Experimental petrology of the Tissint meteorite: Redox estimates,crystallization curves,and evaluation of petrogenetic models

Tissint is an olivine‐phyric shergottite from an incompatible element depleted Martian mantle source. Oxythermobarometry applied to Tissint mineral phases demonstrates that the Tissint magma underwent an increase in oxygen fugacity, from ~3.5 log units below the quarz‐fayalite‐magnetite (QFM ) buffer during the early stages of crystallization, to QFM ?1.4 during the latter stages. This is the first time that such an oxidation event has been observed in a depleted shergottite. The reason for the oxidation event is unclear; however, calculations using the MELTS thermodynamic model suggest that auto‐oxidation is insufficient to cause more than ~1 log unit of oxidation, and therefore an external oxidation mechanism—such as oxidation by degassing—is required. If volatiles are responsible for the oxidation, then it indicates that volatiles are not exclusively tied to the enriched Martian mantle reservoir. A series of experiments using the Tissint parental magma were carried out under fixed (isothermal) or variable (cooling rate) temperature control, and at either reducing (QFM ?3.2) or oxidizing (QFM ?1) redox conditions. The observed liquid line of descent supports a potential genetic relationship between basaltic shergottites and olivine‐phyric shergottites. A peritectic relation where olivine is resorbed to form pyroxene is favored by increased oxygen fugacity; if oxidation during crystallization is more common than presently believed, it may explain why olivine is typically anhedral in olivine‐phyric shergottites. Results from a cooling‐rate experiment in which the oxygen fugacity was changed during the latter stages of crystallization resulted in olivine with a Cr compositional profile consistent with oxidized isothermal experiments, despite forming primarily under reducing conditions. A similar profile is observed in Tissint olivines, consistent with its redox history. Our results provide insights into the potential influence of oxidation events on the compositional zoning of minor or trace elements in olivine in olivine‐phyric basalts.     

Insights into the Martian mantle: The age and isotopics of the meteorite fall Tissint

The recent witnessed fall of the meteorite Tissint represents the delivery of a pristine new sample from the surface of Mars. This meteorite provides an unprecedented opportunity to study a variety of aspects about the planet's evolution. Using the Rb–Sr and Sm–Nd isotopic systems, we determined that Tissint, a depleted shergottite, has a crystallization age of 574 ± 20 Ma, an initial ε¹⁴³Nd = +42.2 ± 0.5, and an initial ⁸⁷Sr/⁸⁶Sr = 0.700760 ± 11. These initial Nd and Sr isotopic compositions suggest that Tissint originated from a mantle source on Mars that is distinct from the source reservoirs of the other Martian meteorites. The known crystallization ages, geochemical characteristics, ejection ages, and ejection dynamics of Tissint and other similarly grouped Martian meteorites suggest that they are likely derived from a source crater up to approximately 90 km in diameter with an age of approximately 1 Ma that is located on terrain that is approximately 600 million years old.     

NanoSIMS analysis of organic carbon from the Tissint Martian meteorite: Evidence for the past existence of subsurface organic‐bearing fluids on Mars

Two petrographic settings of carbonaceous components, mainly filling open fractures and occasionally enclosed in shock‐melt veins, were found in the recently fallen Tissint Martian meteorite. The presence in shock‐melt veins and the deuterium enrichments (δD up to +1183‰) of these components clearly indicate a pristine Martian origin. The carbonaceous components are kerogen‐like, based on micro‐Raman spectra and multielemental ratios, and were probably deposited from fluids in shock‐induced fractures in the parent rock of Tissint. After precipitation of the organic matter, the rock experienced another severe shock event, producing the melt veins that encapsulated a part of the organic matter. The C isotopic compositions of the organic matter (δ¹³C = ?12.8 to ?33.1‰) are significantly lighter than Martian atmospheric CO₂ and carbonate, providing a tantalizing hint for a possible biotic process. Alternatively, the organic matter could be derived from carbonaceous chondrites, as insoluble organic matter from the latter has similar chemical and isotopic compositions. The presence of organic‐rich fluids that infiltrated rocks near the surface of Mars has significant implications for the study of Martian paleoenvironment and perhaps to search for possible ancient biological activities on Mars.     

