Boron and chlorine contents of upper oceanic crust; basement samples from IODP Hole 1256D

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doi: 10.1029/2008GC002182
Author(s): Sano, Takashi; Miyoshi, Masaya; Ingle, Stephanie; Banerjee, Neil R.; Ishimoto, Mitsunori; Fukuoka, Takaaki
Author Affiliation(s): Primary:
National Museum of Nature and Science, Department of Geology and Paleontology, Tokyo, Japan
Other:
Kumamoto University, Japan
University of Southampton, United Kingdom
University of Western Ontario, Canada
University of Tokyo, Japan
Risso University, Japan
Volume Title: Geochemistry, Geophysics, Geosystems - G<sup>3</sup>
Source: Geochemistry, Geophysics, Geosystems - G>3`, 9(12). Publisher: American Geophysical Union and The Geochemical Society, United States. ISSN: 1525-2027
Note: In English. 78 refs.; illus., incl. 2 tables
Summary: Boron, Cl, Ti, K, Sm, and Gd concentrations of oceanic crust samples were determined by prompt gamma neutron activation analysis. The samples include 63 basalts and 5 gabbros obtained at various depths (369-1503 m below seafloor) from Hole 1256D during Ocean Drilling Program Leg 206 and Integrated Ocean Drilling Program Expedition 309 and 312. The results show stepwise downhole variations, B content and B/K decrease, and Cl content and Cl/K increase with increasing depth. High B content (>1.5 ppm) in shallower rocks (extrusive lavas) is probably achieved by low-temperature seawater alteration, and high Cl contents (up to 1400 ppm) in the deeper rocks (plutonic section) would show result of high-temperature hydrothermal alteration. Average B and Cl values for the upper oceanic crust in Hole 1256D are 1.5 ppm and 334 ppm, respectively.
Year of Publication: 2008
Research Program: IODP Integrated Ocean Drilling Program
ODP Ocean Drilling Program
Key Words: 02 Geochemistry; 07 Marine Geology and Oceanography; Alteration; Basalts; Boron; Chlorine; Crust; East Pacific; Equatorial Pacific; Expeditions 309/312; Gabbros; Geophysical methods; Guatemala Basin; Halogens; Hydrothermal alteration; Igneous rocks; Integrated Ocean Drilling Program; Leg 206; Major elements; Metasomatism; Mineral composition; Neutron-gamma methods; North Pacific; Northeast Pacific; ODP Site 1256; Ocean Drilling Program; Oceanic crust; Pacific Ocean; Plutonic rocks; Sea water; Trace elements; Upper crust; Volcanic rocks; Water-rock interaction; Weathering
Coordinates: N064400 N064400 W0915600 W0915600
Record ID: 2009080498
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