Paleomagnetic and environmental magnetic properties of sediments from IODP Site U1333 (Equatorial Pacific)
Abstract
Sediment samples recovered during Integrated Ocean Drilling Program Expeditions 320 and 321 of the Pacific Equatorial Age Transect (PEAT) program retrieved well preserved continuous core material from the equatorial eastern Pacific providing an excellent archive for the study of paleoclimatic, paleoceanographic, paleoproductivity, and other paleoenvironmental changes and to provide chronostratigraphic, plate tectonic, and geomagnetic constraints. We will present first results from the upper part of Site U1333 (10°30.996'N, 138°25.159'W), which is located ~440 km north of the Clipperton Fracture Zone and ~570 km south of the Clarion Fracture Zone in 4853-m deep water over seafloor basement with an estimated age of 46 Ma. The pelagic sediments in the top 40 m below seafloor consist predominantly of late Oligocene to early Miocene-aged nannofossil and radiolarian oozes with varying amounts of clay. Paleomagnetic and rock magnetic measurements were carried out at 1-cm resolution (equivalent to ~0.9 to 1.6 ka) on 55 m of U-channel samples from the composite stratigraphic section at the site with the goal of extracting a high-resolution record of the magnetostratigraphy, the relative geomagnetic paleointensity, and the variability of the paleoenvironmental conditions. Stepwise demagnetization of the natural remanent magnetization yields an excellent magnetostratigraphy over a time interval of 5.6 m.y. between the base of Chron C6n (19.722 Ma) and the base of Chron C8n.1r (25.306 Ma). A viscous isothermal remanent magnetization drilling overprint was effectively removed during the 20 mT demagnetization step. The paleomagnetic data are characterized by shallow inclinations, consistent with the site being near the paleoequator, and by 180° alternations in declinations downhole, reflecting magnetic polarity zones. Magnetic susceptibility measurements of the sediments correlate well with the observed major changes in lithology and in bulk physical properties.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2010
- Bibcode:
- 2010AGUFMGP13A0761P
- Keywords:
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- 1520 GEOMAGNETISM AND PALEOMAGNETISM / Magnetostratigraphy