Bear Lake, Utah-Idaho Geochemical and Mineralogical Data ----------------------------------------------------------------------- World Data Center for Paleoclimatology, Boulder and NOAA Paleoclimatology Program ----------------------------------------------------------------------- NOTE: PLEASE CITE ORIGINAL REFERENCE WHEN USING THIS DATA!!!!! NAME OF DATA SET: Bear Lake, Utah-Idaho Geochemical and Mineralogical Data LAST UPDATE: 3/2009 (Original receipt by WDC Paleo) CONTRIBUTOR: Walter E. Dean, U. S. Geological Survey, Denver, Colorado IGBP PAGES/WDCA CONTRIBUTION SERIES NUMBER: 2009-028 WDC PALEO CONTRIBUTION SERIES CITATION: Dean, W.E. 2009. Bear Lake, Utah-Idaho Geochemical and Mineralogical Data. IGBP PAGES/World Data Center for Paleoclimatology Data Contribution Series # 2009-028. NOAA/NCDC Paleoclimatology Program, Boulder CO, USA. ORIGINAL REFERENCES: Dean, W.E., R. Forester, S. Colman, A. Liu, G. Skipp, K. Simmons, P. Swarzenski, and R. Anderson. 2005. Modern and Glacial-Holocene Carbonate Sedimentation in Bear Lake, Utah-Idaho. U.S. Geological Survey Open-File Report 2005-1124. (http://pubs.usgs.gov/of/2005/1124) Dean, W., J. Rosenbaum, G. Skipp, S. Colman, R. Forester, A. Liu, K. Simmons, and J. Bischoff. 2006. Unusual Holocene and late Pleistocene carbonate sedimentation in Bear Lake, Utah and Idaho, U.S.A. Sedimentary Geology, v. 185, p. 93-112. Dean, W.E. 2009. Endogenic carbonate sedimentation in Bear Lake, Utah and Idaho over the last two glacial-interglacial cycles, in Rosenbaum, J.G., and Kaufman, D.S., eds., Paleoenvironments of Bear Lake, Utah and Idaho, and Its Catchment. Geological Society of America, Special Paper 450, ISBN: 9780813724508 Bischoff, J.L., K. Simmons, and D.D. Shamp. 2005. Geochemistry of sediments in cores and sediment traps from Bear Lake, Utah and Idaho. U.S. Geological Survey Open-File Report 2005-1215. (http://pubs.usgs.gov/of/2005/1215) GEOGRAPHIC REGION: Western North America PERIOD OF RECORD: 25 KYrBP - present FUNDING SOURCES: U.S. Geological Survey DESCRIPTION: Piston cores were collected in 1996 from three localities in Bear Lake using the University of Minnesota, Limnological Research Center's (UMN-LRC) Kullenberg coring system (Dean et al., 2006). Core BL96-1 is 5 m long from a water depth of 50 m. Core BL96-2 is 4 m long from a water depth of 40 m. Core BL96-3 is 4 m long from a water depth of 30 m. Overlapping cores provide a 25,000-year record. Unknown amounts of sediments were missing from the tops of the piston cores, so surface sediments (up to 50 cm) were collected with a gravity corer in 1998 (Dean et al., 2007). Core BL98-4 is 17 cm m long from a water depth of 30 m. Core BL98-6 is 20 cm long from a water depth of 30 m. Core BL98-9 is 30 cm long from a water depth of 40 