An Archaean heavy bombardment from a destabilized extension of the asteroid belt

Bottke, W. F.; Vokrouhlický, David; Minton, David A.; Nesvorný, David; Morbidelli, Alessandro; Brasser, R.; Simonson, Bruce M.; Levison, Harold F.

doi:10.1038/nature10967

Cited by 369 publications

(370 citation statements)

References 120 publications

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“…Phosphides are the major P mineral in enstatite chondrites, which have recently been proposed as the source of heavy bombardment impactors (22). Corrosion of the meteoritic phosphide mineral schreibersite likely provided the phosphite detected in the present study, because few other sources of phosphite are known, and none was as widespread and voluminous as meteoritic bombardment early in Earth's history (23).…”

Section: Discussionmentioning

confidence: 65%

Evidence for reactive reduced phosphorus species in the early Archean ocean

Pasek

Harnmeijer

Buick

et al. 2013

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

168

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: Discussionmentioning

confidence: 65%

Evidence for reactive reduced phosphorus species in the early Archean ocean

Pasek

Harnmeijer

Buick

et al. 2013

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

168

170

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“…For instance, Bottke et al (2012) argued that the impactors should have mostly come from the E belt, Appendices are available in electronic form at http://www.aanda.org a hypothesized continuation of the early asteroid main belt to heliocentric distances less than 2 AU. Gomes et al (2005) had found earlier that the main belt itself would have provided roughly half the impactors; the other half coming from the transplanetary, icy planetesimal disk.…”

Section: Introductionmentioning

confidence: 99%

Monte Carlo methods to calculate impact probabilities

Rickman

Wiśniowski

Wajer

et al. 2014

A&A

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Context. Unraveling the events that took place in the solar system during the period known as the late heavy bombardment requires the interpretation of the cratered surfaces of the Moon and terrestrial planets. This, in turn, requires good estimates of the statistical impact probabilities for different source populations of projectiles, a subject that has received relatively little attention, since the works of Öpik (1951, Proc. R. Irish Acad. Sect. A, 54, 165) and Wetherill (1967, J. Geophys. Res., 72, 2429. Aims. We aim to work around the limitations of the Öpik and Wetherill formulae, which are caused by singularities due to zero denominators under special circumstances. Using modern computers, it is possible to make good estimates of impact probabilities by means of Monte Carlo simulations, and in this work, we explore the available options. Methods. We describe three basic methods to derive the average impact probability for a projectile with a given semi-major axis, eccentricity, and inclination with respect to a target planet on an elliptic orbit. One is a numerical averaging of the Wetherill formula; the next is a Monte Carlo super-sizing method using the target's Hill sphere. The third uses extensive minimum orbit intersection distance (MOID) calculations for a Monte Carlo sampling of potentially impacting orbits, along with calculations of the relevant interval for the timing of the encounter allowing collision. Numerical experiments are carried out for an intercomparison of the methods and to scrutinize their behavior near the singularities (zero relative inclination and equal perihelion distances). Results. We find an excellent agreement between all methods in the general case, while there appear large differences in the immediate vicinity of the singularities. With respect to the MOID method, which is the only one that does not involve simplifying assumptions and approximations, the Wetherill averaging impact probability departs by diverging toward infinity, while the Hill sphere method results in a severely underestimated probability. We provide a discussion of the reasons for these differences, and we finally present the results of the MOID method in the form of probability maps for the Earth and Mars on their current orbits. These maps show a relatively flat probability distribution, except for the occurrence of two ridges found at small inclinations and for coinciding projectile/target perihelion distances. Conclusions. Our results verify the standard formulae in the general case, away from the singularities. In fact, severe shortcomings are limited to the immediate vicinity of those extreme orbits. On the other hand, the new Monte Carlo methods can be used without excessive consumption of computer time, and the MOID method avoids the problems associated with the other methods.

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“…One end-member is an intensive LHB model which assumes that most impact basins, including degraded ones, were formed during this short period (e.g., Ryder, 2002). A LHB model with a less intensive mass flux and a broader peak in time has alternatively been proposed based on a dynamical evolution 25 model (e.g., Bottke et al, 2012;Morbidelli et al, 2012). Another hypothesis, which can explain a peak in ages of impact melts without an increase in impact flux, has also been proposed (e.g., Hartmann, 2003); the high rate of early impacts leads to pulverization of early impact melts, and only late impact melts survive.…”

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confidence: 99%

The relative timing of Lunar Magma Ocean solidification and the Late Heavy Bombardment inferred from highly degraded impact basin structures

Kamata

Sugita

Abe

et al. 2015

Icarus

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The solidification of the Lunar Magma Ocean (LMO) and formation of impact basins are important events that took place on the early Moon. The relative timing of these events, however, is poorly constrained. The aim of this study is ing substantial viscous lateral flow in the crust. Recent geodetic measurements reveal that the lunar crust is thinner than previously estimated, indicating that an extremely high crustal temperature is required for lateral flow to occur. In this study, we calculate lunar thermal evolution and viscoelastic deformation of basins and investigate the thermal state at the time of basin formation using recent crustal thickness models. We find that a Moho temperature >1300-1400K at the time of basin formation is required for substantial viscous relaxation of topography to occur; the implied elastic thickness at the time of loading is <30 km. Such a high temperature can be maintained only for a short time (i.e., <50Myr for most conditions) after solidification of the LMO or after mantle overturn if it took place; relaxed impact basins forming ≥150 Myr later than LMO solidification are unlikely. This result is in conflict with an intensive Late Heavy Bombardment (LHB) model, which assumes that most impact basins were formed at ∼3.9 Ga, since it requires LMO solidification time extremely later than previous theoretical estimates. Either the LHB was moderate, or the majority of proposed early PN basins were not in fact formed by impacts.

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An Archaean heavy bombardment from a destabilized extension of the asteroid belt

Cited by 369 publications

References 120 publications

Evidence for reactive reduced phosphorus species in the early Archean ocean

Evidence for reactive reduced phosphorus species in the early Archean ocean

Monte Carlo methods to calculate impact probabilities

The relative timing of Lunar Magma Ocean solidification and the Late Heavy Bombardment inferred from highly degraded impact basin structures

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