The Distribution of Transition Metals in Basic Rocks As Determined by Activation Analysis

Dale, Ian M (1972) The Distribution of Transition Metals in Basic Rocks As Determined by Activation Analysis. PhD thesis, University of Glasgow.

Abstract

The research carried out may conveniently be summarised in two sections. In the first section, accurate analyses have been obtained for the scandium, titanium, chromium, manganese, iron, cobalt and nickel content of basic volcanic rocks from a wide variety of geographical locations. (Reunion Island, British Solomon Islands, Juan Fernandez Islands, Hawaii, Red Sea Islands, Iceland and Greenland). Neutron activation analysis has been shown to be an excellent method for the determination of scandium, chromium, manganese, iron, cobalt and nickel in small samples of rock material. The results obtained for a number of international standard rocks are in very good agreement with reported analyses and indicate that activation analysis should be considered one of the most accurate and sensitive techniques available for the analyses of geological samples. The second section has dealt with the transition metal concentrations in the minerals of basic volcanic rocks. Results were obtained for systems which have hitherto not been investigated. It has been shown that the non-spherical distribution of the d-electrons surrounding the transition metal ion exerts a major influence on the partitioning of the ion between olivine and clinopyroxene phenocrysts and the groundmass of basic volcanic rocks. It has been demonstrated, for the first time, that a linear relationship exists between Ink, where k, the partition coefficient, is defined as: [M] crystal [M] groundmass, M being a transition metal ion, and the octahedral site preference energy (O.S.P.E.) of the ion, defined as the tetrahedral crystal field stabilisation energy minus the octahedral crystal field stabilisation energy for the partitioning of the divalent transition metal ions, Mn2+, Fe2+, Co2+ and Ni2+ between olivine and groundmass and clinopyroxene and groundmass of a range of basic volcanic rocks. Zoning of the phenocrysts does not seem to effect the linearity of the plot of Ink Vs O.S.P.E. No systematic variation of the slope of the line Ink Vs O.S.P.E. with either alkalic or tholeiitic basalt type is evident. However, these rock samples containing only olivine phenocrysts tend to have lower values for the partition coefficients. Crystal field effects have also been shown to be significant in the partitioning of the trivalent transition metal ions, Sc3+ and Cr3+, between clinopyroxene phenocrysts and the groundmass of a range of basic volcanic rocks. These results are consistent with and can be explained by the assumption that these transition metal ions occupy tetrahedral and octahedral sites in the magma while only octahedral or near octahedral sites are available in the olivine and pyroxene structures.

• Item Type: Thesis (PhD)
• Qualification Level: Doctoral
• Keywords: Geochemistry, Petrology
• Date of Award: 1972
• Depositing User: Enlighten Team
• Unique ID: glathesis:1972-78584
• Copyright: Copyright of this thesis is held by the author.
• Date Deposited: 30 Jan 2020 15:09
• Last Modified: 30 Jan 2020 15:09
• URI: https://theses.gla.ac.uk/id/eprint/78584