Salty Matters

The Blog is written by me, John Warren. Once every three or four weeks or so I will post an article or two on an evaporite topic that has piqued my interest. On the Saltwork Publications webpage (under "the Works") there is a growing library of pdfs and epubs based on these blogs. These articles on the website have much higher resolution extractable graphics in than in the blog. There is also a link to this set of pdfs and epubs on the home page (www.saltworkconsultants.com).

Seawater chemistry (2 of 2): Precambrian evolution of brine proportions

John Warren - Wednesday, August 26, 2015

We saw in the previous Salty Matters article (part 1 of 2) that ionic proportions of major ions in seawater and oceanic salinity have changed through the Phanerozoic and so influenced the make-up of bittern precipitates once the lower salinity salts (carbonates, gypsum and halite) had precipitated. In the Phanerozoic, seawater was dominantly a Na-K-Mg-Ca-Cl (Ca-rich) brine that changed periodically to a Na-K-Mg-Cl-SO4 (SO4-rich) type, as in the modern ocean. This oscillation across 600 million years forces  number of questions, for example, do similar oscillations in ocean chemistry extend back across the Precambrian? How consistent is the chemistry of the world’s oceans since the early Archean? Does the evaporite evidence in Precambrian sediments support a notion of a primordial reducing atmosphere and/or higher levels of bicarbonate in an early Archean ocean?

Some authors postulate that there have been no significant changes in the major ion proportions in seawater and hence the evaporation mineral series for the past 4 Ga (Morse and Mackenzie, 1998). Others assert that the Archean was dominantly a time of little or no atmospheric oxygen and that ocean waters were reducing anoxic fluids and so sulphate levels were low and sulphide levels high in evaporative marine waters (Krupp et al., 1994). Yet others propose that the bicarbonate to calcium ratio was so high in Archean and Palaeoproterozoic seawater compared to today that all the calcium was used up in widespread abiotic marine aragonite and Mg-calcite precipitates (Sumner and Grotzinger, 2000). In this case trona or nahcolite are likely marine evaporites in the early Archean bitterns (see Figure 1 in part 1). Still others have theorised cyclic changes in oceanic chemistry occurred across much of the Precambrian were similar to those of the Phanerozoic. Such changes were perhaps related to changes in styles and rates of sea floor spreading-hydrothermal circulation in midoceanic ridges (Channer et al., 1997) and the development of tonalitic continents (Knauth, 1998). 

Given that the world's oldest known halites occur in the Bitter Springs Formation in the Amadeus Basin of Australia and that they were deposited some 840 Ma, we can only extend a halite chevron inclusion-based study of ocean chemistry back to that time. These brines were sulphate-depleted, while recrystallised halite from the uppermost Neoproterozoic Salt Range Formation (ca. 545 Ma) in Pakistan, contains solitary inclusions indicating SO4-rich brines (Kovalevych et al., 2006). This supports a similar late Neoproterozoic ocean chemistry to today, as do proportions derived from primary fluid inclusions from the Neoproterozoic Ara Formation of Oman (ca. 545 Ma). It seems that  SO4-rich seawater existed during latest Neoproterozoic time. In contrast while recrystallised halite from the somehat older Bitter Springs Formation contains brine inclusions that are entirely Ca-rich, implying ambient basin brines and the mother seawater were Ca-rich some 830-840 Mas. These combined data, supported by the timing of aragonite and calcite seas, as preserved in various marine carbonates, suggest that during the Neoproterozoic, significant oscillations of the chemical composition of marine brines, and seawater occurred over the last 250 million years of the NeoProterozoic, and that the end-members were similar to those of the Phanerozoic oceans. It seems that Ca-rich seawater dominated for a substantial period of Late Precambrian time (more than 200 Ma) from 850 Ma, until some 650 Ma, this was replaced by SO4-rich seawater, returning to Ca-rich seawater at 530 Ma. 

The detail for much of the remaineder of the Precambrian back to 4 Ga is far less precise than when modelling inclusion chemistries based on actual halites. The oldest documented chevron halite is 850Ma and the oldest bedded anhydrite is 1.2Ga, beyond that, only evaporite pseudomorphs are available to study. So, beyond the 850 Ma record established by halite inclusions in the Bitter Springs Fm., can other Precambrian evaporites especially the calcium sulphates with a record that extends back patchily to the Mesoproterozoic, give indirect clues as to a chemical scenario for the world’s paleo-oceans and brine?

