The norite belt in the Mesoarchaean Maniitsoq structure, southern West Greenland: conduit-type Ni-Cu mineralisation in impact-triggered, mantle-derived intrusions?

摘要

With the recent discovery of the giant, deeply eroded, 3 GaManiitsoq impact structure in southern West Greenland(Garde 2010), an enigmatic, c. 75 by 15 km large, curvilinearbelt of undeformed norite intrusions with Ni-Cu mineralisationwas re-interpreted as representing crustally contaminatedmelts derived from the mantle in the wake of the impact(Fig. 1; Garde et al. 2012). The norite belt (Nielsen 1976;Secher 1983) was discovered in the early 1960s by the miningand exploration company Kryolitselskabet ?resund A/S,and more than one hundred shallow exploration holes weredrilled by the company in the period 1965–1971. The mineralisationhas subsequently been investigated by ComincoLtd., Falconbridge Ltd. and NunaMinerals A/S. In 2011, there-interpretation of the norite belt, and recent availability ofimproved airborne geophysical exploration tools, promptedthe Canadian company North American Nickel Inc. (NAN)to resume exploration.