LAKE MICHIGAN CORE SAMPLE DATABASE

Steven M. Colman

U.S. Geological Survey

Woods Hole, MA 02543

INTRODUCTION

The following is a description of the relational databases that contain all measurements and samples from cores taken as part of the U.S. Geological Survey's Southern Lake Michigan Project. The cores were collected on two cruises in 1988 and 1989 during which multiple cores, including box cores, gravity cores, piston cores, and vibracores, were taken at 29 sites. Colman and Foster (1990) provide a complete discussion of field methods, as well as a map of core locations and extensive descriptions of each core. The analytical data contained in the databases described here were obtained by a multidisciplinary team of U.S. Geological Survey analysts and academic researchers.

DATABASE STRUCTURE

The primary database file is called LMSAMPLE; it contains all information related to the samples or measurements themselves. The first three fields in this database file are SAMPLE, SITE, and TYPE. All of the fields in each of the database files are described in detail later, but these fields are mentioned here because they are used to link the various database files.

Information related to the location, depth, and length of the cores is contained in the database file CORELOC. It is linked to LMSAMPLE by the common combined fields SITE and TYPE.

All measurements and analyses are contained in a series of database files called XXXX-RES, where XXXX is denotes the particular type of analysis. The XXXX-RES databases are linked to LMSAMPLE by the field SAMPLE.

The relations between the database files are shown diagramatically below, where "...." indicates additional fields that are described in detail later.

CORELOC: SITE TYPE ....

|-----|

LMSAMPLE: SAMPLE SITE TYPE ....

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XXX1-RES: SAMPLE .... .... ....

|

XXX2-RES: SAMPLE .... .... ....

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XXX3-RES: SAMPLE .... .... ....

CORE LOCATIONS

CORELOC contains the basic information on location, depth, and length of the cores it contains the following fields.

SITE: The site number of the coring station. Multiple cores were collected at each site.

TYPE: The type of core collected:

B, box core, Mini-Sutar type, sampled in 10 cm thin-walled tubes

G, gravity core, Woods Hole giant gravity corer, 10 cm diameter

P, piston core, modified Benthos type, 6.3 cm diameter

V, vibracore, Alpine type, 9 cm diameter

LATITUDE: Latitude in decimal degrees north.

LONGITUDE: Longitude in decimal degrees west.

DEPTH: Water depth in meters

LENGTH: Length of recovered core in cm

The combination of core SITE and core TYPE is unique and is used as the link to the LMSAMPLE database file

SAMPLE DESCRIPTIONS

LMSAMPLE is the main sample and measurement database. It is linked to CORELOC by the unique combination of core SITE and core TYPE. It contains all the basic data related to each sample or measurement. It is linked to the various analysis databases by the field SAMPLE. It contains the following fields:

SAMPLE: Sample number; every sample number is unique.

SITE: Core site number

TYPE: Type of core: B, box; G, gravity; P, piston; V, vibracore. See description of CORELOC for details.

TOP: Top of sampling interval, in cm.

BOT: Bottom of sampling interval, in cm. Same as TOP if sample is a point sample.

ANALYSIS: Type of analysis or measurement, as follows:

1. 18O-13C: Stable isotope measurements (18O and 13C) on biogenic carbonate. Results are stored in the database ISO-RES.

2. 210Pb: Lead-210 analyses. Results are stored in PB-RES.

3. AMS: AMS radiocarbon analyses. Results are stored in AMS-RES.

4. clay mins: Clay mineralogy. Results are stored in CLAY-RES.

5. geochem: Sulfur, sulfur isotope, carbon, phosphorus, and iron geochemistry. Results are stored in CHEM-RES.

6. mollusks: Mollusk abundances. Results are stored in MOLL-RES.

7. MS: Magnetic susceptibility measurements. Results are stored in MSR-RES and MSK-RES.

8. paleo: Paleontology (ostracodes, diatoms, and pollen). Because of poor preservation of diatoms and pollen, only ostracode results are reported, in OSTR-RES.

9. pmag: Paleomagnetic analyses. Results are stored in PMR-RES and PMK-RES.

10. rmag: Analyses of sediment magnetic properties. Results are stored in RMAG-RES.

11. texture: Grain-size analyses. Results are stored in TEX-RES.

12. water cont: Water content analyses. Results are stored in H2O-RES.

ANALYST: Last name of person who performed analysis (us = Colman et al.)

DATEOUT: Date sample submitted for analysis or date analysis begun.

DATEIN: Date results of analysis received.

COMMENT: Any comments about sample.

