13. SITE Shipboard Scientific Party 2

Transcription

1 3. STE 668 Shipboard Scientific Party 2 HOLE 668A Date occupied: 3 April 986, 230 UTC Date departed: 4 April 986, 0730 UTC Time on hole: 0 hr Position: 'N, 'W Water depth (sea level; corrected m, echosounding): Water depth (rig floor; corrected m, echosounding): Bottom felt (rig floor; m, drill pipe measurement): Distance between rig floor and sea level (m): 0.5 Total depth (rig floor, m): Penetration (m): 8.8 Number of cores (including cores with no recovery): Total length of cored section (m): 8.8 Total core recovered (m): 8.8 Core recovery (%): 00 Oldest sediment cored: Depth (mbsf): 8.8 Nature: calcareous nannofossil ooze Age: Pleistocene HOLE 668B Date occupied: 4 April 986, 97 UTC Date departed: 4 April 986, 2225 UTC Ruddiman, W., Sarnthein, M., Baldauf, J., et al., 988. Proc, nit. Repts. (Pt. A), ODP, William Ruddiman (CoChief Scientist), LamontDoherty Geological Observatory, Palisades, NY 0964; Michael Sarnthein (CoChief Scientist), GeologischPalaontologisches nstitut, Universitat Kiel, Olshausenstrasse 40, D2300 Kiel, Federal Republic of Germany; Jack Baldauf, ODP Staff Scientist, Ocean Drilling Program, Texas A&M University, College Station, TX 77843; Jan Backman, Department of Geology, University of Stockholm, S06 9 Stockholm, Sweden; Jan Bloemendal, Graduate School of Oceanography, University of Rhode sland, Narragansett, R ; William Curry, Woods Hole Oceanographic nstitution, Woods Hole, MA 02543; Paul Farrimond, School of Chemistry, University of Bristol, Cantocks Close, Bristol BS8 TS, United Kingdom; Jean Claude Faugeres, Laboratoire de GeologieOceanographie, Universite de Bordeaux, Avenue des Facultes, Talence 33405, France; Thomas Janacek, LamontDoherty Geological Observatory, Palisades, NY 0964; Yuzo Katsura, nstitute of Geosciences, University of Tsukuba, baraki 305, Japan; Helene Manivit, Laboratoire de Stratigraphic des Continents et Oceans, (UA 39) Universite Paris V, 4 Place Jussieu, Paris Cedex, France; James Mazzullo, Department of Geology, Texas A&M University, College Station, TX 77843; Jiirgen Mienert, GeologischPalaontologisches nstitut, Universitat Kiel, Olshausenstrasse 40, D2300 Kiel, Federal Republic of Germany, and Woods Hole Oceanographic nstitution, Woods Hole, MA 02543; Edward Pokras, LamontDoherty Geological Observatory, Palisades, NY 0964; Maureen Raymo, LamontDoherty Geological Observatory, Palisades, NY 0964; Peter Schultheiss, nstitute of Oceanographic Sciences, Brook Road, Wormley, Godalming, Surrey GU8 5UG, United Kingdom; Riidiger Stein, GeologischPalaontologisches nstitut, Universitat Giessen, Senckenbergstrasse 3, 6300 Giessen, Federal Republic of Germany; Lisa Tauxe, Scripps nstitution of Oceanography, La Jolla, CA 92093; JeanPierre Valet, Centre de Faibles Radioactivites, CNRS, Avenue de la Terrasse, 990 GifsurYvette, France; Philip Weaver, nstitute of Oceanographic Sciences, Brook Road, Wormley, Godalming, Surrey GU8 5UG, United Kingdom; Hisato Yasuda, Department of Geology, Kochi University, Kochi 780, Japan. Time on hole: 3. hr Position: 'N, 'W Water depth (sea level; corrected m, echosounding): Water depth (rig floor; corrected m, echosounding): Bottom felt (rig floor; m, drill pipe measurement): Distance between rig floor and sea level (m): 0.5 Total depth (rig floor, m): Penetration (m): 3.2 Number of cores (including cores with no recovery): 4 Total length of cored section (m): 3.2 Total core recovered (m): 3.3 Core recovery (%): 00 Oldest sediment cored: Depth (mbsf): 3.2 Nature: calcareous nannofossil ooze Age: latest Pliocene Principal results: Site 668 is located in the eastern equatorial Atlantic at 'N, 'W, at a water depth of 2690 m on the relatively flat crest of the Sierra Leone Rise (Fig. ). The site is situated in a region of wellstratified, moderately reflective acoustical layering that ranges in character from relatively flatlying to hummocky rolling sediment waves. Our primary objective was to obtain a relatively shallowwater Pliocene to Holocene sequence for use as part of a depth transect to study deepwater isolation in the eastern equatorial Atlantic. A secondary objective was to use this set of cores to monitor longterm fluxes in CaC0 3 from surface waters, along with CaC0 3 dissolution and downslope redistribution. We also planned to core a single, deeper hole to retrieve a long Neogene sequence for biostratigraphic and paleomagnetic studies. Operational problems, followed by the illness of a crew member, kept us from reaching most of our primary objectives at this site. We retrieved one 8.8m mudline core from Hole 668A, which was occupied from 230 UTC on 3 April to 0730 UTC, 4 April 986, a total of 0 hr. (All times are Universal Time Coordinated, formerly GMT, Greenwich Mean Time.) From Hole 668B, we retrieved four advanced piston corer (APC) cores, totaling 3.2 m in length with 00% recovery. Hole 668B was occupied from 97 to 2225 on 4 April 986. The sediments recovered were calcareous nannofossil ooze and varied from muddy nannofossil ooze to muddy foraminifernannofossil ooze to mudbearing, foraminiferbearing nannofossil ooze. Secondary components included clay (5%30%), quartz (0%2%), and opal (0%5%). Paleomagnetic stratigraphy defined the Matuyama/Brunhes chron boundary and the top and bottom of the Olduvai subchron. Nannofossils and planktonic foraminifers provided several biostratigraphic datums. Preservation of calcareous fossils was good, but few diatoms were observed. Deposition rates averaged 2 to 7 m/m.y. in the uppermost Pliocene to Holocene sequence (02.0 Ma). Too few shipboard analyses were performed (e.g., only five CaC0 3 analyses) to detect significant trends at Site 668. From both the lithology and the state of preservation, the overall sediment sequence is characteristic of a lowproductivity, surfacewater environment and a deepwater regime not heavily undersaturated with CaC0 3. BACKGROUND AND SCENTD7C OBJECTVES Site 668 (target Site Eq3) was the shallowest of the sites that make up the depth transect on the southern margin of the Sierra 93