m. Core BL98-10 is 36 cm long from a water depth of 40 m. Core BL98-12 is 38 cm long from a water depth of 30 m. Core BL98-13 is 36 cm long from a water depth of 30 m. Piston cores and gravity cores were collected at five localities at the northern end of the lake in 2002. Geochemical and mineralogical data were collected on two of the piston cores and gravity cores from the same localities. Core BL02-3PC is 475 cm long and BL02-3GC is 15 cm long, both from a water depth of 40 m. Core BL02-4PC is 380 cm long and BL02-4GC is 40 cm long, both from a water depth of 30 m. The data set includes files of carbon data, X-ray diffraction (XRD) mineralogy, carbon- and oxygen-isotope data on bulk carbonate, Sr isotope data on bulk carbonate, and HCl-leach chemistry. Not all data were collected on sediments from all cores. Bear Lake: 42°0'N, 111°20'W, 1805m elev. BEAR LAKE METHODS: Carbon Analyses Concentrations of total carbon and inorganic (total carbonate) carbon were determined by coulometry (Engleman and, others, 1985) in USGS laboratories in Denver, CO. Inorganic carbon (IC) in the untreated sample is reacted with perchloric acid to liberate CO2, which is then titrated in a coulometer cell to measure carbonate carbon. Total carbon (TC) is measured by liberating CO2 by combustion of an untreated sample and titrating the CO2. Values of organic carbon (OC) were determined by difference between TC and IC. Replicate analyses demonstrate the coulometer technique has a precision of better than ±1% for both carbonate and total carbon. Percent CaCO3 was calculated by dividing percent carbonate carbon by 0.12, the fraction of carbon in CaCO3. Reference: Engleman, E. E., Jackson, L. L., Norton, D. R., and Fischer, A. G., 1985, Determination of carbonate carbon in geological materials by coulometric titration. Chemical Geology, v. 53, p. 125-128. Isotope Analyses Measurements of ratios of stable isotopes of carbon and oxygen were made on aliquots of the carbon samples (see Dean et al., 2006, 2007 for methods). Isotope measurements on samples from the 1996 cores, 1998 cores, and sediment traps were made in the stable isotope laboratory at the University of Minnesota. Isotope measurements on samples from the 2002 cores were made in the stable isotope laboratory at the University of Arizona. Results of analyses are reported in the usual per mil (‰) d-notation relative to the Vienna Pee Dee Belemnite (VPDB) marine-carbonate standard for carbon and oxygen: d‰=[(Rsample/RVPDB)-1]x103 where R is the ratio (13C:12C) or (18O:16O). Measurements of Sr isotope ratios (86Sr/87Sr) were made on samples from six cores, in Samples were leached in 5M acetic acid, and the leachate was centrifuged and purified with conventional ion-exchange methods. Samples were loaded on