05.02.2013 Views

Minerals Report - International Seabed Authority

Minerals Report - International Seabed Authority

Minerals Report - International Seabed Authority

SHOW MORE
SHOW LESS

You also want an ePaper? Increase the reach of your titles

YUMPU automatically turns print PDFs into web optimized ePapers that Google loves.

Depth (km)<br />

0 100 200<br />

0<br />

1<br />

2<br />

3<br />

4<br />

5<br />

O 2<br />

µmol/kg<br />

OMZ<br />

nmol/kg for (Mn)<br />

µmol/kg for (PO )<br />

4<br />

0 1 2 3 4<br />

Figure 2. Profiles of dissolved manganese and phosphate compared to oxygen content<br />

of seawater over a seamount; low-oxygen seawater (the oxygen minimum zone, OMZ)<br />

is a reservoir for high manganese contents.<br />

Crusts become thinner with increasing water depth because of mass<br />

movements and reworking of the deposits on the seamount flanks. Most Fe-<br />

Mn crusts on the middle and lower seamount flanks consist of encrusted talus<br />

rather than encrusted rock outcrop, the latter however typically having<br />

thicker crusts (8). Many seamounts and ridges are capped by pelagic<br />

sediments and therefore do not support the growth of crusts on the summit.<br />

Other volcanic edifices are capped by limestone (drowned reefs), which<br />

commonly supports thinner crusts than underlying volcanic and<br />

Mn<br />

PO 4<br />

INTERNATIONAL SEABED AUTHORITY 196

Hooray! Your file is uploaded and ready to be published.

Saved successfully!

Ooh no, something went wrong!