Preliminary paleomagnetic and rock magnetic results from sediments and rocks of IODP's Costa Rica Seismogenesis Project (CRISP) Expedition 334

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Author(s): Zhao, X.; Usui, Yoichi; Kanamatsu, Toshiyaki; Yamamoto, Yuzuru
Integrated Ocean Drilling Program, Expedition 334 Scientists
Author Affiliation(s): Primary:
University of California, Santa Cruz, Department of Earth and Planetary Sciences, Santa Cruz, CA, United States
Other:
Japan Agency for Marine-Earth Science and Technology, Japan
Volume Title: AGU 2011 fall meeting
Source: American Geophysical Union Fall Meeting, Vol.2011; American Geophysical Union 2011 fall meeting, San Francisco, CA, Dec. 5-9, 2011. Publisher: American Geophysical Union, Washington, DC, United States
Note: In English
Summary: We report paleomagnetic and rock magnetic results from our post-expedition (and underway) studies on IODP's Exp. 334 sediments and rocks sampled offshore the Osa Peninsula where the Cocos Ridge is subducting beneath the Caribbean plate. Initial shipboard paleomagnetic results have demonstrated that sediments and basement rocks from the drill sites contain both reversely and normally magnetized samples. Preliminary interpretations of shipboard biostratigraphic data at these sites also indicate that the fossils needed to anchor the biostratigraphy are available. Our post-expedition study involves detailed alternating field and thermal demagnetization analysis of discrete samples. Stable characteristic remanent magnetization (ChRM) components are observed throughout the studied cores, following removal of a low stability drilling-induced remanence. Inclination values of ChRM are moderate downward or upward, consistent with the expected inclination for the sites. In order to examine the origin of the ChRM, supportive rock magnetic experiments on the same samples that used for magnetostratigraphy were also conducted. These experiments include hysteresis loop parameters measurements, and thermomagnetic measurements for Curie temperature and other critical transition temperatures determinations. Rock magnetic study demonstrates that the ChRM components of both polarities are mostly carried by fine grains of magnetite. The new magnetic results from this study should help refine the age history of the sedimentation process and tectonic activities above and within the Costa Rica seismogenic zone.
Year of Publication: 2011
Research Program: IODP Integrated Ocean Drilling Program
Key Words: 07 Marine Geology and Oceanography; Biostratigraphy; Caribbean Plate; Caribbean region; Central America; Characteristic remanent magnetization; Cocos Ridge; Costa Rica; Costa Rica Seismogenesis Project; East Pacific; Expedition 334; Integrated Ocean Drilling Program; Magnetic properties; Magnetization; Magnetostratigraphy; North Pacific; Northeast Pacific; Ocean floors; Offshore; Osa Peninsula; Pacific Ocean; Paleomagnetism; Plate tectonics; Remanent magnetization; Sedimentation
Coordinates: N082400 N084200 W0840000 W0841100
Record ID: 2015099564
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