ANALYSIS RESULTS

The following databases contain the analytical results of the various types of measurements and analyses performed on core samples. Each database is linked to LMSAMPLE by its first field, SAMPLE, which is unique to each sample.

AMS-RES: This database contains the results of accelerator-mass spectrometer (AMS) radiocarbon analyses. Carbonate samples were obtained by hand-picking 5 to 10 mg of ostracodes and small (< 2 mm diameter) mixed-species mollusk shells. Carbon dioxide was obtained by acidifying the shells with phosphoric acid in vacuo (Jones et al., 1989). For hand-picked carbon and total organic carbon samples, the sample was acidified with organic-free HCl and filtered through a nominal 1 m diameter pre-cleaned quartz-fiber filter. Reaction tubes were cleaned by soaking overnight in a chromerge solution, then roasted in air at 550 oC for two hours. The sediment and filter were added to the reaction tube along with 2 g of copper oxide and a 2-by-12 mm strip of silver foil. The tube was evacuated, flame sealed, and then heated in a muffle furnace at 550 oC for 5 hours.

Carbon dioxide from the shell and organic carbon samples was reduced to carbon monoxide over hot zinc and further reduced over hot iron to elemental graphite (Slota et al., 1987). The graphite targets were prepared at the Woods Hole Oceanographic Institution and analyzed at the National Accelerator Facility at the University of Arizona.

The database contains the following fields:

SAMPLE: Sample number, linked to LMSAMPLE.

AGE: Calculated age, in years B.P. (before 1950), corrected for 13C fractionation. A value of -2 indicates insufficient sample after hand picking; a value of -1 indicates insufficient sample during or after perparation to the CO2 stage.

ERROR: Analytical error (one sigma), in years.

MATERIAL: Code for analyzed material: CARB, biogenic carbonate (ostracodes or mollusks); TOC, total organic carbon; POM, hand-picked organic matter.

WHLABNO: Laboratory sample number at the Woods Hole Oceanographic Intitution's radiocarbon preparation laboratory.

AZLABNO: Laboratory sample number at the National Accelerator Facility at the University of Arizona (one sample was run at the Woods Hole Ocean Sciences facility, indicated by an OS- prefix).

CHEM-RES: This database contains the results of wet chemical determinations of sulfur, specific forms of sulfur (including acid volatile sulfide, pyrite sulfur, sulfate, and organic sulfur), iron associated with each form of sulfur, sulfur isotopic data for acid volatile and pyrite sulfur, phosphate, and total and carbonate carbon analyses. Organic carbon can be determined by the difference between these two carbon values.

Sulfur distribution among a series of residence sites was determined using the method of Tuttle et al. (1986). This sulfur speciation scheme separates sulfur into four fractions: acid volatile, disulfide, sulfate, and organic. Acid volatile sulfur (SAV) is defined as sulfur released in the form of H2S and trapped by AgNO3 when a sample is treated with boiling 6 N HCl. This fraction corresponds to sulfur in iron monosulfides that include amorphous FeS, mackinawite, pyrrhotite, and greigite (Fe3S4). Also included in this fraction is any H2S trapped in carbonate inclusions and any sulfur bound in base metal sulfides such as galena (PbS) or sphalerite (ZnS). Disulfide sulfur (SS22-) is sulfur released as H2S when a sample is treated with a boiling 6 N HCl, 1 N CrCl2 solution. Sulfate sulfur, SSO42-, is determined by the precipitation of BaSO4 from the filtrate of the SAV extraction. It includes evaporitic sulfur and sulfate formed by either in situ or post-coring sulfide oxidation. Organic sulfur (Sorg) is determined by a MgO-NaCO3 (Eschka) fusion of the filtrant from the SS22- step and represents S not released by other treatments. If any elemental sulfur is present, it will be reduced along with disulfide in the CrCl2 treatment.

Sulfur isotopes of Ag2S and BaSO4 precipitates from the sulfur speciation experiments were determined by the technique of Tuttle (1988) by Carol Gent of the USGS Branch of Geochemistry. Precision of duplicate analyses was within ±0.2 per mil. The accuracy of these analyses was demonstrated by analysis of the NBS-123 sphalerite standard, which read 16.7 per mil.

Iron associated with AVS and SS22- was determined using atomic adsorption spectroscopy and the method of standard additions.

Phosphate was determined colorimetrically forming a blue paramolybdate complex according to the method of Olsen and Sommers (1982).

Total carbon and total sulfur were determined using Leco combustion using ASTM method D-4239.

The database contains the following fields:

SAMPLE: Sample number, linked to LMSAMPLE.

