摘要
Mierostrueture, paragenesis, oxidation during later stages of magenatie evolution,.variation in major and minor elements, and the temperature of formation have been studied for iron-titanium oxide minerals from three layered basie-ultrabasie intrusive bodies. In the light of mineral assemblage and structure, as wen as our experimental data on natural titanifcrous magnetites at 750℃ and 1,000 arm., it has been confirmed that the ilmenite contained in the titaniferous magnetite is formed from ulvoespinel by oxidation during later stages of magmatie process. The titaniferous magnetite and coexisting ilmenite in the layered iron- and titanium-rich anorthosite-gabbro intrusive body (P) crystallized out at 740--970℃. The temperature of formation of irontitanium oxide in Intrusive L, which consists mainly of ultramafie rocks, cannot be determined by the method proposed by A. F. Buddington et al. Textural and experimental evidence suggests that the crystallization of titaniferous magnetites earlier than .titanaugite in Intrusive L took place at temperatures ranging from 1,000° to,100℃. The proportion of irontitanium oxides and the rhythmic variation in their major and minor element contents may reflect an intermittent but periodic differentiation of the magma and are considered to be due to discontinuous introduction of an undifferentiated magma to the magma chamber.
Microstructure, paragenesis, oxidation during later stages of magmatie evolution, variation in major and minor elements, and the temperature of formation have been studied for iron-titanium oxide minerals from three layered basic-ultrabasic intrusive bodies. In the light of mineral assemblage and structure, as well as our experimental data on natural titaniferous magnetites at 750℃ and 1,000 atm., it has been confirmed that the ilmenite contained in the titaniferous magnetite is formed from ulvospinel by oxidation during later stages of magmatie process. The titaniferous magnetite and coexisting ilmenite in the layered iron- and titanium-rich anorthosite-gabbro intrusive body (P) crystallized out at 740-970℃. The temperature of formation of iron-titanium oxide in Intrusive L, which consists mainly of ultramafic rocks, cannot be determined by the method proposed by A. F. Buddington et al. Textural and ex-perimental evidence suggests that the crystallization of titaniferous magnetites earlier than titanaugite in Intrusive L took place at temperatures ranging from 1,000° to 1,10)0℃. The proportion of irontitanium oxides and the rhythmic variation in their major and minor element contents may reflect an intermittent but periodic differen-tiation of the magma and are considered to be due to discontinuous introduction of an undifferentiated magma to the magma chamber.
出处
《地球化学》
CAS
1974年第1期1-24,共24页
Geochimica