The history of the Tissint meteorite,from its crystallization on Mars to its exposure in space: New geochemical,isotopic, and cosmogenic nuclide data

The Tissint meteorite fell on July 18, 2011 in Morocco and was quickly recovered, allowing the investigation of a new unaltered sample from Mars. We report new high‐field strength and highly siderophile element (HSE) data, Sr‐Nd‐Hf‐W‐Os isotope analyses, and data for cosmogenic nuclides in order to examine the history of the Tissint meteorite, from its source composition and crystallization to its irradiation history. We present high‐field strength element compositions that are typical for depleted Martian basalts (0.174 ppm Nb, 17.4 ppm Zr, 0.7352 ppm Hf, and 0.0444 ppm W), and, together with an extended literature data set for shergottites, help to reevaluate Mars’ tectonic evolution in comparison to that of the early Earth. HSE contents (0.07 ppb Re, 0.92 ppb Os, 2.55 ppb Ir, and 7.87 ppb Pt) vary significantly in comparison to literature data, reflecting significant sample inhomogeneity. Isotope data for Os and W (¹⁸⁷Os/¹⁸⁸Os = 0.1289 ± 15 and an ε¹⁸²W = +1.41 ± 0.46) are both indistinguishable from literature data. An internal Lu‐Hf isochron for Tissint defines a crystallization age of 665 ± 74 Ma. Considering only Sm‐Nd and Lu‐Hf chronometry, we obtain, using our and literature values, a best estimate for the age of Tissint of 582 ± 18 Ma (MSWD = 3.2). Cosmogenic radionuclides analyzed in the Tissint meteorite are typical for a recent fall. Tissint's pre‐atmospheric radius was estimated to be 22 ± 2 cm, resulting in an estimated total mass of 130 ± 40 kg. Our cosmic‐ray exposure age of 0.9 ± 0.2 Ma is consistent with earlier estimations and exposure ages for other shergottites in general.     

Grove Mountains 020090 enriched lherzolitic shergottite: A two‐stage formation model

Grove Mountains (GRV) 020090 is an enriched lherzolitic shergottite, distinct from other lherzolitic shergottites, except RBT 04262/1. Its characteristics include high abundance of plagioclase (24.2 vol% in the nonpoikilitic area), presence of K‐feldspar, common occurrence of baddeleyite, high FeO contents of olivine (bimodal peaks at Fa 33 mol% and Fa 41 mol%) and low‐Ca pyroxenes (bimodal peaks at Fs 23.8–31.7 mol% and Fs 25.7–33.9 mol%), and significant LREE enrichment of phosphates (500–610 × CI). The bulk composition of GRV 020090 suggests derivation from partial melting of an enriched reservoir. However, the REE patterns of the cores of pigeonite oikocrysts and the olivine chadacrysts are indistinguishable from those of GRV 99027 and other moderately depleted lherzolitic shergottites, and reveal a LREE‐depleted pattern of the primordial parent magma. We propose that the primordial parent magma of GRV 020090 was derived from a moderately depleted Martian upper mantle reservoir, and later the residual melt was contaminated by oxidized and enriched Martian crustal materials as it ascended up to the subsurface. GRV 020090 and RBT 04262/1 may have sampled an igneous unit different from other lherzolitic shergottites.     

Portales Valley: Petrology of a metallic‐melt meteorite breccia

Abstract— Portales Valley (PV) is an unusual metal‐veined meteorite that has been classified as an H6 chondrite. It has been regarded either as an annealed impact melt breccia, as a primitive achondrite, or as a meteorite with affinities to silicated iron meteorites. We studied the petrology of PV using a variety of geochemical‐mineralogical techniques. Our results suggest that PV is the first well‐documented metallic‐melt meteorite breccia. Mineral‐chemical and other data suggest that the protolith to PV was an H chondrite. The composition of FeNi metal in PV is somewhat fractionated compared to H chondrites and varies between coarse vein and silicate‐rich portions. It is best modeled as having formed by partial melting at temperatures of ?940–1150 °C, with incomplete separation of solid from liquid metal. Solid metal concentrated in the coarse vein areas and S‐bearing liquid metal concentrated in the silicate‐rich areas, possibly as a result of a surface energy effect. Both carbon and phosphorus must have been scavenged from large volumes and concentrated in metallic liquid. Graphite nodules formed by crystallization from this liquid, whereas phosphate formed by reaction between P‐bearing metal and clinopyroxene components, depleting clinopyroxene throughout much of the meteorite and growing coarse phosphate at metal‐silicate interfaces. Some phosphate probably crystallized from P‐bearing liquids, but most probably formed by solid‐state reaction at ?975‐725 °C. Phosphate‐forming and FeO‐reduction reactions were widespread in PV and entailed a change in the mineralogy of the stony portion on a large scale. Portales Valley experienced protracted annealing from supersolidus to subsolidus temperatures, probably by cooling at depth within its parent body, but the main differences between PV and H chondrites arose because maximum temperatures were higher in PV. A combination of a relatively weak shock event and elevated pre‐shock temperatures probably produced the vein‐and‐breccia texture, with endogenic heating being the main heat source for melting, and with stress waves from an impact event being an essential trigger for mobilizing metal. Portales Valley is best classified as an H7 metallic‐melt breccia of shock stage S1. The meteorite is transitional between more primitive (chondritic) and evolved (achondrite, iron) meteorite types and offers clues as to how differentiation could have occurred in some asteroidal bodies.     

