Postemplacement deformation of plutons and their metasedimentary host, Mt Dromedary area, southern Victoria Land, Antarctica

Abstract

Abstract The Mt Dromedary massif, in the Precambrian‐Paleozoic Wilson Terrane of the Transantarctic Mountains, consists of about 10 plutons intruded into a metasedimentary sequence dominated by marble. The plutons and the meta‐sediments have been deformed after pluton intrusion. The foliation in the metasediments has been recrystallised and realigned during postplutonic deformation, and now parallels pluton margins. Postplutonic folds are rare and concentrated in zones at the ends or margins of some plutons. A postplutonic lineation is generally steeply plunging and lies parallel to folds where present. A 6 km long, southeast trending, high strain zone with shallow‐plunging stretching lineation formed in a narrow (<1 km) belt of metasediment between the Dromedary Metagabbro and a granite pluton. The margins of both plutons were affected by this high strain zone up to 1 km beyond pluton margins. The high strain zone dies out laterally into a lower strain, complexly folded zone. The structure of the Dromedary area can be interpreted in terms of rigid bodies (plutons) that have remained largely internally undeformed while strain was concentrated in relatively incompetent metasediments between plutons.