# Peru Margin Surface Sediment Geochemistry Data #----------------------------------------------------------------------- # World Data Center for Paleoclimatology, Boulder # and # NOAA Paleoclimatology Program #----------------------------------------------------------------------- # NOTE: Please cite Publication, and Online_Resource and date accessed when using these data. # If there is no publication information, please cite Investigators, Title, and Online_Resource and date accessed. # # # Online_Resource: http://hurricane.ncdc.noaa.gov/pls/paleox/f?p=519:1:::::P1_STUDY_ID:16356 # # Original_Source_URL: ftp://ftp.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/arthur2013/arthur2013carbon12s.txt # # Description/Documentation lines begin with # # Data lines have no # # # Archive: Paleoceanography #-------------------- # Contribution_Date # Date: 2014-04-08 #-------------------- # Title # Study_Name: Peru Margin Surface Sediment Geochemistry Data #-------------------- # Investigators # Investigators: Arthur, M.A.; Dean, W.E. #-------------------- # Description_and_Notes # Description: Organic matter data from surface sediments collected from an oxygen-minimum zone (OMZ) on the Peru margin. # Samples of sediment in 36 box cores, 26 gravity cores, and 18 multicores deployed from the R/V Seward Johnson, # and box and push cores deployed during 31 submersible dives with DS/V Johnson Sea-Link II were collected for this investigation # (Jahnke and others, 1993). The submersible dives resulted in high-resolution video coverage of bottom operations, sediment types, # and organisms, and recovery of 108 push cores, 32 pore-water cores, 25 small box cores, a large number of bottom-sediment slurp samples # into buckets, and numerous samples of crusts, nodules, and other materials using the mechanical arm of the submersible. For this study # of surface-sediment characteristics, we collected samples at 0-1 cm and 1-2 cm intervals from most sub-deployed push cores, and at 0-2 cm # intervals from selected deck-deployed box cores. # # Inorganic Geochemical Analyses # Splits of surface-sediment samples from box and submersible push cores for geochemical analyses were air dried and ground in a ceramic mill # to pass a 100-mesh sieve. Concentrations of 30 major, minor, and trace elements [aluminum (Al), iron (Fe), magnesium (Mg), calcium (Ca), # sodium (Na), potassium (K), titanium (Ti), phosphorus (P), manganese (Mn, arsenic (As), barium (Ba), cadmium (Cd), cerium (Ce), cobalt (Co), # chrome (Cr), copper (Cu), gallium (Ga), lanthanum (La), lithium (Li), molybdenum (Mo), niobium (Nb), neodymium (Nd), nickel (Ni), lead (Pb), # scandium (Sc), strontium (Sr), thorium (Th), vanadium (V), yttrium (Y), and zinc (Zn)] in 81 samples from the 13.5S transect and 66 samples # from the 12S transect were determined by inductively coupled, argon-plasma, atomic emission spectrometry (ICP-AES; Briggs, 2002). # Concentrations of 10 major elements [silicon Si, Al, Fe, Mg, Ca, Na, K, Ti, P, and Mn] in 68 of the 81 samples from the 13.5S transect were # measured by wavelength-dispersive X-ray fluorescence spectrometry (XRF; Taggert and others, 1987). For most elements, the precision of the # method, determined by analyzing USGS rock standards and duplicating 10% of the samples, was better than 