Convective activity in a Martian magma chamber recorded by P‐zoning in Tissint olivine

The Tissint Martian meteorite is an unusual depleted olivine‐phyric shergottite, reportedly sourced from a mantle‐derived melt within a deep magma chamber. Here, we report major and trace element data for Tissint olivine and pyroxene, and use these data to provide new insights into the dynamics of the Tissint magma chamber. The presence of irregularly spaced oscillatory phosphorous (P)‐rich bands in olivine, along with geochemical evidence indicative of a closed magmatic system, implies that the olivine grains were subject to solute trapping caused by vigorous crystal convection within the Tissint magma chamber. Calculated equilibration temperatures for the earliest crystallizing (antecrystic) olivine cores suggest a Tissint magma source temperature of 1680 °C, and a local Martian mantle temperature of 1560 °C during the late Amazonian—the latter being consistent with the ambient mantle temperature of Archean Earth.     

Chemical layering in the upper mantle of Mars: Evidence from olivine‐hosted melt inclusions in Tissint

Melting of Martian mantle, formation, and evolution of primary magma from the depleted mantle were previously modeled from experimental petrology and geochemical studies of Martian meteorites. Based on in situ major and trace element study of a range of olivine‐hosted melt inclusions in various stages of crystallization of Tissint, a depleted olivine–phyric shergottite, we further constrain different stages of depletion and enrichment in the depleted mantle source of the shergottite suite. Two types of melt inclusions were petrographically recognized. Type I melt inclusions occur in the megacrystic olivine core (Fo_76‐70), while type II melt inclusions are hosted by the outer mantle of the olivine (Fo_66‐55). REE‐plot indicates type I melt inclusions, which are unique because they represent the most depleted trace element data from the parent magmas of all the depleted shergottites, are an order of magnitude depleted compared to the type II melt inclusions. The absolute REE content of type II displays parallel trend but somewhat lower value than the Tissint whole‐rock. Model calculations indicate two‐stage mantle melting events followed by enrichment through mixing with a hypothetical residual melt from solidifying magma ocean. This resulted in ~10 times enrichment of incompatible trace elements from parent magma stage to the remaining melt after 45% crystallization, simulating the whole‐rock of Tissint. We rule out any assimilation due to crustal recycling into the upper mantle, as proposed by a recent study. Rather, we propose the presence of Al, Ca, Na, P, and REE‐rich layer at the shallower upper mantle above the depleted mantle source region during the geologic evolution of Mars.     

Phase equilibria of the Shergotty meteorite: Constraints on pre‐eruptive water contents of martian magmas and fractional crystallization under hydrous conditions

Abstract— An experimental investigation of the Shergotty meteorite was performed at 0.1 MPa under anhydrous conditions at the quartz‐fayalite‐magnetite buffer and at 100 and 200 MPa under H₂O‐saturated conditions at the nickel‐nickel oxide buffer. The results of these experiments are used to infer magmatic conditions recorded by co‐crystallization of augite and pigeonite phenocrysts found in Shergotty and to investigate the effect of H₂O on fractional crystallization paths followed by shergottite magmas. The phase relations and compositions of the homogeneous magnesian pyroxene cores in Shergotty are most closely approximated by crystallization under H₂O‐saturated conditions at 1120 °C (± 10 °C) and 56 MPa (± 18 MPa), corresponding to dissolved H₂O contents of 1.8 wt% (± 0.6 wt%) and a depth of 5 km (± 1.5 km) in the martian crust (uncertainties are 2s? values). The Shergotty magma then lost this water during ascent and eruption. Fractional crystallization of the Shergotty magma under anhydrous conditions produces liquids that follow a strong Fe‐enrichment trend at nearly constant SiO₂. Crystallization under H₂O‐saturated conditions generates derivative liquids, depleted in FeO and Al₂O₃ and enriched in SiO₂, that are compositionally similar to the Mars Pathfinder andesite rock composition. The presence of ～1.8 wt% water in Shergotty parental magmas could result from assimilation of hydrated crustal materials or from dehydration of hydrous phases in the mantle source region.     

