Paleomagnetic and rock magnetic study of the Mistastin Lake impact structure (Labrador, Canada): Implications for geomagnetic perturbation and shock effects

Hervé, Gwenaël; Gilder, Stuart; Marion, C. L.; Osinski, G. R.; Pohl, J.; Petersen, N.; Sylvester, Paul J.

doi:10.1016/j.epsl.2015.02.011

Cited by 12 publications

(13 citation statements)

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“…Moreover, Hervé et al . [] found that the anorthosite basement rocks at Mistastin trend from multidomain to single domain when approaching the center of the crater where pressures were greater. In sum, we interpret that the higher than expected remanence ratios and lower than expected coercivity ratios of the titanomagnetite‐bearing basement rocks at Manicouagan reflect both pressure and temperature effects related to the impact.…”

Section: Resultsmentioning

confidence: 99%

A paleomagnetic and rock magnetic study of the Manicouagan impact structure: Implications for crater formation and geodynamo effects

et al. 2016

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We report rock magnetic and paleomagnetic data from the ~214 Ma Manicouagan (Canada) impact crater based on 25 widely distributed sites of impact melt and basement rocks collected at the surface as well as from boreholes drilled to depths ≤1.5 km. Titanomagnetite and titanohematite carry the magnetic remanence in impact melts above 320 m elevation and in most basement rocks. Impact melts below 320 m contain solely titanomagnetite. Magnetic susceptibility and saturation magnetization, proxies for titanomagnetite concentration, increase more than tenfold toward the base of the thickest impact melt that underwent fractional crystallization. The titanomagnetite‐enriched zone partially contributes to a 2000 nT magnetic anomaly in the crater's center. Stepwise demagnetization reveals a single, normal polarity magnetization component in all samples regardless of the magnetic phases present. Coeval lock‐in remanence times for titanomagnetite and titanohematite indicate that the titanohematite formed >570°C during oxi‐exsolution. The average paleomagnetic direction and intensity coincide well with 214 Ma reference values. We find no evidence for an aberration of the geomagnetic field over the several thousands of years it took to cool a 481 m thick portion of the impact melt body. Hence, the energy released by the Manicouagan impact that created one of the 10 largest known craters on Earth provoked no measurable disturbance of the geodynamo. Magnetic anisotropy of clast‐free impact melts define magnetic lineation directions that are, in places, radially oriented with respect to the crater's center. Centrifugal flow of the melt within the evolving transient crater probably generated the fabric.

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Section: Resultsmentioning

confidence: 99%

A paleomagnetic and rock magnetic study of the Manicouagan impact structure: Implications for crater formation and geodynamo effects

et al. 2016

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“…On the other hand, one may find metallic iron spherules due to impactor contamination [48,49]. The present synthesis will build on the two new Siberian impact glasses studied above, previous synthesis [9] as well as magnetic studies on Lappajärvi crater melt rocks [50], Lonar crater glass [51,52], of Mistastin crater melt rocks [53], of Jänisjärvi crater melt rocks [10], of Pantasma crater glass [11], complemented with M RS data from [20]. Data from [12] on irghizites will also be used to complement the database [9].…”

Section: Overview Of Impact Glasses With Variable Ferromagnetic Contentmentioning

confidence: 86%

“…Table 3. Synthesis on magnetic properties of non paramagnetic impact glasses, after [9] complemented with data from [10][11][12]20,50,52,53] and this work. Sites are ordered by increasing mean susceptibility, with impact melt sheets at the end.…”

Section: Overview Of Impact Glasses With Variable Ferromagnetic Contentmentioning

confidence: 88%

“…Mean Magnetic mineralogy of these impact glasses is dominated by substituted magnetite [9][10][11][12]51], as expected by their generally oxidized nature indicated for example by XANES (for LDG, Aouelloul, irghizite, Wabar; [27,45]) or Mössbauer spectroscopy studies (for Aouelloul, irghizite, Wabar; [44]). Substitution in magnetite is revealed by the spread of Curie or remanence unblocking temperatures well below 580 • C, as well as the lack or subdued character of the Verwey transition [10,12,53]. Besides the very fine-grained magnetite inclusions, one may encounter large oxide inclusions, likely derived from the melting of large iron oxides grains present within the target.…”

Section: Glassmentioning

confidence: 99%

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Magnetic Properties and Redox State of Impact Glasses: A Review and New Case Studies from Siberia

et al. 2019

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High velocity impacts produce melts that solidify as ejected or in-situ glasses. We provide a review of their peculiar magnetic properties, as well as a new detailed study of four glasses from Siberia: El’gygytgyn, Popigai, urengoites, and South-Ural glass (on a total of 24 different craters or strewn-fields). Two types of behavior appear: 1) purely paramagnetic with ferromagnetic impurities at most of the order of 10 ppm; this corresponds to the five tektite strewn-fields (including the new one from Belize), urengoites, and Darwin glass. Oxidation state, based in particular on X-ray spectroscopy, is mostly restricted to Fe2+; 2) variable and up to strong ferromagnetic component, up to the 1 wt % range, mostly due to substituted magnetite often in superparamagnetic state. Accordingly, bulk oxidation state is intermediate between Fe2+ and Fe3+, although metallic iron, hematite, and pyrrhotite are sometimes encountered. Various applications of these magnetic properties are reviewed in the field of paleomagnetism, magnetic anomalies, recognition of glass origin, and formation processes.

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“…The farther away an impact VGP is from a pole of a given age, the less likely it is to have formed at that age (see similar discussion in Hervé et al. and Carpozen and Gilder ). In order to estimate the probability of the Tunnunik VGP having arisen through secular variation throughout the Phanerozoic, the approach developed by Fairchild et al.…”

Section: Discussionmentioning

confidence: 88%

A Paleozoic age for the Tunnunik impact structure

Lepaulard

Gattacceca

Swanson‐Hysell

et al. 2019

Meteorit & Planetary Scien

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We report paleomagnetic directions from the target rocks of the Tunnunik impact structure, as well as from lithic impact breccia dikes that formed during the impact event. The target sedimentary rocks have been remagnetized after impact‐related tilting during a reverse polarity interval. Their magnetization is unblocked up to 350 °C. The diabase dikes intruding into these sediments retained their original magnetization which unblocks above 400 °C. The impact breccia records a paleomagnetic direction similar to that of the overprints in the target sedimentary rocks. The comparison of the resulting virtual geomagnetic pole for the Tunnunik impact structure with the apparent polar wander path for Laurentia combined with biostratigraphic constraints from the target sedimentary rocks is most consistent with an impact age in the Late Ordovician or Silurian, around 430–450 Ma, soon after the deposition of the youngest impacted sedimentary rocks. Our results from the overprinted sedimentary rocks and diabase dikes imply that the postimpact temperature of the studied rocks was about 350 °C.

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Paleomagnetic and rock magnetic study of the Mistastin Lake impact structure (Labrador, Canada): Implications for geomagnetic perturbation and shock effects

Cited by 12 publications

References 64 publications

A paleomagnetic and rock magnetic study of the Manicouagan impact structure: Implications for crater formation and geodynamo effects

A paleomagnetic and rock magnetic study of the Manicouagan impact structure: Implications for crater formation and geodynamo effects

Magnetic Properties and Redox State of Impact Glasses: A Review and New Case Studies from Siberia

A Paleozoic age for the Tunnunik impact structure

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