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on the north flank of the far eastern outer ridge (Eittreim 214 and Ewi ng, 1972) whi ch shows greatly reduced 1 i ght scattering in the nepheloid layer. However, it is possible that some of the easterly flow along the north flank has not reached this longitude, but has escaped to the south through interveITing depressions in the outer ridge. The zone of current shear whi ch shi fts N-S across the boundary between the north flank of the eastern Greater Antilles Outer Ridge and the Nares Abyssal Plain is also probably associated with preferential deposition, but rates of accumulation there would be reduced since the Western Boundary Undercurrent has already lost much of its suspended load when it reaches that area; the westerly-flowing AABW also contains very little suspended matter. There is probably little erosion of the fine-grained co h e s i ve sed i men t n n the G re ate r An till e s 0 ute r Rid g eat present, since maximum current speeds are only 15-20 cm/sec. Southard and others (1971) found that velocities of 15-20 em/sec were necessary for incipient erosion of calcareous Ooze of 1 ess than 30 percent 1 uti te when the water content of the sediment approximated that found in the deep sea. Postma (1967, Fig. 1) noted that velocities greater than 30 em/see would probably be necessary to erode sediment with a water content and grain size similar to those on the outer ridge. \ ) .)
) ) J Any extensive erosion on the Greater Antilles Outer Ri dge shoul d be detected by a strong near-bottom nephel oi d layer, but this is not observed (Fig. 7.2). Furthermore, there is no evidence in high-frequency sub-bottom profiles taken over the outer ridge for the small-scale lensing or unconformities that erosion would create (Fig. 2.1). Although transient current speeds may infrequently become high enough to erode the outer ridge sediment, the average current speeds observed are low enough that most of the 215 material thus entrained is probably redeposited very quickly, and the area must be characterized as largely depositional. The activity of benthic organisms on the Greater Antilles Outer Ridge may also resuspend sediment (see Fig. 4.4), but the intensity of resuspension and the character of the re- worked detritus are uncertain. Therefore it is not possible at present to evaluate the significance of this mechanism. DISCUSSION The volume of transparent sediments above Datum A on the Greater Antilles Outer Ridge is roughly 6 x 104km3, and the mass approximately 1.2 x 1020g at an average sediment density of 2.0 g/cm3. Using the present water-volume transport of 1.6 x 106m3/sec and a suspended matter concen- tration of 50 ~g/i, approximately 1.2 x 1020 grams of sediment could have been transported into the region of the Greater Anti 11 es Outer Ri dge since mi ddl e Eocene ti me (the assumed age of Datum A). These rough calculations indicate
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I "a f IMods Hole '" ~ o c.,,~tlOGR
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parent sediment on the eastern oute
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esearch. 5 )
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Res u 1 ts. . . . . . . . . . . . .
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Figure 3.12 Echo-sounding profile (
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Fi gure 6.14 6. 15 7. 1 7.2 7.3 7.4
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\ I ) Table 4. 1 4.2 5.1 5.2 5.3 6.
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CHAPTER I INTRODUCTION The area inv
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) \ .1 Fi gure i. 1. Bathymetry of
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~. ~ 71° 70° tI 68 fJ0 25° 7' 25
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) ) This is expected since most of
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GENERAL DES CRI PT I ON CHAPTE R I
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j
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egi onal contours. An area centered
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this region. However, all of these
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'"-, i~ 7t 70° 6f 68 67° 25° 72
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Fig u r e 3. 2 . CON RA D 10 s e is
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sequence corresponds to layered tur
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) . .) Figure 3.3. Map showing domi
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"- '''--.- 25° ................. .
