Sediment spectral reflectance measurements were generated aboard the JOIDES Resolution during Ocean Drilling Program Leg 162 shipboard operations. The large size of the raw data set (over 1.3 gigabytes) and limited computer hard disk storage space precluded detailed analysis of the data at sea, although broad band averages were used as aids in developing splices and determining lithologic boundaries. This data report describes the methods used to collect these data and their shipboard and postcruise processing. These initial results provide the basis for further postcruise research

Mix, Alan C.

O'Connell, Suzanne

Ortiz, Joseph D.

Undetermined

ScholarsArchive@OSU

Raymo, M.E., Jansen, E., Blum, P., and Herbert, T.D. (Eds.), 1999Proceedings of the Ocean Drilling Program, Scientific Results, Vol. 16219. DATA REPORT: SPECTRAL REFLECTANCE OBSERVATIONS FROM RECOVERED SEDIMENTS1Joseph D. Ortiz,2 Suzanne O’Connell,3 and Alan Mix4ABSTRACTSediment spectral reflectance measurements were generated aboard the JOIDES Resolution during Ocean Drilling ProgramLeg 162 shipboard operations. The large size of the raw data set (over 1.3 gigabytes) and limited computer hard disk storagespace precluded detailed analysis of the data at sea, although broad band averages were used as aids in developing splices anddetermining lithologic boundaries. This data report describes the methods used to collect these data and their shipboard andpostcruise processing. These initial results provide the basis for further postcruise research.ed,sure-rat- areed,spottactentsht forp-ycleightref-libra-rawd tot forThis idealnce withredhested byhisgingner-er-(ad-m a. Tocoresen-on-na- ratecien-dur-wereINTRODUCTIONSpectral reflectance provides a rapid, high-resolution, noninva-sive tool for characterization of downcore mineralogical variations indeep-sea sediments. This can be demonstrated by comparison of thepercent reflectance data with shipboard carbonate measurements (fig.9, Shipboard Scientific Party, 1996b). On board the JOIDES Resolu-tion, sediment reflectance measurements were used as an aid in iden-tifying lithologic unit boundaries and for assistance in developingcomposite, spliced records at each site. Reflectance provided the pri-mary criteria for splice determination at Site 982, which lacked astrong lithogenic signal. The processed reflectance data described inthis report are included on the Ocean Drilling Program (ODP) Leg162 Scientific Results volume CD-ROM (see back pocket, this vol-ume) for scientific use.METHODSSediment reflectance was measured at sea during Leg 162 usingthe Oregon State University (OSU) split-core analysis track (SCAT).Measurements were conducted by the shipboard sedimentologists onthe lightly scraped archive half of wet sediment cores during the coredescription process. Sections were not wrapped in plastic (e.g., Glad-wrap) during measurement. Plastic wrapping is recommended for usewith the shipboard, handheld Minolta CM-2002 spectrophotometerto protect its integrating sphere and/or the glass lens of its granularmaterials cover set from direct contact with sediments (ShipboardScientific Party, 1995; Balsam et al., 1997). However, plastic wrap-ping of sections before reflectance measurement with the SCATwould interfere with its conductivity landing system. It is thus unnec-essary because the sample port of the SCAT’s integrating sphedesigned not to touch the sediments. The Leg 162 configurationthe SCAT was first used during postcruise operations during OLeg 154 (Harris et al., 1997). Reflectance measurements with thversion of the instrument have a signal-to-noise ratio that is an oof magnitude better than the prototype instrument deployed durLeg 138 (Harris et al., 