摘要
Experiments have been carried out at 400°--800℃ and 500--1,000 bars. Starting materials include intermediateacidic igneous rocks, volcanic rocks, metamorphic rocks,earbonatites of various purities and chemical reagents of analytical purity-grade. Experimental media are: NaC1, NaCl+CaCl2, NaCl+CaCl2+MgCl2, Na2CO3 and Na2SiO3 solutions. Experimental results show that skarns can be formed under wide physico-chemical conditions: T=400°---800℃, P=500-1,000bars, pH=4-ll, and fo2=10^-28-10^-11 bar.The mineralogy of skarns and the chemical compositions of skarn minerals are generally controlled by the combined factors: the chemical composition of original rocks, pH values, redoxidation conditions, temperatures and pressures. Isomorphous substitution of one mineral for another may have much influence on the temperatures of formation of and fo2 of some major skarn minerals. It is found that skarnization occurs preferentially in the media of NaCl and NaCl+CaCl2 solutions and subortinately in the NaCO3 and Na2SiO3 solutions.
Experiments have been carried out at 400°—800℃ and 500—1,000 bars. Starting materials include intermediateacidic igneous rocks, volcanic rocks, metamorphic rocks, carbonatites of various purities and chemical reagents of analytical purity-grade. Experimental media are: NaCl, NaCl+CaCl_2, NaCl+CaCl_2+MgCl_2, Na_2CO_3 and Na_2SiO_3 solutions.Experimental results show that skarns can be formed under wide physico-chemical conditions: T=400°—800℃, P=500—1,000bars, pH=4—11, and fo_2=10^(-23)—10^(-11) bar. The mineralogy of skarns and the chemical compositions of skarn minerals are generally controlled by the combined factors; the chemical composition of original rocks, pH values, redoxidation conditions, temperatures and pressures. Isomorphous substitution of one mineral for another may have much influence on the temperatures of formation of and fo_2 of some major skarn minerals. It is found that skarnization occurs preferentially in the media of NaCl and NaCl+CaCl_2 solutions and subortinately in the NaCO_3 and Na_2SiO_3 solutions.
出处
《地球化学》
CAS
1983年第3期256-267,331,共13页
Geochimica
