Hf同位素制约冥古代地壳的熔融条件
Temperature is a fundamental issue in graniticmagmas.Hf is otopic variations in magmatic zircons of granitoid rocks record Hf diffusion that is a tempera-ture-dependent constant.Thus the variation can beused to evaluate the melt temperature of granitoidrocks. Our modeling based on Hf isotopic variation ofzircons derived from the Jack Hills conglomerates，Western Australia，suggests a temperature of>770℃and possibly higher than 810℃ for granitic melts gen-erated in Hadean time，assuming a melt accumulationtime of less than 1 million years. This is higher thanthe previous results by Ti-in-zircon thermometry andindicates an amphibole一dehydration melting，ratherthan a low-temperature water-saturated melting，forEarth”s earliest crust. This may further suggest that freewater or other complementary fluids may not have pre-vailed in the deep-seated melting zones of the earliestcrust and that the earth”s Hadean protocrust was domi-nantly of mafic in composition.
构造地质学 古代地壳 熔融作用 铪同位素
王孝磊
南京大学地球科学与工程学院国科学院,内生金属矿床成矿机制研究国家重点实验室,南京210046
国内会议
中国矿物岩石地球化学学会第九次全国会员代表大会暨第16届学术年会
西安
中文
192-192
2017-04-18（万方平台首次上网日期，不代表论文的发表时间）