Petrology of the Mount Luxmore intrusion

Sise, John Renault.

The Mt. Luxmore intrusion defines one of several clearly delineated magnetic anomalies in eastern Fiordland which form linear belts extending from Lake Hauroko to the Homer Tunnel. It is a concentrically zoned body with steep inwardly dipping contacts, having a dunite core and a gabbroic margin. Alteration is more intense near the contact with the Wet Jacket Formation.
Olivine compositions ranging from Fo86 in the core to Fo70 at the margins and plagioclase ranging from An96 to An70 over the same interval, support the concentric distribution of the units.
Corona textures, which are well developed in the troctolites, suggest that the intrusion has undergone amphibolite grade metamorphism and that serpentinization and zeolitization are the result of subsequent low temperature alteration processes.
An origin by flowage differentiation within a feeder dyke type structure is envisaged. The time of intrusion may be closely related to plutonism during the Rangitata Orogeny which now possibly defines the Hedian "Tectonic" Zone.

vi, 40 leaves : illus., maps. (2 fold. in pocket) ; 31 cm.

1974Sise

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