Perry, Jr, Edward A; Gieskes, Joris M; Lawrence, James R (1976): Chemical composition of sediments from DSDP Hole 149 [dataset publication series]. PANGAEA, https://doi.org/10.1594/PANGAEA.700892, Supplement to: Perry, Jr, EA et al. (1976): Mg, Ca and O18/O16 exchange in the sediment-pore water system, hole 149, DSDP. Geochimica et Cosmochimica Acta, 40(4), 413-423, https://doi.org/10.1016/0016-7037(76)90006-5
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Abstract:
The diagenesis and geochemical evolution of deep-sea sediments are controlled by the interaction between sediments and their associated pore waters. With increasing depth, the pore water of Hole 149 (DSDP) exhibits a strong depletion in Mg and a corresponding enrichment in Ca, while the alkalinity remains relatively constant. Dissolved SiO2 is nearly constant in the upper 100 m of sediment, but is highly enriched in the deepest pore waters. The pore waters exhibit a depletion in K with increasing depth, and O18/O16 pore water ratios also decrease.
The sediment section has three zones of sedimentary regimes with increasing depth in the drill hole: an upper 100 m section of detrital clays, a middle section enriched in calc-akalic volcanics which have undergone submarine weathering to a smectite phase, and a lower section of siliceous ooze which still has a diagenetic smectite phase. The quartz-feldspar ratios and O18/O16 composition of the silicate phases are in agreement with these interpretations.
The submarine weathering of volcanics to a smectite can account for the observed pore water gradients. Volcanics release Ca and Mg to the pore waters causing the alkalinity values to increase. Smectite is formed, depletes the pore waters in Mg and O18 and causes the alkalinity to decrease. The net reaction allows for the observed relationship between pore water Ca and Mg gradients with little net change in alkalinity. Given the abundance of volcanics in many deep-sea sediments, especially in lower sections which often form near ridge crests, the submarine formation of smectite may be an additional oceanic Mg sink which has not yet been fully considered.
Project(s):
Deep Sea Drilling Project (DSDP)
Coverage:
Latitude: 15.104200 * Longitude: -69.364200
Date/Time Start: 1971-01-05T00:00:00 * Date/Time End: 1971-01-05T00:00:00
Event(s):
15-149 * Latitude: 15.104200 * Longitude: -69.364200 * Date/Time: 1971-01-05T00:00:00 * Elevation: -3972.0 m * Penetration: 390 m * Recovery: 239.4 m * Location: Caribbean Sea/BASIN * Campaign: Leg15 * Basis: Glomar Challenger * Method/Device: Drilling/drill rig (DRILL) * Comment: 43 cores; 390 m cored; 0 m drilled; 61.4 % recovery
License:
Creative Commons Attribution 3.0 Unported (CC-BY-3.0)
Size:
2 datasets
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Datasets listed in this publication series
- Perry, Jr, EA; Gieskes, JM; Lawrence, JR (1976): (Table 1) Chemical composition of the carbonate-free fraction of dry bulk sediments from DSDP Hole 149. https://doi.org/10.1594/PANGAEA.700890
- Perry, Jr, EA; Gieskes, JM; Lawrence, JR (1976): (Table 2) Chemical composition of the <1 µm grain size fraction of sediments from DSDP Hole 149. https://doi.org/10.1594/PANGAEA.700891