Description of a very dense meteorite collection area in western Atacama: Insight into the long‐term composition of the meteorite flux to Earth

We describe the geological, morphological, and climatic settings of two new meteorite collections from Atacama (Chile). The “El Médano collection” was recovered by systematic on‐foot search in El Médano and Caleta el Cobre dense collection areas and is composed of 213 meteorites before pairing, 142 after pairing. The “private collection” has been recovered by car by three private hunters and consists of 213 meteorites. Similar to other hot desert finds, and contrary to the falls and Antarctica finds, both collections show an overabundance of H chondrites. A recovery density can be calculated only for the El Médano collection and gives 251 and 168 meteorites larger than 10 g km^?2, before and after pairing, respectively. It is by far the densest collection area described in hot deserts. The Atacama Desert is known to have been hyperarid for a long period of time and, based on cosmic‐ray exposure ages on the order of 1–10 Ma, to have been stable over a period of time of several million years. Such a high meteorite concentration might be explained invoking either a yet unclear concentration mechanism (possibly related to downslope creeping) or a previously underestimated meteorite flux in previous studies or an average terrestrial age over 2 Myr. This last hypothesis is supported by the high weathering grade of meteorites and by the common terrestrial fragmentation (with fragments scattered over a few meters) of recovered meteorites.     

Differentiation and evolution of the IVA meteorite parent body: Clues from pyroxene geochemistry in the Steinbach stony‐iron meteorite

Abstract— We analyzed the Steinbach IVA stony‐iron meteorite using scanning electron microscopy (SEM), electron microprobe analysis (EMPA), laser ablation inductively‐coupled‐plasma mass spectroscopy (LA‐ICP‐MS), and modeling techniques. Different and sometimes adjacent low‐Ca pyroxene grains have distinct compositions and evidently crystallized at different stages in a chemically evolving system prior to the solidification of metal and troilite. Early crystallizing pyroxene shows evidence for disequilibrium and formation under conditions of rapid cooling, producing clinobronzite and type 1 pyroxene rich in troilite and other inclusions. Subsequently, type 2 pyroxene crystallized over an extensive fractionation interval. Steinbach probably formed as a cumulate produced by extensive crystal fractionation (?60–70% fractional crystallization) from a high‐temperature (?1450–1490 °C) silicate‐metallic magma. The inferred composition of the precursor magma is best modeled as having formed by ≥30–50% silicate partial melting of a chondritic protolith. If this protolith was similar to an LL chondrite (as implied by O‐isotopic data), then olivine must have separated from the partial melt, and a substantial amount (?53–56%) of FeO must have been reduced in the silicate magma. A model of simultaneous endogenic heating and collisional disruption appears best able to explain the data for Steinbach and other IVA meteorites. Impact disruption occurred while the parent body was substantially molten, causing liquids to separate from solids and oxygen‐bearing gas to vent to space, leading to a molten metal‐rich body that was smaller than the original parent body and that solidified from the outside in. This model can simultaneously explain the characteristics of both stony‐iron and iron IVA meteorites, including the apparent correlation between metal composition and metallographic cooling rate observed for metal.     

Low‐temperature phase decomposition in iron‐nickel metal of the Portales Valley meteorite

Abstract— The Portales Valley meteorite provides an opportunity to investigate and compare the microstructure in Fe‐Ni metal of the metallic particles in the chondritic portion and in the metal veins. The low‐temperature phase decomposition of Fe‐Ni metal was investigated using scanning electron microscopy, transmission electron microscopy, and atomic force microscopy. The microstructure is formed as the Portales Valley meteorite cooled from high temperatures and includes the outer taenite rim, the cloudy zone, clear taenite, and martensite. Martensite in turn decomposes into a fine admixture of fcc rods in a bcc matrix. The width of the island phase of the cloudy zone in the metal particles of the chondritic portion and the metal veins can be used to estimate a low‐temperature cooling rate. The microstructural evidence indicates that the chondritic portions and the metal veins in the Portales Valley meteorite cooled together as a mixture with a cooling rate of roughly 6.5 K/Ma.     