 

Pseudomorphs, especially of halite hoppers, occur in marine rocks as old as Archean, but are far more common, as are the actual salts, in Proterozoic strata (Figure 1; Warren, 2016). Halite or its pseudomorphs characterise areas of widespread marine chemical sedimentation from the Archean to the present. CaSO4 pseudomorph distribution is more enigmatic. In the 1980s and 1990s, the oldest documented CaSO4 pseudomorphs were thought to cm-sized growth-aligned barytes and cherts in 3.45 Ga metasediments in the Pilbara/North Poleregion of Western Australia. They were interpreted as replacing primary bottom-nucleated gypsum (Figure 2; Barley et al., 1979; Lowe, 1983; Buick and Dunlop, 1990). These barytes and cherts occur in volcaniclastics in association with what are possibly the world’s oldest stromatolites (Hofmann et al., 1999; Allwood et al., 2007). Similar growth-aligned baryte crystals, which initially were also interpreted as likely primary gypsum pseudomorphs, occur in the Nondweni greenstones in South Africa, some 3.4 Ga (Wilson and Versfeld, 1994).

 

Sequences in both regions are now completely silicified or barytised. At the time they were first documented, the recognition of what were considered shallow-water Early Archean gypsum pseudomorphs at North Pole, Pilbara Craton, caused a re-evaluation of models of a totally reducing Archean atmosphere (Dimroth and Kimberley, 1975; Clemmey and Badham, 1982). The presence of free sulphate in surface brines of the Archean world was thought to imply an at least locally oxygenated hydrosphere. Gypsum precipitating in Archean ocean waters also meant calcium levels in the ocean waters were in excess of bicarbonate, as is in the modern oceans. The presence of free-standing gypsum on the seafloor is incompatible with any model of the Early Archean ocean as a “soda lake.”

However, in both the Pilbara and the South African sequences there are no actual calcium sulphate evaporites preserved, only growth-aligned crystal textures, now preserved as baryte or chert. Textures in baryte ore from Frasnian sediments in Chaudfontaine, Belgium, are near identical to those observed at North Pole, Australia. The Belgian barytes are primary shallow subsea-bottom precipitates with no precursor mineral phase (Figure 2 inset; Dejonghe, 1990). Some workers in the Pilbara feel that the growth-aligned Archean baryte in this region is also a primary seafloor precipitate, formed in the vicinity of hydrothermal vents (Vearncombe et al., 1995; Nijman et al., 1999; Runnegar et al., 2001). As such, it is not secondary after gypsum. A similar hydrothermal discharge model has been developed for aligned barytes in the Barberton Greenstone belt (de Ronde et al., 1994, 1996). 

Based on this more recent analysis, levels of Archean sulphate in the world ocean were probably less than a few percent of the current levels and probably remained so until the evolution of a widespread oxygen-producing biota into the Proterozoic (Figures 3, 4; Habicht and Canfield, 1996; Kah et al., 2004). Barium sulphate is highly insoluble in modern oxygenated seawater. To carry large volumes of barium or sulphur (as sulphide) in seawater solution to the precipitation site required anoxic conditions. If the aligned baryte crystals are primary, their formation still requires sulphate to be locally present on the seafloor, at least in the vicinity of the depositional site. A possible source for local sulphate production in the shallow waters that characterised the North Pole site was shortwave ultraviolet photoxidation of volcanic SO2, indicating an inorganic association (Runnegar et al., 2001). Within barytes in the same 3.47-Ga-old barytes there are microscopic sulphides. These sulphide inclusions show a d34S of 11.6‰, possibly indicating microbial sulphate reduction with H2 as electron donor in what was an anoxic seafloor (Canfield et al. 2004; Shen et al., 2009).

According to Nijman et al. (1999) the occurrence of the North Pole baryte in sedimentary mounds atop growth faults meant sulphate was locally derived via boiling of escaping hydrothermal vent waters enriched in Ba, Si and sulphide. As these hydrothermal waters vented beneath marine water columns perhaps 50 metres deep, they boiled or violently degassed. Consequent mixing with normally stratified seawater, caused instantaneous oxidization of sulphide into sulphate that then, on cooling, combined with the Ba to precipitate as growth-aligned baryte crystals on the seafloor. Conflicting notions (replaced gypsum versus primary baryte) mean that at this stage of our understanding, the bedded baryte evidence cannot be reliably used to support an evaporite paragenesis of gypsum and so infer an Archean ocean with ionic proportions similar to those of today.

Archean and Proterozoic distributions of gypsum have been further complicated by the misidentification of primary aragonite splays and pinolitic siderite marbles as gypsum replacements (Warren 2016; Chapter 15). When these misidentifications are removed from the record it is obvious that calcium sulphate precipitating directly from Archean seawater to form widespread beds did not occur, and that precipitation of aragonite as thick crusts on the sea floor was significantly more abundant than during any subsequent time in earth h istory. In contrast to gypsum, halite pseudomorphs are found throughout the Precambrian (Figure 1;e.g. Boulter and Glover, 1986). 