1997; Mix et al., 1992, 1995).1Raymo, M.E., Jansen, E., Blum, P., and Herbert, T.D. (Eds.), 1999. Proc. ODP,Sci. Results, 162: College Station, TX (Ocean Drilling Program).2Lamont-Doherty Earth Observatory of Columbia University, Rt. 9W, Palisades,NY 10964, U.S.A. jortiz@ldeo.columbia.edu 3Department of Earth and Environmental Sciences, 265 Church St., Wesleyan Uni-versity, Middletown, CT 06459, U.S.A.4College of Oceanic and Atmospheric Sciences, 104 Ocean Administration Build-ing, Corvallis, OR 97330-5503, U.S.A.re is ofDPisrderingThe SCAT system consists of a computer-controlled, motorizhorizontal track assembly that advances a core section into meament position under a light-integrating sphere (Fig. 1). The integing sphere is lowered, and the conductivity and/or strain sensorsbrought into contact with the sediment using a computer-controllvertical stepping motor. Measurements are conducted on a 2-cm size. Temperature, conductivity, and strain sensors determine conwith the sediment and gently land the sensor head on the sedimfor measurement. Light of known spectral properties from two ligsources—one for visible and infrared wavelengths and a secondUV wavelengths—is supplied to the integrating sphere via fiber otics and directed by a beam-steering mirror. Each measurement cconsists of an internal black background measurement (with no linput), an internal white calibration measurement of a Spectralon erence target, and the sample measurement. These internal cation measurements allow instrument counts to be converted to percent reflectance. In addition, external calibration measurements are conducteensure that there are no section-to-section offsets and to correcscattering errors associated with the integrating sphere (Fig. 1). step is necessary because real-world integrating spheres are notreflectors (Clarke and Compton, 1986). The raw percent reflectameasurements are corrected using external Spectralon standardsknown reflectance of 2%, 40%, 75%, and 100% that were measuapproximately every 7 to 14 sections (10–20 m) to ensure the higquality data.The light that is diffusely reflected off the sediments is integratwithin the sphere and then divided into its constituent wavelengthsa diffraction grating and collected with a multichannel detector. Tdetector measures 1024 wavelength bands (0.68 nm wide) ranfrom 250 to 950 nm (UV to nIR). These measurements were geally taken at 8-cm intervals, although higher resolution (4-cm intval) measurements were taken when time permitted. All cores vanced hydraulic piston corer and some extended core barrel) frodesignated hole (usually the “A” hole) were scanned at each siteensure that composite reflectance splices could be generated, from additional holes at each site (guided by comparison to multissor track data) were selected for analysis. Because of time cstraints, the upper sections of Site 981 (~0–90 mcd) were not alyzed: this sediment sequence represents a lower sedimentationrepeat of the upper sediment sequence at Site 980 (Shipboard Stific Party, 1996a).DATAA total of 55,159 reflectance measurements were generated ing the shipboard operations of Leg 162. These measurements 259DATA REPORTatterisonnd 4gne-theproduced for one or more holes at all of the sites that were drilled dur-ing this leg. Summary statistics of these data are provided in Table 1.Processed data from all of these sites are available in a number offorms. For shipboard analysis, percent reflectance was averaged intofour 50-nm-wide bands defined as UV (250–300 nm), blue (450–5nm), red (650–700 nm), and nIR (900–950 nm). These data cafound in the TABLE_2 directory on the volume CD-ROM (bacpocket, this volume). During shipboard operations, blue band percreflectance