Morphological, structural and lithological records of terrestrial impacts: an overview

Масайтис, В. Л.

doi:10.1080/08120090500170427

Cited by 21 publications

(11 citation statements)

References 48 publications

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“…Only relatively young impact craters preserve their original shape including remnants of fallout ejecta, e.g. the Meteor crater (Masaitis, 2005). Most old impact craters, especially those of Mesozoic, Palaeozoic, and late Precambrian ages have lost their initial coptogenic landforms completely and are usually referred to as impact structures (Grieve and Therriault, 2004).…”

Section: Discussion: Geological Origin Of the Ibn-batutah Structurementioning

confidence: 99%

Ibn-Batutah: A possible simple impact structure in southeastern Libya, a remote sensing study

Ghoneim

2009

Geomorphology

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Section: Discussion: Geological Origin Of the Ibn-batutah Structurementioning

confidence: 99%

Ibn-Batutah: A possible simple impact structure in southeastern Libya, a remote sensing study

Ghoneim

2009

Geomorphology

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“…Calculation of fabric parameters was derived from best-fit ellipsoid variations. Masaitis (2005) has proposed that crater-fill deposits exhibit a broad three-fold subdivision. This study of core segments from borehole LB-07A suggests that the crater-fill material at the Bosumtwi impact site has a broad two-fold subdivision.…”

Section: Discussionmentioning

confidence: 99%

“…Subsequent localized variations in post-depositional cooling and crystallization processes can modify any primary depositional fabrics (Knauth et al 2005;Bringmeier 1994). Masaitis (2005) suggests that most craterfill deposits conform to a simple three-layer sequence. From bottom to top the three layers comprise a basal layer of "coarse lithic breccias," an intermediate layer of "suevite and tagamite," and an upper layer of "fine grained lithic breccia."…”

Section: Introductionmentioning

confidence: 99%

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Clast fabric examination of impact‐generated breccias, borehole LB‐07A, Bosumtwi, Ghana

Morris

Ugalde

Clark

et al. 2007

Meteorit & Planetary Scien

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Abstract-An impact event always creates a cloud of ejecta generated through excavation of the target. Subsequent in-filling of the void by crater-fill deposits provides a record of post-impact processes. Full-core digital photographic scans of core segments from borehole LB-07 in the Bosumtwi impact crater provide a complete record of the in-fill process. The shape, orientation, and size of clasts within the impact breccia were measured using a best-fit ellipsoid approach. Clast size and variance, together with clast orientation data, suggest the impact breccias at Bosumtwi can be divided into a simple two-fold subdivision that loosely agrees with the lithological zonation of a lower monomict breccia overlain by a polymict breccia. The lower unit is characterized by a uniform and finer-grained clast size together with a uniform flat-lying clast orientation. The boundary between the two zones is defined by a sharp increase in clast size. The upper zone shows an average increase in clast size with decreasing depth, but full grain size spectrum together with increased grain size deviation suggest that this is a result of mixing between two populations with different grain size distribution. The main population of clasts shows an incremental decrease of clast size with decreasing depth. The upper zone also contains weakly defined shallowly dipping clast fabrics, which may be suggestive of horizontal transport or deposition onto an inclined surface.

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“…Similar to other impact structures (Masaitis 2005), the impact lithologies within the Jänisjärvi include impact melt rocks (tagamites), suevites, and lithic breccias. In particular, the approximately 15-20 m thick tagamite layer overlies suevites and the lithic breccias.…”

Section: Geographical and Geological Settingmentioning

confidence: 99%

Paleomagnetism and petrophysics of the Jänisjärvi impact structure, Russian Karelia

Salminen

Donadini

Pesonen

et al. 2006

Meteoritics &Amp; Planetary Science

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Abstract-Paleomagnetic, rock magnetic, and petrophysical results are presented for impactites and target rocks from the Lake Jänisjärvi impact structure, Russian Karelia. The impactites (tagamites, suevites, and lithic breccias) are characterized by increased porosity and magnetization, which is in agreement with observations performed at other impact structures. Thermomagnetic, hysteresis, and scanning electron microscope (SEM) analysis document the presence of primary multidomain titanomagnetite with additional secondary titanomaghemite and ilmenohematite. The characteristic impact-related remanent magnetization (ChRM) direction (D = 101.5°, I = 73.1°, α 95 = 6.2°) yields a pole (Lat. = 45.0°N, Long. = 76.9°E, dp = 9.9°, dm = 11.0°). Additionally, the same component is observed as an overprint on some rocks located in the vicinity of the structure, which provides proofs of its primary origin. An attempt was made to determine the ancient geomagnetic field intensity. Seven reliable results were obtained, yielding an ancient intensity of 68.7 ± 7.6 μT (corresponding to VDM of 10.3 ± 1

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Morphological, structural and lithological records of terrestrial impacts: an overview

Cited by 21 publications

References 48 publications

Ibn-Batutah: A possible simple impact structure in southeastern Libya, a remote sensing study

Ibn-Batutah: A possible simple impact structure in southeastern Libya, a remote sensing study

Clast fabric examination of impact‐generated breccias, borehole LB‐07A, Bosumtwi, Ghana

Paleomagnetism and petrophysics of the Jänisjärvi impact structure, Russian Karelia

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