2 STE N o? 7 / / / / *09 / h 08 J / t VA5 A6 A7 V3V"* % V / 668 0»N **: X^ O Vsf 6 Vpr ^06 ^ V 22 W / OS li 04 J A9 L 2' Figure. Seismic track lines near Site 668. Leone Rise (Fig. 2; "Background and Scientific Objectives" section, Site 665 chapter). The nearest drill site was DSDP Site 366, where extensive recovery of rotarydrilled sediment provided a good stratigraphic basis for predicting downhole ages and lithologies. We planned two major types of objectives at Site 668, one as part of the fourcore depth transect of Sites 665 to 668 and the other focusing on broader paleoceanographic objectives, especially the deeper Neogene section planned for this site. Our depthrelated objectives were as follows:. To determine the late Neogene history of relative isolation of eastern Atlantic deep waters, based on depletion of 5 3 C and on the organiccarbon content. For this purpose, Site 668 was chosen as a shallow control core at a bathymetric level unaffected by the partial deepwater isolation. 2. To assess late Neogene changes in () the flux of CaC0 3 from the surface waters, (2) dissolution of CaC0 3 by deep waters, and (3) redistribution of all sediment components by bottom currents. Broader paleoenvironmental objectives at Site 668 were the following:. To measure late Neogene fluxes of eolian dust and freshwater diatoms as indicators of continental sourcearea aridity and of wind strength. 2. To monitor changes in surfacewater temperature during the Pliocene and Pleistocene using planktonic foraminifers and other indicators. 3. To obtain a highquality, undissolved reference section of CaC0 3 rich equatorial sediments for detailed biostratigraphic and paleomagnetic studies. Geologic and Topographic Setting Site 668 is located in the eastern equatorial Atlantic on the southwest margin of the relatively flat crest of the Sierra Leone Rise (Fig. ; see also Fig. 2, Site 665 chapter). Airgun records from this region indicate a little more than s of sediments above acoustic basement (Figs. 2 and 3). Layering is wellstratified and moderately reflective and ranges from relatively flatlying sediment to hummocky, rolling layers that thin and thicken over short lateral distances. Site 668 was chosen at a point where the upper 0.3 s of sediment was particularly thick. The echogram character from this region indicates standing sediment waves, with average amplitudes of up to 0 m and average wavelengths of about nmi. The origin of the sediment waves and hummocky subbottom layering cannot be determined solely from these records, but it probably involves focusing of nearbottom energy on this shallow topographic feature, causing moderate redistribution of sediments. The basement at Site 668 is Cretaceous (about 80 Ma), based on the age surmised for Site 366. The sediments in the upper 50 to 200 m are middle Miocene to Holocene nannofossil oozes and marls, with possible Miocene unconformities. OPERATONS After departing Site 667, we steamed at 3 kt to a way point at 4 44'N, 2 00'W, which was reached at 307 UTC on 3 932