Grotzinger and Kasting (1993) argue that high levels of atmospheric CO2 meant HCO3/Ca ratios were much higher in the Archean and the Palaeoproterozoic oceans than today. All the calcium in seawater was deposited as marine cementstones and other alkaline earth precipitates well before bicarbonate was depleted and there was no Ca left over to precipitate as gypsum. The early Archean ocean was perhaps a Na–Cl–HCO3 sea, and not the Na–Cl ocean of today (Kempe and Degens, 1985; Maisonneuve, 1982). This early Archean hydrosphere had a chemistry similar to that found in modern soda lakes like Lake Magadi and Lake Natron (pathway I brines) and hence the term “soda-lake oceans” (see Figure 1 in part 1) This rather different marine brine chemistry would have precipitated halite and trona/nahcolite, not halite/gypsum. It probably meant that if gypsum did ever precipitate from Archean seawater it did so only in minor amounts well after the onset of halite precipitation. Excessive sodium in the ocean may help explain the ubiquity of stratiform albitites in much of the Archean. They would have formed throughout the marine realm as early diagenetic replacements of labile volcaniclastics/zeolites in volcanogenic/greenstone terranes).

A case for nahcolite (NaHCO3) as a primary evaporite, along with halite, in the 3.42 Ga rocks of the Barberton greenstone belt was documented by Lowe and Fisher-Worrell (1999). Sugitani et al. (2003) reported silicified nahcolite (the high CO2 form of sodium carbonate salts) in ≈3.2 Ga rocks in the northern part of the Eastern Pilbara block, Western Australia. Coarse, upward-radiating, silicified evaporite crystals in the ca. 3.47–3.46 Ga Strelley Pool Chert (Lowe, 1983) show the same habit, geometry, and environmental setting as nahcolite in the Barberton belt and also probably represent silicified NaHCO3 precipitates (Lowe and Tice, 2004).


Marine nahcolite in the 3.5-3.2 Ga sedimentary record is thought to be evidence of surface temperatures around 70±15°C (Figures 3b, c, 4; Lowe and Tice, 2004). Contemporary early Archean nahcolite (NaHCO3) as a primary evaporitic mineral in a very aggressive weathering regime, in the absence of land vegetation, is best explained by a mixed CH4 and CO2 atmospheric greenhouse. CH4/CO2 ratios were <<1 and pCO2 was at least 100-1000 times the present value, perhaps as high as several bars (Kaufman and Xiao, 2003). The formation of large areas of continental crust at 3.2-3.0 Ga, including the Kaapvaal and Pilbara cratons, resulted in the gradual depletion of atmospheric CO2 through weathering and a lack of marine nahcolite since the early Archean. By 2.9-2.7 Ga, declining pCO2 was associated with climatic cooling and siderite-free soils. 

Transitory CH4/CO2 ratios of ~1 may have resulted in the sporadic formation of organic haze from atmospheric CH4, and are reflected in one or more isotopic excursions involving global deposition of abnormally 13C-depleted organic carbon in sediments of this age. Surface temperatures of <60°C after 2.9 Ga may have allowed an increase in the distribution and productivity of oxygenic photosynthetic microbes (and a decrease in sulphur dependent thermophiles). Eventual lowering of newly formed continental blocks by erosion, reduced loss of atmospheric CO2 due to weathering, and continued long-term tectonic recycling of CO2 resulted in rising pCO2 and decreasing CH4/CO2 ratios in the later Archean and eventual re-establishment of a mainly CO2 greenhouse. Similar events may have been repeated in the latest Archean and earliest Proterozoic, but gradually rising production of O2 effectively kept CH4/CO2 ratios to <<1.

 

By 2.2-2.0 Ga and perhaps as early as 2.5 Ga, reliable examples of pseudomorphs after primary marine-sourced calcium sulphate first appear in the rock record, but aside from the Karelian beds associated with the Lomagundi Event (LE), widespread stratiform sulphate beds of anhydrite do not appear until 1.2 Ga (Figure 5a). Undeniable CaSO4 nodular and lenticular pseudomorphs are widespread in latest NeoArchean of South Africa and Palaeoproterozoic to Mesoproterozoic sediments of the McArthur Basin, Northern Territory, Australia, and in rocks of Great Slave Lake in northern Canada. For example, in the Malapunyah Formation (1.65 Ga) of the Northern Territory, Australia, the outer portions of numerous decimetre to metre-diameter silicified anhydrite nodules still retain outlines of felted anhydrite laths (pers. obs). The oldest reliable sulphate pseudomorphs after anhydrite and gypsum in Australia come from Palaeoproterozoic cherts in the 2.0-2.2 Ga Bartle Member of the Killara Formation, western Australia (Pirajno and Grey, 2002). These cherts locally retain small amounts of anhydrite (verified by XRD, as well as appearing as highly birefringent flecks in thin sections). Other widespread but younger sulphate pseudomorphs occur in the 1.2 Ga Amundsen Basin in the Canadian Arctic Archipelago. Actual CaSO4 beds outcrop in the 1.2 Ga Society Cliff Formation in Baffin and Bylot Islands of the Canadian Archipelago (Kah et al., 2001, 2004). Sulphate evaporite pseudomophs and nodules in all these Neoproterozoic basins are hosted in sedimentary layers up to tens of metres thick and with lateral extents measured in hundreds of square kilometres. All were laid down in shallow marine, coastal, and alluvial environments under an increasingly oxygenated Meso- to Neoproterozoic atmosphere (Jackson et al., 1987; Walker et al., 1977). After passing from the Archean, by the Mesoproterozoic the hydrosphere contained free sulphate and Ca/HCO3 ratios were lower, leading to a decrease in molar-tooth, herringbone and other carbonate textures indicative of widespread inorganic calcium carbonate saturation in shallow oceanic waters (Figure 6). However, oceanic mother brines for these now-widespread calcium-sulphate evaporites were largely H2S rich with only moderate levels of oxygen in the atmosphere until some 800 Ma (Figure 3a).

