Why aqueous alteration in asteroids was isochemical: High porosity ≠ high permeability

Bland, P. A.; Jackson, Matthew D.; Coker, R. F.; Cohen, B. A.; Webber, J. Beau W.; Lee, Martin; Duffy, Christina M.; Chater, Richard J.; Ardakani, M.G.; McPhail, David S.; McComb, David W.; Benedix, Gretchen

doi:10.1016/j.epsl.2009.09.004

Cited by 133 publications

(147 citation statements)

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“…40). The estimated low permeability of chondritic meteorites 41 and the lack of variations in bulk chemical compositions between meteorites with different degrees of aqueous alteration 1,2,42 imply that the alteration occurred in a chemically closed system, with the fluid flow being restricted to 10-100 mm, which is consistent with rare occurrences of short veins in aqueously altered chondrites (Fig. 1d).…”

Section: Discussionsupporting

confidence: 63%

Early aqueous activity on the ordinary and carbonaceous chondrite parent bodies recorded by fayalite

et al. 2015

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Chronology of aqueous activity on chondrite parent bodies constrains their accretion times and thermal histories. Radiometric 53 Cr dating has been successfully applied to aqueously formed carbonates in CM carbonaceous chondrites. Owing to the absence of carbonates in ordinary (H, L and LL), and CV and CO carbonaceous chondrites, and the lack of proper standards, there are no reliable ages of aqueous activity on their parent bodies. Here we report the first 53 Mn-53 Cr ages of aqueously formed fayalite in the L3 chondrite Elephant Moraine 90161 as 2:4 þ 1:8 À 1:3 Myr after calcium-aluminium-rich inclusions (CAIs), the oldest Solar System solids. In addition, measurements using our synthesized fayalite standard show that fayalite in the CV3 chondrite Asuka 881317 and CO3-like chondrite MacAlpine Hills 88107 formed 4:2 þ 0:8 À 0:7 and 5:1 þ 0:5 À 0:4 Myr after CAIs, respectively. Thermal modelling, combined with the inferred conditions (temperature and water/rock ratio) and 53 Cr ages of aqueous alteration, suggests accretion of the L, CV and CO parent bodies B1.8 À 2.5 Myr after CAIs.

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Section: Discussionsupporting

confidence: 63%

Early aqueous activity on the ordinary and carbonaceous chondrite parent bodies recorded by fayalite

et al. 2015

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“…Chondritic IDPs and meteorites are porous [61][62][63]. With the exception of the nucleobases potentially formed due to surface photochemistry [12], any soluble nucleobases delivered to the prebiotic Earth by carbonaceous IDPs and meteorites would have layed frozen in the pores of these sources upon them entering the atmosphere.…”

Section: Nucleobase Outflow and Mixingmentioning

confidence: 99%

“…Therefore given that nucleobases are < 1 nm in diameter and the bulk of pore diameters in, for example, the Acfer 094 carbonaceous chondrite, range from 20-200 nm [63], we can neglect δ from the listed models.…”

