Distribution of tetraether lipids in the 25-ka sedimentary record of Lake Challa: extracting reliable TEX86 and MBT/CBT palaeotemperatures from an equatorial African lake

Environmental conditions in the South Atlantic (Angola Basin) during the Early Cretaceous

“…As a result, the GDGT-0 index can be used to assess the contribution of methanogenic archaea to the sedimentary GDGT pool (e.g. Blaga et al, 2009;Sinninghe Damsté et al, 2012). The low GDGT-0 index (< 15%) suggests that the dominant source of isoGDGTs was marine Thaumarcheota and indicates that archaeal methanogenesis was not widespread in the Angola Basin during the Early Cretaceous.…”

Impacts of Paleoecology on the TEX86 Sea Surface Temperature Proxy in the Pliocene‐Pleistocene Mediterranean Sea

“…The TEX 86 ratio is a sea surface temperature (SST) proxy derived from the distribution of the isoprenoid glycerol dialkyl glycerol tetraether (iGDGT) membrane lipids of planktonic Thaumarchaeota (Schouten et al, ). TEX 86 records have been especially valuable in environments where other temperature proxies, such as the algal lipid‐based , are absent or outside the calibration range (e.g., Inglis et al, ), in the study of large lacustrine systems (e.g., Sinninghe Damsté et al, ), and in carbonate‐free marine sediments (e.g., Schouten et al, ). However, TEX 86 records sometimes disagree with other SST proxies such as (e.g., Becker et al, ; Menzel et al, ; Seki et al, ), and the empirical correlation between TEX 86 and SST varies regionally (Ho et al, ; Kim et al, ; Pearson & Ingalls, ; Tierney & Tingley, ; Trommer et al, ).…”

DeepCHALLA: Two Glacial Cycles of Climate and Ecosystem Dynamics from Equatorial East Africa

“…Combination of the BIT and diatom d 18 O records showed how decoupled variation in annual rainfall and seasonal drought controlled long-term variation in the region's savanna fire regimes (Nelson et al, 2012). Comparison of the d 13 C record of plant leaf-wax alkanes preserved in Lake Challa with the BIT record, the TEX 86 record of central African temperature from Lake Tanganyika (Tierney et al, 2008;Sinninghe Damsté et al, 2012), and the ice-core record of atmospheric pCO 2 allowed assessing principal environmental controls on the proportion of regional plants using the C 3 or C 4 photosynthetic pathway . These and other studies have demonstrated Lake Challa's status as a tropical climate archive of global significance, and they create confidence that the deeper Lake Challa sediments will reveal a truly unique record of quintessentially equatorial climate change and ecosystem dynamics over glacial-interglacial timescales.…”