Table 2. Previous interstitial water studies by scientific ocean drilling in the Leg 167 region.

Table 2. Previous interstitial water studies by scientific ocean drilling in the Leg 167 region.

Leg

Site name
(latitude)

Site
number

Analyses
(total depth range sampled)

Observations

Reference

DSDP Leg 63, California Borderland sites:

San Miguel Gap (34°N)
467 pH, alkalinity, salinity, chloride, sulfate, Ca, Mg(795 mbsf)
Sulfate depletion by 63 mbsf; alkalinity maximum of 50 mM at 158 mbsf; Ca minimum of 4.2 mM at 63 mbsf; sharp decrease in Mg in shallow portion; chloride depletion with depth Gieskes et al. (1981)

Patton Escarpment (32.5°N) 468 pH, alkalinity, salinity, chloride, sulfate, Ca, Mg (341 mbsf) No sulfate depletion; small changes in Ca and Mg with depth

Foot of Patton Escarpment (32.5°N) 469 pH, alkalinity, salinity, chloride, sulfate, Ca, Mg plus ammonium, silicate, strontium, manganese, lithium, and potassium (390 mbsf) Sulfate depletion to ~20 mM by 63 mbsf; alkalinity maximum of 5 mM at 63 mbsf; ammonium maximum of 0.46 mM at 109 mbsf; Ca increases, Mg decreases with depth; silicate increases to >1000 mM at 185 mbsf, then decreases to 54 mM at 390 mbsf

East of Guadalupe Island (29°N)* 470 pH, alkalinity, salinity, chloride, sulfate, Ca, Mg plus ammonium, silicate, strontium, manganese, lithium, and potassium (165 mbsf) No sulfate depletion, minor increase in Ca, minor decrease in Mg with depth

ODP Leg 146: Santa Barbara Basin 893 pH, alkalinity, salinity, chloride, sulfate, Ca, Mg, silicate, sodium, lithium, and potassium (58 mbsf) Sulfate depleted to <1 mM by 21 mbsf; alkalinity >40 mM; Ca below seawater values throughout, with 4.5 mM at 1.5 mbsf, decreasing to 2.1 mM at 58 mbsf; dissolved silicate >1000 mM by 58 mbsf Kastner (1995)

Leg	Site name (latitude)	Site number	Analyses (total depth range sampled)	Observations	Reference
DSDP Leg 63, California Borderland sites:
	San Miguel Gap (34°N)	467	pH, alkalinity, salinity, chloride, sulfate, Ca, Mg(795 mbsf)	Sulfate depletion by 63 mbsf; alkalinity maximum of 50 mM at 158 mbsf; Ca minimum of 4.2 mM at 63 mbsf; sharp decrease in Mg in shallow portion; chloride depletion with depth	Gieskes et al. (1981)
	Patton Escarpment (32.5°N)	468	pH, alkalinity, salinity, chloride, sulfate, Ca, Mg (341 mbsf)	No sulfate depletion; small changes in Ca and Mg with depth
	Foot of Patton Escarpment (32.5°N)	469	pH, alkalinity, salinity, chloride, sulfate, Ca, Mg plus ammonium, silicate, strontium, manganese, lithium, and potassium (390 mbsf)	Sulfate depletion to ~20 mM by 63 mbsf; alkalinity maximum of 5 mM at 63 mbsf; ammonium maximum of 0.46 mM at 109 mbsf; Ca increases, Mg decreases with depth; silicate increases to >1000 mM at 185 mbsf, then decreases to 54 mM at 390 mbsf
	East of Guadalupe Island (29°N)*	470	pH, alkalinity, salinity, chloride, sulfate, Ca, Mg plus ammonium, silicate, strontium, manganese, lithium, and potassium (165 mbsf)	No sulfate depletion, minor increase in Ca, minor decrease in Mg with depth
ODP Leg 146:	Santa Barbara Basin	893	pH, alkalinity, salinity, chloride, sulfate, Ca, Mg, silicate, sodium, lithium, and potassium (58 mbsf)	Sulfate depleted to <1 mM by 21 mbsf; alkalinity >40 mM; Ca below seawater values throughout, with 4.5 mM at 1.5 mbsf, decreasing to 2.1 mM at 58 mbsf; dissolved silicate >1000 mM by 58 mbsf	Kastner (1995)

Note: * = data compared well to data from the Mohole site (from Siever et al., 1965, as quoted in Gieskes et al., 1981).