The work of Kah et al. (2004) shows that prior to 2.2 Ga, when oxygen began to accumulate in the Earth’s atmosphere, sulphate concentrations in the world’s oceans were low, <1 mM and possibly <200 μM (Figure 5). By 0.8 Ga, oxygen and thus sulphate levels had risen significantly. Sulphate levels were between 1.5 and 4.5 mM, or 5–15% of modern values, for more than a billion years after initial oxygenation of the Earth’s biosphere some 2.2-2.4 Ga and mid -ocean depth waters were anoxic for most of that time (Brocks et al., 2005). Marine sulphate concentrations probably remained low, no more than 35% of modern values, for nearly the entire Proterozoic. A significant rise in biospheric oxygen, and thus oceanic sulphate, may not have occurred until the latest Neoproterozoic (0.54 Ga), just before the Cambrian explosion, when sulphate levels may have reached 20.5 mM, or 75% of present day levels. This is a time when thick sulphate platforms first characterised the salt basins of Oman, prior to that most actual calcium sulphate is in the form of nodules or relatively thin beds.

In a refinement of the sulphate model, Bekker and Holland (2012) note that free sulphate bottom-nucleated sulphate evaporites and not just pseudomorphs were present during the Lomagundi Event (2.22 to 2.06 Ga), and then became relatively scarce once more until some 1.2 Ga. For example, there is a 200 m thick stratigraphic interval of sulphate evaporites of Lomagundi-age, preserved in a shallow-water open-marine siliciclastic and carbonate succession (Lower Jatuli informal group) of Karelia, Russia (Morozov et al., 2010). The Lomagundi Event defines the most extreme and longest lasting isotope excursion of carbon in the world’s marine carbonate record. Bedded gypsum pseudomorphs in the Malmani Group some 2.5 Ga (Gandin and Wright, 2007; Eriksson and Warren, 1983) implies that elevated oceanic sulphate levels that typify the Lomagundi Event may have extended a little further back in time, at least locally (Figure 5).

At the same time as the Lomagundi event, the average ferric iron to total iron (expressed as Fe2O3/Fe|Fe2O3|) ratio of shales increased dramatically. At the end of the Lomagundi Event (LE), the first economic sedimentary phosphorites were deposited, and the carbon isotope values of marine carbonates returned to ≈0.0‰VPDB (Figure 2.50). Thereafter marine sulphate evaporites and phosphorites again became scarce, while the average Fe2O3/Fe|Fe2O3| ratio of shales decreased to values intermediate between those of the Archean and Lomagundi-age shales.

In support of this notion of an “oxygen overshoot,” sulphur isotope work by Reuschel et al. (2012) on the 2.1 Ga dolomitic Tulomozero Fm, which entrains abundant CaSO4 pseudomorphs, concluded that there was a minimum level of 2.5 mM sulphate in the world ocean at that time (Figure 5).

Bekker and Holland (2012) argue the short appearance of sulphate evaporites in Logamundi and the other associated events can be regarded as a ca. 200 Ma “glitch” in the gradual oxidation of the atmosphere–ocean system. It was driven by a positive feedback between the rise in atmospheric O2, the oxidation of pyrite in rocks undergoing weathering, a decrease in the pH of soil and ground water, and an increase in the phosphate flux to the oceans. This sequence led to a major increase in the rate of organic matter burial, a rise in atmospheric oxygen, a large increase in the 13C value for marine carbonates, the deposition of marine evaporites containing gypsum and anhydrite, and the formation of the first commercially important phosphorites. The end of the LE was probably brought about by the weathering of sediments deposited during the LE.