The Kaidun meteorite: Clasts of alkaline‐rich fractionated materials

Abstract— Clasts of alkaline (the second find in meteorites) and subalkaline rocks were found in the Kaidun meteorite. One of them (#d4A) is a large crystal of albite with inclusions of fluorapatite, arfvedsonite, aenigmatite, and wilkinsonite. The two latter minerals were previously unknown in meteorites. Another clast (#d[3–5]D) has a melt crystallization texture of mainly feldspar (oligoclase) composition and contains relict grains of both high‐Ca and low‐Ca pyroxene and fluorapatite. The mineralogical characteristics of these clasts suggest a genetic relationship and an origin from the same parent body. The textural and mineralogical characteristics of the clasts indicate origin by extensive igneous differentiation. Such processes most likely took place in a rather large differentiated body. The material of clast #d(3–5)D is similar in some mineralogical respects to basaltic shergottites.     

Classification of the Didwana‐Rajod meteorite: A Mössbauer spectroscopic study

Abstract— Mössbauer spectroscopic studies of the Didwana‐Rajod chondrite, which fell on 1991 August 12 in western Rajasthan, India, are presented. The results are compared with the Mössbauer data of several enstatite and ordinary chondrites including the Dhajala chondrite for which Mössbauer data were acquired during the present study. The Didwana‐Rajod chondrite's iron phases and its oxidation states strongly suggest that it should be classified as an H‐type ordinary chondrite instead of the earlier suggestion (based on petrographic studies) that it could be an enstatite chondrite. The present study demonstrates that Mössbauer spectroscopy is a very powerful technique for aiding in the classification of meteorites.     

Mineral chemistry of MUSES‐C Regio inferred from analysis of dust particles collected from the first‐ and second‐touchdown sites on asteroid Itokawa

The mineralogy and mineral chemistry of Itokawa dust particles captured during the first and second touchdowns on the MUSES‐C Regio were characterized by synchrotron‐radiation X‐ray diffraction and field‐emission electron microprobe analysis. Olivine and low‐ and high‐Ca pyroxene, plagioclase, and merrillite compositions of the first‐touchdown particles are similar to those of the second‐touchdown particles. The two touchdown sites are separated by approximately 100 meters and therefore the similarity suggests that MUSES‐C Regio is covered with dust particles of uniform mineral chemistry of LL chondrites. Quantitative compositional properties of 48 dust particles, including both first‐ and second‐touchdown samples, indicate that dust particles of MUSES‐C Regio have experienced prolonged thermal metamorphism, but they are not fully equilibrated in terms of chemical composition. This suggests that MUSES‐C particles were heated in a single asteroid at different temperatures. During slow cooling from a peak temperature of approximately 800 °C, chemical compositions of plagioclase and K‐feldspar seem to have been modified: Ab and Or contents changed during cooling, but An did not. This compositional modification is reproduced by a numerical simulation that modeled the cooling process of a 50 km sized Itokawa parent asteroid. After cooling, some particles have been heavily impacted and heated, which resulted in heterogeneous distributions of Na and K within plagioclase crystals. Impact‐induced chemical modification of plagioclase was verified by a comparison to a shock vein in the Kilabo LL6 ordinary chondrite where Na‐K distributions of plagioclase have been disturbed.     

A new model of angular momentum transfer from the rotating central body of a two‐body system to the orbital motion of the system

In a previous paper we treated within the framework of our Projective Unified Field Theory (Schmutzer 2004, 2005a) the 2‐body system (e.g. Earth‐Moon system) with a rotating central body in a rather abstract manner. Here a concrete model of the transfer of angular momentum from the rotating central body to the orbital motion of the whole 2‐body system is presented, where particularly the transfer is caused by the inhomogeneous gravitational force of the Moon acting on the oceanic waters of the Earth, being modeled by a spherical shell around the solid Earth. The theory is numerically tested. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Remnants of altered meteorite in the Cretaceous‐Paleogene clay boundary in Poland

Fossil iron meteorites are extremely rare in the geological sedimentary record. The paleometeorite described here is the first such finding at the Cretaceous‐Paleogene (K‐Pg) boundary. In the boundary clay from the outcrop at the Lechówka quarry (Poland), fragments of the paleometeorite were found in the bottom part of the host layer. The fragments of meteorite (2–6 mm in size) and meteoritic dust are metallic‐gray in color and have a total weight of 1.8181 g. Geochemical and petrographic analyses of the meteorite from Lechówka reveal the presence of Ni‐rich minerals with a total Ni amount of 2–3 wt%. The identified minerals are taenite, kamacite, schreibersite, Ni‐rich magnetite, and Ni‐rich goethite. No relicts of silicates or chromites were found. The investigated paleometeorite apparently represents an independent fall and does not seem to be derived from the K‐Pg impactor. The high degree of weathering did not permit the chemical classification of the meteorite fragments. However, the recognized mineral inventory, lack of silicates, and their pseudomorphs and texture may indicate that the meteorite remains were an iron meteorite.     