10% of the amount present and usually # better than 5% of the amount present for elements in concentrations greater than 10 times the detection limit. # # Carbon Analyses # Concentrations of total carbon (TC) and inorganic carbon (IC) were determined by coulometry (Engleman and others, 1985) in splits of the # geochemistry samples. Carbonate in the untreated sample is reacted with phosphoric acid to liberate CO2, which is then titrated in a coulometer # cell to measure inorganic carbon. Percent CaCO3 is calculated by dividing % IC by 0.12, the fraction of IC in CaCO3. Total carbon is measured # by liberating CO2 by combustion of an untreated sample at 1050C in a stream of oxygen and titrating the CO2. Concentrations of organic carbon (OC) # were determined by difference between TC and IC. The accuracy and precision for both TC and TIC, determined from hundreds of replicate standards # (reagent grade CaCO3 and a Cretaceous Corg-rich marlstone), usually are better than 0.10 wt %. Methods for characterization of Peru margin organic # matter by Rock-Eval pyrolysis and carbon-isotope techniques have been presented in Arthur and others (1998). # # Methods References: # Arthur, M. A., Dean, W. E., and Laarkamp, K., 1998, Organic carbon accumulation and preservation in surface sediments on the Peru margin: Chemical Geology, v. 152, p. 273-286. # Briggs, P.H., 2002. The determination of forty elements in geological and botanical samples by inductively coupled plasma-atomic emission spectrometry, In: Taggart, J.E., (Ed.), Analytical methods for chemical analyses of geologic and other magterials, U.S. Geological Survey Open-File Report 02-223, pp. G1-20. # Engleman, E.E., Jackson, L.L., Norton, D.R., Fischer, A.G., 1985. Determination of carbonate carbon in geological materials by coulometric titration. Chemical Geology 53, 125-128. # Jahnke, R. A., Arthur, M. A., and Shipboard Party, 1993, Cruise Report, Peru Margin Expedition, SJ10-92, R/V Seward Johnson, 226 p. # # Abbreviations: BC: deck-deployed box core SPC: submersible push core JSL 33xx: Jonson Sea-Link dive number # #-------------------- # Publication # Authors: Michael A. Arthur and Walter E. Dean # Published_Date_or_Year: 2013-10-17 # Published_Title: Oceanographic controls on sedimentary and geochemical facies on the Peru outer shelf and upper slope # Journal_Name: US Geological Survey Open-File Report # Volume: # Edition: 2013-1105 # Issue: # Pages: # DOI: # Online_Resource: http://pubs.usgs.gov/of/2013/1105 # Full_Citation: Arthur, M.A., and Dean, W.E., 2013. Oceanographic controls on sedimentary and geochemical facies on the Peru outer shelf and upper slope: U.S. Geological Survey Open-File Report 2013–1105, 38 p. # Abstract: Concentrations and characteristics of organic matter in surface sediments deposited under an intense oxygen-minimum zone (OMZ) on the Peru margin were mapped and studied in samples from deck-deployed box cores and push cores acquired by submersible on two east-west transects spanning depths of 75 to 1,000 meters (m) at 12S and 13.5S. On the basis of sampling and analyses of the top 1-2 centimeters (cm) of available cores, three main belts of sediments were identified on each transect with increasing depth: (1) muds rich in organic carbon (OC); (2) authigenic phosphatic mineral crusts and