SAV: Acid Volatile sulfide as determined by Tuttle et al. method (ppm)

S2: Disulfide Sulfur (ppm)

SO4: Sulfate Sulfur (ppm)

SORG: Organic Sulfur (ppm)

STOT(SUM): Total Sulfur determined by the addition of forms of sulfur (ppm)

STOT(MEAS): Total sulfur measured by LECO (ppm)

CTOT: Total Carbon measured by LECO (ppm)

CORG: Organic carbon, measured by LECO after HCl digestion (ppm)

CCARB: Difference between total and organic carbon (ppm)

CR FE: Iron released during disulfide sulfur determination (ppm)

AV FE: Iron released during acid volatile sulfide determination (ppm)

ELEM P: Phosphorus released during acid volatile sulfide determinations (ppm)

DEL-34SAV: 34S composition of acid volatile sulfide (per mil relative to Canon Diablo Chondrite)

DEL-34S2: 34S composition of pyrite sulfide (per mil relative to Canon Diablo Chondrite)

DEL-34SORG: 34S composition of organic sulfide (per mil relative to Canon Diablo Chondrite)

CLAY-RES: This database contains the results of clay mineral analyses. No results are available at the present time.

H2O-RES: This database contains the results of water content analyses. Measured volumes (ca. 3-5 cm3) of sediment were taken from the split core soon after the core was split, using a syringe as a small piston corer. Samples were weighed before and after dring at 60 oC overnight. Values that depend on volume (bulk density and grain-specific gravity) are potentially in error because of the difficulty in measuring volume accurately. Grain-specific gravity values of 2.5 to 2.7 suggest accurate volume values. Water content, which does not depend on volume, is more accurate than bulk density.

The database contains the following fields:

SAMPLE: Sample number, linked to LMSAMPLE.

PER_H2O: Water content, in weight percent

WET_SG: Wet specific gravity (bulk density), i.e. weight of solids and liquids divided by volume, in g/cm3.

DRY_SG: Dry specific gravity (bulk density), i.e. weight of solids only divided by volume, in g/cm3.

GSG: grain specific gravity (bulk density), i.e. weight of solids divided by volume of solids, in g/cm3.

ISO-RES: This database contains the results of stable carbon and oxygen isotopic analyses. Samples were prepared for stable-isotope analysis by selecting a few ostracode or mollusk shells from the samples prepared for paleontologic analyses and lightly crushing them in methanol. The samples were acidified with phosphoric acid in vacuo, and were analyzed on a VG Micromass 602D mass spectrometer following the procedures outlined by Keigwin (1979). All values are reported relative to the PDB standard.

The database contains the following fields:

SAMPLE: Sample number, linked to LMSAMPLE.

SPECIES: Species of ostacode or mollusk that was analyzed. See OSTR-RES databas for species abbreviations.

Del_18O: Content of 18O, per mil.

Del_13C: Content of 13C, per mil

MOLL-RES: This database contains the results of mollusk identifications and abundances. No results are available at the present time.

MSK-RES: This database contains results of whole-core magnetic susceptibility measurements. Magnetic susceptibility of the cores was measured at a frequency of 565 Hz by J.W. King at 3-cm intervals using a Bartington MS2C core pass-through scanner.

The database contains the following fields:

SAMPLE: Sample number, linked to LMSAMPLE.

DEPTH: Depth in centimeters of the core that was placed in the middle of the measurement coil.

Ms- SI: Magnetic susceptibility value in volume SI x 10-6 units.

MSR-RES: This database contains results of whole-core magnetic susceptibility measurements. Magnetic susceptibility of the cores was measured at a frequency of 800 Hz by R. L. Reynolds at 3-cm intervals using a pass-through Sapphire Instruments SI-2 coil having a measurement field of about 6 cm.

The database contains the following fields:

SAMPLE: Sample number, linked to LMSAMPLE.

DEPTH: Depth indicates the depth in centimeters of the core that was placed in the middle of the measurement coil.

Ms- SI: Magnetic susceptibility value in volume SI x 10-6 units.

