Microbial habitability of the Hadean Earth during the late heavy bombardment

Abramov, O.; Mojzsis, Stephen J.

doi:10.1038/nature08015

Cited by 255 publications

(148 citation statements)

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“…If it is assumed that the phosphite to phosphate ratio has been minimally altered since deposition and is representative of the Archean ocean, then the amount of meteoritic material required to provide this quantity of phosphite to the early Earth oceans is about 10 19 -10 20 kg, assuming an ocean volume equivalent to present day and that the average meteorite is composed of 0.1% reduced P in phosphide minerals by weight (8). This quantity is about 1% of the mass of the Earth's crust and is comparable to other estimates of total meteorite fluxes at the time (25)(26)(27). Obviously, if other natural sources of phosphite can be identified, such as widespread production in hydrothermal systems (17), then the total meteoritic mass necessary to provide this phosphite may be reduced.…”

Section: Discussionsupporting

confidence: 62%

Evidence for reactive reduced phosphorus species in the early Archean ocean

Pasek

Harnmeijer

Buick

et al. 2013

Proc. Natl. Acad. Sci. U.S.A.

171

170

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It has been hypothesized that before the emergence of modern DNA-RNA-protein life, biology evolved from an "RNA world." However, synthesizing RNA and other organophosphates under plausible early Earth conditions has proved difficult, with the incorporation of phosphorus (P) causing a particular problem because phosphate, where most environmental P resides, is relatively insoluble and unreactive. Recently, it has been proposed that during the Hadean-Archean heavy bombardment by extraterrestrial impactors, meteorites would have provided reactive P in the form of the iron-nickel phosphide mineral schreibersite. This reacts in water, releasing soluble and reactive reduced P species, such as phosphite, that could then be readily incorporated into prebiotic molecules. Here, we report the occurrence of phosphite in early Archean marine carbonates at levels indicating that this was an abundant dissolved species in the ocean before 3.5 Ga. Additionally, we show that schreibersite readily reacts with an aqueous solution of glycerol to generate phosphite and the membrane biomolecule glycerol-phosphate under mild thermal conditions, with this synthesis using a mineral source of P. Phosphite derived from schreibersite was, hence, a plausible reagent in the prebiotic synthesis of phosphorylated biomolecules and was also present on the early Earth in quantities large enough to have affected the redox state of P in the ocean. Phosphorylated biomolecules like RNA may, thus, have first formed from the reaction of reduced P species with the prebiotic organic milieu on the early Earth.origin of life | prebiotic chemistry | phosphorylation | astrobiology | exobiology P hosphorus (P) is the limiting nutrient in many ecosystems; its scarcity is linked to the insoluble nature of phosphate minerals (1, 2). Phosphorus species may have been important reagents during prebiotic chemical evolution, but their presumed low abundance has presented a problem in understanding the origin of key phosphorylated biomolecules, such as RNA (3, 4). This was recognized early in the study of prebiotic chemistry, and a possible role for more reduced P compounds was suggested because these are more soluble than phosphate (5, 6). However, no potential source of reduced P was known at the time, leaving phosphate as the only available P species under typical geochemical conditions (7).Phosphide minerals such as schreibersite (Fe,Ni) 3 P are ubiquitous minor constituents of meteorites (8) and are potential sources of reduced P (9-12). Schreibersite reacts with water to release P compounds that are reduced relative to the geologically abundant P 5+ phase phosphate PO 4 3− , including P 3+ phosphite HPO 3 2− and P 1+ hypophosphite H 2 PO 2 − (9-14). Both of these compounds are significantly more soluble than phosphate in waters of neutral pH and rich in the divalent cations Ca 2+ and Mg 2+ , such as modern seawater (5). Schreibersite reaction rates indicate complete phosphide dissolution when submerged in water over about 10 y (12), implying rapid reaction with w...

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Section: Discussionsupporting

confidence: 62%

Evidence for reactive reduced phosphorus species in the early Archean ocean

Pasek

Harnmeijer

Buick

et al. 2013

Proc. Natl. Acad. Sci. U.S.A.

171

170

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“…Impacts have been studied in the context of early Venus, Earth, and Mars in terms of their potential to cause heating and modification of the atmosphere and surface (Zahnle et al 1988;Abramov & Mojzsis 2009;Segura et al 2008). Delivery of volatiles by impactors during the late stages of planet formation is also of course a major determinant of a planet's final water inventory, as we discussed in the Introduction.…”

Section: Water Loss Due To Impactsmentioning

confidence: 99%

WATER LOSS FROM TERRESTRIAL PLANETS WITH CO₂-RICH ATMOSPHERES

Wordsworth

Pierrehumbert

2013

ApJ

199

169

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Water photolysis and hydrogen loss from the upper atmospheres of terrestrial planets is of fundamental importance to climate evolution but remains poorly understood in general. Here we present a range of calculations we performed to study the dependence of water loss rates from terrestrial planets on a range of atmospheric and external parameters. We show that CO 2 can only cause significant water loss by increasing surface temperatures over a narrow range of conditions, with cooling of the middle and upper atmosphere acting as a bottleneck on escape in other circumstances. Around G-stars, efficient loss only occurs on planets with intermediate CO 2 atmospheric partial pressures (0.1-1 bar) that receive a net flux close to the critical runaway greenhouse limit. Because G-star total luminosity increases with time but X-ray and ultraviolet/ultravoilet luminosity decreases, this places strong limits on water loss for planets like Earth. In contrast, for a CO 2 -rich early Venus, diffusion limits on water loss are only important if clouds caused strong cooling, implying that scenarios where the planet never had surface liquid water are indeed plausible. Around M-stars, water loss is primarily a function of orbital distance, with planets that absorb less flux than ∼270 W m −2 (global mean) unlikely to lose more than one Earth ocean of H 2 O over their lifetimes unless they lose all their atmospheric N 2 /CO 2 early on. Because of the variability of H 2 O delivery during accretion, our results suggest that many "Earth-like" exoplanets in the habitable zone may have ocean-covered surfaces, stable CO 2 /H 2 O-rich atmospheres, and high mean surface temperatures.

