Introduction to 'Magnetic iron minerals in sediments and their relation to geologic processes, climate, and the geomagnetic field'

摘要

Iron is the fourth most common element on Earth and gives rise to the magnetic properties of rock-forming minerals. Magnetic iron minerals are, therefore, abundant and occur in almost every type of geological material. Scientific interest in the occurrence of magnetic minerals in sediments was triggered over 60 years ago by paleomagnetic and magnetostratigraphic applications that relate to the capability of these minerals to record the Earth's magnetic field shortly after deposition, and to store this information over geological timescales (e.g. Johnson et al., 1948; King, 1955; Irving and Major, 1964). Marine sediments are a key source of long and continuous paleomagnetic records, which are essential for reconstructing past geomagnetic field variations and for dating using global geomagnetic reversals (Ogg and Smith, 2004). Magnetic polarity stratigraphy, combined with other age determination methods, has become an essential tool in sedimentary geochronology. Important aspects of sedimentary paleomagnetism, such as the mechanism, efficiency and timing of acquisition of a natural remanent magnetization (NRM), its preservation during diagenetic processes, and possible overprinting by magnetic minerals that formed long after deposition, are intensively investigated and have not yet been fully explained (e.g. Tauxe, 2006; Roberts et al., 2013).