In yet another proposal of hydrosphere-atmosphere evolution, Huston and Logan (2004) argue that the presence of relatively abundant bedded sulphate deposits before 3.2 Ga (as the contentious Archean barytes and chert mentioned earlier) and after 1.8 Ga (as CaSO4 salts), and the peak in banded iron formation abundance between 3.2 and 1.8 Ga, and the aqueous geochemistry of sulphur and iron, when taken together suggest that the redox state and the abundances of sulphur and iron in the hydrosphere varied widely during the Archean and Proterozoic. They propose a layered hydrosphere prior to 3.2 Ga in which sulphate was enriched in an upper oceanic layer, whereas the underlying layer was reduced and sulphur-poor. The sulphate was produced by atmospheric photolytic reactions with volcanic gases in a reducing atmosphere. Mixing of the upper and lower water masses allowed the banded barytes to form prior to 3.2 Ga and created an ocean chemistry where nahcolite was a marine evaporite. Between 3.2 and 2.4 Ga, decreasing volcanogenesis and sulphate reduction removed sulphate from the upper layer, producing broadly uniform, reduced, sulphur-poor and iron-rich oceans.

Whatever the origin of the early Archean baryte and chert, around 2.2 - 2.4 Ga, as a result of increasing atmospheric oxygenation, the flux of sulphate into the hydrosphere by oxidative weathering was greatly enhanced, producing layered oceans, with sulphate-enriched, iron-poor surface waters and reduced, sulphur-poor and iron-rich bottom waters. Gypsum evaporites were increasingly likely as marine precipitates. The rate at which this process proceeded varied between basins depending on the size and local environment of the basin. By 1.8 Ga, the hydrosphere was relatively sulphate-rich and iron-poor throughout. Gypsum was now a widespread marine evaporite. Variations in sulphur and iron abundances suggest that the redox state of the oceans was buffered by iron before 2.4 Ga and by sulphur after 1.6 to 1.8 Ga (Figure 1).

Gypsum in combination with halite was the marine evaporite association from then until now. Seawater was predominantly a Na-Cl±SO4 ocean. Neoproterozoic stratiform sulphates along with widespread halokinetic halite, occur in the Bitter Springs Formation of the Amadeus basin, central Australia (0.8 Ga), its equivalents in the Officer Basin, the Callana beds of the Flinders Ranges and the younger Infracambrian salt basins of the Arabian (Persian) Gulf (≈0.545 Ga; Wells, 1980; Cooper, 1991; Mattes and Conway-Morris, 1990; Edgell, 1991).


The transition to calcium sulphate textures in evaporite pseudomorphs mirrors a marked change in the style of marine carbonates that began around 2.2 to 2.3 Ga when herringbone calcite and precipitated carbonate beds become much less common and the precipitation mode shifted from the seafloor to the water column (Figure 6; Sumner and Grotzinger, 1996, 2000). The boundary also corresponds to the “rusting” of the oceans when oxygen levels became high enough to precipitate widespread banded iron deposits on the seafloor. Microdigitate stromatolites cross this boundary with little effect, suggesting the marked decrease in dissolved iron exerted little influence on them.

The relative scarcity of actual Pre-Phanerozoic salts, not pseudomorphs, especially in the Archean has been used by some to argue that conditions were less favourable for widespread evaporite deposition in the early Precambrian (Cloud, 1972). Others, myself included, feel that the relative scarcity of preserved evaporites in older sequences reflects the greater likelihood of fluid flushing, evaporite dissolution and metasomatism in progressively older rocks. It is likely that oceanic calcium-sulphate evaporites were less common in the Archean, and that sodium carbonates mixed with halite were dominant evaporite salts in the seawater-fed saline giants in appropriate tectonic seepage depressions of the Early Archean. But widespread evaporite deposition from sodium-dominated brines did occur throughout the Archean in large drawdown basins isolated from a surface connection with the ocean. A paucity of preserved bedded evaporite salts in the Precambrian reflects an increased probability of partial or complete evaporite dissolution, remobilization and metasomatism with increasing geological age (see meta-evaporite).

In what is an inclusion study of oldest actual halite, Spear et al., (2014) characterised marine brine chemistry using brine inclusions in the 830 Ma salt of the Browne Formation, Officer Basin, Australia (equiv. to Bitter Springs Fm.). It seems that concentrations of the major ions in these inclusions, except K+ and possibly SO42−, fall within the known range of Phanerozoic seawaters. This ananlysis suggests that mid-Neoproterozoic marine sulphate concentrations were lower (≈90%) than modern values. By the terminal Neoproterozoic, fluid inclusions in halite and evaporite mineralogy from the Khewra Salt of Pakistan and the Ara salt in Oman indicate seawater sulphate levels had risen significantly, to 50%-80% of modern concentrations, which parallels increases in atmospheric and oceanic oxygen.

