Carbon isotope evidence for a magmatic origin for Archaean gold-quartz vein ore deposits
Abstract
Sediments from three sites in the Santa Barbara Basin were examined with a 160X power light microscope and TEM equipment to characterize the magnetostatic bacteria (MB) in the samples. Both the free magnetite and the crystals in the MB in the samples had lengths from 40-60 nm in length and increased in size from one end to the next. An intact magnetosome was also observed. Scanning the sediments with saturation isothermal remanent magnetization (SIRM) and altering field demagnetization techniques using a SQUID magnetometer yielded coercivity spectra which showed that the primary remanence carrier in the sediments was single domain magnetite. Although it is expected that the predominance of the bacterial magnetite component will decrease with depth in the open ocean basin, single-domain bacteria as old as 50 Myr have been observed in oceanic sediments.
- Publication:
-
Nature
- Pub Date:
- June 1986
- Bibcode:
- 1986Natur.321..849B
- Keywords:
-
- Bacteria;
- Biomagnetism;
- Magnetite;
- Marine Biology;
- Sediments;
- Electron Microscopy;
- Geomagnetism;
- Remanence;
- Squid (Detectors);
- Geophysics