3 STE SE 0300 UTC A2754 4/20/ UTC NW * 3.0 NW V2206 5/9/ UTC 00 UTC 0900 UTC SE 0800 UTC Figure 2. Seismicreflection records near Site 668. A = cruise A2754. B = cruise V2206. April 986. We slowed to 5 kt and streamed out our geophysical gear (80in. 3 water guns and a magnetometer) on a course of 072. Reaching a second way point at 'N, 'W at 507, we turned to a course of 242 and headed back toward the site location at 'N, 'W. We crossed over the site location, dropped a beacon at 600, pulled in our geophysical gear, and then returned, with a stop over the beacon at 700 on 3 April. From 700 to 230 on 3 April, we ran drill pipe into Hole 668A. First, we retrieved a water core. On our second attempt, we spudded in with a mudline core, but the sand line parted. Between 235 on 3 April and 0030 on 4 April, we fished for the broken wire and for Core 08668AH with a wireline spear. Finally, we were forced to pull out of the hole to recover the core barrel because the wire was broken in two places. We pulled out of the hole from 0730 until 30 on 4 April. 933

4 STE UTC 0200 UTC Figure 3. Highresolution, seismicreflection record near Site 668 from GEOTROPEX'85. We then began running pipe into Hole 668B from 30 to 800 on 4 April, and, at the same time, offset 5 m to the south. We spudded in at 97, and the mudline core (08668B H) came on board at We recovered three more APC cores (Table ), orienting Cores 08668B3H and 668B4H. The last core at this hole (Core 08668B4H) came on board at At this point, illness of a member of the scientific crew forced us to end coring of Hole 668B and the scientific portion of Leg 08. We pulled out of the hole from 2225 on 4 April until 0445 on 5 April. With the drill string on board, we got under way for Dakar at 0445 on 5 April. Some 3840 m of sedi Table. Site 668 coring summary (drilling depths). Core no AH 08668BH 08668B2H 08668B3H 08668B4H Date (April 986) Time (UTC) Depths (mbsf) Length cored (m) H = hydraulic piston. UTC = Universal Time Coordinated. Length recovered (m) Recover (%)