References

Allwood, A. C., M. R. Walter, I. W. Burch, and B. S. Kamber, 2007, 3.43 billion-year-old stromatolite reef from the Pilbara Craton of Western Australia: Ecosystem-scale insights to early life on Earth: Precambrian Research, v. 158, p. 198-227.

Barley, M. E., J. S. R. Dunlop, J. E. Glover, and D. I. Groves, 1979, Sedimentary evidence for an Archaean shallow-water volcanic-sedimentary facies, eastern Pilbara Block, Western Australia: Earth and Planetary Science Letters, v. 43, p. 74-84.

Bekker, A., and H. D. Holland, 2012, Oxygen overshoot and recovery during the early Paleoproterozoic: Earth and Planetary Science Letters, v. 317-318, p. 295-304.

Bekker, A., and H. D. Holland, 2012, Oxygen overshoot and recovery during the early Paleoproterozoic: Earth and Planetary Science Letters, v. 317-318, p. 295-304.

Boulter, C. A., and J. E. Glover, 1986, Chert with relict hopper moulds from Rocklea Dome, Pilbara Craton, Western Australia; an Archean halite-bearing evaporite: Geology, v. 14, p. 128-131.

Brocks, J. J., G. D. Love, R. E. Summons, A. H. Knoll, G. A. Logan, and S. A. Bowden, 2005, Biomarker evidence for green and purple sulphur bacteria in a stratified Palaeoproterozoic sea: Nature, v. 437, p. 866-870.

Buick, R., 1992, The antiquity of oxygenic photosynthesis; evidence from stromatolites in sulphate-deficient Archaean lakes: Science, v. 255, p. 74-77.

Buick, R., and J. S. R. Dunlop, 1990, Evaporitic sediments of early Archaean age from the Warrawoona Group, North Pole, Western Australia: Sedimentology, v. 37, p. 247-277.

Canfield, D. E., K. B. Sørensen, and A. Oren, 2004, Biogeochemistry of a gypsum-encrusted microbial ecosystem: Geobiology, v. 2, p. 133-150.

Channer, D. M. D., C. E. J. de Ronde, and E. T. C. Spooner, 1997, The Cl-Br-I composition of ≈ 3.23 Ga modified seawater: Implications for the geological evolution of ocean halide chemistry: Earth and Planetary Science Letters, v. 150, p. 325-335.

Clemmey, H., and N. Badham, 1982, Oxygen in the Precambrian atmosphere; an evaluation of the geological evidence: Geology, v. 10, p. 141-146.

Cloud, P. E., 1972, A working model of the primitive earth: Am. J. Sci., v. 272, p. 537-548.

Cooper, A. M., 1991, Late Proterozoic hydrocarbon potential and its association with diapirism in Blinman #2, Central Flinders Ranges.: Honours thesis, University of Adelaide - National Centre Petroleum Geology and Geophysics.

De Ronde, C. E. J., M. J. Dewit, and E. T. C. Spooner, 1994, Early Archean (>3.2 Ga) Fe-oxide rich, hydrothermal discharge vents in the Barberton Greenstone belt, South Africa: Geological Society of America Bulletin, v. 106, p. 86-104.

de Ronde, C. E. J., and T. W. Ebbesen, 1996, 3.3 BY age of organic compound formation near sea-floor hot springs: Geology, v. 24, p. 791-794.

Dejonghe, L., 1990, The sedimentary structures of barite: examples from the Chaudfontaine ore deposit, Belgium: Sedimentology, v. 37, p. 303-323.

Dimroth, E., and M. M. Kimberley, 1975, Precambrian atmospheric oxygen; evidence in the sedimentary distributions of carbon, sulfur, uranium, and iron: Canadian Journal of Earth Sciences, v. 13, p. 1161-1185.

Edgell, H. S., 1991, Proterozoic salt basins of the Persian Gulf area and their role in hydrocarbon generation: Precambrian Research, v. 54, p. 1-14.

Eriksson, K. A., E. L. Simpson, S. Master, and G. Henry, 2005, Neoarchaean (c.2.58 Ga) halite casts: implications for palaeoceanic chemistry: Journal Of The Geological Society, v. 162, p. 789-799.

Eriksson, K. A., and J. K. Warren, 1983, A paleohydrologic model for Early Proterozoic dolomitization and silicification: Precambrian Research, v. 21, p. 299-321.

Gandin, A., and D. T. Wright, 2007, Evidence of vanished evaporites in Neoarchaean carbonates of South Africa: Geological Society, London, Special Publications, v. 285, p. 285-308.

Gandin, A., and D. T. Wright, 2007, Evidence of vanished evaporites in Neoarchaean carbonates of South Africa: Geological Society, London, Special Publications, v. 285, p. 285-308.

