INTEGRATED BEDROCK GEOLOGIC MAPPING IN THE ADIRONDACK HIGHLANDS OF NEW YORK
New mapping in the Crown Point and Ticonderoga area illustrates the topics addressed. Granulite facies Mesoproterozoic paragneiss, marble, and amphibolite hosted the emplacement of anorthosite-mangerite-charnockite-granite (AMCG) plutonic rocks at ~1.18-1.15 Ga. The earliest of four phases of deformation (D1) is characterized by gneissosity, rarely preserved F1 isoclinal folds, and migmatite in both AMCG and host rocks. Subsequent D2 deformation produced a composite penetrative gneissosity, migmatite, and large isoclinal F2 folds. Towards the end of D2, felsic magmatism including the regionally extensive Lyon Mountain Granite Gneiss (LMG), spread semi-concordant alkali feldspar granite sheets by penetrative migration, sub-parallel to S2 and into previously deformed lithologies. The LMG crystallized at ~1.15 Ga and displays syn-kinematic F2 folds thus constraining the time of D2 deformation. Exhumation during D3 produced F3 folds exhibited in regional domes and basins, local re-activation of the S2 foliation, partial melting, metamorphism, metasomatism, iron ore re-mobilization, and intrusion of magnetite-bearing pegmatite both as layer-parallel sills and cross-cutting dikes. D4 created NE- and NW-trending boudinage, local high-grade ductile shear zones, and cross-cutting granitic pegmatite dikes. Km-scale lineaments readily seen in LiDAR data are Ediacaran mafic dikes and Phanerozoic brittle faults. These findings provide a framework for ongoing investigations into historically significant iron and graphite deposits in the Adirondacks.