Indian Ocean carbonate compensation depth

Figure 4 Comparison of carbonate saturation profiie for the eastern equatorial Indian Ocean with measurements of foraminiferal fragmentation and carbonate content (weight-%) from depth-distributed modern sediment samples in this region. The saturation horizon with respect to caicite (ACOa " = 0) occurs iocaiiy in the water column at a depth of 3800 m. This level corresponds with both the foraminiferai iysociine and carbonate iysociine as recognized in the sediments. The carbonate compensation depth (CCD) in this region is found at a depth of approximateiy 5000 m. increased foraminiferal fragmentation and decreases in sedimentary carbonate content are the resuit of dissoiution and carbonate ioss beiow the iysociine. Carbonate saturation data are from GEOSECS Station 441 (5°2 S, 91°47 E Takahashi et al. 1980) modern sediment data are from Peterson and Prell (1985).

Atlantic Ocean Nodule abundance in the Atlantic Ocean appears to be more limited than in the Pacific or Indian Oceans, probably as a result of its relatively high sedimentation rates. Another feature which inhibits nodule abundance in the Atlantic is that much of the seafloor is above the calcium carbonate compensation depth (CCD). The areas of the Atlantic where nodules do occur in appreciable amounts are those where sedimentation is inhibited. The deep water basins on either side of the Mid-Atlantic Ridge which are below the CCD and which accumulate only limited sediment contain nodules in reasonable abundance, particularly in the western Atlantic. Similarly, there is a widespread occurrence of nodules and encrustations in the Drake Passage-Scotia Sea area probably due to the strong bottom currents under the Circum-Antarctic current inhibiting sediment deposition in this region. Abundant nodule deposits on the Blake Plateau can also be related to high bottom currents. 

Peterson LC, Murray DW, Ehrmann WU, Hempel P (1992) Cenozoic carbonate accnmnlation and compensation depth changes in the Indian Ocean. In Duncan R, Rea D, Kidd R, von Rad U, Weissel J (eds) Synthesis of Results from Scientific Drilling in the Indian Ocean. Am Geophys Union, Geophys Monogr 70 311-333... 

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See also in sourсe #XX -- [ ]

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