GEOCHEMICAL CHARACTERIZATION OF THE MINERALIZED TRANSITION BETWEEN THE GOLDENVILLE AND HALIFAX FORMATIONS AND THE INTERACTION WITH ADJACENTGRANITOID INTRUSIONS OF THE LISCOMB COMPLEX, NOVA-SCOTIA

The mineralized transition between the Goldenville and Halifax formati ons of the Meguma Group was intruded by granodiorite and monzogranite of the Liscomb Complex near Eastville, Nova Scotia. Mineral and whole- rock chemical studies of samples from drillholes and surface exposures allow documentation of the chemical nature and a preliminary assessme nt of the magnitude of interaction between the granitoid bodies and th eir metasedimentary host rocks. Mg/(Mg+Fe) broadly increased, whereas Mn decreased in biotite and chlorite with increasing grades of metamor phism toward the contact with the Liscomb Complex in the eastern secti on of the map area. Fe and Mn, two transition elements with similar ch emical behaviour, were mobilized and incorporated into Fe-rich contact metamorphic minerals such as almandine garnet and staurolite. Garnet in the granodiorite shows reversals in zoning, with Mg and Fe decreasi ng sharply and Mn increasing at the rim. Reversely zoned garnet crysta llized with falling temperature and likely represents a highly modifie d xenocrystic type. Standard discriminant diagrams confirm that the Me guma metasedimentary rocks were deposited on a continental margin and that the granitoid intrusions formed as crustal melts during continent al collision. Assimilation of Meguma country rock by the Liscomb grani toid intrusions is indicated by the detection of a characteristic trac e element signature imparted by the transition between the Goldenville and Halifax formations near Eastville. Although not certain proof, th e strong contrast between Pb/Zn ratios in the Meguma metasedimentary r ocks and the Liscomb granodiorite (similar to 0.45) and the rest of th e South Mountain Batholith (1.19-2.26) suggests a variant petrogenetic process for the two granitoid bodies.