values were compared with the closest available carate measurements to determine if there was a consistent relationbetween sediment carbonate content and reflectance (Fig. 2).Postcruise analysis consisted in part of quality control to assthat there were no measurement offsets and of averaging the hresolution data into a 10-nm resolution percent reflectance dataThese data can be found in the TABLE_3 directory on the voluCD-ROM (back pocket, this volume). The 10-nm resolution dawere used in conjunction with shipboard percent CaCO3 data to de-velop proxy percent CaCO3 records. Examples of downcore reflectance variations at the 10-nm wavelength band centered on 665for Sites 980_984 are plotted in Figure 3. This band is selected forlustration because it is close to the maximum output response oinstrument. The first derivative of the reflectance spectra (i.e., its “spectshape”) is useful for assessment of sediment mineralogy (BalsamDeaton, 1991; Deaton and Balsam, 1991). The 10-nm resolution were used to calculate center-weighted, first-derivative spectra the TABLE_4 directory on the volume CD-ROM [back pocket, thvolume]). We use centered-weighted first derivatives (calculabased on data from above and below the central wavelength) rathan simple first-difference derivatives (calculated between two flectance measurements) because they are numerically more s(Press et al., 1992). Examples of downcore variations of the firstrivative at 565 nm for Sites 980–984 are plotted in Figure 4. Increain the first derivative at this wavelength are related to increasesediment hematite concentration (Deaton and Balsam, 1991). Theerage reflectance spectra for Sites 980–984 (Fig. 5) exhibit peakPCCore SectionCore TrackIntegratingSphereVisible-IRLightSourceBeamSteererCooled CCD ArraySUNToSamplePortToReferencePort2x 650MBdisks,5GB tapeFocusingMirrorsDiffraction GratingEntrance SlitFiber OpticsLanderSpectro-radiometerUV LightSourceTo DetectorEthernetConnectionFigure 1. A schematic illustrating the various compo-nents of the OSU SCAT system. (Drawing not to scale.)26000n bekentbon-shipureigh- set.meta- nm il-f theral anddata(seeistedtherre-table de-sess in av-s forsmectite, chlorite, hematite, and a broad absorption band. The lis associated with organic carbon absorption based on comparwith the factors described in Deaton and Balsam (1991).For ease of comparison, the reflectance data in Figures 3 ahave been plotted vs. age (Ma), based on biostratigraphic and matostratigraphic age constraints determined during Leg 162. With Table 1. Statistics on the reflectance observations collected during Leg162.Note: S.D. = standard deviation.HoleMean percent red reflectance (600–650 nm)S.D. percent red reflectance (600–650 nm)Number of observations162-980A 20.23 9.59 2087980B 20.25 9.78 1526980C 17.63 9.26 1221981A 35.33 10.51 2997981B 30.98 8.63 878981C 31.91 9.74 688982A 54.41 14.36 2044982B 56.44 13.39 3526982C 55.11 15.64 1160982D 29.80 12.90 57983A 8.39 2.77 3128983B 7.65 2.93 3402983C 7.58 2.74 3242984A 7.34 2.09 1822984B 6.51 2.29 3459984C 6.51 2.27 3191984D 7.60 2.42 170907B 9.37 3.94 3217907C 8.41 2.54 3093985A 9.78 3.07 3292985B 10.80 3.80 1567986A 7.60 2.06 1631986B 10.54 2.41 168986C 7.54 2.00 1707987A 8.75 1.98 1930987B 8.95 2.64 755987C 10.66 2.98 516987D 8.54 1.98 2450DATA REPORTa-e atllab-as-nt tonticing-hodte-di-ne–m–tol-.,ec-. 