In this section
@article{Berndt:2017:10.1016/j.epsl.2017.02.033,
author = {Berndt, T and Ramalho, RS and Valdez-Grijalva, MA and Muxworthy, AR},
doi = {10.1016/j.epsl.2017.02.033},
journal = {Earth and Planetary Science Letters},
pages = {70--81},
title = {Paleomagnetic field reconstruction from mixtures of titanomagnetites},
url = {http://dx.doi.org/10.1016/j.epsl.2017.02.033},
volume = {465},
year = {2017}
}
TY - JOUR
AB - Stepwise thermal demagnetization and alternating field (AF) demagnetization are commonly used in paleomagnetic studies to isolate remanent magnetic components of different origins. The magnetically hardest, i.e. highest unblocking temperature/peak field component is often interpreted as the primary magnetization and magnetically softer components as subsequent remagnetizations due to geological events posterior to the formation of the rock, such as reheating or formation of new magnetic minerals. The correct interpretation of the sequence of the geological events such as tectonic rotations from paleomagnetic data often relies on correctly attributing the observed magnetic directions to the remanence carriers and acquisition mechanisms. Using a numerical model to simulate remanence acquisition and stepwise thermal and AF demagnetization experiments, we show that the presence of mixtures of different magnetic minerals, such as magnetite and titanomagnetites of varying titanium-content can have very significant effects on Zijderveld plots. In thermal demagnetization experiments a spurious third component at intermediate temperatures or a continuous curvature may arise from an overlap of the primary remanence with a subsequent thermal or viscous remagnetization carried by small-grained iron-rich magnetite and large-grained titanium-rich titanomagnetite. AF demagnetization plots of magnetic mixtures are even more complex: primary and secondary remanences carried by different minerals may appear as either three or four components in Zijderveld plots. During alternating field demagnetization the highest coercivity component is not necessarily equivalent to the primary remanence and does not necessarily correspond to the highest temperature component in an analogous thermal demagnetization experiment, i.e., the primary remanence direction cannot be recovered. The effects are shown to be due to the different responsiveness of magnetite and titanomagnetites towards viscous or
AU - Berndt,T
AU - Ramalho,RS
AU - Valdez-Grijalva,MA
AU - Muxworthy,AR
DO - 10.1016/j.epsl.2017.02.033
EP - 81
PY - 2017///
SN - 0012-821X
SP - 70
TI - Paleomagnetic field reconstruction from mixtures of titanomagnetites
T2 - Earth and Planetary Science Letters
UR - http://dx.doi.org/10.1016/j.epsl.2017.02.033
UR - http://hdl.handle.net/10044/1/45348
VL - 465
ER -