Efforts to determine the relationship between mafic, microgranular enclaves and their host granitic rocks have been hindered by the effects of metasomatism and diffusion obscuring the initial composition of the enclaves. Without being able to see through these metasomatic effects, petrologists are unable to some to a consensus regarding the petrogenesis of the host rocks in which they reside. In our previous work on the enclaves in the Nepheline Sodaline Syenite of the Red Hill complex, New Hampshire, rather than trying to decipher enclave host rock relationships by traditional  bulk-rock techniques, we have analyzed apatite and clinopyroxene that crystallized prior to the enclaves being incorporated in the host magma. Mineral compositions were compared with the compositions of the same minerals in the host rock to determine if the trace element variations in both sets of minerals support or deny a consanguineous relationship between enclaves and host rocks. We observed that REE abundances display systematic variations from these enclave apatites and clinopyroxenes to their Nepheline Sodalite Syenite counterparts. These trace element variations indicate that the enclaves are genetically related to the Nepheline Sodalite Syenite, representing parental magmas that intruded up into the cap of the zoned, Nepheline Sodalite Syenite chamber. Based on these results which suggested enclave/syenite consanguinity, the enclave bulk-rock compositions  were examined to determine which of the major  and/or trace element abundances preserve evidence of initial enclave compositions. Of the elements analyzed, only the REE seem to yield an unambiguous signature of the initial enclave compositions. Total REE abundances and La/Yb ratios systematically decline from the enclaves to the Nepheline Sodalite Syenite. These variations are primarily function of apatite  fractionation. Apatite in the Nepheline Sodalite Syenite has large mineral/liquid REE partition  co-fficients, large enough to totally dominate the Ree budget.

A consanguineous relationship between enclaves and syenites allows examination of larger scale petrogenetic problems associated with the Red Hill complex because the mildly silica-undersaturated enclaves represent a potential candidate for a common magma for both the undersaturated  and oversaturated magmas. To date, no data have been obtained suggesting that the enclave magma was also parental for the  oversaturated suite.