Rim Formation in Complex Lunar and Terrestrial Impact Craters PDF Download

Author: Tim Krüger
Publisher:
ISBN:
Category :
Languages : en
Pages :

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Author: David John Roddy
Publisher: Pergamon
ISBN:
Category : Science
Languages : en
Pages : 1326

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Aspects of cratering phenomenology are considered along with material properties and shock effects, theoretical cratering mechanics, ejecta, and problems of scaling. Attention is given to the application of high explosion cratering data to planetary problems, cratering mechanisms observed in laboratory-scale high-explosive experiments, nuclear cratering experiments, complex craters in alluvium, terrestrial impact structures, the Ries impact crater, buried impact craters in the Williston basin and the adjacent area, crater morphometry from bistatic radar, a Fourier analysis of planimetric lunar crater shape, a stratigraphic model for Bessel Crater and southern Mare Serenitatis, a nested-crater model of lunar ringed basins, Martian fresh crater morphology and morphometry, the distribution and emplacement of ejecta around Martian impact craters, the nature of the present interplanetary crater-forming projectiles, cratering mechanics and future Martian exploration, the response of rocks to large stresses, the dynamical implications of the petrology and distribution of impact melt rocks, and a review and comparison of hypervelocity impact and explosion cratering calculations.

Author: G. R. Osinski
Publisher: John Wiley & Sons
ISBN: 140519829X
Category : Science
Languages : en
Pages : 362

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Impact cratering is arguably the most ubiquitous geological process in the Solar System. It has played an important role in Earth’s history, shaping the geological landscape, affecting the evolution of life, and generating economic resources. However, it was only in the latter half of the 20th century that the importance of impact cratering as a geological process was recognized and only during the past couple of decades that the study of meteorite impact structures has moved into the mainstream. This book seeks to fill a critical gap in the literature by providing an overview text covering broad aspects of the impact cratering process and aimed at graduate students, professionals and researchers alike. It introduces readers to the threat and nature of impactors, the impact cratering process, the products, and the effects – both destructive and beneficial. A series of chapters on the various techniques used to study impact craters provide a foundation for anyone studying impact craters for the first time.

Author: Wylie Poag
Publisher: Springer Science & Business Media
ISBN: 3642189008
Category : Science
Languages : en
Pages : 529

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The authors have synthesized 16 years of geological and geophysical studies which document an 85-km-wide impact crater buried 500 m beneath Chesapeake Bay in south eastern Virginia, USA. In doing so, they have integrated extensive seismic reflection profiling and deep core drilling to analyze the structure, morphology, gravimetrics, sedimentology, petrology, geochemistry, and paleontology of this submarine structure. Of special interest are a detailed comparison with other terrestrial and extraterrestrial craters, as well as a conceptual model and computer simulation of the impact. The extensive illustrations encompass more than 150 line drawings and core photographs.

Author: Grant Heiken
Publisher: CUP Archive
ISBN: 9780521334440
Category : Science
Languages : en
Pages : 796

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The only work to date to collect data gathered during the American and Soviet missions in an accessible and complete reference of current scientific and technical information about the Moon.

Author: Henrik Hargitai
Publisher: Springer
ISBN: 9781461431336
Category : Science
Languages : en
Pages : 0