pavements; and (3) glaucony facies. Sediments rich in OC on the 12S transect were mainly located on the outer shelf and upper slope (150-350 m), but they occurred in much shallower water (approximately 100 m) on the 13.5S transect. The organic matter is almost entirely marine as confirmed by Rock-Eval pyrolysis and isotopic composition of OC. Concentrations of OC are highest (up to 18 percent) in sediments within the OMZ where dissolved oxygen (DO) concentrations are <5 micromoles per kilogram (uM). Even at these low concentrations of DO, however, the surface sediments from within the OMZ are dominantly unlaminated. Concentrations of DO may have the dominant effect on organic matter characteristics, but reworking of fine-grained sediment and organic matter by strong bottom currents with velocities as high as 30 centimeters per second (cm/s) on the slope between 150 and 300 m and redeposition on the seafloor in areas of lower energy and higher DO concentration also exert important controls on OC concentration and degree of oxidation in this region. Phosphate-rich sediments and crusts occurred at depths of about 300 to 550 m on both transects. Nodular crusts of sediment cemented by carbonate-fluorapatite (CFA; phosphorite) or dolomite form within the OMZ. These phosphorite crusts evolve through cementation from light olive-green, stiff but friable, phosphatized claystone "protocrusts" through dense, dark phosphorite crusts, cemented breccias, and pavements. The degree of phosphatization and thickness of the crusts depend on the rates of sediment supply and on the strength and frequency of currents that re-expose crusts on the seafloor. Phosphorite crusts and pavements on the Peru margin can only become buried and incorporated into the geologic record once bottom currents slacken sufficiently to allow fine-grained sediment to accumulate. Glaucony-rich surface sediments, relatively undiluted by other components, were found mainly in deeper water on the 13.5S transect (750 m to at least 1,067 m). These sediments consist almost entirely of sand-size glaucony pellets. These widespread glaucony sands formed in place and were then concentrated and reworked by strong currents that winnowed away the fine-grained matrix. Although the glaucony occurs in sand-size pellets, the pellets are made up of aggregates of authigenic, platy, micaceous clay minerals. Glaucony is predominantly a potassium (K), sodium (Na), iron (Fe), magnesium (Mg) aluminosilicate with an approximate formula of (K,Na)(Fe3+,Al,Mg)2(Si,Al)4O10(OH)2. The glaucony on the 13.5S transect forms by alteration of one or more original "framework" minerals (carbonate and [or] aluminosilicates) to form pellital aggregates of Fe-, K-, and Mg-rich clay minerals. Because Fe, K, and Mg are derived from seawater, sedimentation rates must be extremely slow in order for the original framework minerals to remain in contact with seawater. The close association of glaucony and phosphorite indicates a delicate balance between the slightly oxidizing conditions at the base of the OMZ that form glaucony and the slightly reducing conditions that mobilize iron and phosphate to form phosphorite. #------------------ # Publication # Authors: Michael A. Arthur, Walter E. Dean, Kirsten Laarkamp # Published_Date_or_Year: 1998 # Published_Title: Organic carbon accumulation and preservation in surface sediments on the Peru margin # Journal_Name: Chemical Geology # Volume: 152 # Edition: # Issue: 3-4 # Pages: 273-286 # DOI: 10.1016/S0009-2541(98)00120-X # Online_Resource: http://www.sciencedirect.com/science/article/pii/S000925419800120X # Full_Citation: # Abstract: Concentrations and characteristics of organic matter in surface sediments deposited under an intense oxygen-minimum zone on the Peru margin were studied in samples from deck-deployed box cores and push cores acquired by submersible on two transects spanning depths of 75 to 1000 m at 12 and 13.5S. The source of organic matter to the seafloor in these areas is almost entirely marine material as confirmed by the narrow range of d13C of organic carbon obtained in the present study (-20.3 to -21.6 per mil PDB) and the lack of any relationship between pyrolysis hydrogen index and carbon isotope composition. Organic carbon contents are highest (up to 16%) on the slope at depths between 75 and 350 m in sediments deposited under intermediate water masses with low dissolved oxygen concentrations (<5 umol/kg). Even at these low concentrations of dissolved oxygen, however, the surface sediments that were recovered from these depths are dominantly unlaminated. Strong currents (up to 30 cm/s) associated with the poleward-flowing Peru Undercurrent were measured at depths between 160 and 300 m on both transects. The seafloor in this range of water depths is characterized by bedforms stabilized by bacterial mats, extensive authigenic mineral crusts, and (or) thick organic flocs. Constant advection of dissolved oxygen, although in low concentrations, active resuspension of surficial organic matter, activity of organisms, and transport of fine-grained sediment to and from more oxygenated zones all contribute to greater degradation and poorer initial preservation of organic matter than might be expected under oxygen-deficient conditions. Dissolved-oxygen concentrations ultimately may be the dominant affect on organic matter characteristics, but reworking of fine-grained sediment and organic matter by strong bottom currents and redeposition on the seafloor in areas of lower energy also exert important controls on organic carbon concentration and degree of oxidation in this region. #------------------ # Funding_Agency # Funding_Agency_Name: US Geological Survey # Grant: #------------------ # Site_Information # Site_Name: Peru Margin # Location: Ocean>Pacific Ocean>Eastern Pacific Ocean # Country: # Northernmost_Latitude: -12.0 # Southernmost_Latitude: -13.5 # Easternmost_Longitude: -77.8 # Westernmost_Longitude: -76.4 # Elevation: -75 to -850 m #------------------ # Data_Collection # Collection_Name: Arthur2013Carbons12S # Earliest_Year: # Most_Recent_Year: # Time_Unit: # Core_Length: m # Notes: #------------------ # Chronology: # # # #---------------- # Variables # # Data variables follow are preceded by "##" in columns one and two. # Data line variables format: Variables list, one per line, shortname-tab-longname-tab-longname components (9 components: what, material, error, units, seasonality, archive, detail, method, C or N for Character or Numeric data) # ##Core Number Core Number ##Depth_cm Depth in cm ##% TC Percent total carbon by coulometry ##% CC Percent