a single tantalum filament with phosphoric acid. Isotope ratios were measured with an automated VG54 sector multi-collector, thermal ionization mass spectrometer in dynamic mode. Mass dependent fractionation was corrected assuming a 86Sr/87Sr ratio of 0.1194. Strontium isotope ratios are reported relative to SRM-987 standard value of 0.71025. X-ray Diffraction Analyses Semi-quantitative estimates of mineral contents in splits of the carbon samples were determined by standard X-ray diffraction (XRD) techniques (e.g., Moore and Reynolds, 1989) in USGS laboratories in Denver, CO. Each sample was packed into an aluminum holder and scanned from 15° to 50° 2Q at 2° 2Q/min using Ni-filtered, Cu-Ka radiation at 45 kv, 30 ma, and peak intensities recorded as counts per second (cps). Results are reported as the peak intensity of the main XRD peak for each mineral. Reference: Moore, D.M., and Reynolds, R.C., Jr., 1989. X-ray diffraction and identification and analysis of clay minerals. Oxford University Press, 332 pp. Inorganic Geochemical Analyses Samples for inorganic geochemical analyses were leached in 3N HCl overnight, and the supernatant was analyzed by inductively coupled, argon-plasma, atomic-emission spectrometry (ICP-AES) for major components (percent) Ca, Fe, and Mg, and minor components (parts per million, ppm) Na, Mn, Ba, Sr and Li (Bischoff et al., 2005). Reference: Bischoff, J.L., Simmons, K., and Shamp, D.D., 2005. Geochemistry of sediments in Bear Lake cores and sediment traps. U.S. Geol. Survey, Open-File Report 2005-1215. http://pubs.usgs.gov/of/2005/1215. Abbreviations: cmblf, centimeters below lake floor; ICP, inductively coupled, argon-plasma, emission spectrometry; XRD, X-ray diffraction; VPDB, Vienna Pee Dee Belemnite marine-carbonate standard for carbon and oxygen isotopes DATA: 1. BL96-2 carbon Depth depth in core in cm below lake floor % TC percent total carbon by coulometry % IC percent inorganic carbon by coulometry % OC percent organic carbon by difference between TC and IC % CaCO3 percent calcium carbonate = % IC/0.12 AdjDepth %TC %IC %OC %CaCO3 0 10.64 7.84 2.81 65.31 4 10.56 7.75 2.81 64.6 8 10.75 7.86 2.89 65.53 12 10.55 7.79 2.76 64.89 16 10.04 7.66 2.38 63.86 20 9.85 8.04 1.82 66.96 24 9.89 8.2 1.69 68.31 28 10.38 8.19 2.19 68.25 32 10.49 8.55 1.94 71.27 36 10.75 9.01 1.74 75.06 40 10.69 8.76 1.93 73 44 10.3 8.7 1.59 72.53 48 10.46 8.69 1.77 72.44 52 10.33 8.52 1.81 71.01 56 10.27 8.59 1.68 71.57 60 10.16 8.4 1.75 70.02 64 9.96 8.48 1.48 70.64 68 9.51 8.55 0.96 71.26 72 9.89 8.6 1.29 71.64 76 9.88 8.71 1.18 72.56 80 9.83 8.64 1.19 72.03 84 9.76 8.76 1 73.01 88 9.64 8.69 0.95 72.42 92 9.8 8.62 1.18 71.82 96 9.67 8.81 0.86 73.4 100 9.95 8.79 1.15 73.28 104 9.6 8.55 1.05 71.27 108 9.58 8.46 1.13 70.46 112 9.79 