Shau, Yen-Hong; Torii, Masayuki; Horng, Chorng-Shern; Liang, Wen-Tzong (2004): Magnetic properties of mid-ocean-ridge basalts from Ocean Drilling Program Leg 187. Texas A&M University, Ocean Drilling Program, College Station, TX, United States, In: Pedersen, Rolf B., Christie, David M., Miller, D. Jay, Balzer, Vaughn G., Einaudi, Florence, Gee, M. A. Mary, Hauff, Folkmar, Kempton, Pamela D., Liang, Wen-Tzong, Lysnes, Kristine, Meyzen, Christine M., Pyle, Douglas G., Russo, Christopher J., Sato, Hiroshi, Thorseth, Ingunn H., Proceedings of the Ocean Drilling Program; scientific results; mantle reservoirs and migration associated with Australian Antarctic rifting; covering Leg 187 of the cruises of the drilling vessel JOIDES Resolution; Fremantle, Australia, to Fremantle, Australia, Sites 1152-1164; 16 November 1999-10 January 2000, 187, georefid:2005-011571

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 petrography 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 titanomagnetite. Some samples from unaltered massive basalts contain nearly unoxidized titanomagnetite as the main magnetic mineral. A metadiabase sample showing greenschist facies metamorphism contains magnetic minerals dominated by magnetite. The pillow basalts contain titanomaghemite ranging from stable single-domain to pseudosingle-domain (PSD) grains, and the majority are characterized by a single stable component of remanence. The massive basalts show hysteresis features of larger PSD grains and contain a very low coercivity remanence. The values of natural remanent magnetization (NRM) of the samples in this SEIR area are on the same order as those of other oceanic ridge basalts. They show a general decreasing trend of NRM with increasing crust age. However, the values of NRM show no correlation either with the tectonic zonations (Zone A vs. Zone B) or with the mantle provinces (Pacific vs. Indian types).
West: 126.0000 East: 135.0000 North: -41.1500 South: -46.0000
Expedition: 187
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