Models proposed to explain the genesis of anorogenic granites are diverse. This may result from the fact that the A-type class includes several petrogenetically different granites, as shown in this work based an a detailed study of the Sm-Nd isotope characteristics and petrologic variability of the Corsican Anorogenic Province. Three different anorogenic granite types are defined: aluminous subsolvus (AS), peralkaline (P) and aluminous hypersolvus (AH). AS granites are the least radiogenic and have the mast variable epsilon(Ndi) values at the scale of the province (from +0.5 to -5.8 but mostly around -4 to -5; i.e. Delta epsilon(Ndi) = 6.3). They also display significant within-intrusion Nd isotope heterogeneity. P granites have the most radiogenic epsilon(Ndi) values and their province-scale scatter is more restricted than for AS types (from +0.5 to -1.4, Delta epsilon(Ndi) = 1.9). P granites are isotopically homogeneous at the intrusion scale. Similarly, AH granites present a moderate scatter of their epsilon(Ndi) at the scale of the province (from -0.1 to -2.2, Delta epsilon(Ndi) = 2.1), but they are generally less radiogenic (epsilon(Ndi) mostly below -1.4) compared with P types. AH granites are also isotopically homogeneous at the scale of an intrusion. This feature, coupled with a large range of Sm/Nd ratios, has allowed the first whole-rock Sm-Nd isochron on a Phanerazoic (i.e. Triassic) granite to be obtained. The close correlation between granite petrology and Nd isotope characteristics demonstrates that these different granite types originate from contrasting source materials and/or have subsequently undergone variable petrogenetic processes. The lack of petrologic evidence for a shallow crustal contamination (e.g. xenoliths of country rocks), the low viscosities of the parental magmas of these granites allowing a fast ascent in the crust and their high Nd concentrations relative to their country racks suggest that the isotope characteristics were mostly acquired in the deep crust. It is inferred that AS granites were generated through partial melting of lower-crustal reservoirs displaying low and very heterogeneous epsilon(Ndi) values. In contrast, P and AH granites are probably mantle-derived magmas that have interacted with the deep crust. The lack of correlation between epsilon(Ndi) values and Nd concentrations Precludes assimilation and factional crystallization as major processes. Instead, this cantamination may have occurred at an early stage, through mixing with lower-crustal components. Clear correlations between epsilon(Ndi) values and indices of agpaicity, (i.e. amiphibole compositions and whole-rock Zr concentrations) suggest that the AH granites have similar parental magmas to P-type granites, but they have assimilated a greater amount of crustal materials. The sensitivity of Nd isotope compositions of AH and AS granites to the presence of recent mafic rocks in the underlying crust suggests that the lower-crustal component involved in the genesis of these granites is most probably mafic. This is supported also by the decrease of the (Si + Na + K)/(Ca + Al-IV) ratio of amphiboles as crustal contamination increases, and by the observation that perthitic granites are also present in infra-oceanic environments. Rough mixing calculations suggest that the proportion of the the mantle-derived component in AH and P granites ranges from 40 to 85%.
