The source of long-wavelength aeromagnetic anomalies appears to originate from the earth's deep crust. Constrained by previous studies on geochemical, petrologic analysis, the eclogite and serpentinized peridoti...The source of long-wavelength aeromagnetic anomalies appears to originate from the earth's deep crust. Constrained by previous studies on geochemical, petrologic analysis, the eclogite and serpentinized peridotite samples from drill hole ZK703 at Donghai in the western Sulu ultrahigh-pressure (UHP) terrane, East China, were unambiguously exhumed from the lower crust and the upper mantle, providing significant information about the magnetic properties of rocks at a deeper part of the crust. Results show that the serpentinization process favors the neoformation of nearly stoichiometric magnetite, resulting in the enhancement of its magnetization up to 8.6 A/m, which is sufficient enough to contribute to some magnetic anomalies. In contrast, eclogite samples have only weaker magnetization (generally less than 0.05 A/m) compared to serpentinized peridotite. Nevertheless, experiments under the lower crustal conditions are necessary to further support these conclusions.展开更多
Magnetosomes of magnetotactic bacteria are of great interest in understanding biomineralization and possi- ble links between organisms and geomagnetic field. Fossil magnetosomes are ubiquitous in marine and lake sedim...Magnetosomes of magnetotactic bacteria are of great interest in understanding biomineralization and possi- ble links between organisms and geomagnetic field. Fossil magnetosomes are ubiquitous in marine and lake sediments and may significantly contribute to magnetic signals. In this review, we firstly introduce some characteristics of magneto- tactic bacteria, followed by considering recent progress in magnetosome formation, magnetic measurements, and iden- tification of bacterial magnetites in bulk sediments as well as their paleoenvironmental implications. Finally, we briefly discuss potential future breakthroughs in magnetosome studies and its applications.展开更多
文摘The source of long-wavelength aeromagnetic anomalies appears to originate from the earth's deep crust. Constrained by previous studies on geochemical, petrologic analysis, the eclogite and serpentinized peridotite samples from drill hole ZK703 at Donghai in the western Sulu ultrahigh-pressure (UHP) terrane, East China, were unambiguously exhumed from the lower crust and the upper mantle, providing significant information about the magnetic properties of rocks at a deeper part of the crust. Results show that the serpentinization process favors the neoformation of nearly stoichiometric magnetite, resulting in the enhancement of its magnetization up to 8.6 A/m, which is sufficient enough to contribute to some magnetic anomalies. In contrast, eclogite samples have only weaker magnetization (generally less than 0.05 A/m) compared to serpentinized peridotite. Nevertheless, experiments under the lower crustal conditions are necessary to further support these conclusions.
文摘Magnetosomes of magnetotactic bacteria are of great interest in understanding biomineralization and possi- ble links between organisms and geomagnetic field. Fossil magnetosomes are ubiquitous in marine and lake sediments and may significantly contribute to magnetic signals. In this review, we firstly introduce some characteristics of magneto- tactic bacteria, followed by considering recent progress in magnetosome formation, magnetic measurements, and iden- tification of bacterial magnetites in bulk sediments as well as their paleoenvironmental implications. Finally, we briefly discuss potential future breakthroughs in magnetosome studies and its applications.
