|
Region
|
Site
|
Water
depth (m) |
Sulfate
concentration minimum (mM) |
Depth
(mcd) |
Alkalinity
concentration maximum (mM) |
Depth
(mcd) |
Phosphate
concentration maximum (µM) |
Depth
(mcd) |
Ammonium
concentration maximum (mM) |
Depth
(mcd) |
Methane
concentration maximum (ppmv) |
Shallowest
depth (mcd) |
Calcium
concentration minimum (mM) |
Depth (mcd)
|
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Limited to no sulfate reduction |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
| Nazca Ridge | 1236 | 1323 | <26 | 170-191 | 2.2 | — | 2 | 3 | <0.005 | — | BDL |
|
Increases with depth |
|
|
|
1237 | 3212 | <26 | 5-63 | >5 | 9-20 | 9 | 5 | >0.25 | 9-33 | 8 | 42-63 | Increases with depth |
|
| Cocos Rise | 1241 | 2027 | Little depletion | — | >5 | 63-95 | 5 | 3 | >0.4 | 53-106 | 13 | 189 | Increases with depth |
|
| Intermediate sulfate reduction |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
| Carnegie Ridge | 1238 | 2203 | <10 | 75 | >17 | 83-93 | >15 | 10-64 | 3 | 82-386 | <100 |
|
6.1 | 54 |
| Panama Basin* | 1240 | 2921 | <15 | 135-200 | >17 | 147-190 | >30 | 147-190 | >2 | 147-200 | 57 | 147 | <3.5 | 104-179 |
| Complete sulfate reduction |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
| Chile Basin | 1232 | 4072 | <2 | 26 | >30 | 26-159 | >50 | Throughout | >2 | 37 | >10,000 | >60 | <6 | 27 |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
<4 | 93-105 |
| Chile margin | 1233 | 838 | BDL | 21 | >60 | 21-44 | >210 | 11-55 | >5 | 11-77 | High | 23 | <2 | 5-11 |
|
|
1234 | 1015 | BDL | 10 | >63 | 18-52 | >120 | 10-52 | >11 | 40-88 | High | 9 | <2 | 10-112 |
|
|
1235 | 489 | BDL | 20 | >60 | 31-42 | >200 | 20-42 | >8 | 31-42 | High | 20 | <2 | 20-109 |
| Carnegie Ridge | 1239 | 1414 | BDL | 71 | >28 | 92-123 | >20 | 61-113 | >6 | 133-378 | Moderate-high | 100 | 5.5 | 71-82 |
| Cocos Rise | 1242 | 1364 | BDL | 23 | >25 | 23-94 | 60 | 34 | >7.5 | 94-170 | High | 35 | 2.5 | 34 |
Notes: * = Site 1240 is influenced by fluid flow in the underlying basalt, and its geochemistry is discussed separately in the text as a consequence. BDL = below detection limit. Sulfate detection limit was typically 1 mM or lower.