8.63 1.16 71.88 116 9.88 8.83 1.05 73.58 120 9.69 8.82 0.88 73.46 124 9.75 8.92 0.82 74.37 128 9.64 8.73 0.91 72.76 132 9.79 8.82 0.97 73.49 136 9.91 8.92 0.99 74.31 140 9.78 8.91 0.87 74.23 144 10.01 8.82 1.19 73.48 148 10.35 8.95 1.4 74.55 152 9.23 8.37 0.86 69.75 156 9.49 8.39 1.1 69.95 160 9.82 8.5 1.31 70.86 164 9.25 8.11 1.14 67.55 168 9.41 8.46 0.95 70.52 172 9.11 7.96 1.16 66.33 176 9.17 8.1 1.07 67.49 180 8.69 7.24 1.45 60.34 184 8.31 7.14 1.17 59.49 188 9.23 7.88 1.35 65.65 191 9.33 7.98 1.35 66.5 195 9.82 8.35 1.47 69.54 199 9.3 7.73 1.57 64.38 203 9.47 7.07 2.4 58.9 207 9.79 8.41 1.38 70.08 211 9.93 8.44 1.48 70.34 215 10.33 8.54 1.79 71.15 219 9.57 8.03 1.54 66.93 223 9.51 7.8 1.72 64.97 227 9.43 8.6 0.83 71.69 231 8.74 6.87 1.86 57.28 235 8.52 6.72 1.8 55.99 239 9.05 7.23 1.82 60.27 243 7.94 5.07 2.86 42.26 247 7.27 4.35 2.92 36.27 251 6.43 4.54 1.88 37.86 255 6.18 4.28 1.9 35.69 259 6.55 4.82 1.73 40.18 263 6.51 5.01 1.5 41.74 267 6.07 4.5 1.57 37.5 271 6.5 4.88 1.62 40.68 275 6.69 5.04 1.66 41.98 279 6.29 4.85 1.44 40.4 283 6.44 4.97 1.47 41.45 287 6.22 4.66 1.56 38.85 291 5.88 4.16 1.72 34.68 294 6.05 4.28 1.77 35.64 298 5.95 4.22 1.73 35.17 302 5.44 3.68 1.76 30.63 306 4.55 2.74 1.81 22.81 310 3.96 2.04 1.92 16.96 314 3.05 1.36 1.69 11.37 318 2.15 0.9 1.25 7.49 322 2.07 0.89 1.18 7.39 326 1.75 0.93 0.82 7.79 330 1.81 1.11 0.7 9.26 334 1.83 1.2 0.63 10.01 338 1.9 1.38 0.52 11.53 342 1.92 1.35 0.57 11.29 346 1.9 1.34 0.56 11.13 350 1.96 1.54 0.42 12.86 354 2.01 1.64 0.37 13.7 358 1.99 1.59 0.4 13.26 362 1.85 1.58 0.26 13.21 366 1.94 1.62 0.32 13.54 370 1.84 1.55 0.29 12.9 374 1.93 1.65 0.28 13.72 378 1.68 1.4 0.28 11.67 382 1.66 1.44 0.22 12.03 386 1.46 1.22 0.24 10.17 390 1.76 1.53 0.24 12.73 2. BL96-2 stable isotopes Depth (cmblf) depth in core in cm below lake floor 13C (VPDB) delta 13C relative to standard VPDB 18O (VPDB) delta 18O relative to standard VPDB Depth 13C 18O 0 2.78 -4.41 4 3.19 -3.81 8 3.14 -3.74 12 2.91 -3.54 16 2.85 -4.14 20 2.73 -4.01 24 2.56 -4.53 28 2.85 -3.96 30 3.21 -3.8 32 2.88 -4 36 3.02 -4.39 40 2.94 -4.3 52 2.86 -4.29 56 3 -4.28 60 2.9 -4.3 64 2.84 -4.44 68 2.79 -4.44 72 2.59 -4.6 76 2.66 -4.83 80 2.56 -4.88 84 2.53 -5.11 88 2.19 -5.58 92 2.42 -5.35 96 2.32 -5.7 100 2.35 -5.62 104 2.29 -5.24 108 2.52 -5.25 112 2.53 -5.28 116 2.37 -5.75 120 2.23 -6.1 124 2.29 -5.75 128 2.41 -5.33 132 2.29 -5.37 136 2.42 -5.34 144 2.51 -5.3 148 2.64 -4.84 152 2.71 -4.51 156 2.4 -4.96 160 2.5 -5.1 164 2.35 -4.97 168 2.17 -5.54 172 2 -5.83 176 1.89 -6.39 180 1.22 -7.59 184 0.38 -8.29 191 0.5 -8.44 195 0.59 -8.58 199 2.11 -7.44 203 2.43 -6 207 2.52 -5.11 211 2.57 -5.05 215 2.51 -4.97 219 2.36 -5.09 223 2.23 -5.87 231 1.57 -7.02 235 0.88 -7.52 243 0.67 -8.97 247 -0.28 -9.88 251 -0.59 -10.66 255 -0.86 -10.74 259 -0.84 -10.9 263 -1.06 -11.16 267 -1.04 -11.02 271 -0.92 -11.08 275 -1.18 -11.4 279 -1.18 -11.34 283 -1.21 -11.52 287 -1.03 -11.3 291 -0.81 -11.05 294 -0.91 -11.28 298 -1.02 -11.43 306 -0.9 -10.59 310 -1.2 -9.91 314 -1.74 -9.18 322 -1.5 -7.19 326 -1.54 -6.85 330 -2.27 -8.59 334 -2.17 -8.97 338 -2.37 -9.28 342 -2.39 -9.47 346 -2.34 -8.97 350 -2.39 -9.28 358 -3 -9.7 362 -3.12 -9.89 366 -2.76 -9.33 370 -2.98 -9.61 374 -3.1 -9.25 378 -3.01 -9.09 382 -2.81 -9.2 386 -2.84 -9.25 390 -2.88 -9.38 3. BL96-3 XRD Depth (cmblf) depth in core in cm below lake floor aragonite (cps) XRD aragonite peak intensity in counts per second quartz (cps) XRD quartz peak intensity in counts per second calcite (cps) XRD calcite peak intensity in counts per second dolomite (cps) XRD dolomite peak intensity in counts per second Depth Arag. Quartz Calcite Dolomite 0 2876 1286 739 361 4 2946 1536 586 227 8 2847 1238 683 281 12 2994 1852 855 404 16 2824 1862 1252 272 20 2578 1360 822 253 24 2649 1175 879 222 28 2756 1521 821 350 32 3233 1187 634 257 36 3079 1148 1163 316 40 3933 999 600 270 44 3007 1226 797 268 48 3051 1024 826 187 52 2983 1230 688 260 56 3053 1049 768 227 60 2898 1360 747 230 64 2991 1252 747 249 68 3033 1583 891 400 72 3220 1393 782 282 76 3193 1313 727 325 80 3142 1456 703 307 84 3113 1370 741 232 88 3144 1414 743 347 92 3236 1558 835 408 96 3059 1296 721 445 100 3192 1555 881 270 104 2788 1330 705 354 108 3074 1461 753 246 112 3231 1298 618 569 116 3146 1457 585 301 120 3196 1547 762 469 124 3241 1344 547 229 128 3177 1366 751 291 132 2662 1123 615 365 136 3086 1117 587 343 140 3253 1103 653 353 144 3029 1148 572 345 148 3146 1434 613 270 152 2851 1585 816 301 156 3040 1212 664 204 160 3157 1171 646 220 164 2969 1571 929 343 168 3091 1900 945 299 172 2856 1747 869 396 176 2808 1942 1246 284 180 1118 2843 4662 296 184 331 1947 6546 316 188 394 1399 7158 240 191 451 1620 7189 359 195 808 1484 6314 324 199 2162 1479 1197 270 203 2411 1780 1079 622 207 2914 1317 805 417 211 2724 1484 700 546 215 2890 1285 812 301 219 2959 1530 1000 327 223 2814 1911 963 521 227 2664 1661 1346 325 231 1735 1682 2136 297 235 425 2055 5317 274 239 242 2409 5151 318 243 296 3114 5969 398 247 0 3028 5913 648 251 0 3704 5315 453 255 292 3596 5209 634 259 259 3056 5720 379 263 276 3064 6199 459 267 276 3792 4983 571 271 251 2607 5213 367 275 246 3262 6158 323 279 0 3341 5696 428 283 0 3254 6211 384 287 253 2603 5243 407 291 291 3358 5516 634 294 0 3253 5507 569 298 0 3762 5259 476 302 0 4550 4539 775 306 0 5328 3244 751 310 0 6120 2184 956 314 0 8625 1224 1160 318 0 8030 324 984 322 0 7769 427 1038 326 0 1869 686 1015 330 0 7592 1043 819 334 0 7642 1185 819 338 0 7562 1488 1157 342 0 7804 1751 1065 346 0 7816 1351 1002 350 0 7023 1789 670 354 0 7037 1913 679 358 0 7836 