Broecker, Wallace S; Clark, Elizabeth (2009): (Table 2) Calcium carbonate content in deep-sea surface sediments [dataset]. PANGAEA, https://doi.org/10.1594/PANGAEA.831705, Supplement to: Broecker, WS; Clark, E (2009): Ratio of coccolith CaCO3 to foraminifera CaCO3 in late Holocene deep sea sediments. Paleoceanography, 24(3), PA3205, https://doi.org/10.1029/2009PA001731
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Abstract:
The reconstruction of paleocarbonate ion concentrations provides an important constraint on the contribution of the CaCO3 cycle to the decrease in atmospheric CO2 content during glacial time. Such reconstructions have been challenging because each of the existing paleo-[CO3]2- indices has serious limitations. In this study, we reexamine the Broecker-Clark CaCO3 size index by analyzing the <20 µm, 20 to 38 µm, and 38 to 63 µm fractions in sediments from the Ontong-Java Plateau and the Ceara Rise. Scanning electron microscope analyses demonstrate that the less than 20 µm CaCO3 is dominated by coccoliths and the greater than 20 µm CaCO3 is dominated by foraminifera. Our results clearly indicate that the coccoliths are far more resistant to dissolution than the foraminifera. Referenced to a core top sample from 2.31 km depth in a core top sample from 4.04 km depth on the Ontong-Java Plateau, ~70% of the foraminifera CaCO3 was dissolved as opposed to only ~7% of the coccolith CaCO3. We found that the dissolution of foraminifera shells did not produce a significant amount of fragments smaller than 63 µm in size, and thus the Broecker-Clark size index is not a measure of the extent of fragmentation. Rather, it is a measure of the extent of differential dissolution of foraminifera relative to coccoliths. On the basis of these results, we propose a new dissolution index which involves the ratio of dissolution-susceptible foraminifera CaCO3 to total CaCO3.
Related to:
Chiu, Tzu-Chien; Broecker, Wallace S (2008): Toward better paleocarbonate ion reconstructions: New insights regarding the CaCO3 size index. Paleoceanography, 23(2), PA2216, https://doi.org/10.1029/2008PA001599
Coverage:
Median Latitude: 3.273310 * Median Longitude: -140.895612 * South-bound Latitude: -38.270000 * West-bound Longitude: 1.967000 * North-bound Latitude: 39.950000 * East-bound Longitude: -10.610000
Date/Time Start: 1954-03-07T00:00:00 * Date/Time End: 1984-12-20T00:00:00
Minimum DEPTH, sediment/rock: 0 m * Maximum DEPTH, sediment/rock: 0 m
Event(s):
MW9109-15GGC * Latitude: 0.000000 * Longitude: 158.000000 * Elevation: -2300.0 m * Location: Central Pacific * Campaign: MW9109 * Basis: Moana Wave * Method/Device: Giant gravity corer (GGC)
RC08-107 * Latitude: 14.550000 * Longitude: -72.570000 * Date/Time: 1964-04-25T00:00:00 * Elevation: -3210.0 m * Recovery: 8.38 m * Campaign: RC08 * Basis: Robert Conrad * Method/Device: Piston corer (PC)
RC09-99 * Latitude: -24.600000 * Longitude: -115.500000 * Date/Time: 1965-02-24T00:00:00 * Elevation: -2681.0 m * Recovery: 6.1 m * Campaign: RC09 * Basis: Robert Conrad * Method/Device: Piston corer (PC)
Comment:
MW9109-15GGC by WHOI's Dan McCorkle and published previously by Chiu and Broecker (2008).
Parameter(s):
| # | Name | Short Name | Unit | Principal Investigator | Method/Device | Comment |
|---|---|---|---|---|---|---|
| 1 | Event label | Event | ||||
| 2 | Latitude of event | Latitude | ||||
| 3 | Longitude of event | Longitude | ||||
| 4 | Elevation of event | Elevation | m | |||
| 5 | DEPTH, sediment/rock | Depth sed | m | Geocode | ||
| 6 | Gear | Gear | Broecker, Wallace S | TW = trigger weight core, P = piston core | ||
| 7 | Calcium carbonate | CaCO3 | % | Broecker, Wallace S | ||
| 8 | Calcium carbonate, fractionated | CaCO3 frac | % | Broecker, Wallace S | >20 µm foraminifera | |
| 9 | Calcium carbonate, fractionated | CaCO3 frac | % | Broecker, Wallace S | <20 µm coccolith | |
| 10 | Ratio | Ratio | Broecker, Wallace S | (coccolith/sum CaCO3)*100 |
License:
Creative Commons Attribution 3.0 Unported (CC-BY-3.0)
Size:
578 data points