Piston cores

The sedimentation history of the upper Hudson Canyon has been measured at the 430 m depth level by Drake et al., [10]. The average sedimentation rate over the past 6,300 years, as determined by 14C dating of a piston core, has been an average of 70-80 cm/103 yrs the past 2,000 years appear to have a sedimentation rate of about 150 cm/103 years, Drake et al., [10]. 

It has been observed that the surface deposits in marine cores do not have the expected age of zero. This disparity has been ascribed to loss of core tops at time of core recovery and the reservoir effect discussed above. It has also been discovered that the dominant control of the apparently constant dates in the top 8 cm of a core is bioturbation. Nozaki et al. (1977) studied a core obtained by a submersible research vessel and therefore exempt from the artifact of mixing or loss of the top of the sediment pile, which commonly occurs during piston coring and recovery. They measured and °Pb, using the latter to determine that bioturbation has indeed occurred and establish its rate constant (Figures 4 and 5). Clearly biomrbation has occurred to a depth of 8 cm, below that depth the absence of bioturbation permits the use of to determine an accumulation rate and establish a chronology. The relationship between depth of bioturbation... 

Schwarz B., Mangini A., and Segl M. (1996) Geochemistry of a piston core from Ontong Java Plateau (western equatorial Pacific) evidence for sediment redistribution and changes in paleoproductivity. Geol. Rundsch. 85, 536—545. 

Fagel et al. (1997, personal communication) provided major and trace element data for hve piston cores (20-30 m long) taken from the central Indian Basin at water depths —4,800-5,400 m (below the carbonate compensation depth). Additional Sr/ Sr and Nd/ Nd data for some samples are given by Fagel et al. (1994). Biogenic silica (mainly radiolarian tests... 

Fig. 2.23 Parasound seismogram section recorded across an inactive meandering channel in the Bengal Fan. The sediments of the terrace were sampled by piston core 47KL marked by the black bar. Vertical exaggeration (VE) of sedimentary structures is 200. The ship s course is displayed above the seismogram section. The terrace exhibits features which might be interpreted as old buried channels. Modified after Breitzke (1997).

In the northern Gulf of Mexico, the recently drilled Garden Banks 754-1, which lies approximately 100 miles west of the Titan mini-basin, provides direct evidence that a similar source-prone environment existed during the late Jurassic. This well penetrated a thick extremely organic rich interval (Jarvie et al. 2002). Biomarker attributes of liquid hydrocarbons recovered in piston cores from the greater Garden Banks 754 area suggest their derivation from a earbonate to... 

Cole, G. A. et al. 2001. The deepwater GOM petroleum system insights from piston coring seepage versus anomalies versus background. Gulf Coast Society of Economic Paleontologists and Mineralogists Research Conference, 315-342. 

Despite the South China Sea being a reservoir of CO2, its area is large and there are many upwellings favorable to the transfer of CO2 from the lower layer to the upper layer (Dai et al., 2001). Based on the organic carbon concentrations, the stable isotope analyses, and the analj es of the distributions of benthic foraminifera in gravity and the piston cores from two observed stations... 

Porewater samples were obtained from subsamples of the piston core by centrifugation within 72 h from coring. Porewater sulfate was determined by the turbidity method (APHA, 1981). 

The depth profile of the TOC content (Fig. 3) in the piston core shows the highest TOC content (1.07%) at the surface and an abrupt decrease to 0.6% at 7 cm. Between 7 and 50 cm, the TOC content fluctuates between 0.47 and 0.75%. Below 50 cm, TOC content shows little change. The down-core profile of sulfate in porewater (Fig. 3) shows a typical depletion trend with depth. The sulfate depletion rate is very rapid in the upper 40 cm, with a mean gradient of — 0.18mMcm whereas the depletion rate becomes much lower (—0.02 mM cm ) below 50 cm. TS contents measured in this piston core (Fig. 3) range from 0.02 to 0.10% with no apparent down-core trend. These values are also significantly lower than the mean value (0.22%) of modem fine-grained sediments (Berner, 1982). 

Fig. 3. The depth profiles of TOC (%), TS (%) and porewater sulfate concentration (mM) of the piston core. The mean gradients of sulfate depletion in the upper and lower sediment column are shown by numerals and illustrated by dashed lines.

Fig. 4. The depth profiles of (a) TOC (%), (b) TS (%), (c) Fex (%) and (d) Foa (%) in the seven box cores. The depth profiles of the same properties in the piston core represented by plus signs (+) are also shown for reference. Similarly those of surficial sediments from the same area are also plotted at the top of each panel.

Hydraulic piston corer (HPC-15). (Data from Walton, W.H. et at, Geotechnical engineering characterization of hydraulically piston-cored deep ocean sediments. In Initial Reports DSDP 71, Barker, RF. et al., eds., Washington, DC, 537-549,1982.)... 

Kullenberg, B. 1947. The piston core sampler. Svenska hydrogr. bid. Komm. Skr., 1(2) 46. 

Personnel of the Ross Ice Shelf Project melted a hole through the ice shelf at a site known as J9 (82°22.5 S, 168°87.5 S) and used it to recover several piston cores (Clough and Hansen 1979). The ice at that location is 360 m thick and is followed by 237 m of seawater. The reports arising from this project were published in Science (vol. 203, No. 4379,1979). 

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