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Eocene to 01 i gocene (Monroe, 1968). If the stratified layer was deposited before the Puerto Rico Trench formed, its present flat layering indicates that the tectonic movement associated with trench formation was localized in the immediate area of the trench. There is some indication that normal faulting may have disturbed 223 the stratified unit in a few places under the Greater Antilles Outer Ridge, much as it has on the no~th wall of the trench (Chase and Hersey, 1968), but this effect is not pronounced. Although the gentle northward slope of Datum A under the eastern Greater Antilles Outer Ridge may indicate that the sea floor was elevated there while the Puerto Rico Trench was forming, the slope may also represent the original attitude of the layering. Seismic profiles over the far eastern outer ri dge show Datum A under the Nares Abyssal Plain but not under the Greater Antilles Outer Ridge (Fig. 3.5), .suggesting that the basement ridge under the outer ri dge was an el evated feature even before the Puerto Ri co Trench formed. The possi bi 1 i ty of transcurrent faul ti ng associated with formation of the Puerto Rico Trench is lar~ely eliminated by the presence of unbroken, northwest- southeast trending magnetic lineations across its present north slope (Griscom and Geddes, 1966). Al though the formati on of the Puerto Ri co Trench undoubtedly had a si gni fi cant effect on mechani sms of sediment deposition on the Greater Antilles Outer Ridge, .)
) ) there are also other factors whích must be considered. The abyssal circulation of the North Atlantic probably was initiated sometime between Paleocene and middle Eocene time, when Greenland and Scandinavia separated far enough to allow cold dense water to invade the North Atlantic Basin from the Norwegian Sea (Jones and others, 1970; Berggren and Hollister, 1972; Ewing and Hollister, 1972). The introduction of this cold water mass probably correlates with the initiation of the Western Boundary Undercurrent, and we could expect that the WBUC was transporting sediment from the continental margin of North America to the Greater Antilles Outer Ridge by early to middle Eocene time. Fur the r m 0 r e, i fLay erA i nth e Sou t hAt 1 ant i cis s y n c h r 0 n 0 us wi th Hori zon A in the North Atl anti c, as proposed by Le Pichon and others (1971), then the sequence of seismic reflectors recorded in Vema Channel in the South Atlantic suggests that Antarctic Bottom Water must also have entered the western North Atlantic basin about this time (Fig. 8.2). These abys sa l-ci rcul ati on/sedi mentati on events, together with the cessation of downslope sedimentation to the Greater Antilles Outer Ridge from Puerto Rico, are suggested here as the cause for the acoustic and compositional changes which are marked by Datum A. The effect of these events on source areas for the sediment composing the Greater Antilles Outer Ridge is evident in data on sediment composition from DSDP Site 28 224
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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
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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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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
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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
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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
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
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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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