Magnetic properties of plutonic rocks at DSDP Leg 82 holes

Ten samples of gabbro and peridotite, with varying degrees of serpentinization, were studied by magnetic techniques and reflected light microscopy. Evidence from these methods suggests that the natural remanent magnetization is primarily of chemical origin. It is generally weak for the gabbros and much stronger for the peridotites. This difference is offset by the fact that the peridotites have generally lower magnetic stability and Koenigsberger ratios. There is a considerable variation in both magnetic parameters and petrology even among closely spaced samples, which suggests that some combination of source heterogeneity and tectonic mixing was involved in the production of these rocks. However, the small number of samples makes this conclusion tentative. There may also have been significant postemplacement alteration involved. All samples show a significant anisotropy of weak field susceptibility that appears to be related to deformation. This anisotropy may be useful in defining petrofabrics.

Tab. 1: Längenänderungen der Gletscherenden 1981/82

Im Berichtsjahr wurden 17 Gletscherberichte mit insgesamt 215 Seiten und 351 Fotos abgegeben, aus denen der vorliegende Sammelbericht zusammengestellt wurde. Mit den gegenüber dem Vorjahr stark vermehrten Fotos (plus 121 Stück) wird die außergewöhnliche Ausaperung des Jahres 1982 sehr gut dokumentiert. Das Beobachtungsnetz ist um 6 Gletscher erweitert worden.