2139 1145 362 0 6174 1850 700 366 0 6512 1920 942 370 0 6491 1887 867 374 0 6814 1963 604 378 0 5039 1521 736 382 0 6145 1701 617 386 0 5468 1505 633 390 0 6003 1845 789 4. BL96-2 leach chemistry Depth depth in core in cm below lake floor Na (ppm) parts per million sodium by ICP Ca (%) percent calcium by ICP CaCO3 (%) percent calcium carbonate calculated as %Ca/0.4 Mg (%) percent magnesium by ICP Fe (%) percent iron by ICP Ti (ppm) parts per million titanium by ICP Mn (ppm) parts per million manganese by ICP Ba (ppm) parts per million barium by ICP Sr (ppm) parts per million strontium by ICP Li (ppm) parts per million lithium by ICP Depth Na Ca% CaCO3% Mg% Fe% Ti Mn Ba Sr Li 4 800 24.61 61.521 1.57 0.26 40 120 264 552 6 12 1000 24.17 60.413 1.37 0.26 49 110 268 552 5 16 800 25.93 64.815 1.3 0.29 46 135 276 577 7 20 800 23.5 58.745 1 0.3 41 125 244 513 4 24 700 25.21 63.036 0.88 0.28 44 127 249 533 5 28 800 26.53 66.334 0.92 0.27 41 122 261 537 5 32 700 20.39 50.971 0.75 0.19 35 89 202 425 3 36 800 26.79 66.966 0.78 0.24 34 102 254 553 6 40 800 26.13 65.329 0.74 0.21 37 97 249 544 6 44 900 32.82 82.053 0.98 0.25 47 135 307 670 7 48 700 27.03 67.584 0.76 0.24 41 108 256 555 6 52 700 24.97 62.413 0.8 0.22 38 110 241 521 5 56 800 25.38 63.455 0.78 0.23 40 114 243 525 6 60 700 21.35 53.376 0.61 0.19 32 98 208 438 5 64 800 26.72 66.81 0.74 0.26 42 142 257 550 6 68 700 24.46 61.144 0.58 0.22 38 123 233 504 6 72 800 26.19 65.476 0.55 0.24 39 127 251 541 7 76 700 25.2 62.99 0.5 0.24 35 122 240 529 6 80 700 27.22 68.04 0.52 0.26 43 136 259 575 5 84 800 28.6 71.494 0.49 0.21 42 136 270 607 5 88 700 26.69 66.724 0.46 0.22 37 134 253 565 4 92 700 28.23 70.566 0.46 0.17 38 140 271 606 3 96 700 30.8 77.01 0.48 0.19 42 146 294 679 5 100 800 28.27 70.681 0.44 0.15 43 138 268 604 4 104 700 26.68 66.701 0.43 0.14 34 132 256 573 3 108 800 27.74 69.359 0.49 0.23 37 145 273 601 5 112 700 26.59 66.47 0.42 0.16 32 123 251 568 3 116 700 26.7 66.759 0.38 0.12 35 117 253 583 3 120 800 28.02 70.044 0.38 0.15 35 135 265 629 5 124 600 19.27 48.186 0.29 0.12 30 85 192 470 5 132 700 25.45 63.625 0.37 0.13 32 105 251 614 2 136 800 29.63 74.076 0.44 0.15 40 122 297 732 4 140 700 28.16 70.404 0.4 0.16 37 122 289 727 3 144 700 23.77 59.429 0.33 0.14 30 95 248 586 3 148 700 27.36 68.389 0.4 0.17 35 104 299 692 3 152 800 25.48 63.692 0.51 0.15 36 145 293 672 3 160 700 25.8 64.505 0.36 0.12 27 105 292 740 4 164 700 25.57 63.928 0.49 0.16 48 141 301 693 5 168 800 26.21 65.528 0.44 0.16 36 132 294 728 1 172 700 25.21 63.015 0.48 0.16 35 149 297 735 2 176 700 24.74 61.838 0.51 0.18 33 163 297 728 3 180 700 23.84 59.594 0.96 0.19 31 286 289 673 3 184 600 21.08 52.689 1.05 0.18 42 333 233 471 3 188 500 22.15 55.375 1.02 0.14 19 359 235 482 2 191 600 25.09 62.729 1.12 0.21 29 