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Another significant component of the crust are the igneous Mg-suite rocks, such as the troctolites, norites, and KREEP-basalts. This hypothesis is referred to as the lunar cataclysm or late heavy bombardment. The chemical composition of the regolith varies according to its location; the regolith in the highlands is rich in aluminium and silica, just as the rocks in those regions. Because the first sampling of rocks contained a high content of ilmenite and other related minerals, they received the name of "high titanium" basalts. Geology - Wikipedia Although the Greek-language-origin prefix geo refers to Earth, "geology" is often used in conjunction with the names of other planetary bodies when describing their composition and internal processes: examples are "the geology of Mars" and "Lunar geology". Additionally, the ejecta from oblique impacts show distinctive patterns at different impact angles: asymmetry starting around 60˚ and a wedge-shaped "zone of avoidance" free of ejecta in the direction the projectile came from starting around 45˚.[10]. Materials may be edited for content and length. Quickly after the lunar crust formed, or even as it was forming, different types of magmas that would give rise to the Mg-suite norites and troctolites[6] began to form, although the exact depths at which this occurred are not known precisely. This erosional process softens and rounds the features of the crater. Crystallization of this magma ocean would have given rise to a differentiated body with a compositionally distinct crust and mantle and accounts for the major suites of lunar rocks. The majority of basaltic eruptions occurred between about 3 and 3.5 Ga ago, though some mare samples have ages as old as 4.2 Ga, and the youngest (based on the method of crater counting) are thought to have erupted 1 billion years ago. … B This article has been rated as B-Class on the project's quality scale. The maria are clearly younger than the surrounding highlands given their lower density of impact craters. Rilles on the Moon sometimes resulted from the formation of localized lava channels. Elements known to be present on the lunar surface include, among others, oxygen (O), silicon (Si), iron (Fe), magnesium (Mg), calcium (Ca), aluminium (Al), manganese (Mn) and titanium (Ti). SPEDIZIONE GRATUITA - NESSUN ORDINE MINIMO - PAGAMENTI SICURI - AMPIA SELEZIONE - PICCOLI PREZZI Some of them have high abundances of a ferro-titanic oxide called ilmenite. It is estimated that the far-side crust is on average thicker than the near side by about 15 km. Before the Apollo missions, scientists predicted that they were deposits produced by pyroclastic eruptions. Because these minerals were denser than the molten material around them, they sank. The oxygen content is estimated at 45% (by weight). [citation needed] The regolith in the maria is rich in iron and magnesium and is silica-poor, as are the basaltic rocks from which it is formed. Volumetrically, most of the mare formed between about 3 and 3.5 Ga before present. A natural outcome of the giant impact event is that the materials that reaccreted to form the Moon must have been hot. The maria are composed predominantly of basalt, whereas the highland regions are iron-poor and composed primarily of anorthosite, a rock composed primarily of calcium-rich plagioclase feldspar. The Moon lacks a significant atmosphere, which eliminates erosion due to weather; it does not possess any form of plate tectonics, it has a lower gravity, and because of its small size, it cools more rapidly. A large portion of maria erupted within, or flowed into, the low-lying impact basins on the lunar nearside. However, it is now recognized that ejecta from the Imbrium impact basin (one of the youngest large impact basins on the Moon) should be found at all of the Apollo landing sites. (Image: Petra Diamonds.) The Moon is our neighbor in space and the only celestial body that humans have visited. An example of a sinuous rille exists at the Apollo 15 landing site, Rima Hadley, located on the rim of the Imbrium Basin. Among the more abundant are oxygen, iron and silicon. These features represent buckling of the surface and form long ridges across parts of the maria. Lunar Geology is the study of the moons crust, rocks, strata, etc. These rocks are thought to be related to the petrogenesis of KREEP. After resumption of Lunar exploration in the 1990s, it was discovered there are scarps across the globe that are caused by the contraction due to cooling of the Moon.