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TOPIC: Matt Wilson crater

Blobrana

L

Posts: 131433

Date: May 6 15:16 2009

RE: Matt Wilson crater	Permalink

Expand (149kb, 800 x 600) Position: -15.49835°S, 131.18370° E __________________

Blobrana

L

Posts: 131433

Date: May 5 23:46 2009

	Permalink
Latitude: 15°29'53.05"S, Longitude: 131°10'51.15"E __________________

Blobrana

L

Posts: 131433

Date: May 5 23:20 2009


Geological map and profile of the complete crater	Imbricated beds of the central uplift with preferred dip direction to the NE

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Blobrana

L

Posts: 131433

Date: May 5 22:19 2009

Matt Wilson impact structure	Permalink

Title: Asymmetric signatures in simple craters as an indicator for an oblique impact direction Authors: Thomas Kenkmann, and Michael H. Poelchau In oblique impacts with an impact angle under 45°, the bilateral shape of the distal ejecta blanket is used as the strongest indicator for an impact vector. This bilateral symmetry is attenuated and is superimposed by radial symmetry towards the crater rim, which remains circular for impact angles down to 10 - 15°. The possibility that remnants of bilateral symmetry might still be present in the most proximal ejecta, the overturned flap and the crater rim was explored with the intention of deducing an impact vector. A model is presented that postulates bilateral patterns using proximal ejecta trajectories and predicts these patterns in the orientation of bedding planes in the crater rim. This model was successfully correlated to patterns described by radial grooves in the proximal ejecta blanket of the oblique Tooting crater on Mars. A new method was developed to detect structural asymmetries by converting bedding data into values that express the deviation from concentric strike orientation in the crater rim relative to the crater center, termed "concentric deviation." The method was applied to field data from Wolfe Creek crater, Western Australia. Bedding in the overturned flap implies an impactor striking from the east, which refines earlier publications, while bedding from the inner rim shows a correlation with the crater rim morphology. Read more (PDF) Matt Wilson structure: record of an impact event of possible Early Mesoproterozoic age, Northern Territory Read more __________________

Blobrana

L

Posts: 131433

Date: May 5 17:31 2009

Matt Wilson crater	Permalink

Title: Low-angle collision with Earth: The elliptical impact crater Matt Wilson, Northern Territory, Australia Authors: Thomas Kenkmann, and Michael H. Poelchau Nearly all meteorite impact craters on Earth are circular. However, ~4% of craters should be formed by impacts at angles lower than 12° from the horizontal, which should result in elongated crater structures. The crater-forming process that produces elliptical shapes is poorly understood. We document the first elliptical crater on Earth that contains a central uplift and that provides insights into the mechanisms of crater formation at a critical threshold angle of 10° - 15°. The dimensions of the Proterozoic Matt Wilson impact structure, Northern Territory, Australia, are 7.5 by 6.3 km, corresponding to an aspect ratio of 1.2, with its long axis trending northeast-southwest. The exposed crater floor shows a preferred stacking of thrust sheets within the central uplift and in the surrounding syncline, indicating northeast-southwest shortening and a material transport top-to-the-SW. This is consistent with an up-range to down-range motion of rock, caused by remnant horizontal momentum transferred from the impacting projectile to the target. This preferential deformation interferes with a radially oriented convergent material flow characteristic for crater collapse. The Matt Wilson crater provides evidence for the usefulness of structural asymmetries as a diagnostic tool to infer impact vectors. The new impact crater is confirmed by the presence of planar deformation features, planar fractures in quartz grains, and its structural inventory. See more __________________

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