Metal-enriched sediments from the TAG Hydrothermal Field

A SERIES of sediment samples from the TAG Hydrothermal Field 1 have been collected and analysed for transition metals, and for uranium and thorium isotopes. We show here that metal enrichment of sediment samples is ubiquitous, but geographically variable. Non-detrital metal accumulation rates in one core are Fe and Mn 15.0 and 0.7 mg cm −2 10 −3 yr; and Ni, 180; Co, 93; Cu, 134; and Cr, 148 µg cm −2 10 −3 yr. The hydrothermal field is located on the eastern wall of the Mid-Atlantic Ridge Rift Valley at 26°N and covers ∼100 km 2 . It is characterised by extensive deposits of thick, rapidly growing MnO 2 (ref. 2) and by a magnetic low in the axial anomaly 1 .