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: )<br />

)<br />

abundances (Biscaye, 1965; Rateev and others, 1966)<br />

strongly suggests a detrital origin for chlorite in the deep<br />

sea.<br />

The effect of glacial/interglacial changes in sediment<br />

source and/or competence of currents which transport the<br />

sedi ment mi ght be expected to appear in the sedi ments.<br />

Zimmerman (1972), for example, found consistent differences in<br />

the clay mineralogy of Holocene (montmorillonite-amphibole<br />

100<br />

rich) and Pleistocene (montmorillonite-amphibole poor) facies<br />

beneath the Western Boundary Undercurrent on the New England<br />

continental rise. However, cores from the Greater Antilles<br />

Outer Ridge show no systematic differences in mineralogy<br />

between glacial and interglacial sediments (Cores AII60-8:GC2,<br />

GC16, GC19; Table 4.1). It is likely that mineral-dilution<br />

effects during the presumed long transport of the sediment<br />

damp out subtle mineralogical variations.<br />

The samples from the north slope of the Puerto Rico<br />

Trench (CH57, core 12, 190 and 265 cm; Table 4.1) are<br />

typical of the sediments found there. Most of the sediment<br />

cored on the north slope is lithologically similar to the<br />

sample at 190 em in core CH57-12 and probably has a similar<br />

composition. The sequenc~of altered ash in these cores<br />

would have a composition like the sample at 265 cm. It<br />

is likely that the ashes were deposited during the Pliocene-<br />

P 1 e i s t 0 c e n e vol can ism i nth e Ant ill e s ( W ey 1, 1 9 6 8) 0 rat a n<br />

even earlier time (see Chapter V).

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