Grotzinger, J. P., 1986a, Cyclicity and paleoenvironmental dynamics, Rocknest Platform, northwest Canada: Geol. Soc. America Bull., v. 97, p. 1208-1231.

Grotzinger, J. P., 1986b, Shallowing upward cycles of the Wallace Formation, Belt Supergroup, northwestern Montana and northern Idaho: Montana Bureau of Mines Geol. Spec. Pub., v. 94, p. 143-160.

Grotzinger, J. P., and J. F. Kasting, 1993, New constraints on Precambrian ocean composition: Journal of Geology, v. 101, p. 235-243.

Habicht, K. S., and D. E. Canfield, 1996, Sulphur isotope fractionation in modern microbial mats and the evolution of the sulphur cycle: Nature, v. 382, p. 342-343.

Hofmann, H. J., K. Grey, A. H. Hickman, and R. I. Thorpe, 1999, Origin of 3.45 Ga coniform stromatolites in Warrawoona Group, Western Australia: Bulletin Geological Society of America, v. 111, p. 1256-1262.

Huston, D. L., and G. A. Logan, 2004, Barite, BIFs and bugs: evidence for the evolution of the Earth’s early hydrosphere: Earth and Planetary Science Letters, v. 220, p. 41-45.

Jackson, M. J., M. D. Muir, and K. A. Plumb, 1987, Geology of the southern McArthur Basin: BMR Bulletin, v. 220, Bureau Mineral Resources, Canberra, Australia, 173 p.

Kah, L. C., T. W. Lyons, and J. T. Chesley, 2001, Geochemistry of a 1.2 Ga carbonate-evaporite succession, northern Baffin and Bylot Islands: implications for Mesoproterozoic marine evolution: Precambrian Research, v. 111, p. 203-234.

Kah, L. C., T. W. Lyons, and T. D. Frank, 2004, Low marine sulphate and protracted oxygenation of the Proterozoic biosphere: Nature, v. 431, p. 834-838.

Kaufman, A. J., and S. Xiao, 2003, High CO2 levels in the Proterozoic atmosphere estimated from analyses of individual microfossils: Nature, v. 425, p. 279-282.

Kempe, S., and E. T. Degens, 1985, An early soda ocean?: Chemical Geology, v. 53, p. 95-108.

Knauth, L. P., 1998, Salinity history of the Earth's early ocean: Nature, v. 395, p. 554-555.

Kovalevych, V. M., T. Marshall, T. M. Peryt, O. Y. Petrychenko, and S. A. Zhukova, 2006, Chemical composition of seawater in Neoproterozoic: Results of fluid inclusion study of halite from Salt Range (Pakistan) and Amadeus Basin (Australia): Precambrian Research, v. 144, p. 39-51.

Krupp, R., T. Oberthür, and W. Hirdes, 1994, The early Precambrian atmosphere and hydrosphere: Thermodynamic constraints from mineral deposits: Economic Geology, v. 89, p. 1581-1598.

Lindsay, J. F., 1987, Upper Proterozoic evaporites in the Amadeus Basin, central Australia, and their role in basin tectonics: Geological Society of America Bulletin, v. 99, p. 852-865.

Lowe, D. R., 1983, Restricted shallow-water sedimentation of early Archean stromatolitic and evaporitic strata of the Strelley Pool Chert, Pilbara Block, Western Australia: Precambrian Research, v. 19, p. 239-283.

Lowe, D. R., and G. Fisher-Worrell, 1999, Sedimentology, mineralogy, and implications of silicified evaporites in the Kromberg Formation, Barberton Greenstone Belt, South Africa, in D. R. Lowe, and G. R. Byerly, eds., Geologic evolution of the Barberton Greenstone Belt, South Africa, Geological Society of America Special Paper, v. 329, p. 167-188.

Lowe, D. R., and M. M. Tice, 2004, Geologic evidence for Archean atmospheric and climatic evolution: Fluctuating levels of CO2, CH4, and O2 with an overriding tectonic control: Geology, v. 32, p. 493-496.

Maisonneuve, J., 1982, The composition of the Precambrian ocean waters: Sedimentary Geology, v. 31, p. 1-11.

Mattes, B. W., and S. Conway-Morris, 1990, Carbonate/evaporite deposition in the Late Precambrian-Early Cambrian Ara Formation of southern Oman, in A. H. F. Robertson, M. P. Searle, and A. C. Ries, eds., The geology and tectonics of the Oman region, v. 49, Geological Society Special Publications, p. 617-636.

Melezhik, V. A., A. E. Fallick, D. V. Rychanchik, and A. B. Kuznetsov, 2005, Palaeoproterozoic evaporites in Fennoscandia: implications for seawater sulphate, the rise of atmospheric oxygen and local amplification of the delta C-13 excursion: Terra Nova, v. 17, p. 141-148.