5 STE 668 ment was on board, and although we had not totally fulfilled everyone's dreams, we recovered riches enough for all. LTHOSTRATGRAPHY AND SEDMENTOLOGY Unit Core 08668AH; depth, 08.8 mbsf; age, late Pleistocene. Cores 08668BH through 668B4H, CC; depth, 03.2 mbsf; age, late Pliocene to Holocene. Site 668 consists of one unit, with interbedded layers of foraminiferbearing, muddy nannofossil ooze; mudbearing, foraminiferbearing nannofossil ooze; and muddy foraminifernannofossil ooze. The upper 2 m of this unit is generally brown to light yellowish brown. Below 2 mbsf, colors are generally light gray, light olive gray, or olive. Foraminifer concentrations vary from approximately 5% to greater than 40%. Calcareous nannofossil concentrations vary from 50% to 75%. The noncarbonate fraction is principally clay (5% to 30%), with minor amounts of quartz (up to 2%) and accessory minerals (5%). Biogenic opal is present in trace amounts up to 5%. Depositional Environment The sediments deposited at Site 668 are typical of carbonate oozes deposited in lowproductivity environments. Sediments are rich in foraminifers and nannofossils and poor in diatoms and radiolarians. The clay, quartz, and accessory minerals deposited at this site probably are eolian material derived from northern Africa. The change in color at about 2 mbsf probably reflects the late Pleistocene increase in eolian material that occurred in response to changes in North African aridity. BOSTRATGRAPHY The four cores recovered from Site 668 show abundant, wellpreserved planktonic foraminifers and nannofossils but contain diatoms only in the uppermost cores of each hole (Fig. 4). The fauna and flora indicate tropical conditions, with little evidence of reworking in any of the studied samples. Calcareous Nannofossils The uppermost Pliocene through Holocene nannofossil assemblages at Site 668 show good preservation and contain three 0 Q i20 n 30 Hole B Calcareous nannofossils Age (Ma) 0.47 }.89 Zone NN2 NN20 NN9 NN8 Epoch Pleistocene late Pliocene Planktonic foraminifers Zone Globorotalia truncatulinoides PL6 Age (Ma).8< Hole B Diatoms Zone P. doliolus Figure 4. Zonal assignments for cores recovered from Hole 668B. Unzoned reliable species events that were determined using lightmicroscopy techniques. The extinction of Pseudoemiliania lacunosa occurs between Samples 08668B2H4, 30 cm, and 668B 2H5, 30 cm. Hole 668A is represented by a single core, of which the corecatcher sample represents a level above the extinction of P. lacunosa. Helicosphaera sellii was observed in Sample 08668B4H, 0 cm, but it was not accompanied by Calcidiscus macintyrei. This latter species has its last occurrence (LO) in Sample 08668B4H2, 30 cm. Discoasters are present only in Section 08668B4H6. The Discoaster triradiatus acme interval was observed up to Sample 08668B4H6, 90 cm. This level approximates the Zone NN8/NN9 boundary. Planktonic Foraminifers Planktonic foraminifers are abundant and wellpreserved at Site 668. One core recovered from Hole 668A (08668AH) and two of the four recovered from Hole 668B (08668BH and 668B2H) were assigned to the Pleistocene Globorotalia truncatulinoides Zone. Two cores (08668B3H and 668B4H) were assigned to the late Pliocene PL6 zone. The overlap in the ranges of G. truncatulinoides and Globigerinoides obliquus was identified in Sample 08668B3H, CC. All samples are tropical in nature and contain abundant Globigerinoides ruber, Globigerinoides trilobus, and Neogloboquadrina dutertrei. Globorotalia tumida is abundant only in Sample 08668AH, CC of Hole 668A. Benthic Foraminifers Benthic foraminifers occur in all corecatcher samples examined from Hole 668B. Samples 08668BH, CC through 668B4H, CC contain common, wellpreserved specimens. The characteristic species of this assemblage are Globocassidulina subglobosa, Oridorsalis tener, Planulina wuellerstorfi, and Uvigerina peregrina. Common Hoeglundina elegans are found only in Sample 08668BH, CC. Uvigerinids are common throughout the samples examined. n addition, a few specimens of two species of Melonis occur in Sample 08668B4H, CC. Diatoms Few diatoms were encountered in Samples 08668AH, CC and 668BH, CC. Sample preservation is poor. The presence of Pseudoeunotia doliolus without Nitzschia reinholdii in Sample 08668AH, CC suggests an age of less than 0.65 Ma; however, the sparseness of this assemblage makes this age assignment only tentative. A single unidentifiable diatom fragment was seen in Sample 08668B2H, CC; Samples 08668B 3H, CC and 668B4H, CC were barren of diatoms. PALEOMAGNETSM Magnetostratigraphy The single core from Hole 668A arrived on deck in such a mangled state that magnetic studies were not appropriate. All four cores from Hole 668B were measured at 3cm intervals. Data from Cores 08668B3H and 668B4H were corrected for core orientation using the multishot photographic device. Data from the core tops and disturbed intervals were not considered satisfactory and were deleted. One discrete sample per core section was measured; results agree well with those of the continuous measurements and indicate high stability of magnetic remanence. We plot data from the archive halves of Hole 668B in Figure 5. Correlation with the geomagnetic polarity time scale is given on the right of the figure. The Matuyama/Brunhes and Jaramillo boundaries were missing from the record. 935