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“…Our geochemical studies are insufficient to select between these two environments but both are likely processes associated with impacts. For example, Abramov and Mojzsis (28) calculated that the LHB bombardment episode would have resurfaced about a quarter of the Earth. Wielicki et al (56) developed a model to assess the temperature distribution of zircons grown from impact melts during a bombardment episode of the inferred scale of the LHB.…”

Section: Discussionmentioning

confidence: 99%

“…The ultimate goal is to obtain sufficient data to reconstruct a T-t path for each zircon's growth and compare results with LHB thermal models (28).…”

mentioning

confidence: 99%

A search for thermal excursions from ancient extraterrestrial impacts using Hadean zircon Ti-U-Th-Pb depth profiles

Abbott

Harrison

Schmitt

et al. 2012

Proc. Natl. Acad. Sci. U.S.A.

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Few terrestrial localities preserve more than a trace lithic record prior to ca. 3.8 Ga greatly limiting our understanding of the first 700 Ma of Earth history, a period inferred to have included a spike in the bolide flux to the inner solar system at ca. 3.85-3.95 Ga (the Late Heavy Bombardment, LHB). An accessible record of this era may be found in Hadean detrital zircons from the Jack Hills, Western Australia, in the form of μm-scale epitaxial overgrowths. By comparing crystallization temperatures of pre-3.8 Ga zircon overgrowths to the archive of zircon temperature spectra, it should, in principle, be possible to identify a distinctive impact signature. We have developed Ti-U-Th-Pb ion microprobe depth profiling to obtain age and temperature information within these zircon overgrowths and undertaken a feasibility study of its possible use in identifying impact events. Of eight grains profiled in this fashion, four have overgrowths of LHB-era age. Age vs. temperature profiles reveal a period between ca. 3.85-3.95 Ga (i.e., LHB era) characterized by significantly higher temperatures (approximately 840-875°C) than do older or younger zircons or zircon domains (approximately 630-750°C). However, temperatures approaching 900°C can result in Pb isotopic exchange rendering interpretation of these profiles nonunique. Coupled age-temperature depth profiling shows promise in this role, and the preliminary data we report could represent the first terrestrial evidence for impactrelated heating during the LHB.early Earth | impact crater | lunar cataclysm | secondary ion mass spectrometry T he LHB is the period from ca. 3.85-3.95 Ga during which an intense flux of asteroidal and/or cometary bodies is hypothesized to have impacted the Moon (1). A variety of theories have been proposed to explain the LHB (2-5) culminating with the "Nice model" (5-7). This model posits that a fundamental shift in orbital resonance among the Jovian planets at ca. 3.9 Ga destabilized the disk of planetesimals in the outer solar system resulting in the scattering of numerous bodies into the inner solar system. Tera et al. (1) introduced the concept of a late lunar cataclysm to explain isotopic fractionations in rocks returned from the heavily cratered lunar highlands. Specifically, U-Pb, and Rb-Sr isochrons yielded recrystallization ages between 3.85-3.95 Ga. The parent/daughter behavior in these two geochronologic systems are quite different but result in similar system disturbances (i.e., U and Sr are highly refractory whereas Pb and Rb are variably volatile). Thus, a profound thermal event, such as from an impact at the appropriate scale of a "cataclysm," could have caused resetting of both chronometers, albeit for different reasons. Much of the evidence in support of the LHB hypothesis comes from 40 Ar∕ 39 Ar age spectra of lunar highland crust samples (3,8,9), interpreted to yield apparent "plateau" ages between 3.8-4.0 Ga due to the resetting of the K-Ar system via collisional heating (see review in 10).

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Microbial habitability of the Hadean Earth during the late heavy bombardment

Cited by 255 publications

References 28 publications

Evidence for reactive reduced phosphorus species in the early Archean ocean

Evidence for reactive reduced phosphorus species in the early Archean ocean

WATER LOSS FROM TERRESTRIAL PLANETS WITH CO₂-RICH ATMOSPHERES

A search for thermal excursions from ancient extraterrestrial impacts using Hadean zircon Ti-U-Th-Pb depth profiles

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Microbial habitability of the Hadean Earth during the late heavy bombardment

Cited by 255 publications

References 28 publications

Evidence for reactive reduced phosphorus species in the early Archean ocean

Evidence for reactive reduced phosphorus species in the early Archean ocean

WATER LOSS FROM TERRESTRIAL PLANETS WITH CO2-RICH ATMOSPHERES

A search for thermal excursions from ancient extraterrestrial impacts using Hadean zircon Ti-U-Th-Pb depth profiles

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WATER LOSS FROM TERRESTRIAL PLANETS WITH CO₂-RICH ATMOSPHERES