OSTR-RES: This database contains the identifications and abundances of ostracodes in core samples. Ostracodes and mollusks were separated from the sediment and processed according to the following procedure. About 40 to 60 g of raw sediment from a core interval of 3 cm was frozen, placed in a beaker, weighed, and allowed to thaw. Once thawed, approximately 500 ml of boiling deionized water was added to the sediment followed by approximately 5 to 7 g of baking soda (NaHCO3). The sample was allowed to cool to room temperature, 5 to 7 grams of commercial Calgon (sodium hexametaphosphate, sodium carbonate, and soap) was added, and the sample was allowed to stand for at least one day to promote disaggregation. The sediment was then stirred and suspended in the beaker and slowly poured over stacked 100 (150 m ) and 230 (63 m ) mesh sieves under a gentle shower-type flow of hot tap water. Any remaining sediment was gently disaggregated, and the washed residue was then rinsed with deionized water. If the residue was low in organic matter it was transferred to paper towels for drying; if the residue was organic-rich it was freeze dried. Ostracode and mollusk shells were hand-picked from the dried residue.

Field names for individual species are used as abbreviations in the LMSAMPLE and ISO-RES databases. The database contains the following fields:

SAMPLE: Sample number, linked to LMSAMPLE

DEPTH: Center point of sampleing depth (cm)

Csubt: Abundance of Candona subtriangulata, in valves per gram of wet sediment

Ccrog: Abundance of Candona crogmaniana, in valves per gram

Clac: Abundance of Cytherissa lacustrisa, in valves per gram

Craw: Abundance of Candona rawsonii, in valves per gram

Lfria: Abundance of Limnocythere friabilis, in valves per gram

Cdist: Abundance of Candona distincta, in valves per gram

Litasca: Abundance of Limnocythere itasca, in valves per gram

Cacuta: Abundance of Candona acuta, in valves per gram

Lpara: Abundance of Candona Subtriangulata, in valves per gram

Cvidua: Abundance of Cypridopsis vidua, in valves per gram

Otherspp: Abundance of all other species, in valves per gram

Totvalve: Total abundance of ostracodes, in valves per gram

PB-RES: This database contains the results of 210Pb analyses of the upper parts of selected cores (9B, 6G, and 4B).

The database contains the following fields:

SAMPLE: Sample number, linked to LMSAMPLE.

PMK-RES: This database contains the results of paleomagnetic direction and moment measurements made by J. W. King and others at the University of Rhode Island on whole cores using a 2G Instruments pass-through cryogenic magnetometer.

The database contains the following fields:

SAMPLE: Sample number, linked to LMSAMPLE.

DEPTH: Depth indicates the depth in centimeters of the core that was placed in the middle of the measurement sensor.

NRM-D: Declination of the NRM (Natural Remanent Magnetization) in degrees clockwise from an arbitrary north. Cores were unoriented with respect to azimuth; thus, remanent declination is not a measure of the ancient magnetic field direction

NRM-I: Inclination of NRM in degrees, positive downward.

NRM-M: Moment (intensity of NRM) in milliAmperes/meter (mA/m).

10MT-D: Declination after alternating-field demagnetization at 10 milliTeslas (mt).

10MT-I: Inclination after alternating-field demagnetization at 10 milliTeslas (mt).

10MT-M: Moment after alternating-field demagnetization at 10 milliTeslas (mt).

15MT-D: Declination after alternating-field demagnetization at 15 milliTeslas (mt).

15MT-I: Inclination after alternating-field demagnetization at 15 milliTeslas (mt).

15MT-M: Moment after alternating-field demagnetization at 15 milliTeslas (mt).

PMR-RES: This database contains the results of magnetic susceptibility as well as paleomagnetic direction and moment measurements made by R.L. Reynolds and D. Sweetkind at the U.S. Geological Survey on samples oriented with respect to the up direction in cores. Each sample was obtained by pushing a beveled-edge 1.9 x 1.9 x 1.9-cm plastic cube into soft sediment, cutting beneath the filled cube to separate it from the core, and then capping the cube with a form-fitted top. Measurements of remanent magnetization were made with a modified Schonstedt DSM-1 spinner magnetometer. Alternating-field demagnetization was done on a Schonstedt GSD-5 degausser. Magnetic susceptibility was measured using a Sapphire Instruments SI-2 device operated at 850 Hz and 0.1 mT.

The database contains the following fields:

SAMPLE: Sample number, linked to LMSAMPLE.

DEPTH: Depth indicates the depth in centimeters of the core at the mid-point of the sample.

MS: Magnetic susceptibility in units of SI volume (x10-6)

NRM-DEC: Declination of the NRM (Natural Remanent Magnetization) in degrees clockwise from an arbitrary north. Cores were unoriented with respect to azimuth; thus, remanent declination is not a measure of the ancient magnetic field direction

NRM-INC: Inclination of NRM in degrees, positive downward.

NRM-M: Moment (intensity of NRM) in milliAmperes/meter (mA/m).

