Previous NSF-supported research has made available over 25 U-Pb zircon ages that have provided an important temporal frame- work for the geological evolution of the Adirondacks. Among these new results are at least two that require further field and chemical investigation. The first ~1300 Ma mettonalitic rocks exposed in the southern and eastern Adirondakcs and exhibiting calcalkaline trends. These rocks, and associated granitic gneiss, suggest the presence of an early collisional magmatic arc. Within the Adirondack Lowlands Hyde School Gneiss of ~1300 Ma age also exhibits calcalkaline trends and perhaps a second early collisional magmatic arc. These two postulated arc-related terranes docked against one another prior to the emplacement of the 1160-1130 Ma mangeritic-charnockitic suite which traverses both regions. It is proposed that chemical studies be critical to the plate tectonic evolution of the Grenville Province. In addition, the intrusive vs. metavolcanic history of the Hyde School Gneiss is to be investigated by field and chemical means. It is also proposed that chemical studies involving the modelling of differentiation trends be applied to ultramafic dikes and sheets in the Diana Complex and on Jenkins Mt. in the Marcy massif. The former crosscuts syenite dated at 1154+3 Ma and the latter carries xenoliths of mangerite from the 1147=6 Ma Stark suite will help constrain the currently uncertain upper age of anorthosite emplacement.
