William Manton - Academia.edu (original) (raw)

Papers by William Manton

Http Dx Doi Org 10 1080 00039896 1977 10667273, Apr 16, 2013

GRANITIC ROCKS OF THE JETTY PENINSULA, AMERY ICE SHELF AREA, EAST ANTARCTICA WI MANTÓN1, ES GREW2... more GRANITIC ROCKS OF THE JETTY PENINSULA, AMERY ICE SHELF AREA, EAST ANTARCTICA WI MANTÓN1, ES GREW2, J. HOFMANN3 and JW SHERATON4 1 Program in Geosciences, University of Texas at Dallas, Richardson, Texas 75083-0688, USA 2Department of ...

Journal of Petrology, 1968

Rubidium-strontium isotope measurements of Lemumbo igneous monocline associated acid and basic ro... more Rubidium-strontium isotope measurements of Lemumbo igneous monocline associated acid and basic rocks to determine earth mantle or crust origin

Chemical Geology: Isotope Geoscience section, 1988

ABSTRACT If Pb is separated from zircons containing < 5 ppm Pb by a single pass through an... more ABSTRACT If Pb is separated from zircons containing < 5 ppm Pb by a single pass through an ion-exchange column, other substances following Pb may suppress and render unstable the emission of Pb ions. This problem can be overcome by adsorbing Pb as the PbBr24- ion onto a single bead of macroporous resin weighing ∼ 300 μg. Although the kinetics are slow, taking 8–12 hr. to reach equilibrium, and although the low solubility of Zr salts and KD-values between 600 and 800 in 0.6 M HBr lead to recoveries between 50% and 60%, the procedure justifies itself by producing Pb of sufficient purity to give strong stable ion beams after a single separation. Insofar as minimal quantities of reagents are required, the procedure has the potential of yielding very small blanks.

Toxicology and Applied Pharmacology, 1998

Endogenous (predominantly bone) and exogenous lead were differentially labeled in two 11-year-old... more Endogenous (predominantly bone) and exogenous lead were differentially labeled in two 11-year-old female cynomolgus monkeys (Macaca fascicularis) to establish the contributions of the two sources to blood lead. The monkeys had been administered a common lead isotope ''mix'' at the rate of about 1300 g Pb/kg body wt/day from age 10 months until the start of the study. On day 0, common lead was replaced in sequence by mixes artificially enriched in 204 Pb, 206 Pb, and 207 Pb, given for periods of from 50 to 281 days. Total lead ingestion rate was held constant except during administration of the 207 Pb-enriched mix to one of the monkeys, when it was reduced to 650 g/kg/day. Blood and bone were sampled at intervals and analyzed for their content of each of the isotope mixes. A physiologically based model of human lead kinetics was scaled to the cynomolgus monkey and fit to the data to test the correctness of the model structure and to assist with interpretation of study results. Fractional absorption was varied to achieve the best visual fits of the scaled model to blood and bone concentration data for each monkey. The model failed to reproduce the sharp drop in isotope concentrations in blood observed after each exchange of isotope mix. Consequently, it was revised to include a rapid-turnover trabecular bone compartment and a slow-turnover cortical bone compartment, using estimates of trabecular and cortical bone turnover rates from histomorphometric studies in adult cynomolgus monkeys. The revised model fit most of the sets of bone and blood concentrations well. About 17% of the blood lead originated from bone after 11 years of exposure, at blood lead concentrations in excess of 50 g/dl. The rate of return of common lead from bone, as estimated from the model, was 28 g/day just before termination of controlled common lead exposure on day 0. Based on the success of the scaled human model in fitting these data and on the absolute and relative values of bone and blood lead concentrations, the metabolism of lead in the cynomolgus monkey appears to be similar to human lead metabolism.

Nature, 1967

ABSTRACT MESOZOIC igneous activity in South-West Africa is shown as lava plateaux and dyke swarms... more ABSTRACT MESOZOIC igneous activity in South-West Africa is shown as lava plateaux and dyke swarms of basaltic composition and as a group of central volcanic complexes representing a highly variable range of rocks1. The Paresis complex (20° 15' S., 15° 42' E.) is one of the latter and is made up of a consanguineous suite of syenites, bostonites, rhyolites and associated foyaitic rocks, as well as minor basalts and gabbros. From structural and geochemical evidence Siedner2,3 concluded that the basaltic rocks of Paresis represent locally preserved remnants of the regional Stormberg volcanics coeval with, but genetically un related to, the central felsic suite. The age of Paresis is thus significant because it dates both the complex and the regional volcanism. The only other published chronological datum on Mesozoic igneous centres in South-West Africa is a potassium-argon age of 190+/-8×106 yr on biotite from the Klein Spitzkop granite4.

