Testing variations within the Tagish Lake meteorite—<scp>II</scp>: Whole‐rock geochemistry of pristine samples

Blinova, A.; Herd, Christopher D. K.; Duke, M. B.

doi:10.1111/maps.12303

Cited by 17 publications

(14 citation statements)

References 37 publications

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“…Morlok et al (2006) calculated that ~1-2 g is the minimum mass of material needed for representative chemical analyses of the CI chondrites. Barrat et al (2012) analysed multiple ~0.5-1 g samples of Orgueil, Ivuna and Alais and still found evidence for chemical heterogeneity in elements such as Na, K, Rb, Cs and U that could be related to local differences in the degree of aqueous alteration (Blinova et al 2014). However, in view of the scarcity of CI material, it is not always possible to obtain a sample of sufficient mass to be an adequate representation of the bulk, and in this study we were limited to ~40 mg aliquots of Ivuna samples for each type of analysis, which is clearly below the mass threshold suggested by Morlok et al (2006) and Barrat et al (2012).…”

Section: Brecciation and Sample Heterogeneitymentioning

confidence: 99%

Terrestrial modification of the Ivuna meteorite and a reassessment of the chemical composition of the CI type specimen

King

Phillips

Strekopytov

et al. 2020

Geochimica et Cosmochimica Acta

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The rare CI carbonaceous chondrites are the most aqueously altered and chemically primitive meteorites but due to their porous nature and high abundance of volatile elements are susceptible to terrestrial weathering. The Ivuna meteorite, type specimen for the CI chondrites, is the largest twentieth-century CI fall and probably the CI chondrite least affected by terrestrial alteration that is available for study. The main mass of Ivuna (BM2008 M1) has been stored in a nitrogen atmosphere at least since its arrival at the Natural History Museum (NHM), London, in 2008 (70 years after its fall) and could be considered the most pristine CI chondrite stone. We report the mineralogy, petrography and bulk elemental composition of BM2008 M1 and a second Ivuna stone (BM1996 M4) stored in air within wooden cabinets. We find that both Ivuna stones are breccias consisting of multiple rounded, phyllosilicate-rich clasts that formed through aqueous alteration followed by impact processing. A polished thin section of BM2008 M1 analysed immediately after preparation was found to contain sulphate-bearing veins that

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Section: Brecciation and Sample Heterogeneitymentioning

confidence: 99%

Terrestrial modification of the Ivuna meteorite and a reassessment of the chemical composition of the CI type specimen

King

Phillips

Strekopytov

et al. 2020

Geochimica et Cosmochimica Acta

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“…The low-temperature storage of these meteorite specimens aims to lower reaction rates, inhibit potential microbial growth, and retain intrinsic volatile organic species within the samples (Herd et al 2016). In addition to its unique collection and curation conditions, Tagish Lake has an unusual mineralogical, petrological, and geochemical heterogeneity that has been attributed to varying degrees of aqueous alteration across the parent body asteroid (Herd et al 2011;Alexander et al 2014;Blinova et al 2014aBlinova et al , 2014bHilts et al 2014). Such variation within one single meteorite has not been observed before and affords the potential for an entirely new window into the chemical processes occurring in asteroid parent bodies.…”

Section: Introductionmentioning

confidence: 99%

“…The first investigation of soluble organic compounds for a pristine Tagish Lake specimen identified a suite of organic compounds, including aliphatic and aromatic hydrocarbons, amino acids, mono-and dicarboxylic acids, pyridine carboxylic acids, and sulfonic acids (Pizzarello et al 2001). Subsequent organic analyses of Tagish Lake have focused primarily on four additional specimens-TL5b, TL11h, TL11i, and TL11v-which have been analyzed in detail for their mineralogical and chemical compositions (Herd et al 2011;Glavin et al 2012;Alexander et al 2014;Blinova et al 2014aBlinova et al , 2014bHilts et al 2014). Mineralogical indicators for aqueous alteration (e.g., increasing replacement of chondrule glass by phyllosilicates in combination with relatively low porosity and a lower proportion of amorphous silicate material) suggest that the degree of aqueous alteration for these specimens is in the increasing order of TL5b < TL11h ( TL11i (Herd et al 2011).…”

Section: Introductionmentioning

confidence: 99%

New insights into the heterogeneity of the Tagish Lake meteorite: Soluble organic compositions of variously altered specimens