Mid‐infrared study of stones from the Sutter's Mill meteorite

The Sutter's Mill meteorite fell in northern California on April 22, 2012. Several fragments of the meteorite were recovered, some of them shortly after the fall, others several days later after a heavy rainstorm. In this work, we analyzed several samples of four fragments―SM2, SM12, SM20, and SM30―from the Sutter's Mill meteorite with two infrared (IR) microscopes operating in the 4000–650 cm^?1 (2.5–15.4 μm) range. Spectra show absorption features associated with minerals such as olivines, phyllosilicates, carbonates, and possibly pyroxenes, as well as organics. Spectra of specific minerals vary from one particle to another within a given stone, and even within a single particle, indicating a nonuniform mineral composition. Infrared features associated with aliphatic CH₂ and CH₃ groups associated with organics are also seen in several spectra. However, the presence of organics in the samples studied is not clear because these features overlap with carbonate overtone bands. Finally, other samples collected within days after the rainstorm show evidence for bacterial terrestrial contamination, which indicates how quickly meteorites can be contaminated on such small scales.     

Petrography,mineral chemistry,and crystallization history of olivine‐phyric shergottite NWA 6234: A new melt composition

Knowledge of Martian igneous and mantle compositions is crucial for understanding Mars' mantle evolution, including early differentiation, mantle convection, and the chemical alteration at the surface. Primitive magmas provide the most direct information about their mantle source regions, but most Martian meteorites either contain cumulate olivine or crystallized from fractionated melts. The new Martian meteorite Northwest Africa (NWA) 6234 is an olivine‐phyric shergottite. Its most magnesian olivine cores (Fo₇₈) are in Mg‐Fe equilibrium with a magma of the bulk rock composition, suggesting that it represents a melt composition. Thermochemical calculations show that NWA 6234 not only represents a melt composition but is a primitive melt derived from an approximately Fo₈₀ mantle. Thus, NWA 6234 is similar to NWA 5789 and Y 980459 in the sense that all three are olivine‐phyric shergottites and represent primitive magma compositions. However, NWA 6234 is of special significance because it represents the first olivine‐phyric shergottite from a primitive ferroan magma. On the basis of Al/Ti ratio of pyroxenes in NWA 6234, the minor components in olivine and merrillite, and phosphorus zoning of olivine, we infer that the rock crystallized completely at pressures consistent with conditions in Mars' upper crust. The textural intergrowths of the two phosphates (merrillite and apatite) indicate that at a very last stage of crystallization, merrillite reacted with an OH‐Cl‐F‐rich melt to form apatite. As this meteorite crystallized completely at depth and never erupted, it is likely that its apatite compositions represent snapshots of the volatile ratios of the source region without being affected by degassing processes, which contain high OH‐F content.     

A contamination assessment of the CI carbonaceous meteorite Orgueil using a DNA‐directed approach

The Orgueil meteorite has become one of the most well‐studied carbonaceous meteorites, after it fell in France 150 yr ago. Extraterrestrial organic compounds such as amino acids and nucleobases in the parts per billion ranges were identified in Orgueil samples with supporting isotopic analyses. However, speculations of terrestrial contamination such as organic inclusions in the form of microbes and seeds accompanied the analyses of the Orgueil meteorite ever since its fall. By using molecular analysis, we performed DNA extractions and spiking experiments combined with 16S and 18S rRNA gene targeted PCR amplification to quantify the level of terrestrial biocontamination. Our results indicate that terrestrial contamination with DNA was insignificant in the investigated meteorite fraction. We also remeasured and confirmed concentrations of amino acids found in previous studies and conclude that their rather high concentrations and distribution cannot be explained by terrestrial contamination with microorganisms alone. These results represent the first analysis using DNA‐directed tools in the analysis of the Orgueil meteorite to determine trace levels of biomarkers.