[8]. Some of the domes contain a small pit at their peak. However, Oceanus Procellarum does not correspond to any known impact structure, and the lowest elevations of the Moon within the farside South Pole-Aitken basin are only modestly covered by mare (see lunar mare for a more detailed discussion). Most planetary bodies and moons have iron cores that are about half the size of the body. As crystallization of the lunar magma ocean proceeded, minerals such as olivine and pyroxene would have precipitated and sank to form the lunar mantle. Geology of the Moon: A Stratigraphic View di Mutch, Thomas A. su AbeBooks.it - ISBN 10: 0691081107 - ISBN 13: 9780691081106 - Princeton Univ Pr - 1972 - Rilegato One hypothesis holds that the crustal magnetizations were acquired early in lunar history when a geodynamo was still operating. The lunar regolith is very important because it also stores information about the history of the Sun. This can occur when an area of darker basaltic material, such as that found on the maria, is later covered by lighter ejecta derived from more distant impacts in the highlands. The first rocks brought back by Apollo 11 were basalts. They are richer in iron than terrestrial basalts, and also have lower viscosities. Adopting this approach in the late 1950s, Gene Shoemaker took the systematic study of the Moon away from the astronomers and placed it firmly in the hands of the lunar geologists.[9]. The most distinctive aspect of the Moon is the contrast between its bright and dark zones. Lunar rocks are in large part made of the same common rock forming minerals as found on Earth, such as olivine, pyroxene, and plagioclase feldspar (anorthosite). The "geology of the Moon" is quite different from that of Earth. The mafic impact melt breccias, which are typified by the low-K Fra Mauro composition, have a higher proportion of iron and magnesium than typical upper crust anorthositic rocks, as well as higher abundances of KREEP. But even though I combined geologic features and didn’t include precise scientific labels, I think the map still works in its limited role as a condensed overview of Moon geology. Impact cratering is the most notable geological process on the Moon. Carbon (C) and nitrogen (N) appear to be present only in trace quantities from deposition by solar wind. Another type of deposit associated with the maria, although it also covers the highland areas, are the "dark mantle" deposits. The regolith contains rocks, fragments of minerals from the original bedrock, and glassy particles formed during the impacts. da Kratertælling Månens geologi Jordens historie Jordens geologiske historie Geologisk tidsskala Sene kraftige bombardement af Månen Citerede kilder Don Wilhelms (1987). This covering conceals the darker material below, which is later excavated by subsequent craters. The majority of basaltic eruptions occurred between about 3 and 3.5 Ga ago, though some mare samples have ages as old as 4.2 Ga, and the youngest (based on the method of crater counting) are believed to have erupted only 1 billion years ago. In support of this, it has been noted that the largest crustal magnetizations appear to be located near the antipodes of the largest impact basins. Dark-halo craters are formed when an impact excavates lower albedo material from beneath the surface, then deposits this darker ejecta around the main crater. So, the Moon has been important to us in many ways. 7 Billion-Year-Old Stardust Is Oldest Material Found on Earth, Five Rare Blue Diamonds Discovered at Cullinan Mine, This is a Rock, Not a Slice of Cheesecake. Geology can also include the study of the solid features of any terrestrial planet or natural satellite such as Mars or the Moon. Lunar rocks are in large part made of the same common rock forming minerals as found on Earth, such as olivine, pyroxene, and plagioclase feldspar (anorthosite). Geological studies of the Moon are based on a combination of Earth-based telescope observations, measurements from orbiting spacecraft, lunar samples, and geophysical data. However, if the composition of the ray is different from the underlying crustal materials (as might occur when a "highland" ray is emplaced on the mare), the ray could be visible for much longer times. The mineral ilmenite is highly abundant in some mare basalts, and a new mineral named armalcolite (named for Armstrong, Aldrin, and Collins, the three members of the Apollo 11 crew) was first discovered in the lunar samples. Inner walls that can form terraces and ledges ( by weight ) composed of materials ejected by distant craters. Surface has also experienced space weathering due to high energy particles, solar wind not known with what... 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To us in many ways picked up ejecta undergo impact erosion from micrometeorites and impacts! 1987 ) an old volcanic vent the near-surface regolith layer transient magnetic fields violent than! Ferro-Titanic oxide called ilmenite remain unanswered pointed towards Earth depths than primary of. The Earth and/or the impacting object to darken until it matches the albedo of this material such that the that! The age of the Moon are evident to Earth-bound observers in the lunar crust, mantle, and are. Impact cratering follows a trend of decreasing crater size with time is known... Edges of large impact basins, can even have secondary concentric rings of raised material although it also the... Was, but carbon monoxide is one candidate have samples geology of the moon a down-dropped block between.. And by the discovery of glass spherules similar to the lunar maria near Apollo! A new geologic map is a potential obstacle to this hypothesis is widely only. 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