Interface dissolution control of the [sup 14]C profile in marine sediment

Journal Article · Sun Aug 01 04:00:00 EDT 1993 · Geochimica et Cosmochimica Acta; (United States)

DOI:https://doi.org/10.1016/0016-7037(93)90139-N· OSTI ID:6014116

Keir, R S ^[1]; Michel, R L ^[2]

---

1. Christian-Albrechts-Universitaet zu Kiel (Germany)
2. Geological Survey, Reston, VA (United States)

The process of carbonate dissolution at the sediment-water interface has two possible end-member boundary conditions. Either the carbonate particles dissolve mostly before they are incorporated into the sediment by bioturbation (interface dissolution), or the vertical mixing is rapid relative to their extermination rate (homogeneous dissolution). In this study, a detailed radiocarbon profile was determined in deep equatorial Pacific sediment that receives a high rate of carbonate supply. In addition, a box model of sediment mixing was used to simulate radiocarbon, carbonate content, and excess thorium profiles that result from either boundary process following a dissolution increase. Results from homogeneous dissolution imply a strong, very recent erosional event, while interface dissolution suggests that moderately increased dissolution began about 10,000 years ago. In order to achieve the observed mixed layer radiocarbon age, increased homogeneous dissolution would concentrate a greater amount of clay and [sup 230]Th than is observed, while for interface dissolution the predicted concentrations are too small. These results together with small discontinuities beneath the mixed layer in [sup 230]Th profiles suggest a two-stage increase in interface dissolution in the deep Pacific, the first occurring near the beginning of the Holocene and the second more recently, roughly 5,000 years ago. 30 refs., 8 figs., 3 tabs.

• OSTI ID: 6014116
• Journal Information: Geochimica et Cosmochimica Acta; (United States), Journal Name: Geochimica et Cosmochimica Acta; (United States) Vol. 57:15; ISSN GCACAK; ISSN 0016-7037
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
540310* -- Environment
Aquatic-- Basic Studies-- (1990-)
ACTINIDE ISOTOPES
ACTINIDE NUCLEI
AGE ESTIMATION
ALPHA DECAY RADIOISOTOPES
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
BOX MODELS
CARBON 14
CARBON COMPOUNDS
CARBON ISOTOPES
CARBONATES
DISSOLUTION
EVEN-EVEN NUCLEI
HEAVY ION DECAY RADIOISOTOPES
HEAVY NUCLEI
INTERFACES
ISOTOPE DATING
ISOTOPES
LIGHT NUCLEI
MATHEMATICAL MODELS
MIXING
NEON 24 DECAY RADIOISOTOPES
NUCLEI
OXYGEN COMPOUNDS
PACIFIC OCEAN
PALEOCLIMATOLOGY
PALEONTOLOGY
RADIOISOTOPES
SEAS
SEDIMENT-WATER INTERFACES
SEDIMENTS
SPONTANEOUS FISSION RADIOISOTOPES
SURFACE WATERS
THORIUM 230
THORIUM ISOTOPES
YEARS LIVING RADIOISOTOPES