REASSIGNMENT OF METASEDIMENTARY ROCKS OF THE MASSABESIC GNEISS COMPLEX IN THE CANDIA 7.5 MINUTE QUADRANGLE

Meta-pelites, meta-psammites and granofels identified by an EDMAP investigation of the Candia 7.5 minute quadrangle have intimate relationships with, and bound, the late Proterozoic Massabesic Gneiss Complex (MGC). The nature of these relationships pose questions concerning the age(s) of the MGC and the role the metasediments played in creating migmatites. The bounding metasedimentary rocks northwest of the Campbell Hill-Hall Mt. Fault (CHHMF) have been assigned to the Silurian Rangeley Formation (Sr) of the Central Maine Terrane (CMT), and those in the southeast corner of the quadrangle to the Siluro-Ordovician Berwick Formation (SOb) of the Merrimack Group. The metasedimentary rocks near and within the MGC (SE of the CHHMF)that have not been previously studied are here redefined as Sr based on lithologic similarities. There are also rocks in the south of the quadrangle that are assigned CMT? that could be SObw or Sr. Geochemical work done by Dorais and Wintsch (2001) indicating that Sr and SOb have the same provenance and rare earth/trace element patterns suggests that the two formations share more similarities than previously considered. Field relationships indicate that the metasedimentary rocks were partially melted along with migmatites of the MGC and that there was some involvement with abundant previously unmapped granites that crop out throughout the central and northern parts of the quadrangle. Some of these granites also have gradational contacts with the migmatites suggesting they were produced in situ. These observations can be explained if the metasedimentary rocks within the MGC are undefined late-Proterozoic unit(s), or parts of the MGC are younger than late-Proterozoic.