Record number :
2305808
Title of article :
Salvaging primary remanence from hydrothermally altered oceanic gabbros in the Oman ophiolite: A selective destructive demagnetization approach
Author/Authors :
Usui، نويسنده , , Yoichi and Yamazaki، نويسنده , , Shusaku، نويسنده ,
Issue Information :
روزنامه با شماره پیاپی سال 2010
Pages :
11
From page :
1
To page :
11
Abstract :
Widespread hydrothermal alteration and formation of secondary magnetite have been problems for paleomagnetic work on gabbros in the Oman ophiolite. Mechanical removal of hydrothermally altered ferromagnesian minerals from gabbro and gabbronorite in the Wadi Rajmi area revealed a cryptic remanence which could not be detected by stepwise demagnetization of bulk rock core samples. After the mechanical removal, samples consist of plagioclase and clinopyroxene. These samples exhibit remanence directions of southeast declination and shallow inclination. This direction is consistent with previously reported paleomagnetic directions at crystallization of the Oman ophiolite. In contrast, bulk rock core samples yielded north declination, resembling the younger remanence directions associated with the obduction of the ophiolite. Microscopic observation and paleomagnetic directional comparison concluded that the cryptic remanence is a primary magnetization carried by exsolved magnetite in plagioclase and clinopyroxene. Our results suggest that previous paleomagnetic data from whole rock gabbros in the Oman ophiolite as well as tectonically active ocean floor should be taken with care.
Keywords :
Marine magnetic anomalies , oceanic crust , Paleomagnetic microanalysis , The Oman ophiolite , Exsolved magnetite
Journal title :
PHYSICS OF THE EARTH AND PLANETARY INTERIORS
Serial Year :
2010
Link To Document :
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