Dykes at Nussbaun Riegel

I. Smith and V. Neall

During November and December 1966, 25 days were spent at Nussbaun Riegel, to the east of Lake Bonney and to the south of a arcuate gorge in the Taylor Valley. Nussbaun Riegel stands several thousand feet above the Taylor Valley and is connected with the Kukri Hills to the south by a moraine-mantled platform.

Igneous dykes have been reported from as far north as Admiralty Range and as far south as the Darwin Mountains. Nussbaum page 4 Riegel contains one of the best exposed and most readily accessible dyke swarms and the various petrological types were collected and the field relations of the dykes determined.

The dykes were previously mapped as being entirely lamprophyres but the more detailed studies have showm that they are more correctly termed dolerites. One is possibly a quartz porphyry.

Most of the dykes strike at right angles to the general strike of the basement rock, and are dextrally displaced by three faults, the amount of displacement at each fault being about 200 ft and the sense of displacement dextral.

The dyke rocks are at present being studied in detail and samples are being prepared for K/Ar dating.