Rubidium/strontium geochronology of the granitic intrusives of the Hobbs Coast region, Marie Byrd Land, west Antarctica

Field mapping and sample collection of the igneous intrusive rocks in the Hobbs Coast region of Marie Byrd Land were carried out between October and December, 1977. The igneous rocks exposed within the study area consist predominantly of a light-colored granodioritic intrusive here termed the Hobbs Coast Granodiorite. In the Berry and Venzke Glaciers area a light pink granodiorite, hereby designated the Mt. Prince Granodiorite, is exposed at the north ends of the Perry and Demas Ranges. Post-intrusion mafic and felsic dikes have cut the granitic rocks. Contemporaneous with or following dike emplacement, the region was affected by a regional extensional event generating fractures which have been filled by epidote, chlorite and calcite. Major oxide data for the intrusive rocks indicate that the intrusive rocks of the Hobbs Coast region are petrogenetically similar to the granitic intrusives exposed in the Antarctic Peninsula, Ellsworth Land and southern Chile. (Abstract shortened by UMI.)