Diamond and silicon carbide in impact melt rock from the Ries impact crater

Hough, R. M.; Gilmour, I.; Pillinger, C. T.; Arden, J. W.; Gilkess, K. W. R.; Yuan, Jun; Milledge, H. J.

doi:10.1038/378041a0

Cited by 114 publications

(66 citation statements)

References 19 publications

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“…However, irrespective of any such possible artifacts, any isotopic fractionation during shock conversion from graphite to diamond is expected to be quite small (less than 0.1‰, based on the estimation above) and, therefore, cannot be detected in natural shock-induced diamond-graphite systems, such as those related to terrestrial impact cratering processes (e.g., Hough et al 1995;Koeberl et al 1997;Gilmour 1998). Naturally occurring graphite has an original isotopic heterogeneity that is much larger than the isotopic variation reported in this study (e.g., 3.5‰ within gneiss of the Popigai impact structure; Gilmour 1998).…”

Section: ------------------------------------------------------------mentioning

confidence: 99%

Carbon isotope fractionation between graphite and diamond during shock experiments

Maruoka

Koeberl

Matsuda

et al. 2003

Meteorit & Planetary Scien

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Abstract-Carbon isotopic compositions were measured for shock-produced diamond and shocked graphite formed at peak pressures ranging from 37 to 52 GPa. The δ 13 C values of diamonds produced in a sealed container were generally lower than that of the initial graphite. The differences in the carbon isotopic composition between initial graphite and shocked graphite/diamond may reflect kinetic isotopic fractionation during the oxidation of the graphite/diamond and/or analytical artifacts possibly induced by impurities in the samples. The pressure effect on the isotopic fractionations between graphite and diamond can be estimated from the δ 13 C values of impurity-free diamonds produced using a vented container from which gases, including oxygen, in pore spaces escaped during or after the diamond formation (e.g., 0.039 ± 0.085‰ at a peak pressure of 52 GPa). Any isotopic fractionation induced by shock conversion of graphite to diamond is too small to be detected in natural shock-induced diamond-graphite systems related to terrestrial impact cratering processes.

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confidence: 99%

Carbon isotope fractionation between graphite and diamond during shock experiments

Maruoka

Koeberl

Matsuda

et al. 2003

Meteorit & Planetary Scien

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“…This method is now widely commercialized. Subsequently, natural diamonds were also discovered in terrestrial impact structures, e.g., at the Popigai crater (Masaitis et al 1995;Koeberl et al 1997;Masaitis 1998), the Ries crater (Hough et al 1995;El Goresy et al 2001;Schmitt et al 2005), and within the globally distributed Chicxulub ejecta layer at the Cretaceous-Tertiary boundary (Gilmour et al 1992). Diamonds of the Popigai impact structure were found in strongly shocked gneiss fragments contained in suevites and impact melt rock.…”

Section: Introductionmentioning

confidence: 99%

Experimental shock synthesis of diamonds in a graphite gneiss

Kenkmann

Hornemann

Stöffler

2005

Meteorit & Planetary Scien

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Experimental shock synthesis of diamonds in a graphite gneissAbstract-The occurrence of diamonds in terrestrial impact craters and meteorites is related to dynamic shock loading during hypervelocity impacts. To understand the mechanism of impact diamond formation in natural rocks, shock-recovery experiments with graphite gneiss were carried out at shock pressures between 35 and 79 GPa. This is the first report on the successful shock synthesis of microdiamonds in a natural rock. Micrometer-size diamonds and a wide range of intermediate, presently unclassified, amorphous, and disordered carbon phases were observed within vesiculated biotite melts in the vicinity of relic graphite grains using microRaman spectrometry. We explain these findings by jetting mechanisms of carbon and graphite clusters, originating at the edges of graphite grains, into the very hot and volatile rich biotitic melt veins during shock loading. This environment enabled the thermally activated crystallization of diamonds during shock compression in a period of less than 0.5 µsec. Regraphitization of diamonds during pressure release was widespread and caused the formation of the amorphous to disordered carbon phases recorded frequently with microRaman spectroscopy. The surviving diamonds must have cooled down to 2000 K during the compression phase at local thermal sinks and cooler interfaces to avoid regraphitization.

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“…Based on the results of Abbott et al (1998), the source of the carbon for diamonds in the Ries suevites was derived either from a mixture of C sources or from a heterogeneous single C source such as graphite (Hough et al 1995). The basement graphite also provided a suitable C source to yield lighter C isotopic compositions for diamonds found in the shock-produced glasses (Abbott et al 1998).…”

Section: Discussionmentioning

confidence: 99%

“…Subsequently, impact diamonds have been investigated in the Ries crater by several groups. They were found in suevite whole-rock samples (Hough et al 1995, Abbot et al 1998, in glass bombs (Rost et al 1978, Abbott et al 1996, Siebenshock et al 1998, and in highly shocked crystalline fragments (El Goresy et al 1999). According to Schmitt et al (1999) the major carriers of diamonds in Ries are glass bombs of the fallout suevite formed by melting at shock pressures above 60 GPa, and the source of impact diamonds seems to be highly shocked graphite-bearing gneisses.…”

Section: Introductionmentioning

confidence: 99%

“…According to Schmitt et al (1999) the major carriers of diamonds in Ries are glass bombs of the fallout suevite formed by melting at shock pressures above 60 GPa, and the source of impact diamonds seems to be highly shocked graphite-bearing gneisses. Other carbon phases are also known from the Ries crater, e.g., chaoite (El Goresy and Donnay 1968) and silicon carbide (Hough et al 1995).…”

Section: Introductionmentioning

confidence: 99%

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The search for fullerenes in rocks from the Ries impact crater

Frank

Jehlička

Hamplová

et al. 2005

Meteoritics &Amp; Planetary Science

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Abstract-Since their discovery, fullerenes have been reported from various geological environments. One group of these findings has been related to bolide impacts, e.g., the Sudbury crater and the K-T and P-T boundaries. Impact rocks of the Ries crater, Germany, including samples of suevites, metamorphosed crystalline clasts, and glass bombs, have been collected in the Otting, Alteb¸rg, and Seelbronn quarries. No fullerenes in concentrations above 1 ppb have been found in analyzed samples. Laser desorption time-of-flight mass spectrometry (LD-TOF-MS) confirmed the absence of fullerenes in the analyzed samples. These results support the concept that the Ries impactor was a stony meteorite.

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Diamond and silicon carbide in impact melt rock from the Ries impact crater

Cited by 114 publications

References 19 publications

Carbon isotope fractionation between graphite and diamond during shock experiments

Carbon isotope fractionation between graphite and diamond during shock experiments

Experimental shock synthesis of diamonds in a graphite gneiss

The search for fullerenes in rocks from the Ries impact crater

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