2.5MT-DEC: Declination after alternating-field demagnetization at 2.5 milliTeslas (mt).

2.5MT-INC: Inclination after alternating-field demagnetization at 2.5 milliTeslas (mt).

2.5MT-M: Moment after alternating-field demagnetization at 2.5 milliTeslas (mt).

The last three fields are repeated for demagnetization steps between 5 mt and 100 mt.

RMAG-RES: This database contain the results of rock (sediment) magnetic properties measured on individual samples by J.W. King at the University of Rhode Island. Magnetic susceptibility was measured at two frequencies using a Bartington MS2 system. Measurement of remanent magnetization were made using a 2G Instruments single-sample cryogenic magnetometer and a Molspin spinner magnetometer. Samples were obtained by pushing a beveled-edge 1.9 x 1.9 x 1.9-cm plastic cube into soft sediment, cutting beneath the filled cube to separate it from the core, and then capping the cube with a form-fitted top.

SAMPLE: Sample number, linked to LMSAMPLE.

DEPTH: Depth indicates the depth in centimeters of the core at the mid-point of the sample.

Klf- SI Magnetic susceptibility in units of SI volume (x10-6) measured at about 430 Hz.

Khf- SI Magnetic susceptibility in units of SI volume (x10-6) measured at about 4300 Hz.

Arm-SI Anhysteretic remanent magnetization, in A/m, acquired in a D.C. field of 0.1 T while in an alternating field that decays from a peak of 100 mT. Data measured by King for Core 6G may have used a different DC and(or) AC field.

Sirm-SI@1.2 Isothermal remanent magnetization, in A/m, acquired in a field of 1.2 T.

Birm-SI@0.3 Isothermal remanent magnetization, in A/m, acquired in a backfield of 0.3 T.

TEX-RES: This database contains the results of grain-size measurements on core samples. Samples were taken from the core tops, from continuous channel sampling of selected cores, and from other selected intervals; down-core grain-size samples were generally taken at continuous 3-cm intervals. The sand fraction was measured using standard sieving techniques and the silt and clay fraction were measured using a multi-aperture model TA-2 Coulter counter.

The data is in the form of cumulative weight percents on the phi scale (minus log to the base 2 of the size in mm). The database contains the following fields:

SAMPLE: Sample number, linked to LMSAMPLE.

P10_11: Cumulative weight percent coarser than 10 phi.

P9_10: Cumulative weight percent coarser than 9 phi.

P8_9: Cumulative weight percent coarser than 8 phi.

P7_8: Cumulative weight percent coarser than 7 phi.

P6_7: Cumulative weight percent coarser than 6 phi.

P5_6: Cumulative weight percent coarser than 5 phi.

P4_5: Cumulative weight percent coarser than 4 phi.

P3_4: Cumulative weight percent coarser than 3 phi.

P2_3: Cumulative weight percent coarser than 2 phi.

P1_2: Cumulative weight percent coarser than 1 phi.

P0_1: Cumulative weight percent coarser than 0 phi.

Pn1_0: Cumulative weight percent coarser than -1 phi.

Pn2_n1: Cumulative weight percent coarser than -2 phi.

REFERENCES CITED

Colman, S.M., and Foster, D.S. 1990. Stratigraphy, descriptions, and physical properties of sediments cored in Lake Michigan. U.S. Geological Survey Open-File Report 90-478, 92 pp.

Jones, G.A., Jull, A.J.T., Linick, T.W., & Donahue, D.J. 1989. Radiocarbon dating of deep-sea sediments--a comparison of accelerator mass spectrometer and beta-decay methods. Radiocarbon 31: 104-116.

Olsen, S. R. and L. E. Sommers, 1982. Phosphorus. in Methods of Soil Analysis, Part 2. Chemical and Microbiological Properties. Agronomy Monograph no. 9 (2nd Edition). p. 403-430. Soil Science Society of America. Madison, WI.

Slota, P.J., Jr., Jull, A.J.T., Linick, T.W., & Toolin, L.J., 1987. Preparation of small samples for 14C accelerator targets by catalytic reduction of CO. Radiocarbon 29: 303-306.

Tuttle, M. L. 1988. Geochemical evolution and depositional history of sediment in modern and ancient saline lakes: evidence from sulfur geochemistry. Ph.D. Thesis. Colorado School of Mines, Golden, CO 80401.

Tuttle, M.L., M. B. Goldhaber, and D. L. Williamson, 1986. An analytical scheme for determining forms of sulphur in oil shales and associated rocks. Talanta. V 33, no 12 pp 953-961.