410 263 521 3 195 600 26.38 65.947 0.99 0.17 34 396 258 555 3 199 500 22.26 55.662 0.58 0.29 59 229 296 789 5 203 500 21.38 53.441 0.52 0.27 62 197 272 715 3 207 600 25.04 62.604 0.39 0.19 56 168 339 836 3 211 600 26.61 66.52 0.38 0.18 60 169 352 829 4 215 500 26.8 66.995 0.44 0.23 59 181 358 725 4 219 600 25.88 64.711 0.48 0.26 58 209 350 680 2 223 600 25.95 64.886 0.49 0.26 57 229 331 660 2 227 500 24.72 61.811 0.51 0.26 58 248 317 634 4 231 400 22.51 56.277 0.72 0.34 58 357 277 561 4 235 300 22.84 57.097 1.13 0.4 60 588 223 406 2 239 300 23.23 58.075 1.05 0.4 57 656 218 404 3 243 300 18.07 45.174 0.91 0.48 62 511 154 287 5 247 300 17.25 43.117 0.83 0.54 59 479 143 264 2 251 300 14.79 36.967 0.82 0.62 62 432 128 225 5 255 300 14.26 35.647 0.83 0.6 57 427 126 213 6 259 300 16.13 40.332 0.81 0.57 51 452 144 235 3 263 300 16.65 41.613 0.8 0.53 48 471 142 239 3 267 300 14.9 37.249 0.81 0.55 49 474 128 217 3 271 300 16.32 40.791 0.82 0.57 49 483 145 236 3 275 300 16.49 41.214 0.8 0.54 45 512 146 231 3 283 300 15.94 39.85 0.75 0.49 44 491 141 208 4 287 300 16.31 40.764 1.01 1.1 71 504 149 210 9 291 400 14.69 36.737 0.99 1.19 84 474 164 193 11 294 300 14.41 36.023 1.01 1.18 78 488 130 181 12 298 300 14.3 35.758 1.05 1.17 72 485 108 174 10 302 300 12.56 31.395 1.12 1.27 84 444 112 156 10 306 300 9.62 24.045 1.25 1.41 92 400 97 128 12 310 300 6.67 16.668 1.33 1.54 97 360 102 92 12 314 300 4.41 11.037 1.47 1.82 107 340 82 65 12 318 300 2.56 6.4104 1.45 1.84 114 308 92 45 11 322 300 2.54 6.35 1.39 1.9 116 317 107 46 13 326 300 2.84 7.1101 1.35 1.76 105 326 130 51 14 330 300 3.77 9.4273 1.33 1.76 93 349 133 64 14 334 300 4.01 10.015 1.3 1.72 90 410 128 68 16 338 200 4.85 12.131 1.28 1.69 77 449 128 79 12 342 300 4.75 11.871 1.35 1.77 87 442 158 76 14 346 300 4.88 12.199 1.31 1.83 81 546 148 77 14 350 300 5.67 14.18 1.21 1.87 76 491 157 83 15 354 200 6.08 15.211 1.2 1.69 65 458 154 90 14 358 300 5.8 14.511 1.15 1.73 68 589 153 84 13 362 300 5.49 13.722 1.09 1.48 61 508 154 82 13 366 300 5.67 14.18 1.14 1.53 66 500 162 85 15 370 300 6.06 15.14 1.25 1.69 75 516 171 91 14 374 300 6.05 15.121 1.18 1.59 69 526 170 90 14 378 300 5.26 13.158 1.19 1.7 60 552 168 84 17 382 200 5.36 13.41 1.19 1.76 62 584 178 82 15 386 300 4.73 11.82 1.15 1.79 58 592 170 75 17 390 300 5.55 13.885 1.21 1.78 57 871 164 86 13 5. BL96-2 Sr isotopes Depth depth in core in cm below lake floor 87Sr/86Sr ratio of 87Sr to 86Sr Depth 87Sr/86Sr 8 0.71033 20 0.71031 24 0.71031 52 0.71035 72 0.7103 76 0.71027 82 0.7103 112 0.71031 120 0.71023 136 0.71022 148 0.71018 168 0.71002 180 0.7096 191 0.7095 199 0.70935 207 0.70984 215 0.71012 223 0.71012 227 0.7101 239 0.70988 251 0.70963 271 0.70962 287 0.70969 306 0.70977 318 0.71015 330 0.71012 352 0.7101 358 0.70991 370 0.70998 386 0.7098