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The technique of the mapping of planetary surfaces and the methods used for the identification of various planetary landforms improved much in the last 400 years. Until the 20th century, telescopic observers could interpret planetary landforms solely based on their appearance, while today various data sets acquired by space probes can be used for a more detailed analysis on the composition and origin of the surface features. Before the Greeks, the Earth and the Heavens were indisputably of different origin and nature. It was a major philosophical breakthrough - first appeared as an a priori theory, later based on observations - that the Heavens (planetary bodies) and the Earth share common features: gravity, composition and solar distance may be different, but the nature of the physical processes shaping the landforms are essentially the same. It has been a long way since we have arrived from the first telescopic description of lunar craters to the identification of various geological formations on Mars or on minor planets. Relief features of the Moon have first been observed by Galileo Galilee, via his telescope. During the next centuries, a multitude of Lunar landforms have been identified. Theories based on observations have been connected together by a scientific paradigm which explained their origin in a logical and seemingly undisputable manner. Telescopes showed a Lunar surface full of circular landforms, called craters, a landscape with no parallel on Earth. But the individual landforms had a morphological equivalent, volcanoes, which naturally led to the conclusion that craters had been created by volcanic processes. Maria ("seas") served as natural basins for water bodies. Observations clearly showed that water and air are hardly found on the Moon, the lack of clouds indicated the lack of precipitation. But the flat surface of the maria (obviously composed of marine sediments) and the meandering valleys suggested the presence of liquid water and a higher atmospheric pressure in the past - during the age of active volcanism and degassing. There were no observable active volcanic processes but some craters (though to be volcanoes) have been observed as being active: flashes of light - interpreted as eruptions - have been reported by several observers. The presence of pyroclasts thrown out from the volcanic vents of craters provided an independent evidence: meteor showers and individual meteorites falling from the sky - originating from Lunar craters. The logical and interconnected set of explanations based on observations proved to be completely false by the second half of the 20th century. The new paradigm interpreted the very same features in a new context. The case of Mars was different. There were no telescopes capable of observing relief forms (no shadows on Mars are visible from the Earth, because Mars always shows a nearly full Mars phase), so only albedo features could be seen and used for interpretation. The lack of visible relief features were interpreted as a lack of considerable topography: an unnoticed distortion in the observational data. The hue and contrast of dark and bright, orange, grey and white spots have changed seasonally, the polar areas clearly showed a polar cap made of ice and snow, but clouds have not been observed. Since Mars is farther away from the Sun than the Earth, it was evident that temperature values are lower there. Scientists concluded that Mars is an ancient, arid world. Then contemporary geology taught the theory according to which waters on the Earth are going to infiltrate underground in time, making the surface dry - observations showed that this had already happened on Mars. The last surface reservoirs of water were the polar caps. Some observers reported seeing a global network of linear features, but other have only seen very few of such albedo markings. These features were interpreted as "canals," made by a civilization for irrigation, carrying water from the poles to all around the flat plains of Mars. What was observable from the Earth were the broad stripes of irrigated vegetation (like those along the Nile), the canals themselves were too narrow to be visible from here. All theories converged - supposing that the features seen by some, but not seen by others, were real. There was no chance for verification until spacecrafts have been developed which were able to make local observations. Instead of canals, the first pictures returned revealed a surface full of craters - a landform not expected by anyone. A paradigm shift was needed to explain the features of the "new" Mars. On the Moon, features were observable, but the interpretation was wrong. On Mars, only blurred albedo markings could be observed, along with sharp lines of imagination, which again were interpreted falsely. In the case of Venus, there was no data on surface features. Only its bright cloud top could be observed from the Earth. But this fact along with the planet's orbital parameters provided enough information for a popular view on its surface conditions: a hot world (inferred from its proximity to the Sun) and also a rainy one (from its complete cloud cover). The conclusion: Venus is a global jungle possibly with dinosaurs, like the hot and wet world of the then-discovered Mesozoic era. Our current knowledge originated from these early attempts of interpreting surface conditions and geological origin of landforms from a very little set of available data. Today we have a huge set of images and other physical data which makes it possible to create models on the inner structure and thermal history of planetary bodies. Combined data sets lead to better supported models on the formation of surface features. Today we believe that most models give reliable explanation for the origin of planetary landforms. New, higher resolution images reveal new sets of meso- and microscale landforms, while images from previously not imaged dwarf planets, satellites, asteroids and cometary nuclei show landforms never seen before. In the future exoplanets are expected to provide brand new types of relief features no predictable by our Earth-and Solar System bound imagination. There are so many different landforms on planetary surfaces that it is nearly impossible for anybody to overview all of them who does not work exactly with that certain feature type. The Encyclopedia helps with presenting the landforms in searchable, alphabetical order. The book contains more than a simple list of various features: it provides context and connections between them and point to their origin. For example sand dunes were found on Venus, Mars and Titan, fluvial valleys and shorelines are present on Mars and Titan, impact craters have many different types - all are presented and explained here. Beyond the texts, references, schematic figures, images and planetary maps accompany the description of landforms, providing a wide background for detailed analyses even for geomorphologists working in planetary science. This book is to help the reader to discover the great variety of planetary landforms.

Author: Mitali Chandnani
Publisher:
ISBN:
Category : Lunar basins
Languages : en
Pages : 426