carbonate (inorganic) carbon by coulometry ##% TOC Percent total organic carbon by coulometry ##% CaCO3 Percent total calcium carbonate by coulometry ##Water Depth (m) Water Depth (m) ##Latitude (S) Latitude (S) ##Longitude (W) Longitude (W) ##Latitude Latitude decimal degrees ##Longitude Longitude decimal degrees # #---------------- # Data: # Data lines follow (have no #) # Data line format - tab-delimited text, variable short name as header # Missing Values: # Core Number Depth_cm % T-C % C-C % TOC % CaCO3 Water Depth (m) Latitude (S) Longitude (W) Latitude Longitude BC-09 0-2 10.07 0.03 10.04 0.25 106 13 31.350 76 27.420 13.5225 76.4570 BC-21 0-2 4.3 0.08 4.22 0.67 73 13 31.070 76 20.000 13.5178 76.3333 BC-43 0-5 1.04 0.06 0.98 0.50 781 13 30.670 77 01.830 13.5112 77.0305 BC-51 0-5 1.11 0.03 1.08 0.25 932 13 28.750 77 02.950 13.4792 77.0492 BC-54 0-5 1.58 0.06 1.52 0.50 1067 13 30.010 77 04.020 13.5002 77.0670 BC-76 0-2 8.84 1.02 7.82 8.50 725 13 30.100 76 59.000 13.5017 76.9833 BC-87 0-2 4.35 2.86 1.49 23.83 188 12 00.520 77 44.930 12.0087 77.7488 BC-91 0-2 16.19 0.05 16.14 0.42 309 11 59.660 77 47.920 11.9943 77.7987 BC-93 0-2 6.91 0.11 6.8 0.92 100 11 59.970 77 20.090 11.9995 77.3348 BC-97 0-2 4.75 1.98 2.77 16.50 430 11 59.660 77 50.110 11.9943 77.8352 BC-116 0-2 3.1 1.22 1.88 10.17 480 11 59.620 77 50.930 11.9937 77.8488 BC-117 0-2 5.5 1.14 4.36 9.50 405 12 00.370 77 49.000 12.0062 77.8167 BC-123 0-2 4.09 1.21 2.88 10.08 655 11 59.660 77 49.330 11.9943 77.8222 BC-125 0-2 13.1 1.17 11.93 9.75 340 11 59.850 77 48.430 11.9975 77.8072 BC-129 0-2 16.76 1 15.76 8.33 277 12 00.140 77 46.650 12.0023 77.7775 BC-153 0-2 16.87 0.75 16.12 6.25 249 11 03.700 78 04.000 11.0617 78.0667 JSL 3360 SPC#4 0-1 5.89 0.64 5.25 5.33 102 12 00.538 77 19.345 12.0090 77.3224 JSL 3360 SPC#4 1-2 5.69 0.06 5.63 0.50 102 12 00.538 77 19.345 12.0090 77.3224 JSL 3360 SPC#3 0-1 5.77 0.84 4.93 7.00 103 12 00.538 77 19.463 12.0090 77.3244 JSL 3360 SPC#3 1-2 5.99 0.2 5.79 1.67 103 12 00.538 77 19.463 12.0090 77.3244 JSL 3360 SPC#1 0-1 7.85 0.23 7.62 1.92 109 12 00.361 77 20.094 12.0060 77.3349 JSL 3360 SPC#1 1-2 8.31 0.14 8.17 1.17 109 12 00.361 77 20.094 12.0060 77.3349 JSL 3372 SPC#1 0-1 11.83 0.71 11.12 5.92 164 12 00.088 77 35.789 12.0015 77.5965 JSL 3372 SPC#1 1-2 9.42 0.06 9.36 0.50 164 12 00.088 77 35.789 12.0015 77.5965 JSL 3358 SPC#4 0-2 11.56 0.48 11.08 4.00 165 13 29.530 76 41.741 13.4922 76.6957 JSL 3358 SPC#3 0-2 1.4 0.34 1.06 2.83 166 13 29.479 76 41.896 13.4913 76.6983 JSL 3372 SPC#2 0-1 8.95 0.28 8.67 2.33 169 12 00.130 77 36.196 12.0022 77.6033 JSL 3372 SPC#2 1-2 6.39 0.17 6.22 1.42 169 12 00.130 77 36.196 12.0022 77.6033 JSL 3372 SPC#3 0-1 13.95 0.21 13.74 1.75 170 12 00.162 77 36.519 12.0027 77.6087 JSL 3372 SPC#3 1-2 9.28 0.13 9.15 1.08 170 12 00.162 77 36.519 12.0027 77.6087 JSL 3358 SPC#1 0-4 14.12 0.06 14.06 0.50 172 13 29.134 76 42.273 13.4856 76.7046 JSL 3371 SPC#2 0-1 12.96 1.85 11.11 15.42 174 12 00.089 77 41.636 12.0015 77.6939 JSL 3371 SPC#2 1-2 14.33 1.27 13.06 10.58 174 12 00.089 77 41.636 12.0015 77.6939 JSL 3371 SPC#4 0-1 10.14 0.84 9.3 7.00 175 12 00.275 77 40.804 12.0046 77.6801 JSL 3371 SPC#4 1-2 8.43 0.51 7.92 4.25 175 12 00.275 77 40.804 12.0046 77.6801 JSL 3359 SPC#1 0-2 2.69 0.84 1.85 7.00 212 12 00.443 77 45.372 12.0074 77.7562 JSL 3368 SPC#3 0-1 12.88 