摘要：

Peraluminous magmas may be generated by a variety of mechanisms. Isotopic studies can provide strong constraints to be imposed on the processes involved. However, the equivocal nature of petrogenetic interpretations based on any one individual criterion requires the combined use of field, chemical, stable- and radiogenic-isotope data. Several plutonic suites in the Caledonides of Britain and the Acadian of Nova Scotia indicate a tendency for (Sr-87/Sr-86)(1) and delta O-18 to increase during the development of peraluminous compositions. This observation can be adequately explained only by the assimilation or fusion of crustal rocks (which in some cases should be sedimentary), processes that best account for the generation of large volumes of peraluminous magma. The processes of vaporphase transfer and fractional crystallization may be important in producing local variations in the ratio A/CNK.

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