USING STRUCTURAL ANALYSES TO ASSESS POSSIBLE FORMATION MECHANISMS OF THE CHEDDAR GNEISS DOME

摘要

INTRODUCTION This project uses structural data from field measurements and oriented samples to provide insight into the formation of the Cheddar Gneiss Dome. The Cheddar Dome is one in a series of five gneiss domes in the Harvey Cardiff Domain of the Central Metasedi-mentary Belt, part of the Mesoproterozoic Grenville Province of Ontario. Gneiss domes are structures associated with major orogenic events worldwide. Definitions vary, but they are generally recognized as circular to oval-shaped bodies consisting of two parts: metamorphic-plutonic cores, and a-surrounding mantle of supracrustal rocks with domical contact parallel layering (e.g. Yin, 2004). The core of the Cheddar Dome is composed of meta-alaskite from the Methuen granite suite (1250-1240 Ma) (Lumbers & Vertolli, 2000; Timmerman et al., 1997). Rocks that mantle the dome consist largely of marble and metasedimentary rocks, predomintantly amphibolites (Lumbers & Vertolli, 2000).