0.89 11.99 7.42 293 12 00.052 77 46.952 12.0009 77.7825 JSL 3368 SPC#3 1-2 11.93 0.61 11.32 5.08 293 12 00.052 77 46.952 12.0009 77.7825 JSL 3361 SPC#4 0-1 11.45 0.99 10.46 8.25 317 12 00.162 77 47.402 12.0027 77.7900 JSL 3361 SPC#4 1-2 14.47 0.38 14.09 3.17 317 12 00.162 77 47.402 12.0027 77.7900 JSL 3368 SPC#2 0-1 13.89 0.91 12.98 7.58 331 11 59.913 77 48.006 11.9986 77.8001 JSL 3368 SPC#2 1-2 14.51 0.12 14.39 1.00 331 11 59.913 77 48.006 11.9986 77.8001 JSL 3368 SPC#1 0-1 11.25 2.15 9.1 17.92 336 11 59.938 77 48.088 11.9990 77.8015 JSL 3368 SPC#1 1-2 13.46 0.25 13.21 2.08 336 11 59.938 77 48.088 11.9990 77.8015 JSL 3361 SPC#3 0-1 12.75 0.93 11.82 7.75 337 11 59.987 77 48.100 11.9998 77.8017 JSL 3361 SPC#3 1-2 14.76 0.32 14.44 2.67 337 11 59.987 77 48.100 11.9998 77.8017 JSL 3361 SPC#2 0-1 8.57 1.36 7.21 11.33 342 11 59.598 77 48.224 11.9933 77.8037 JSL 3361 SPC#2 1-2 11.77 1.96 9.81 16.33 342 11 59.598 77 48.224 11.9933 77.8037 JSL 3361 SPC#1 0-1 11.83 0.57 11.26 4.75 351 11 59.889 77 48.385 11.9982 77.8064 JSL 3361 SPC#1 1-2 12.78 0.25 12.53 2.08 351 11 59.889 77 48.385 11.9982 77.8064 JSL 3367 SPC#4 0-1 4.59 1.17 3.42 9.75 359 12 00.414 77 48.546 12.0069 77.8091 JSL 3367 SPC#4 1-2 5.46 0.68 4.78 5.67 359 12 00.414 77 48.546 12.0069 77.8091 JSL 3356 SPC#2 0-1 3.92 1.49 2.43 12.42 374 13 29.917 76 51.853 13.4986 76.8642 JSL 3356 SPC#2 1-2 4.41 1.16 3.25 9.67 374 13 29.917 76 51.853 13.4986 76.8642 JSL 3367 SPC#3 0-1 4.28 1.04 3.24 8.67 377 12 00.414 77 48.546 12.0069 77.8091 JSL 3367 SPC#3 1-2 4.01 1.04 2.97 8.67 377 12 00.414 77 48.546 12.0069 77.8091 JSL 3367 SPC#2 0-1 4.1 1.53 2.57 12.75 409 12 00.0334 77 49.004 12.0006 77.8167 JSL 3367 SPC#2 1-2 4.5 1.24 3.26 10.33 409 12 00.0334 77 49.004 12.0006 77.8167 JSL 3366 SPC#4 0-1 4.35 1.19 3.16 9.92 427 12 00.134 77 49.285 12.0022 77.8214 JSL 3366 SPC#4 1-2 4.1 0.6 3.5 5.00 427 12 00.134 77 49.285 12.0022 77.8214 JSL 3362 SPC#4 0-1 4.1 1.65 2.45 13.75 442 11 59.956 77 47.720 11.9993 77.7953 JSL 3362 SPC#4 1-2 4.6 1.53 3.07 12.75 442 11 59.956 77 47.720 11.9993 77.7953 JSL 3367 SPC#1 0-1 5.63 1.95 3.68 16.25 445 12 00.242 77 49.430 12.0040 77.8238 JSL 3367 SPC#1 1-2 4.45 0.61 3.84 5.08 445 12 00.242 77 49.430 12.0040 77.8238 JSL 3366 SPC#3 0-1 4.86 1.71 3.15 14.25 448 12 00.091 77 49.631 12.0015 77.8272 JSL 3366 SPC#3 1-2 4.61 0.94 3.67 7.83 448 12 00.091 77 49.631 12.0015 77.8272 JSL 3362 SPC#3 0-1 3.82 1.06 2.76 8.83 459 11 59.882 77 50.049 11.9980 77.8342 JSL 3362 SPC#3 1-2 4.05 2.02 2.03 16.83 459 11 59.882 77 50.049 11.9980 77.8342 JSL 3366 SPC#2 0-1 4.43 1.95 2.48 16.25 461 12 00.052 77 49.923 12.0009 77.8321 JSL 3366 SPC#2 1-2 3.42 0.54 2.88 4.50 461 12 00.052 77 49.923 12.0009 77.8321 JSL 3362 SPC#2 0-1 5.14 1.96 3.18 16.33 470 11 59.854 77 50.269 11.9976 77.8378 JSL 3362 SPC#2 1-2 3.9 0.42 3.48 3.50 470 11 59.854 77 50.269 11.9976 77.8378 JSL 3366 SPC#1 0-1 4.11 1.69 2.42 14.08 473 11 59.999 77 50.119 12.0000 77.8353 JSL 3366 SPC#1 1-2 3.35 0.55 2.8 4.58 473 11 59.999 77 50.119 12.0000 77.8353 JSL 3362 SPC#1 0-1 3.75 1.58 2.17 13.17 483 11 59.783 77 50.529 11.9964 77.8422 JSL 3362 SPC#1 1-2 4.21 1.58 2.63 13.17 483 11 59.783 77 50.529 11.9964 77.8422 JSL 3365 SPC#2 0-2 5.95 1.09 4.86 9.08 752 11 59.472 77 52.273 11.9912 77.8712 JSL 3365 SPC#1 0-2 6.34 0.79 5.55 6.58 846 11 59.358 77 52.363 11.9893 77.8727