Simkus

Aponte

Elsila

et al. 2019

Meteorit & Planetary Scien

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The Tagish Lake carbonaceous chondrite exhibits a unique compositional heterogeneity that may be attributed to varying degrees of aqueous alteration within the parent body asteroid. Previous analyses of soluble organic compounds from four Tagish Lake meteorite specimens (TL5b, TL11h, TL11i, TL11v) identified distinct distributions and isotopic compositions that appeared to be linked to their degree of parent body processing (Herd et al. 2011; Glavin et al. 2012; Hilts et al. 2014). In the present study, we build upon these initial observations and evaluate the molecular distribution of amino acids, aldehydes and ketones, monocarboxylic acids, and aliphatic and aromatic hydrocarbons, including compound‐specific δ13C compositions, for three additional Tagish Lake specimens: TL1, TL4, and TL10a. TL1 contains relatively high abundances of soluble organics and appears to be a moderately altered specimen, similar to the previously analyzed TL5b and TL11h lithologies. In contrast, specimens TL4 and TL10a both contain relatively low abundances of all of the soluble organic compound classes measured, similar to TL11i and TL11v. The organic‐depleted composition of TL4 appears to have resulted from a relatively low degree of parent body aqueous alteration. In the case of TL10a, some unusual properties (e.g., the lack of detection of intrinsic monocarboxylic acids and aliphatic and aromatic hydrocarbons) suggest that it has experienced extensive alteration and/or a distinct organic‐depleted alteration history. Collectively, these varying compositions provide valuable new insights into the relationships between asteroidal aqueous alteration and the synthesis and preservation of soluble organic compounds.

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“…), and exhibit many mineralogical, petrological, and bulk compositional similarities (Blinova et al. , ). Hence, it is clear that all lithologies are from the Tagish Lake parent body and none are xenolithic clasts.…”

Section: Introductionmentioning

confidence: 99%

Elemental, isotopic, and structural changes in Tagish Lake insoluble organic matter produced by parent body processes

Alexander

Cody

Kebukawa

et al. 2014

Meteorit & Planetary Scien

109

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Abstract-Here, we present the results of a multitechnique study of the bulk properties of insoluble organic material (IOM) from the Tagish Lake meteorite, including four lithologies that have undergone different degrees of aqueous alteration. The IOM C contents of all four lithologies are very uniform and comprise about half the bulk C and N contents of the lithologies. However, the bulk IOM elemental and isotopic compositions vary significantly. In particular, there is a correlated decrease in bulk IOM H/C ratios and dD values with increasing degree of alteration-the IOM in the least altered lithology is intermediate between CM and CR IOM, while that in the more altered lithologies resembles the very aromatic IOM in mildly metamorphosed CV and CO chondrites, and heated CMs. Nuclear magnetic resonance (NMR) spectroscopy, C X-ray absorption near-edge (XANES), and Fourier transform infrared (FTIR) spectroscopy confirm and quantitate this transformation from CR-like, relatively aliphatic IOM functional group chemistry to a highly aromatic one. The transformation is almost certainly thermally driven, and probably occurred under hydrothermal conditions. The lack of a paramagnetic shift in 13 C NMR spectra and 1s-r* exciton in the C-XANES spectra, both typically seen in metamorphosed chondrites, shows that the temperatures were lower and/or the timescales were shorter than experienced by even the least metamorphosed type 3 chondrites. Two endmember models were considered to quantitatively account for the changes in IOM functional group chemistry, but the one in which the transformations involved quantitative conversion of aliphatic material to aromatic material was the more successful. It seems likely that similar processes were involved in producing the diversity of IOM compositions and functional group chemistries among CR, CM, and CI chondrites. If correct, CRs experienced the lowest temperatures, while CM and CI chondrites experienced similar more elevated temperatures. This ordering is inconsistent with alteration temperatures based on mineralogy and O isotopes.

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Testing variations within the Tagish Lake meteorite—II: Whole‐rock geochemistry of pristine samples

Cited by 17 publications

References 37 publications

Terrestrial modification of the Ivuna meteorite and a reassessment of the chemical composition of the CI type specimen

Terrestrial modification of the Ivuna meteorite and a reassessment of the chemical composition of the CI type specimen

New insights into the heterogeneity of the Tagish Lake meteorite: Soluble organic compositions of variously altered specimens

Elemental, isotopic, and structural changes in Tagish Lake insoluble organic matter produced by parent body processes

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