Section: Appendix A: Advection and Diffusion Modelmentioning

confidence: 99%

Origin of the RNA world: The fate of nucleobases in warm little ponds

Pearce

Pudritz

Semenov

et al. 2017

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

176

222

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Prior to the origin of simple cellular life, the building blocks of RNA (nucleotides) had to form and polymerize in favourable environments on the early Earth. At this time, meteorites and interplanetary dust particles delivered organics such as nucleobases (the characteristic molecules of nucleotides) to warm little ponds whose wet-dry cycles promoted rapid polymerization. We build a comprehensive numerical model for the evolution of nucleobases in warm little ponds leading to the emergence of the first nucleotides and RNA. We couple Earth's early evolution with complex prebiotic chemistry in these environments. We find that RNA polymers must have emerged very quickly after the deposition of meteorites (< a few years). Their constituent nucleobases were primarily meteoritic in origin and not from interplanetary dust particles. Ponds appeared as continents rose out of the early global ocean but this increasing availability of "targets" for meteorites was offset by declining meteorite bombardment rates. Moreover, the rapid losses of nucleobases to pond seepage during wet periods, and to UV photodissociation during dry periods means that the synthesis of nucleotides and their polymerization into RNA occurred in just one to a few wet-dry cycles. Under these conditions, RNA polymers likely appeared prior to 4.17 billion years ago.Significance: There are currently two competing hypotheses for the site at which an RNA world emerged: hydrothermal vents in the deep ocean and warm little ponds. Because the former lacks wet and dry cycles, which are well known to promote polymerization (in this case, of nucleotides into RNA), we construct a comprehensive model for the origin of RNA in the latter sites. Our model advances the story and timeline of the RNA world by constraining the source of biomolecules, the environmental conditions, the timescales of reaction, and the emergence of first RNA polymers.Keywords: life origins | astrobiology | planetary science | meteoritics | RNA worldOne of the most fundamental questions in science is how life first emerged on the Earth. Given its ubiquity in living cells and its ability to both store genetic information and catalyze its own replication, RNA probably formed the basis of first life [1]. RNA molecules are made up of sequences of 4 different nucleotides, the latter of which can be formed through reaction of a nucleobase with a ribose and a reduced phosphorous (P) source [2,3]. The evidence suggests that first life appeared earlier than 3.7 Gyr ago (Ga) [4,5] and thus the RNA world would have developed on a violent early Earth undergoing meteoritic bombardment at a rate of ∼1-1000 ×10 12 kg/yr [6], which is approximately 8-11 orders of magnitude greater than today [7]. At this time, the atmosphere was dominated by volcanic gases, and dry land was scarce as continents were rising out of the global ocean. [8,9], the answer to these questions are largely unknown.As to the sources of nucleobases, the early Earth's atmosphere was likely dominated by CO 2 , N 2 , SO 2 , and H 2 O [10...

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“…The low permeability of the matrix might limit the incorporation of terrestrial water into the matrices and prevent them from experiencing terrestrial weathering. A similar process might have occurred in the matrices we measured and result in no precipitation of weathering products in them because CV3 matrices would have low permeability (Bland et al 2009). Based on the weathering scale for ordinary chondrites (e.g., Wlotzka 1993), the weathering grades of the sections we studied are estimated to be W1 for CV3 Red RBT 04143 with minor Fe oxide weathering veins and W0 for the rest of the samples with no Fe oxide weathering products.…”

Section: Discussionmentioning

confidence: 99%

Redistribution of Sr and rare earth elements in the matrices of CV3 carbonaceous chondrites during aqueous alteration in their parent body

Jogo

Ito

Nakamura

et al. 2018

Earth Planets Space

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We measured the abundances of Sr and rare earth elements (REEs) in the matrices of five CV3 carbonaceous chondrites: Meteorite Hills (MET) 00430, MET 01070, La Paz ice field (LAP) 02206, Asuka (A) 881317 and Roberts Massif (RBT) 04143. In the MET 00430 and MET 01074 matrices, the Sr/CI and light REE (LREE, La-Nd)/CI ratios positively correlate with the amounts of Ca-rich secondary minerals, which formed during aqueous alteration in the CV3 chondrite parent body. In contrast, in the LAP 02206 and RBT 04143 matrices, although the Sr/CI ratios correlate with the amounts of Ca-rich secondary minerals, the LREE/CI ratios vary independently from the amounts of any secondary minerals. This suggests that the LREE/CI ratios in these matrices were produced prior to the parent body alteration, probably in the solar nebula. The LREE/CI ratios of the LAP 02206 and RBT 04143 matrices reveal the mixing process of matrix minerals prior to the accretion of the CV3 chondrite parent body. The mixing degrees of matrix minerals might be different between these two matrices. Because solid materials would be mixed over time according to the radial diffusion model of a turbulent disk, the matrix minerals consisting of LAP 02206 and RBT 04143 matrices might be incorporated into their parent body with different timing.

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Why aqueous alteration in asteroids was isochemical: High porosity ≠ high permeability

Cited by 133 publications

References 46 publications

Early aqueous activity on the ordinary and carbonaceous chondrite parent bodies recorded by fayalite

Early aqueous activity on the ordinary and carbonaceous chondrite parent bodies recorded by fayalite

Origin of the RNA world: The fate of nucleobases in warm little ponds

Redistribution of Sr and rare earth elements in the matrices of CV3 carbonaceous chondrites during aqueous alteration in their parent body

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