Journal of the Geological Society, 1988

A. E. Shimron writes: Stern & Manton (1987) claim to have identified in Sinai ‘a new tectono-... more A. E. Shimron writes: Stern & Manton (1987) claim to have identified in Sinai ‘a new tectono-magmatic basement province’, designated as area IV in their Arabian-Nubian mosaic, which extends from the Feiran area in west-central Sinai across the Elat

Journal of Petrology, 1994

... In the porphyroclastic and equigranular varieties, kink bands are developed in olivines and b... more ... In the porphyroclastic and equigranular varieties, kink bands are developed in olivines and both olivine and pyroxene grains are highly ... with Tracor Northern 5500 automation or at the Southern Methodist University (SMU) using a JEOL 733 Superprobe with Kristel automation. ...

Experimental Neurology, 1985

The abundance of zinc in hippocampal mossy fibers has stimulated investigation of zinc status in ... more The abundance of zinc in hippocampal mossy fibers has stimulated investigation of zinc status in various pathologic states in which behavioral or anatomic deficits involving the hippocampus are known to occur. Limited autopsy studies of chronic alcoholic humans have suggested that the content of zinc might be reduced in several brain regions whereas reported attempts to replicate these findings in ethanol-exposed experimental animals have produced inconsistent results. In this comparative study, the zinc concentration in 10 brain regions, all spinal cord segments, and microdissected hippocampal subfields was measured by isotope ratio mass spectrometry. A widespread 15 to 20% reduction in zinc content was observed in all regions of chronic alcoholics compared with controls but a selective involvement of hippocampus was not detected. In the experimental studies, groups of rats were exposed to ethanol by one of three routes: inhalation for 2 weeks, as an ethanol/liquid diet for 3 months, or a single intoxicating i.p. dose. Determinations of tissue uptake of radiozinc and of total zinc content were made. In contrast to human pathologic material, zinc pool size and tissue uptakes were not affected by experimental ethanol administration by any route. This study confirmed that a reduction in zinc concentration occurs in the central nervous system of chronic alcoholics. The animal studies indicated, however, that simple ethanol exposure, even for prolonged periods, does not perturb zinc metabolism in brain. Together, these observations argue that the abnormalities of zinc metabolism in chronic alcoholics are possibly secondary to homeostatic alterations associated with hepatic failure.

Earth and Planetary Science Letters, 1971

ABSTRACT Five nodules of eclogite, one nodule of garnet peridotite and one sample of kimberlite f... more ABSTRACT Five nodules of eclogite, one nodule of garnet peridotite and one sample of kimberlite from the Roberts Victor mine were analyzed for concentrations of U, Th, Pb, Rb and Sr and isotopic compositions of Pb and Sr. In the eclogites, U content ranges from 0.09 to 0.26 ppm, Th from 0.35 to 1.1 ppm, Pb from 0.79 to 5.5 ppm, Rb from 2.1 to 28 ppm and Sr from 133 to 346 ppm;206Pb/204Pb ratios range from 14.8 to 18.5,207Pb/204Pb from 14.9 to 15.7,208Pb/204Pb from 35.2 to 38.5. The garnet peridotite contains 0.22 ppm U, 0.97 ppm Th, 1.05 ppm Pb, 6.9 ppm Rb and 108 ppm Sr and the kimberlite contains 2.5 ppm U, 30 ppm Th, 37 ppm Pb, 113 ppm Rb and 2040 ppm Sr. The lead in the eclogites has two components, a lead pyroextractable at 1100–1200° and a non-pyroextractable residual lead. In three of the eclogites, which are to some extent altered, a proportion of the pyroextractable lead may be contaminating lead from the kimberlite, but an altered kyanite eclogite does not appear to be contaminated by this same kimberlite. The pyroextractable lead from a less altered eclogite contains a much larger proportion of206Pb. Compositions calculated for the residual leads vary greatly. In many of the pyroextraction runs the primary eclogitic phases disappeared and the new phases plagioclase, clinopyroxene and a magnetic iron compound were formed. Why part of the lead should have been retained by these new phases is not understood.

Earth and Planetary Science Letters, 1973

Abstract A whole rock U-Th-Pb study was carried out on eight granites from a suite previously dat... more Abstract A whole rock U-Th-Pb study was carried out on eight granites from a suite previously dated at 177 ± 4my(λ = 1.39 × 10 −11 yr −1 ) by Rb-Sr methods. A U-Pb isochron was not obtained owing to recent leaching of U in the outcrop. Seven samples gave a Th-Pb isochron with age 184 ± 16my(λ = 4.99 × 10 −11 yr −1 ), ( 20/8 Pb 204 Pb) 0 = 39.2 ± 0.2 and MSWD 0.8. The eighth sample fell off the line and was rejected on geological grounds. Dissolving 5 g aliquots of the powdered rock markedly improved the reproducibility of U analyses but analysis of the variances suggests that inhomogeneities still might exist between duplicate dissolutions. Th-Pb geochronology needs further development to bring it to the level of precision of the Rb-Sr method.

Clinical Toxicology, 1998