Carbonate Dissolution and Sedimentation on the Mid-Atlantic Continental Margin

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Abstract
The calcium carbonate content was determined for core tops from two transects on the upper slope to lower rise on the mid-Atlantic continental margin. Carbonate content in the sediment increases from ∼ 5 percent (by weight) on the upper slope to more than 30 percent on the upper rise. A zone of low-carbonate content extends from 3000 to 4400 meters. Below 4400 meters, the percent carbonate increases. An examination of dissolution indices in these core tops indicates that the low-carbonate zone is associated with intense dissolution. Below 4400 meters, dissolution decreases and carbonate is well preserved. The decrease in dissolution occurs where the high-velocity core of the Western Boundary Undercurrent is first encountered.