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The transition from simple to complex crater morphology in impact craters with increase in crater size has been modelled and observed in planetary bodies across the Solar System. The transition diameter depends upon the strength and gravity of the planetary body. On the Moon, this transition takes place over a diameter range of several kilometers. This range spans a diversity of crater morphologies including simple, transitional and complex craters. The diameter range of 15 20 km falls within the lunar simple-to-complex transition. All other impactor properties held constant, the 15-20 km range corresponds to a factor of three in the magnitude of impact kinetic energy. I conducted detailed geologic investigation of 244 well-preserved craters in this diameter range to elucidate the root causes of morphological variations. I used panchromatic data for observing crater and surface morphology, Digital Elevation Models (DEMs) for evaluating crater morphometry and topographic variation of pre-impact terrain, near-infrared (NIR) bands for determining the composition of crater cavity and surrounding terrain, thermal infrared bands for examining rock abundance, and Synthetic Aperture Radar (SAR) data for detecting impact melt deposits. The results of my investigation indicate that the morphological differences are primarily governed by target properties. Simple craters are confined to the highlands, and the mare are more abundant in complex craters. The mare are composed of solidified basaltic lava flows interlayered with regolith. The layering creates vertical strength heterogeneities that drive the destabilization of the transient cavity and its collapse, causing the transition to complex craters at smaller diameters in the mare. The non-layered highlands are more vertically homogeneous in strength and therefore favor simple crater formation. Eight atypically deep simple craters were identified in the highlands near the mare highlands boundaries, the most porous terrains on the lunar surface. After detailed examination of these craters in comparison to their normal-depth counterparts, I conclude that part of the energy from impact on porous target was spent in target compaction. The higher the porosity of the target, the deeper the crater and greater its volume, due to increased compaction. That only some of the craters in the high porosity terrains are deep suggests that those craters are on locally extreme-high porosity patches. However, an unusual impactor property, such as a high velocity impact, a high density impactor, or a near-vertical impact may also be a contributor. The simple craters in the highlands were observed to be located on flat or gradually sloping surfaces or degraded rims and terraces of pre-existing craters. Most craters with localized slumps superpose sharp topographic breaks such as well-developed rims and terraces of pre-existing craters. However, the topographic settings of 35% of the craters with localized slumps appeared to be similar to that of the simple craters. More detailed topographic study of the pre-impact terrains of these two morphologies revealed that the pre-impact terrains of 35% of the craters with localized slumps are gradually sloping or have subtle topographic breaks. Both sharp and subtle breaks are characterized with similar sloping directions as the adjacent craters’ walls, which led to over steepening of the transient cavity walls around this part of the rim and their collapse, thereby causing the accumulation of localized slumped material. Several simple craters were also identified to have formed on pre-impact topographic breaks. However, the simple craters’ walls that superpose these breaks were observed to be sloping in directions opposite to that of the breaks. So the ejecta around these walls was deposited along the break slopes, and thus syn-impact mass wasting occurred external (and not internal) to the crater cavity.

Author: National Aeronautics and Space Administration (NASA)
Publisher: Createspace Independent Publishing Platform
ISBN: 9781722245573
Category :
Languages : en
Pages : 92

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Impact cratering of the earth's surface is discussed and compared with lunar craters. The basic types found on earth are either simple craters or complex impact structures and basins. Meteorite fragments and shock metamorphism provide evidence of a crater's formation by meteorite impact. Known craters on earth are ordered by location and a few principal facts are given for each crater and the general terrain in which it is located. A satellite picture of each crater and maps identifying crater locations are provided. Grieve, R. A. F. and Wood, C. A. and Garvin, J. B. and Mclaughlin, G. and Mchone, J. F., Jr. Goddard Space Flight Center; Johnson Space Center...

Author: Bhairavi Shankar
Publisher:
ISBN:
Category :
Languages : en
Pages : 388

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Hyperve locity collisions of asteroids onto planetary bodies have catastrophic effects on the target rocks through the process of shock metamorphism. The resulting features, impact craters, are circular depressions with a sharp rim surrounded by an ejecta blanket of variably shocked rocks. With increasing impact energy, the inner crater cavity can preserve complex morphologies including terraced walls, central uplifts, and melted rocks. The lack of erosion due to the absence of water or an atmosphere makes the Moon the perfect target to study impact crater processes, in particular the distribution of highly shocked materials within impact craters of different sizes. This study focuses on the characterization and distribution of highly shocked impact melt deposits using multispectral satellite datasets around three complex craters on the farside of the Moon. The study sites have varying morphologies of central uplifts on the crater floor: 1) the 81 km Olcott crater has a cluster of peak hills; 2) Kovalevskaya crater i s a 113 km diameter complex crater with a central peak; and 3) Schrödinger basin has a central peak ring. Models propose that the collapse of crater walls and central uplifts during the final stages of crater formation determine where much of the melt rich rocks are eventually emplaced. The results of th is study indicate that for increasing crater sizes, the volume of melt - rich rocks generated also increases - at rates greater than model estimates. Impact melt deposits are emplaced beyond the crater rims at each of the sites and preserve a range of morphologies, including melt veneers, melt sheet, and ponded deposits. The regional and local topography, together with crater modification processes greatly affect where the impact melts are finally emplaced. The compositional analyses of the farside crust, using multispectral reflectance spectroscopy in the UV-VIS-NIR range, indicates that there is increasing evidence of highly mafic compositions (i.e., rocks rich in high-Ca pyroxene, olivine, spinel) intercalate d with in the original crustal highlands (rocks rich in plagioclase feldspar, and low-Ca pyroxenes) on the lunar farside, proving that the lunar farside is a far more geologically complicated terrain than originally assumed.

Author: Grove Karl Gilbert
Publisher:
ISBN:
Category : Lunar geology
Languages : en
Pages : 64

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