Petrology, geochemistry, and magnetic properties of some rocks dredged from the macquarie ridge

Abstract

The magnetic properties and petrological types of the larger samples from six Eltanin rock dredge hauls, taken from the Macquarie Ridge in 1965 to 1967, have been determined. Attempts have been made to relate the ice-rafted materials to their source areas. Five samples are considered to be in situ. These have been chemically analysed. Rocks close to harzburgite in composition are identified, up to 400 km north of the known Macquarie Island harzburgite occurrences. These dredged ultrabasic rocks contain common titanomagnetite and titanohematite fringes on silicates, and finely disseminated sulphides. The resulting high intensity of magnetisation and high ratio of remanent to induced magnetism would be sufficient to account for the large positive linear magnetic anomaly which Hatherton (1967) has defined over the northern 500 km of the Macquarie Ridge. © 1971 Taylor & Francis Group, LLC.