6 STE 668 il 2 s Chron Declination nclination ntensity (degrees) (degrees) log (emu/cm 3 ) Figure 5. Results of the continuous core measurements from Hole 668B. Magnetic Susceptibility Whole cores were measured for volume susceptibility at 3cm intervals throughout Holes 666A (Core 08668AH) and 668B (Cores 08668BH through 668B4H). Preliminary assessment suggests that many of the features in the susceptibility record of about the uppermost 20 mbsf at Site 667 also occur at Site 668. SEDMENTACCUMULATON RATES Sedimentaccumulation rates for Hole 668B were calculated using three nannofossil datums and three paleomagnetic datums. The resulting curve (Fig. 6 and Table 2) has three components: () a rate of 7 m/m.y. from 0 to 0.73 Ma (03.35 m), (2) a rate of 5 m/m.y. from 0.73 to.66 Ma ( m), and (3) a rate of 2 m/m.y. from.66 Ma to.88 Ma ( m). This curve fits all the datums. The LO of G. obliquus was not used because of its unreliability at earlier Leg 08 sites. NORGANC GEOCHEMSTRY One interstitialwater sample was squeezed from Hole 668B. Values for ph and alkalinity were measured in conjunction using a Metrohm 605 phmeter, followed by titration with 0.N HC, and salinities were measured using an optical refractometer. Cl", Ca 2+, and Mg 2+ concentrations were determined by the titrations described in Gieskes and Peretsman (986). SO 2, analyses were performed by ion chromatography using a Dionex 220i instrument. Results from all analyses are presented in Table

7 STE *^ 7m/m.y. A ' ' ORGANC GEOCHEMSTRY From Hole 668B, only five samples were recovered (from Core 08668BH) for determining carbonate and organiccarbon contents. The inorganiccarbon (C) content was measured using the Coulometrics Carbon Dioxide Coulometer. The totalcarbon (TC) content was obtained by means of the Perkin Elmer 240C Elemental Analyzer. The totalorganiccarbon (TOC) content was calculated by difference. Analytical methods are discussed, and data presented in the Appendix (this volume). TOC values are low and vary from 0% to 0.33%. The carbonate content fluctuates between 55% and 8% A * 5m/m.y. V A, Age (Ma) Figure 6. Sedimentaccumulation rates for Hole 668B. 2m/m.y."*> t~ 2.0 PHYSCAL PROPERTES Techniques used for shipboard physicalproperty measurements at Site 668 are outlined in the "ntroduction and Explanatory Notes" (this volume). ndex properties and vane shear strength were measured only for the four cores from Hole 668B. Data for this short hole are shown in Table 4 and are plotted in Figures 7 through 9. All five cores from this site were logged continuously using the Pwave logger (PWL) and the GRAPE. Table 2. Depth and age estimates of biostratigraphic and magnetostratigraphic indicators used to establish accumulation rates for Hole 668B. Datum LO Pseudoemiliania lacunosa Brunhes/Matuyama LO Calcidiscus macintyrei Matuyama/Olduvai Olduvai/Matuyama LO Discoaster brouweri LO = last occurrence. Depth (mbsf) Age (Ma) Table 3. Results of inorganicchemistry analyses conducted for Site 668. Core/ section PH Alkalinity (mmol/l) Salinity (%o) Chlorinity (mmol/l) so (mmol/l) Mg 2 * (mmol/l) Ca 2 + (mmol/l) Table 4. ndexproperties and vaneshearstrength data for Hole 668B. Core/ section nterval (cm) 96 Depth (mbsf) Grain density (cm 3 ) Wetwater content (%) Drywater content (%) Wetbulk density (g/cm 3 ) Drybulk density (g/cm 3 ) Porosity (*) Vane shear strength (kpa)

