Geology of the southeastern Eyre Mountains relevant to tenure review

Several properties within the eastern Eyre Mountains are currently undergoing tenure revue. This report provides geological information relevant to these reviews, particularly on the sequence of glacial deposits south from Kingston. The geology of the Eyre Mountains is dominated by low-grade metasedimentary rocks of the Permian Caples terrane, becoming increasingly schistose toward the northeast. Volcanic rocks and serpentinite occur in the southwest of the area. The semischists are folded into a large synform, producing flat-lying ledges and steep bluffs, also controlled by vertical joints. The Eyre Mountains semischists are cut by several major faults; only the Moonlight Fault shows evidence of Recent activity. The region has been heavily glaciated, leaving deep U-shaped valleys in the central mountains and wide valleys infilled with moraine and outwash deposits to the northwest (Von Oreti Mararoa catchments) and southeast (Mataura catchment). These valley deposits allow major glacial advance ice limits to be inferred for the region, up to c. 500 000 years BP in age. Within the Eyre Mountains, deposits are limited to cirque moraines, valley floor alluvium, fans, and extensive screes. Landslides are developed on slopes underlain by dipping schistosity, especially in the eastern Eyre Mountains. Within the region, there are no known mineral, geological or structural features that are unique or of regional significance. However, the glacial landforms of the Mataura and Von Oreti Mararoa catchments are extremely well preserved, highly visible, of easy access, and of regional to national significance. Developments such as roading, forestry, or building will have negative impacts on these landscapes.