Calcium exchange between olivine and clinopyroxene calibrated as a geothermobarometer for natural peridotites from 2 to 60 kb with applications

Lithospheric Mantle beneath the Korean Peninsula: Implications from Peridotite Xenoliths in Alkali Basalts

“…(Lee, 1996). 경험적인 모델인 휘석-지압계 (Mercier, 1980)와 감람 석-단사휘석 사이의 Ca 분배를 이용한 지압계 (Adams andBishop, 1982, 1986;Köhler and Brey, 1990)가 있을 뿐이다. Ca 분배를 이용한 지압계의 경우, (1) 감람석내 Ca 함량이 매우 낮아(~0.05 wt%) 측정오차 를 주의해야 한다는 점과, (2) 감람석내 Ca 확산속도 가 휘석에 비해 상당히 빨라서 시료내 평형정도에 민 감하다는 단점이 있다.…”

Geochemical and Sr–Nd–Pb isotopic compositions of lithospheric mantle: Spinel lherzolites in alkaline basalts from the northwestern Ethiopian plateau

“…10) in the stability field of spinel (e.g., Wyllie, 1981;Köhler and Brey, 1990). Furthermore, as shown in Figure 10, the temperature and pressure range of the spinel lherzolites display a higher geothermal gradient with heat flow (~70-90 mW/m 2 ) than the normal continental gradient (40 mW/m 2 , Pollack and Chapman, 1977).…”

“…Geothermal gradient is based on 40, 60 and 90 mW/m 2 heat flow (Pollack and Chapman, 1977). Spinel and garnet transition is from Köhler and Brey (1990). The field for southern Ethiopia is from Meshesha et al (2011).…”

Thermodynamic analysis of partitioning of Ca, Fe and Mg between olivine and clinopyroxene.

“…Bishop (1982, 1986) carried out ex periments on Mg-Ca exchange between olivine and clinopyroxene in the CaO-MgO-SiO2 and CaO FeO-MgO-SiO2 systems and calibrated new geobarometers. Kohler and Brey (1990) calibrated the CaO content of olivine coexisting with clinopyroxene as a function of pressure and tem perature in a wide P-T range in the natural lherzolite systems. These experimental studies on the CaO solubility in olivine were carried out within the narrow compositional range, with XFe = 0-0.2 without any considerations for the effects of compositional dependence.…”

“…The apparent discrepancies in the magnitude of the parameters are derived from the differences of the thermodynamic models used. In this paper, thermodynamic analysis was carried out on the Ca-Fe-Mg partition data between olivine and clinopyroxene near the hedenbergite diopside join (Perkins and Vielzeuf, 1992;Kawasaki and Ito, 1994), in equilibrium with orthopyroxene in the system CaO-FeO-MgO-SiO2 (Adams and Bishop, 1986) and in the natural sys tems (Kushiro et al, 1972;Green, 1973;Mori and Green, 1978;Akaogi and Akimoto, 1979;Takahashi and Kushiro, 1983;Elthon and Scarfe, 1984;Takahashi, 1985;Ulmer, 1988;Kohler and Brey, 1990;Brey et al, 1990). As has been men tioned before, the Ca2+ contents of olivine are low and clinopyroxenes are plotted near the hedenbergite-diopside join for the data of Kawasaki and Ito (1994) and Perkins and Vielzeuf (1992).…”