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) ) others, 1973), and the upper po
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) Figure 3.5. CONRAD 8 seismic refl
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. Q) 3W/L NOI.L~ l( . (Y CI s. :: 0
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.) Figure 3.6. Idealized profile al
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) ) a: 0 ~ ~ (J L. Z Q) a: ~ lU UJ
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) ) Figure 3.7. CONRAD 10 seismic r
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i- (Y (1 ~:: en or- LL 47
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) ) THE TRANSPARENT LAYER The distr
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Fi gure 3.8. CH A I N 34 s e ism i
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co . (Y (l So :: O' "r- Li 51
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) 53
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) Figure 3.9. CONRAD 10 seismic ref
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0' (V CJ s. :: O' ... LL 55
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\ J ) Figure 3.10. Seismic reflecti
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or- . (V Q) S- :: rn Li 58
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ì ) Figure 3.11. CONRAD 10 seismic
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l UJ .líliiiP',,:... ¡ '"'" ~ ' ~
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) .I Figure 3.12. Echo-soundi ng pr
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N CV OJ s. :: 01 l. 62
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) ) Figure 3.13. CONRAD 10 seismic
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(' r- (' (j $. :: en 'r- LL 64
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) ) GENERAL LITHOLOGY CHAPTER iv TH
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~ , ) Figure 4.1. General lithology
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.'-/ '..-/ AIr 60-8 A II 60-8 An60~
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average of 80% lutite (~ 2 ~m) and
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10 m2, with an average value of 1.3
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The laminated zones and overlying p
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) ) Figure 4.7. Graph of carbonate
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) ) z 0 N O~ E I i ,,_.' i." I ." .
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) ì i Figure 4.8. Curves of carbon
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currents have transported many Fora
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increased dissolution (elevated lys
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TABLE 4.1. MINERALOGY OF THE c 2 ~m
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the following peaks and weighting f
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Obvi ous ly, di 1 uti on of the nor
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The m i n era log i c a 1 com po si
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gray 1 uti t e s per s i s t n ear
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TABLE 5.1. AVERAGE RATES OF SEDIMEN
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and thus the T-Z zonation (Fig. 5.1
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TABLE 5.2. AVERAGE RATES OF SEDIMEN
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Cl z: c: l/ l. i- c: Cl z: o OJ IX
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consolidated (A.J. Silva, pers. com
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in age, and the ash is probably ass
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122 must result from mixing with th
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eas twa rd flow of NADW between 150
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whi ch recorded currents for about
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,) , ,
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ottom photographs in February, 1972
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Several important features were obs
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141 turn north in the western part
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145 bottle spacing. An example is t
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~() ~ 3.0 ~ ~ ) ~ ~i. ) .. ~ 2.0 ~i
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) ) Figure 6.6. Silicate ("g-atoms/
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) ) ~ 2.2 ~ 2.0 t2 ~ tt ~" 1.8 .. ~
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,) -) 152 structure persist at and
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) ~) 154 Figure 6.7. Current patter
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) ) 72° DEPTH IN CORR. METERS Fi g
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) ) speeds of 2 cm/sec (the stall s
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) I / Fi gure6. 8. 158 Progressi ve
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" ) / ) 10 19 17 5 5616 M 5801 M N
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) ) ~ 160 Figure 6.9. Polar histogr
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,) B(LOWER) START 22 B(UPPER) START
