Deformation of the Sudbury Structure: Paleomagnetic evidence from the Sudbury breccia

Szabo, E.; Halls, H. C.

doi:10.1016/j.precamres.2006.07.010

Cited by 16 publications

(4 citation statements)

References 66 publications

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“…Studies of AMS have been widely used to understand the fabric and deformation of rocks (e.g., Tarling and Hrouda ). Recently, the AMS has been introduced in characterizing the deformation of rocks in context of an impact crater (Szabó and Halls ; Nishioka et al. ; Louzada et al.…”

Section: Rock Magnetic and Paleomagnetic Studymentioning

confidence: 99%

“…Studies of AMS have been widely used to understand the fabric and deformation of rocks (e.g., Tarling and Hrouda 1993). Recently, the AMS has been introduced in characterizing the deformation of rocks in context of an impact crater (Szab o and Halls 2006;Nishioka et al 2007;Louzada et al 2010;Misra et al 2010;Urrutia Fucugauchi et al 2012;Yokoyama et al 2012). The results of laboratory shock experiments reveal that the primary effects of impact on the magnetic properties are generally a slight decrease of magnetic susceptibility (Gilder and Le Goff 2005;Gattacceca et al 2007;Lamali et al 2007), demagnetization or remagnetization and magnetic hardening (e.g., Rochette et al [2003] and references therein; Gattacceca et al 2007).…”

Section: Magnetic Fabricmentioning

confidence: 99%

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Geophysical and magneto‐structural study of the Maâdna structure (Talemzane, Algeria): Insights on its age and origin

Lamali

Rochette

Merabet

et al. 2016

Meteorit & Planetary Scien

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International audienceThe Maâdna structure is located approximately 400 km south of Algiers (33°19' N, 4°19' E) and emplaced in Upper-Cretaceous to Eocene limestones. Although accepted as an impact crater on the basis of alleged observations of shock-diagnostic features such as planar deformation features (PDFs) in quartz grains, previous works were limited and further studies are desirable to ascertain the structure formation process and its age. For this purpose, the crater was investigated using a multidisciplinary approach including field observations, detailed cartography of the different geological and structural units, geophysical surveys, anisotropy of magnetic susceptibility, paleomagnetism, and petrography of the collected samples. We found that the magnetic and gravimetric profiles highlight a succession of positive and negative anomalies, ones that might indicate the occurrence of a causative material which is at least in part identical. Geophysical analysis and modeling suggest the presence of this material within the crater at a depth of about 100 m below the surface. Using soil magnetic susceptibility measurements, the shallowest magnetized zone in the central part of the crater is identified as a recently deposited material. Paleomagnetic and rock magnetic experiments combined with petrographic observations show that detrital hematite is the main magnetic carrier although often associated with magnetite. A primary magnetization is inferred from a stable remanence with both normal and reverse directions, carried by these two minerals. Although this is supposed to be a chemical remagnetization, its normal polarity nature is considered to be a Pliocene component, subsequent to the crater formation. The pole falls onto the Miocene-Pliocene part of the African Apparent Polar Wander Path (APWP). Consequently, we estimate then formation of the Ma^adna crater to have occurred during the time period extending from the Late Miocene to the Early Pliocene. Unfortunately, our field and laboratory investigations do not allow us to confirm an impact origin for the crater as neither shatter cones, nor shocked minerals, were found. A dissolved diapir with inverted relief is suggested as an alternative to the impact hypothesis, which can still be considered as plausible. Only a drilling may provide a definite answer

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Section: Rock Magnetic and Paleomagnetic Studymentioning

confidence: 99%

Section: Magnetic Fabricmentioning

confidence: 99%

Geophysical and magneto‐structural study of the Maâdna structure (Talemzane, Algeria): Insights on its age and origin

Lamali

Rochette

Merabet

et al. 2016

Meteorit & Planetary Scien

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“…The most prominent feature of the current structure is the Sudbury Igneous Complex (SIC), which was deformed into a 30 by 18 km truncated oval by the Penokean Orogeny at approximately 1.85 Ga and the Yavapai Orogeny at approximately 1.75 Ga (Piercey et al. ) and later by the Grenville Orogeny (Szabo and Halls ). There are numerous shock indicators in and around the SIC, including shatter cones, impact breccias, pseudotachylitic breccia, and planar deformation features (PDFs) in quartz, coesite, and impact diamonds (e.g., French ; Rousell et al.…”

Section: Introductionmentioning

confidence: 99%

“…Its original diameter is thought to have been approximately 200-250 km (e.g., Dickin et al 1996;Mungall et al 2004). The most prominent feature of the current structure is the Sudbury Igneous Complex (SIC), which was deformed into a 30 by 18 km truncated oval by the Penokean Orogeny at approximately 1.85 Ga and the Yavapai Orogeny at approximately 1.75 Ga (Piercey et al 2007) and later by the Grenville Orogeny (Szabo and Halls 2006).…”

Section: Introduction Sudbury Structurementioning

confidence: 99%

Petrography and geochemistry of ejecta from the Sudbury impact event

Huber

McDonald

Koeberl

2014

Meteorit & Planetary Scien

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Ejecta from the Connors Creek site in Michigan (500 km from the Sudbury Igneous Complex [SIC]), the Pine River site in western Ontario (650 km from the SIC), and the Coleraine site in Minnesota (980 km from the SIC) were petrographically and geochemically analyzed. Connors Creek was found to have approximately 2 m of ejecta, including shocked quartz, melt droplets, and accretionary lapilli; Pine River has similar deposits about 1 m in thickness, although with smaller lapilli; Coleraine contains only impact spherules in a 20 cm‐thick layer (impact spherules being similar to microkrystites or microtektites). The ejecta transition from chaotic deposits of massively bedded impactoclastic material with locally derived detritus at Connors Creek to a deposit with apparently very little detrital material that is primarily composed of melt droplets at Pine River to a deposit that is almost entirely composed of melt spherules at Coleraine. The major and trace element compositions of the ejecta confirm the previously observed similarity of the ejecta deposits to the Onaping Formation in the SIC. Platinum‐group element (PGE) concentrations from each of the sites were also measured, revealing significantly elevated PGE contents in the spherule samples compared with background values. PGE abundances in samples from the Pine River site can be reproduced by addition of approximately 0.2 wt% CI chondrite to the background composition of the underlying sediments in the core. PGE interelement ratios indicate that the Sudbury impact event was probably caused by a chondritic impactor.

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2017

Nickel Sulfide Ores and Impact Melts

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Deformation of the Sudbury Structure: Paleomagnetic evidence from the Sudbury breccia

Cited by 16 publications

References 66 publications

Geophysical and magneto‐structural study of the Maâdna structure (Talemzane, Algeria): Insights on its age and origin

Geophysical and magneto‐structural study of the Maâdna structure (Talemzane, Algeria): Insights on its age and origin

Petrography and geochemistry of ejecta from the Sudbury impact event

References and Sudbury Bibliography

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