92.exception of the age model for Site 980, these age models are present-ed in the sedimentation rate sections of the Leg 162 Initial Reportsvolume (Jansen, Raymo, Blum, et al., 1996). To match the records forSites 980 and 981 between 1.5 and 1.7 Ma, we visually correlated theSite 980 record with that of Site 981, which has better age control forthis time interval (Table 5). The Site 981 age model used here em-ploys the deeper pick (179.48 mcd) for the Matuyama/Gauss bound-ary (Shipboard Scientific Party, 1996a). SUMMARY OF RESULTSFocusing on the North Atlantic drift sites during the past 2.5 m.y.,the reflectance measurements yield consistent patterns from site tosite that can be described as follows:1. Percent reflectance at Sites 980 through 984 demonstrate asystematic relationship to sediment bulk calcium carbonatecontent (Fig. 2). Higher sediment reflectance (“brightness”)associated with greater sediment bulk calcium carbonate ctent.2. Sediments in the east (Sites 980/981 and 982) exhibit gremean reflectance values and greater variations in percenflectance than sediments from the west (Sites 983 and 9(Table 1; Fig. 3).3. Sediments older than 2.5 Ma exhibit systematically higher pcent reflectance and lower variability than sediments youngthan 2.5 Ma (Fig. 3).4. At Sites 980/981 and 982, the first derivative of the reflectanspectra at 565 nm has low amplitude in sediments older t2.5 Ma. The mean first derivative value at 565 nm at these sincreases with decreasing age.0 10 20 30 40 50 60 70 800102030405060708090100Hole 980AHole 981AHole 982BHole 983AHole 984BBlue band reflectance (%), 450-500 nmBulk CaCO3 (%)Figure 2. Spectral reflectance (450–500 nm) in relation to the bulk calcicarbonate content of sediments recovered from Leg 162, Sites 980 thro984. Open circles = Hole 980A, open diamonds = Hole 981A, stars = H982B, open squares = Hole 983A, × symbols = Hole 984B. (Fig. 9, Ship-board Scientific Party, 1996b.) ison-atert re-84)er-ercehanites5. Sites 983 and 984 exhibit much lower amplitude first-derivtive variations at 565 nm than Sites 980/981 and 982. ACKNOWLEDGMENTSWe thank the captain and crew of the JOIDES Resolution and theco-chief scientists, M. Raymo and E. Jansen, for their assistancsea. Sara Harris at Oregon State University has been an active coorator. We also thank William Rugh, who provided much-needed sistance setting up the SCAT system on the JOIDES Resolution. Thisresearch was supported in part by a postcruise JOI/USSSP graJDO. This data report is LDEO contribution 5791.REFERENCESBalsam, W.L., Damuth, J.E., and Schneider, R.R., 1997. Comparison of ship-board vs. shore-based spectral data from Amazon-fan cores: implicationsfor interpreting sediment composition. In Flood, R.D., Piper, D.J.W.,Klaus, A., and Peterson, L.C. (Eds.), Proc. ODP, Sci. Results, 155: Col-lege Station, TX (Ocean Drilling Program), 193–215.Balsam, W.L., and Deaton, B.C., 1991. Sediment dispersal in the AtlaOcean: evaluation by visible light spectra. Rev. Aquat. Sci., 4:411–447.Clarke, F.J.J., and Compton, J.A., 1986. Correction methods for integratsphere measurement of hemispherical reflectance, Color Res. Appl.,11:253–262.Deaton, B.C., and Balsam, W.L., 1991. Visible spectroscopy: a rapid metfor determining hematite and goethite concentrations in geological marials. J. Sediment. Petrol., 61:628–632.Harris, S.E., Mix, A.C., and King, T., 1997. Biogenic and terrigenous sementation at Ceara Rise, western tropical Atlantic, supports PliocePleistocene deep-water linkage between hemispheres. In Shackleton,N.J., Curry, W.B., Richter, C., and Bralower, T.J., Proc. ODP, Sci.Results, 154: College Station, TX (Ocean Drilling Program), 331–345. Jansen, E., Raymo, M.E., Blum, P., et al., 1996. Proc. ODP, Init. Repts., 162:College Station, TX (Ocean Drilling Program). Mix, A.C., Harris, S.E., and Janecek, T.R., 1995. Estimating lithology frononintrusive reflectance spectra: Leg 138. In Pisias, N.G., Mayer, L.A.,Janecek, T.R., Palmer-Julson, A., and van Andel, T.H. (Eds.), Proc. ODP,Sci. Results, 138: College Station, TX (Ocean Drilling