DOI: 10.5061/dryad.2547d7x5j
title: Data and supporting information for: From source rock to cinnabar – how the giant mercury deposits in earth’s crust formed

description: The largest concentrations of Hg on Earth exist as giant deposits of
 cinnabar (HgS). How such enrichments of Hg formed, based on its known
 crustal abundance has never been fully resolved, nor has the source(s) of
 Hg been unequivocally established. Hg isotopes were used to elucidate
 crustal processes leading to the concentration of Hg during thermal
 maturation of Hg and organic matter enriched sediments and cinnabar
 formation. Mass dependent fractionation (MDF) of Hg isotopes shows
 remarkable enrichment of 202Hg in cinnabar relative to its upper mantle
 source. Two mechanisms contribute to this enrichment: one is the low
 temperature, early diagenetic loss of volatile 198Hg0(g) to an extant gas
 phase; the other is oxidation during cinnabar deposition. Loss of
 198Hg0(g) results in 202Hg enrichment of Hg in residual organic matter in
 source sediments. Evidence for this significant loss of 198Hg0(g) is
 observed as large depletions in the δ202Hg isotopic composition of
 proximal gas condensate liquids in high pressure – high temperature
 (HP/HT) reservoirs in the central North Sea (CNS). Migration of
 hydrocarbons and formation brines from Hg-enriched sediments transports
 reduced Hg0(org, aq) to the site of cinnabar deposition, where oxidation
 of Hg0(org, aq) and H2S further enhances enrichment of 202Hg in cinnabar.
 The large changes in MDF are independent of  mass independent
 fractionation (MIF) of mercury isotopes. Approximately 80% of the cinnabar
 samples examined in this study plot within ± 0.1‰ of the origin on a
 Δ199Hg - Δ201Hg MIF Hg isotope plot and have a Hg isotopic composition
 similar to that of continental flood basalts (CFB), consistent with an
 upper mantle source for Hg. MIF trends defined by coals and euxinic
 sediments on Δ199Hg - Δ201Hg MIF plots have Δ199Hg /Δ201Hg slopes ~ 1.
 These tend to be the most reduced Hg-enriched sediments, deposited in
 anoxic or euxinic environments in which the dominant Hg species is Hg0. In
 open marine environments the dominant Hg species is likely to be Hg2+.
 Δ199Hg /Δ201Hg slopes &gt;1 deviating from these reduced sediment
 trends appear to be controlled by the fugacity of H2S (fH2S), and variable
 proportions of reduced Hg0 to oxidized Hg2+ in progenitor sediments,
 reflecting their environments of deposition and redox state.
description: # Data and supporting information for: From source rock to cinnabar – how
 the giant mercury deposits in earth’s crust formed Dataset DOI:
 [10.5061/dryad.2547d7x5j](https://doi.org/10.5061/dryad.2547d7x5j) **This
 Data and Supporting Information file** **(AJS_FINAL_D_SI.pdf)** **includes
 the following sections:** **Mercury isotopes**: Includes a brief
 description of nomenclature used in reporting both mass dependent and mass
 independent mercury isotopic data, together with a detailed description of
 laboratory and analytical procedures used in sample preparation and
 analysis of mercury isotopic composition in natural mercury-bearing
 samples discussed in this study. **Table S1:** MC-ICP-MS operating
 parameters and measurement conditions for isotope ratio measurements.
 **Supporting references** **Hg isotope data for cinnabar from each deposit
 discussed in this study** Hg isotope data for each deposit were compiled
 from previously published studies, and together with a short summary of
 the geological setting are given in supplementary tables S2-S8, together
 with the published source of the data. 
                                      **Table S2:** Mercury isotope data
 for cinnabar and Hg ore minerals from Terlingua (SW Texas), McDermitt
 (Nevada), and New Idria (California Coast Range), USA **Table S3:**
 Mercury isotope data for cinnabar ore from Huancavelica, Peru **Table
 S4:** Mercury isotope data for cinnabar ore from Indrija mercury mine,
 Slovenia **Table S5:** Mercury isotope data for Hg^0^ and cinnabar ore
 from Almaden, Spain **Table S6:** Mercury isotope data for cinnabar ore
 from Monte Amiata, Tuscany, Italy **Table S7:** Mercury isotopic data for
 Almaden cinnabar and corresponding Pb-Pb ages **Figure S1.** A) MDF versus
 MIF plot for Hg^0^ and HgS from Almaden (Spain). B) HgS and Hg^0^ isotope
 data plotted as a function of their respective Pb-Pb ages. **Table S8:**
 Mercury isotope data for Hg^0^ and cinnabar ore from Wanshan, China **Hg
 isotope data for subsurface formations, hydrocarbons, and source rocks are
 given in supplementary tables S9-S15** **Table S9:** Mercury isotope data
 for subsurface formations – Central North Sea **Table S10:** Mercury
 isotope data for hydrocarbons **Table S11:** Mercury isotope data for
 source rocks and hydrocarbons from Bohai Bay and Sichuan Basin **Table
 S12:** MDF (δ^202^Hg) and MIF (Δ^199^Hg) Hg isotope data from OAE-2 rocks,
 including limestone, marl, black shale and claystone from Rehkogelgraben,
 Austria. **Figure S2.** Caption same as for figure 5 in main text. **Table
 S13:** MDF (δ^202^Hg) and MIF (Δ^199^Hg; Δ^201^Hg) Hg isotope data from
 Cambrian black shales and tuffs, South China **Table S14:** MDF (δ^202^Hg)
 and MIF (Δ^199^Hg) Hg isotope data from PTB sediments **Table S15:** MDF
 (δ^202^Hg) and MIF (Δ^199^Hg) Hg isotope data from LPE sediments **Figure
 S3.** *f*H~2~S versus Δ^199^Hg in gas condensate reservoirs from the CNS
 **Table S16:** Estimated temperatures of cinnabar (HgS) formation from
 δ^202^Hg isotopic composition and assuming equilibrium with
 ^198^Hg^0^*~(g)~* evaporation temperatures (based on the experimental data
 from Estrade et al., 2009). **D&SI References** ## Code/software Not
 Applicable ## Access information All sources of data are listed below
 relevant data tables