically from dredge 24 through dredges 22 and 20 to dredge 23 and there is a comparable increase in $\text{Ce}{}_{\mathrm{N}}\text{Yb}{}_{\mathrm{N}}$. Quantitative modelling suggests that all the basalts can be derived from an essentially similar mantle source (with respect to these elements) through varying degrees of partial melting, but involving some residual clinopyroxene. Basalts from dredge 24 have unusually low concentrations of Ti, P, Zr, Nb, Y, REE and Ni, similar to the values in arc tholeiites, and the more primitive dredge 24 liquids seem to have been generated through high degrees of partial melting (~ 30%) leaving a dunitic residue. Transitional arc tholeiite characteristics are also apparent in the relatively high K, Rb, Ba contents and ${}^{87}\text{Sr}{}^{86}\text{Sr}$ ratios of dredge 24 and 22 basalts, though Nd isotope ratios are uniform. It is considered that fluids derived from the dehydrating subducted slab may have locally penetrated the source regions of the back-arc basalts, carrying K, Rb, Ba and seawater-enriched ⁸⁷Sr, and producing conditions of magma generation similar to that of arc tholeiites. However, it is unlikely that the sources for these and other marginal basin basalts differ fundamentally from the range of mantle sources feeding normal mid-ocean ridges.     

Trace elements in the Allende meteorite—IV. Amoeboid olivine aggregates

INAA data for Ca, Sc, Hf, La, Ce, Sm, Eu, Tb, Yb, Lu, Os, Ir, Ru, Na, Cl, Br, Fe, Mn, Cr, Co, Au, As, and Sb are presented for ten amoeboid aggregates from the Allende meteorite. Only one lacks olivine. Seven of the remainder, as a group, have cosmic proportions of refractory lithophile and siderophile elements and appear to have formed when coarse-grained Allende inclusion material underwent partial reaction with a low-temperature nebular gas and mixture with FeO-rich olivine. The other two have highly fractionated abundances of refractory elements relative to one another compared to Cl chondrites, including Group II REE patterns, and probably formed by the mixing of fine-grained Allende inclusion material with FeO-rich olivine. Non-refractory siderophile components are also different in composition in each type of amoeboid olivine aggregate.