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介绍了壳幔铅混合模式和铅连续生长模式 ,并首次将这两个模式推广到花岗岩成因研究中。通过对世界上一些花岗岩体中长石铅同位素数据的壳幔混合模式计算 ,发现在约 3 1Ga时曾发生过一次全球性的大规模U ,Pb分异事件。将铅连续生长模式计算结果与其它一些一致性信息对比发现 ,该模式对示踪花岗岩的源区时代非常敏感。对以地壳铅为主的花岗岩 ,其铅连续生长模式年龄与其成岩年龄相当 ;而对造山带花岗岩 ,两者之间的关系具有不确定性。对中国南、北秦岭和大别—苏鲁造山带花岗岩中长石铅同位素数据的计算结果对比表明 ,即使属于同一个造山带的岩体 ,其铅的来源和演化历史也存在较大的差别。此外 ,青岛崂山碱性花岗岩的各种铅同位素性质与中国东部其它碱性花岗岩体存在差别 ,但与苏鲁地体花岗岩表现的铅同位素行为一致 ,表明崂山碱性花岗岩的成因与苏鲁花岗岩体的成因具有更强的相关性。
This paper introduced the crust-mantle lead mixed mode and the lead continuous growth mode, and for the first time extended these two models to the genesis research of granite. Based on the crust-mantle mixed model of feldspar Pb isotopic data of some granitic rocks in the world, it was found that a large-scale global U and Pb differential event occurred at about 3 1 Ga. Comparing the calculation results of continuous Pb growth patterns with some other consistent information, it is found that this model is very sensitive to the age of source tracts of tracer granites. For crust-dominated granites, the Pb-bearing continuous growth pattern ages well with their diagenetic age, while for the orogenic granites, the relationship between the two is uncertain. Comparisons of the calculated results of the feldspar Pb isotopic data of granites in the southern, northern Qinling and Dabie-Sulu orogenic belts show that the source and evolution history of lead in the same orogenic mass are quite different . In addition, the lead isotopes of Laoshan alkaline granite in Qingdao are different from other alkaline granites in eastern China, but consistent with the Pb isotopic behavior of granites in the Sulu terrane, indicating that the origin of the Laoshan alkaline granite is similar to that of the Sulu granite The reason is more relevant.