Program), 413427. Mix, A.C., Rugh, W., Pisias, N.G., Veirs, S., Leg 138 Shipboard Sedimenogists (Hagelberg, T., Hovan, S., Kemp, A., Leinen, M., Levitan, MRavelo, C.), and Leg 138 Scientific Party, 1992. Color reflectance sptroscopy: a tool for rapid characterization of deep-sea sedimentsInMayer, L., Pisias, N., Janecek, T., et al., Proc. ODP, Init. Repts., 138 (Pt.1): College Station, TX (Ocean Drilling Program), 67–77. Press, W.H., Teukolsky, S.A., Vetterling, W.T., and Flannery, B.P., 19Numerical Recipes in Fortran: the Art of Scientific Computing, (2nd ed.):New York (Cambridge Press), 180–184.Shipboard Scientific Party, 1995. Explanatory notes. In Curry, W.B., Shack-leton, N.J., Richter, C., et al., Proc. ODP, Init. Repts., 154: College Sta-tion, TX (Ocean Drilling Program), 11–38.Shipboard Scientific Party, 1996a. Sites 980/981. In Jansen, E., Raymo,M.E., Blum, P., et al., Proc. ODP, Init. Repts., 162: College Station, TX(Ocean Drilling Program), 49–90. Shipboard Scientific Party, 1996b. Site 984. In Jansen, E., Raymo, M.E.,Blum, P., et al., Proc. ODP, Init. Repts., 162: College Station, TX (OceanDrilling Program), 169–222. Date of initial receipt: 25 August 1997Date of acceptance: 11 June 1998Ms 162SR-029umughole261DATA REPORT0 0.5 1 1.5 2 2.5020406080Sites 980/981 Reflectance Band 42: 665 nmAge in MaReflectance (%)0 0.5 1 1.5 2 2.5020406080Site 982 Reflectance Band 42: 665 nmAge in MaReflectance (%)0 0.5 1 1.5 2 2.50510152025Site 983 Reflectance Band 42: 665 nmAge in MaReflectance (%)0 0.5 1 1.5 2 2.50510152025Site 984 Reflectance Band 42: 665 nmAge in MaReflectance (%)Figure 3. Downcore variations in diffuse spectral reflectance at 665 nm plotted against age (Ma) based on the shipboard age model for Sites 980 through 984.262DATA REPORT0 0.5 1 1.5 2 2.500.050.10.150.2Sites 980/981 reflectance 1st derivative (δR/δλ) band 31: 565 nmδR/δλ at 565 nm0 0.5 1 1.5 2 2.500.050.10.150.2Site 982 reflectance 1st derivative (δR/δλ) band 31: 565 nmδR/δλ at 565 nm0 0.5 1 1.5 2 2.500.050.1Site 983 reflectance 1st derivative (δR/δλ) band 31: 565 nmδR/δλ at 565 nm0 0.5 1 1.5 2 2.500.050.1Site 984 reflectance 1st derivative (δR/δλ) band 31: 565 nmAge in MaδR/δλ at 565 nmFigure 4. Downcore variations in the first derivative of diffuse spectral reflectance at 565 nm plotted against age (Ma) based on the shipboard age model forSites 980 through 984.263DATA REPORT300 400 500 600 700 800 900-0.1-0.0500.050.10.15Site 984Site 983Site 982Site 981Site 980Corg?Wavelength λ (nm)HematiteChlorite?Smectite?Average 1st derivative (δR/δλ) Figure 5. Average first-derivative spectra for Sites 980–984. Spectral peaks associated with various sedi-ment components are identified based on comparison with the first-derivative factors of Balsam and Deaton (1991). Open circles = Site 980, open diamonds = Site 981, stars = Site 982, open squares = Site 983, × sym-bols = Site 984. 264Table 5. Age model for Site 980.Note: FAD = first appearance datum, LAD = last appearance datum.EventDepth (mcd)Age (Ma)Core top 0.00 0.000FAD E. huxleyi (N) 35.27 0.260LAD P. lacunosa (N) 62.82 0.460Brunhes/Matuyama boundary 87.35 0.780Jaramillo top 100.35 0.990Jaramillo bottom 103.72 1.070LAD Gephyrocapsa A/B (N) 111.46 1.230Tie to 981 125.88 1.516Tie to 981 127.75 1.545Tie to 981 128.37 1.570Tie to 981 129.95 1.595Tie to 981 130.51 1.618Tie to 981 131.15 1.630Tie to 981 131.29 1.644Tie to 981 132.49 1.672Base of reflectance record 135.00 1.730

Data report : spectral reflectance observations from recovered sediments

https://ir.library.oregonstate.edu/downloads/sn00b3640

Data report : spectral reflectance observations from recovered sediments

Abstract

Similar works

Full text

Available Versions

ScholarsArchive@OSU