10.3389/fmicb.2018.01464.s001 Dylan T. Wilmeth Dylan T. Wilmeth Hope A. Johnson Hope A. Johnson Blake W. Stamps Blake W. Stamps William M. Berelson William M. Berelson Bradley S. Stevenson Bradley S. Stevenson Heather S. Nunn Heather S. Nunn Sharon L. Grim Sharon L. Grim Megan L. Dillon Megan L. Dillon Olivia Paradis Olivia Paradis Frank A. Corsetti Frank A. Corsetti John R. Spear John R. Spear Data_Sheet_1_Environmental and Biological Influences on Carbonate Precipitation Within Hot Spring Microbial Mats in Little Hot Creek, CA.DOCX Frontiers 2018 microbial mat carbonate precipitation biomineralization carbon fixation hot spring 2018-07-13 04:16:20 Dataset https://frontiersin.figshare.com/articles/dataset/Data_Sheet_1_Environmental_and_Biological_Influences_on_Carbonate_Precipitation_Within_Hot_Spring_Microbial_Mats_in_Little_Hot_Creek_CA_DOCX/6814178 <p>Microbial mats are found in a variety of modern environments, with evidence for their presence as old as the Archean. There is much debate about the rates and conditions of processes that eventually lithify and preserve mats as microbialites. Here, we apply novel tracer experiments to quantify both mat biomass addition and the formation of CaCO<sub>3</sub>. Microbial mats from Little Hot Creek (LHC), California, contain calcium carbonate that formed within multiple mat layers, and thus constitute a good test case to investigate the relationship between the rate of microbial mat growth and carbonate precipitation. The laminated LHC mats were divided into four layers via color and fabric, and waters within and above the mat were collected to determine their carbonate saturation states. Samples of the microbial mat were also collected for 16S rRNA analysis of microbial communities in each layer. Rates of carbonate precipitation and carbon fixation were measured in the laboratory by incubating homogenized samples from each mat layer with δ<sup>13</sup>C-labeled HCO<sub>3</sub><sup>-</sup> for 24 h. Comparing these rates with those from experimental controls, poisoned with NaN<sub>3</sub> and HgCl<sub>2</sub>, allowed for differences in biogenic and abiogenic precipitation to be determined. Carbon fixation rates were highest in the top layer of the mat (0.17% new organic carbon/day), which also contained the most phototrophs. Isotope-labeled carbonate was precipitated in all four layers of living and poisoned mat samples. In the top layer, the precipitation rate in living mat samples was negligible although abiotic precipitation occurred. In contrast, the bottom three layers exhibited biologically enhanced carbonate precipitation. The lack of correlation between rates of carbon fixation and biogenic carbonate precipitation suggests that processes other than autotrophy may play more significant roles in the preservation of mats as microbialites.</p>