8 STE 668 Figure 0 gives the PWL record of Core 08668B3H to illustrate the cyclic nature of the sedimentation, as revealed by P wave velocity fluctuations of from 540 to 570 m/s. SESMC STRATGRAPHY Coring at Site 668 was delayed initially by operational problems and was terminated prematurely by the illness of a member of the scientific crew. The deepest depth reached was 3.2 mbsf in Hole 668B. Acoustic returns from the equivalent depth range in the sediment column are artifacts of the watergun signals. Thus, no meaningful correlation of seismic units with lithologic units was possible. REFERENCES Gieskes, J. M., and Peretsman, G., 986. Water chemistry procedures aboard JODES Resolution. ODP Technical Note No Vane shear strength (kpa) Grain density (g/cm 3 ) Figure 9. Vaneshearstrength and graindensity profiles for Hole 668B Wetbulk density (g/cm 3 ) Drybulk density (g/cm 3 ) Figure 7. Wet and drybulkdensity profiles for Hole 668B. 0 CO 20 9) Water content (%) Porosity (%) 500 Pwave velocity (m/s) 600 Figure 8. Watercontent and porosity profiles for Hole 668B. Figure 0. Pwavevelocity profile for Core 08668B3H. 938

9 STE 668 HOLE A CORED NTERVAL mbsl; 08.8 mbsf LTH0L06C DESCRPTON FORAMNFERBEARNG, MUDDY NANNOFOSSL OOZE, alternating with MUDDY FORAMNFERNANNOFOSSL OOZE and MUDBEARNG, FORAMNFERBEARNG NANNOFOSSL OOZE AND MUDBEARNG FORAMNFERA NANNOFOSSL OOZE J. ii T l_ * _ T 3 Foraminiferbearing, muddy nannofossil ooze, brownishyellow (0YR 6/6), alternating with muddy foraminifernannotossil ooze, lightyellowishbrown (0YR 6/4, 6/2), and muddy foraminiferbearing nannofossil ooze, darkgray (OYR 4/,2.5YR 4/0); slightly bioturbated. Section 5 contains a coarsegrained, graded, mudbearing foraminifernannofossil ooze, 6065 cm thin nannofossil ooze layers in Section,6068 cm, and Section 2,9502 cm. Minor void in Section 3, 000 cm. SMEAR SLDE SUMMARY (%): 2, 4 2, 99 2, 22 3, 23 3, 37 5, 52 TEXTURE: Sand Silt Clay COMPOSTON: Quartz Clay Foraminifers Nannofossils Diatoms Radiolarians Sponge Spicules Tr 3BS