Morozov, A. F., B. N. Khakhaev, O. V. Petrov, V. I. Gorbachev, G. V. Tarkhanov, L. D. Tsvetkov, Y. M. Erinchek, A. M. Akhmedov, V. A. Krupenik, and K. Y. Sveshnikova, 2010, Rock salt mass in the Paleoproterozoic sequence of the Onega trough in Karelia (from the Onega parametric well data): Doklady Earth Sciences, v. 435, p. 1483-1486.

Morse, J. W., and F. Mackenzie, T., 1998, Hadean ocean carbonate geochemistry: Aquatic Geochemistry, v. 4, p. 301-319.

Nijman, W., K. H. de Bruijne, and M. E. Valkering, 1999, Growth fault control of Early Archaean cherts, barite mounds and chert-barite veins, North Pole Dome, Eastern Pilbara, Western Australia: Precambrian Research, v. 95, p. 245-274.

Pirajno, F., and K. Grey, 2002, Chert in the Palaeoproterozoic Bartle Member, Killara Formation, Yerrida Basin, Western Australia: a rift-related playa lake and thermal spring environment?: Precambrian Research, v. 113, p. 169-192.

Reuschel, M., V. A. Melezhik, M. J. Whitehouse, A. Lepland, A. E. Fallick, and H. Strauss, 2012, Isotopic evidence for a sizeable seawater sulfate reservoir at 2.1 Ga: Precambrian Research, v. 192-195, p. 78-88.

Runnegar, B., W. Dollase, R. Ketcham, M. Colbert, and W. Carlson, 2001, Early Archean sulfates from Western Australia first formed as hydrothermal barites, not gypsum evaporites: Geological society of America, Abstracts with Programs, v. 33, p. A-404.

Schroder, S., A. Bekker, N. J. Beukes, H. Strauss, and H. S. van Niekerk, 2008, Rise in seawater sulphate concentration associated with the Paleoproterozoic positive carbon isotope excursion: evidence from sulphate evaporites in the 2.2-2.1 Gyr shallow-marine Lucknow Formation, South Africa: Terra Nova, v. 20, p. 108-117.

Shen, Y., J. Farquhar, A. Masterson, A. J. Kaufman, and R. Buick, 2009, Evaluating the role of microbial sulfate reduction in the early Archean using quadruple isotope systematics: Earth and Planetary Science Letters, v. 279, p. 383-391.

Spear, N., H. D. Holland, J. Garcia-Veígas, T. K. Lowenstein, R. Giegengack, and H. Peters, 2014, Analyses of fluid inclusions in Neoproterozoic marine halite provide oldest measurement of seawater chemistry: Geology, v. 42, p. 103-106.

Stanworth, C. W., and J. P. N. Badham, 1984, Lower Proterozoic red beds, evaporites and secondary sedimentary uranium deposits from the East Arm, Great Slave Lake, Canada: Journal of the Geological Society, v. 141, p. 235-242.

Sugitani, K., K. Mimura, K. Suzuki, K. Nagamine, and R. Sugisaki, 2003, Stratigraphy and sedimentary petrology of an Archean volcanic-sedimentary succession at Mt. Goldsworthy in the Pilbara Block, Western Australia: implications of evaporite (nahcolite) and barite deposition: Precambrian Research, v. 120, p. 55-79.

Sumner, D. Y., and J. P. Grotzinger, 2000, Late Archean Aragonite Precipitation: Petrography, Facies Associations, and Environmental Significance, in J. P. Grotzinger, and N. P. James, eds., Carbonate Sedimentation And Diagenesis In The Evolving Precambrian World, v. 67: Tulsa, SEPM Special Publication, p. 123-144.

Vearncombe, S., M. E. Barley, D. I. Groves, N. J. McNaughton, E. J. Mikucki, and J. R. Vearncombe, 1995, 3.26 Ga black smoker-type mineralization in the Strelley Belt, Pilbara Craton, Western Australia: Journal of the Geological Society of London, v. 152, p. 587-590.

Walker, R. N., M. D. Muir, W. L. Diver, N. Williams, and N. Wilkins, 1977, Evidence of major sulphate evaporite deposits in the Proterozoic McArthur Group, Northern Territory, Australia: Nature, v. 265, p. 526-529.

Warren, J. K., 2016, Evaporites: A compendium (ISBN 978-3-319-13511-3) Released November 2015: Berlin, Springer, 1600 p.

Wells, A. T., 1980, Evaporites in Australia: Australia Bureau of Mineral Resources Geology & Geophysics, Bulletin, v. 198, p. 104.

Wilson, A. H., and J. A. Versfeld, 1994, The early Archaean Nondweni greenstone belt, southern Kaapvaal Craton, South Africa; Part I, Stratigraphy, sedimentology, mineralization and depositional environment: Precambrian Research, v. 67, p. 243-276.

 

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