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sedi ment was bei ng eroded in the region of the Cai CDS Outer Ridge at the same time that deposition was initiated on the 237 western Greater Antilles Outer Ridge. The thin sediment cover on the sill south of the Silver Abyssal Plain may also be a result of erosion or nondeposition by the Western Boundary Undercurrent. Very slow deposition or erosion is indicated by the presence of the Datum A outcrop (Fig. 3.3) and the Oligocene/Miocene core (CH57-13) recovered from this area (see Chapter V). A decrease in current velocities shortly after this time may have been responsible for sediment deposition on the Caicos Outer Ridge and increased sedimentation on the weakly developed western section of the Greater Antilles Outer Ri dge. Golovchenko and others (1973) found that the Bahama Outer Ridge to the northwest began to develop above a late Miocene turbidite sequence, and they attribute its formation to deposition caused by decreased current velocities. Rapid sedimentation (19 cm/1000 yr) also occurred on the Bl ake Outer Ri dge duri ng the 1 ate Mi ocene (Ewing and Hollister, 1972), and the source of the sediment was the northeastern continental margin of North America (Habib, 1972). The time of initial formation of the Caicos Outer Ridge, the Bahama Outer Ridge, and the western sector of the Greater Antilles Outer Ridge is roughly the same, and it is suggested here that all three features resulted from \ ) )
) / the same event of current-controlled sedimentation. PLIOCENE TO RECENT Since its initial development, the northwest trend of the western sector of the Greater.Antilles Outer Ridge has 238 apparently controlled the flow of the Western Boundary Under- current, and the outer ridge has continued to grow both upward and to the northwest through preferential deposition from the zone of current shear above its crest (Fig. 8.5). The confi gurati on of sei smi c refl ectors resol ved wi thin the transparent layer of the western Greater Antilles Outer Ridge and in the stratified sediments of the flanking abyssal plains (Fig. 3.10) demonstrates that the outer ridge has formed by preferential deposition rather than by erosion of a. pre-existing sediment body. During the development of the Greater Antilles Outer Ridge, the zone of most rapid sediment accumulation has shifted toward the west, and it is now centered on the western sector of the outer ridge, although the eastern sector still accumulates sediment at a rate of several cm per thousand years. At the present time, part of the Western Boundary Under- current probably sti 11 continues southeast toward Puerto Ri co wit h hi g hen 0 ugh vel 0 city to i n h i bit de p 0 sit i on on the sill n ear 2 IoN 1 at., 6 8 0 W 1 n n g . S i mil a r 1 y, rap i d cur re n t s a 1 0 n g the Bahama escarpment probably prevent much deposition above the unconformity created by Miocene erosion (Figs. 3.7, 8.5). The definition of reflectors in the southern edge of
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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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\ )
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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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.\ ! ') )
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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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) ) )
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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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) ) _/
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\ ) \ ì ../
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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
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S e c t ion 2 (F i g s. 6. 1, 6. 7)
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northwest flow along the west flank
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filter (0.50 lJmpore size). After f
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. '! ) ) ,./ 2.2 ~ 2.i () '- 2.0 ~
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) ) Figure 7.3. Light-scattering pr
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'\. './. V 23-7 V 23-6 V 25-74 V 25
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extensive erosion on the lower cont
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) \/ (SEM) to determine composition
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\ ) ) 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 308 and 309: on the north flank of the far easte
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: '\ l ) ~z w u w a: o ~ wz w o u ~ w
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
Page 358 and 359: McCullough, J.R. and G.H. Tupper (1
Page 360 and 361: Swallow, J.C. and L.V. Worthington
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Page 364 and 365: 259 approximation of the amount of
Page 366 and 367: s ~ 0 ~ Q) o '- CO 0 U ~ it \f0 Q)
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Page 370 and 371: Crui se All 11 All 11 AII 60 Leg 8
Page 372 and 373: TABLE A2.1. BOTTOM PHOTOGRAPHS (Con
Page 374 and 375: TABLE A2.1. BOTTOM PHOTOGRAPHS (Con
Page 376 and 377: TAB LE A2. 1. BOTTOM PHOTOGRAPHS (C
Page 378 and 379: CH 19 CH 19 CH 19 CH 34 CH 34 TABLE
Page 380 and 381: KN25 KN 25 KN 25 KN 25 TABLE A2.1.
Page 382 and 383: LL 8 LL 8 LL 8 LL 8 LL 8 SA C ru is
Page 384 and 385: ) )
Page 386 and 387: 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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