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) ) Figure 6.11. Polar histogram of
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) 2700 ) 00 1800 F; g u re 6. 11 C
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, ) ) _/ Figure 6.12. 168 Progress
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\ --~ E START 21 5 30 12 XI 21 xu )
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) / i I .~J the flow recorded at cu
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) Figure 6.13. Directions and relat
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') ./ ) ,j 70° 68° 66° ~~oo · "
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Fig u re 6. 14. i 75 Bottom photogr
Page 258 and 259: S e c t ion 2 (F i g s. 6. 1, 6. 7)
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Page 264 and 265: northwest flow along the west flank
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Page 268 and 269: \ )
Page 270 and 271: filter (0.50 lJmpore size). After f
Page 273 and 274: . '! ) ) ,./ 2.2 ~ 2.i () '- 2.0 ~
Page 275 and 276: ) ) Figure 7.3. Light-scattering pr
Page 277 and 278: '\. './. V 23-7 V 23-6 V 25-74 V 25
Page 279 and 280: extensive erosion on the lower cont
Page 281 and 282: ) \/ (SEM) to determine composition
Page 283: \ ) ) Figure 7.4. 195 Scanning elec
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Page 290 and 291: The less than 2 ~m (lutite) fractio
Page 292 and 293: 201 In a sample where additional cl
Page 294 and 295: TAB LE 7. 1. CALCULATE D CLAY MI NE
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Page 300 and 301: cannot always be accepted at face v
Page 302 and 303: The apparent enrichment of chlorite
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Page 306 and 307: in favor of the concept that the su
Page 310 and 311: that enough suspended matter has be
Page 312 and 313: The following pages describe a mode
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Page 316 and 317: series of ridges associated with an
Page 318 and 319: Eocene to 01 i gocene (Monroe, 1968
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Page 322 and 323: \ i / ') ./
Page 324 and 325: (Table 8.1). The interbedded silts
Page 326 and 327: 229 Chase and Hersey, 1968). The th
Page 329 and 330: \ ! Figure 8.3. 231 Schematic diagr
Page 332 and 333: Downslope sedimentation covered the
Page 335 and 336: ) 235 Fi gure 8.4. Sketch showi ng
Page 337 and 338: '\ l ) ~z w u w a: o ~ wz w o u ~ w
Page 339 and 340: ) / the same event of current-contr
Page 341 and 342: ) Figure 8.5. Idealized representat
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Page 345 and 346: ) \ ) formed earlier depositional s
Page 347 and 348: ) ) homogenei ty of the sediments o
Page 349: ) ) 2 ) Sou t h S lop e - P u e rt
Page 352 and 353: 248 Biscaye, P.E. and S.L. Eittreim
Page 354 and 355: Ericson, D.B., M. Ewing, G. Wollin
Page 356 and 357: Hersey, J.B. (1965) Sediment pondin
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McCullough, J.R. and G.H. Tupper (1
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Swallow, J.C. and L.V. Worthington
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259 approximation of the amount of
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s ~ 0 ~ Q) o '- CO 0 U ~ it \f0 Q)
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Crui se All 11 All 11 AII 60 Leg 8
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TABLE A2.1. BOTTOM PHOTOGRAPHS (Con
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TABLE A2.1. BOTTOM PHOTOGRAPHS (Con
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TAB LE A2. 1. BOTTOM PHOTOGRAPHS (C
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CH 19 CH 19 CH 19 CH 34 CH 34 TABLE
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KN25 KN 25 KN 25 KN 25 TABLE A2.1.
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LL 8 LL 8 LL 8 LL 8 LL 8 SA C ru is
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s. .. M i. 0 1. " .. QJ ..- N .. C'
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~.. c. 0' 0 .. Q)+l- ~ 0' 0' 0 ~ M
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TABLE A3.1. SUSPENDED PARTICULATE M
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) -) APPENDIX IV PHYSICAL PROPERTIE
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) ) Figure A4.1. Plots of water con
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) ) C\' 0 § to ~ ~ ~ 0 ~ ~ ~ CI Q:
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) /) 295 Figure A4.5. Plots of wate
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'-. ~, 160 SHEAR STRENGTH 30 50 (g/
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) ) Figure A4.6. Plots of water con
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) ) 307 Fi gure A4.11. Plots of wat
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"-, ',, WATER CONTENT (% DRY WEIGHT
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) j 309 Figure A4.12. Plots of wate
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) 312 WATER CONTENT (%DRY WT) SHEAR
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) J BIOGRAPHY Born: Ma rch 19, 1946
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') \ ) ~UWDATORY DISTRIBUTION LIST
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) J
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UNCLASSI FIED 1/31/74 SECURITY CLAS
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