MAGNETIC PROPERTIES OF MID-OCEAN-RIDGE BASALTS FROM OCEAN DRILLING PROGRAM

• Main Author: Wen-tzong Liang
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Subjects: Antarctic; Australian-Antarctic Discordance; Indian; Pacific; Southeast Indian Ridge; Antarc*
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.532.6111; http://www.earth.sinica.edu.tw/papers/horngcs/pdf2004b.pdf

The core samples of mid-ocean-ridge basalts (including Indian and Pacific type) recovered from the Southeast Indian Ridge (SEIR) area near the Australian Antarctic Discordance during Ocean Drilling Program Leg 187 were studied using rock magnetism, mineralogy, and petrogra-phy methods. On the basis of thermomagnetic analyses and low-temperature magnetometry, the dominant magnetic carrier in most of the basalt samples (pillow basalts) is characterized as titanomaghemite, which presumably formed by low-temperature oxidation of primary ti-tanomagnetite. Some samples from unaltered massive basalts contain nearly unoxidized titanomagnetite as the main magnetic mineral. A metadiabase sample showing greenschist facies metamorphism con-tains magnetic minerals dominated by magnetite. The pillow basalts contain titanomaghemite ranging from stable single-domain to pseudo-single-domain (PSD) grains, and the majority are characterized by a sin-