10 " ' ' STE 6 68 HOLE B 5 s *~ LU :STC CEN LU _l CL LU _l O Q s BOSTRAT. ZONE/ FOSSL Qi c 3 et) 3 L CD a o CM 2 2 CD Z 2 < < CHARACTER 5! a U cc» z «CS CJ «s» c CQ s CORE 2H STE 668 HOLE B CORED NTERVAL mbsl; mbsf LTHOLOGC DESCRPTC FORAMNFERBEARNG, MUDDY NANNOFOSSL OOZE, alternating with MUDDY FORAMNFERNANNOFOSSL OOZE and MUDDY FORAMNFERBEARNG NANNOFOSSL OOZE Foraminiferbearing, muddy nannofossil ooze, brownishyellow (0YR 6/6), alternating with muddy toraminifernannofossil ooze, lightyellowishbrown (0YR 6/4, 6/2), and muddy, foraminiferbearing nannofossil ooze, darkgray (0YR 4/, 2.5YR 4/0); slightly to moderately bioturbated. Chemistry: C here refers to weight % CaC03 y. GRAPHC % LTHOLOGY * 'i s s ^ " : J ~ i L.' F Hj rj 0.5 _>L :_+ : lii : i~ b.~ J H D CC LL b i* i j h :J_L ;! i_ ~'M j ; :^ : i~ r~ ilb"_ HU H "H " j EJ j :V rt _, ;_L. D 3_ ZL : r : i h.0"u 3 ; :_ j i :i J 3 D" :j_j_ i. Cl j ::+* b HU : ir H~ _H i_" 3 :JL j ^ : jgi ;f_ ī :3L H EH, : j Hr ~ i ^ rt _L HL :? V + :ii ;j" J 3 ~ HL j Hr ~LL : ' 3 : 3 b> : 3_L 3 H_ CORED NTERVAL mbsl; mbsf w. i b. b~ 3r in i s 5 d s " i H a l L [lit 'z~. Jt _ it Hi t T t 2 J. * * * LTHOLOGC DESCRPTON CLAYEY NANNOFOSSL OOZE, alternating with FORAMNFERBEARNG, MUDDY NANNOFOSSL OOZE and MUDDY OOZE FORAMNFERNANNOFOSSL Clayey nannofossil ooze, palebrown (0YR 6/3), alternating with foraminiferbearing, muddy nannofossil ooze, lightyellowishbrown 6/4), and muddy toraminifernannofossil ooze, lightgray (0YR 7/2); (0YR moderate bioturbation. Sharp contact with graded bedding in Section 2, 65 SMEAR SLDE SUMMARY (%): TEXTURE: 3, 60 3, 90 3, 30 D D D Sand Silt Clay COMPOSTON: Clay Accessory Minerals Foraminifers Nannofossils Diatoms 5

11 STE 668 HOLE CORED NTERVAL mbsl; mbsf CORED NTERVAL mbsl; mbsf LTHOLOGC DESCRPTON LTHOLOGC DESCRPTON 3 3 JJ 3~ 'X. 3 _ H 3 Foraminiferbearing, muddy nannofossil ooze, lightolivegray (5Y 6/2) oi olive (5Y 5/3, 5/4), alternating with muddy foraminifernannofossil ooze, lightgray (5Y 7/, 7/2); moderate bioturbation. Flowin in Section 2, 60 c through Section 3, 2 cm. *& Foraminiferbearing, muddy nannofossil ooze, gray {5Y 6/) or lightgray (5Y 7/2), alternating with muddy foraminifernannofossil ooze, white (5Y 8/) and lightgray (5Y 7/); moderate bioturbation; green and purple laminations in Section 5. T

12 % ; : ; STE 668 (HOLE A) cm H H2 H3 H4 H5 H6 H.CC 0 W%?) Hill jail t^s : i*«i,«if 5!..«:' %' ' 'V ^ V V * 90 * «; '' ; :% H t% P 942

13 STE 668 (HOLE B) cm 0 H H2 H,CC 2H 2H2 2H3 2H4 2H

14 STE 668 (HOLE B) cm 0 2H6 m 2H7 2H,CC 3H 3H2 3H3 3H4 3H >.'. r' k% W : m t. '%' m :.' '. ;v 30 : h '! i. % " i. : 4 :: 80.V : *: "T ' ', X > i '. i. ": V! : _ '* 0 20 :.:':,,:: "

15 . : ; STE 668 (HOLE B) 3H6 3H7 4H2 4H3 4H4 4H5 4H6 X X s! U 945

16 STE 668 (HOLE B) cm 4H7 Or <mmm 4H,CC HBHHfli 0 k k