Gosses bluff — diapir, crypto‐volcanic structure or astrobleme?∗

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Abstract
Gosses Bluff, west of Alice Springs, Northern Territory, comprises a roughly circular rim of steeply dipping sandstone, locally overturned with downward facing folds, surrounding a topographically lower core of steeply dipping faulted sandstone, shale, and limestone. Abundant shattercones occur both in outcrop and to depths of 1,000 m. The structure lies on an’ anticlinal trend‐Structural, gravity, seismic and drill hole data indicate that the structure continues to some depth. Shattercones also occur outside the rim of Gosses Bluff. At a nearby prominence, Mt Pyroclast, they occur with peculiar breccias and devitrified glassy rocks, some of which may be of volcanic or impact fusion origin. Gosses Bluff has previously been regarded as a diapir caused by salt intrusion. The evidence now available suggests that it is a crypto‐explosion structure, resulting either from deep‐seated explosive volcanic activity, or from meteorite impact, probably at some time during the Mesozoic Era.