4 research outputs found
The geology of the Kalak Nappe between Revsbotn and Repparfjord Finnmark, Norway
SIGLELD:D47015/83(2vols) / BLDSC - British Library Document Supply CentreGBUnited Kingdo
Subglacial bedrock welding associated with glacial earthquakes
<p>A <3 mm thick, intensely brecciated layer associated with Marinoan (<strong><em>c</em></strong>. 635 Ma) glacial striations on a Neoproterozoic sandstone pavement is documented. Only instantaneous solidification could
have preserved the breccia <strong><em>in situ</em></strong>. Glacier speeds of <strong><em>c</em></strong>. 0.3 m s<sup>−1</sup> would have induced peak flash temperatures sufficient (>1130 °C) to cause partial frictional welding of the deformed quartzitic
bedrock beneath an ice-loaded clast. These results support suggestions that glacial seismicity is due to episodic very rapid
shifts of large ice masses over the substrate (stick–slip movement). They also indicate that significant effective normal
stresses occur at the base of glaciers.
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