Zhao, Xixi et al. (2004): Relationships between physical properties and alteration in basement rocks from the Ontong Java Plateau

ODP 192


Zhao, Xixi
University of California at Santa Cruz, Department of Earth Sciences, Santa Cruz, CA, United States

Antretter, Maria J.
University of Hawaii at Manoa, United States

Kroenke, Loren W.
Ocean Drilling Program, United States

Riisager, Peter
Ludwig-Maximilians-Universitaet Muenchen, Federal Republic of Germany

Hall, Stuart A.
University of Victoria, Canada

Relationships between physical properties and alteration in basement rocks from the Ontong Java Plateau
In: Fitton, J. Godfrey, Mahoney, John J., Wallace, Paul J., Antretter, Maria J., Banerjee, Neil R., Bergen, James A., Cairns, Graeme, Castillo, Paterno R., Chambers, Lynne M., Chazey, William J., III, Coffin, Millard F., Godard, Marguerite M., Hall, Stuart A., Honnorez, Jose, Ingle, Stephanie P., Kroenke, Loren W., MacLeod, Kenneth G., Naruse, Hajime, Neal, Clive R., Ogg, James G., Riisager, Peter, Sano, Takahashi, Sikora, Paul J., van der Werff, Wietze, White, Rosalind V., Zhao, Xixi, Proceedings of the Ocean Drilling Program; scientific results; basement drilling of the Ontong Java Plateau; covering Leg 192 of the cruises of the drilling vessel JOIDES Resolution; Apra Harbor, Guam, to Apra Harbor, Guam; Sites 1183-1187; 8 September-7 November 2000
Texas A&M University, Ocean Drilling Program, College Station, TX, United States
In this manuscript, we present the results of a physical properties investigation carried out on basaltic cores recovered from the four Leg 192 basement sites, focusing on the relationship between physical properties and alteration in basalts. Variations in physical properties in the Leg 192 basement sites closely resemble each other and reflect the amount of alteration and vein formation in the basement basalts. P-wave velocities, magnetic susceptibilities, and densities for the dense massive basalts are higher than those of more altered and heavily veined basalts. Porosity-dependent alteration is observed at Leg 192 basement sites: P-wave velocity displays a general decrease with increasing loss on ignition and potassium content. These trends are consistent with trends documented for typical alteration of oceanic crust and suggest that basalt alteration is largely responsible for the variation of the physical properties exhibited by rocks at Leg 192 basement sites. Our physical property data support the conclusion that only low-temperature seawater-mediated alteration occurred in the lava flows of the Ontong Java Plateau (OJP). This lack of higher-temperature hydrothermal alteration is consistent with the idea that the OJP basement sites are far from their eruptive vents.
Coverage:Geographic coordinates:
West:157.0000East: 164.3000

Igneous and metamorphic petrology; alteration; basalts; basement; body waves; cores; density; elastic waves; geophysical methods; heat flow; hydrothermal alteration; igneous rocks; Leg 192; magnetic properties; magnetic susceptibility; metasomatism; Ocean Drilling Program; Ontong Java Plateau; P-waves; Pacific Ocean; paleomagnetism; physical properties; porosity; seismic methods; seismic waves; thermal conductivity; veins; volcanic rocks; water-rock interaction; West Pacific;