Gebregiorgis, Daniel; Deocampo, Daniel M; Longstaffe, Fred J; Simpson, Alexandra M; Ashley, Gail M; Beverly, Emily J; Delaney, Jeremy S; Cuadros, Javier (2020): Relative proportions of smectite and illite, and illite-smectite oxygen-isotope compositions (δ18OI-S) of 39 mudstone samples collected from a lacustrian section at Paleolake Olduvai [dataset]. PANGAEA, https://doi.org/10.1594/PANGAEA.910866
Always quote citation above when using data! You can download the citation in several formats below.
Published: 2020-01-16 • DOI registered: 2020-02-19
Abstract:
Most clay minerals in sedimentary environments have traditionally been considered to be of detrital origin, but under certain conditions, authigenic clay minerals can form at low temperature through the transformation of precursor clays or as direct precipitates from lake-water. Such clay minerals can hold important information about the prevailing climatic conditions during the time of deposition. We present the first quantitative reconstruction of salinity in paleolake Olduvai based on the oxygen-isotope composition of authigenic clay minerals. We provide a framework illustrating that the isotopic signature of authigenic lacustrine clay minerals is related to the isotopic composition of paleo-waters, and hence to paleosalinity. This new paleosalinity proxy shows that the early Pleistocene East African monsoon was driven by combinations of precession and obliquity forcing, and subsequent changes in tropical SSTs. Such quantitative lacustrine paleosalinity estimates provides a new direction of research for modeling ecosystem change based on an ecologically relevant parameter.
Supplement to:
Gebregiorgis, Daniel; Deocampo, Daniel M; Longstaffe, Fred J; Simpson, Alexandra M; Ashley, Gail M; Beverly, Emily J; Delaney, Jeremy S; Cuadros, Javier (2020): Oxygen Isotopes in Authigenic Clay Minerals: Toward Building a Reliable Salinity Proxy. Geophysical Research Letters, 47(3), e2019GL085576, https://doi.org/10.1029/2019GL085576
Coverage:
Latitude: -2.963083 * Longitude: 35.313583
Date/Time Start: 1999-07-01T00:00:00 * Date/Time End: 1999-07-01T00:00:00
Event(s):
Parameter(s):
| # | Name | Short Name | Unit | Principal Investigator | Method/Device | Comment |
|---|---|---|---|---|---|---|
| 1 | Sample ID | Sample ID | Gebregiorgis, Daniel | Standard sample identification numbers (Deocampo et al., 2017, Geology; Gebregiorgis et al., 2020; GRL) | ||
| 2 | Age model | Age model | ka | Gebregiorgis, Daniel | Estimated ages for 39 mudstone samples from a lacustrian section collected from Paleolake Olduvai | |
| 3 | Illite | Ill | % | Gebregiorgis, Daniel | Illite percentages determined based on glycolated XRD patterns (See Gebregiorgis et al., 2020, GRL and references therein). | |
| 4 | Smectite | Sme | % | Gebregiorgis, Daniel | Smectite percentages determined based on glycolated XRD patterns (See Gebregiorgis et al., 2020, GRL and references therein). | |
| 5 | δ18O, illite-smectite | δ18O Ill-Sme | ‰ SMOW | Gebregiorgis, Daniel | illite-smectite oxygen-isotope compositions (δ18OI-S) (VSMOW) |
License:
Creative Commons Attribution 4.0 International (CC-BY-4.0)
Size:
195 data points
Data
| 1 Sample ID | 2 Age model [ka] | 3 Ill [%] | 4 Sme [%] | 5 δ18O Ill-Sme [‰ SMOW] |
|---|---|---|---|---|
| OLD 165 | 1785 | 100 | 0 | 25.240 |
| OLD 163 | 1788 | 100 | 0 | 24.650 |
| OLD 160 | 1790 | 100 | 0 | 26.240 |
| OLD 157 | 1797 | 42 | 58 | 24.310 |
| OLD 156 | 1798 | 100 | 0 | 25.815 |
| OLD 37 | 1804 | 14 | 86 | 25.980 |
| OLD 38 | 1805 | 95 | 5 | 25.010 |
| OLD 44 | 1813 | 100 | 0 | 24.840 |
| OLD 47 | 1816 | 50 | 50 | 23.630 |
| OLD 50 | 1822 | 5 | 95 | 23.880 |
| OLD 51 | 1824 | 5 | 95 | 25.930 |
| OLD 56 | 1826 | 20 | 80 | 24.530 |
| OLD 58 | 1827 | 80 | 20 | 25.795 |
| OLD 62 | 1833 | 54 | 46 | 25.590 |
| OLD 65 | 1838 | 100 | 0 | 23.160 |
| OLD 147 | 1852 | 100 | 0 | 25.470 |
| OLD 143 | 1856 | 90 | 10 | 24.990 |
| OLD 139 | 1860 | 16 | 84 | 24.810 |
| OLD 135 | 1864 | 16 | 84 | 24.445 |
| OLD 104 | 1866 | 1 | 99 | 24.290 |
| OLD 101 | 1868 | 100 | 0 | 25.540 |
| OLD 99 | 1868 | 75 | 25 | 23.310 |
| OLD 97 | 1869 | 50 | 50 | 25.450 |
| OLD 95 | 1870 | 50 | 50 | 24.440 |
| OLD 92 | 1872 | 0 | 100 | 22.255 |
| OLD 91 | 1872 | 5 | 95 | 24.800 |
| OLD 87 | 1875 | 60 | 40 | 24.460 |
| OLD 84 | 1876 | 90 | 10 | 24.820 |
| OLD 78 | 1878 | 90 | 10 | 25.110 |
| OLD 128 | 1887 | 1 | 99 | 24.930 |
| OLD 123 | 1890 | 16 | 84 | 25.240 |
| OLD 120 | 1893 | 100 | 0 | 24.620 |
| OLD 112 | 1899 | 1 | 99 | 23.410 |
| OLD 35 | 1905 | 1 | 99 | 24.940 |
| OLD 29 | 1910 | 99 | 1 | 25.630 |
| OLD 25 | 1913 | 1 | 99 | 20.180 |
| OLD 21 | 1917 | 50 | 50 | 25.470 |
| OLD 14 | 1919 | 10 | 90 | 23.730 |
| OLD 11 | 1921 | 1 | 99 | 25.170 |