When I See You Again Lunar Maria

Lunar Maria

Moon

Bonnie J. Buratti , in Encyclopedia of Physical Science and Engineering (Tertiary Edition), 2003

V.A.2 Maria and Basins

The lunar maria (or plains), which were formed between iii.1 and iii.ix billion years ago, are the youngest geologic units on the lunar surface, except for more contempo touch on craters. The release of heat from large impacts acquired all-encompassing melting and extrusion of basaltic lavas on the moon. In some cases the extrusions may accept occurred in two stages: kickoff from the impact melt itself and later on from eruptions caused past subsequent heating. Several maria are large filled-in touch on features, or basins, with clearly circular delineations. Some basins, such as Mare Orientale, are multiring structures.

Large mountain chains at the edges of the large basins were uplifted at the time of impact. Wrinkle ridges, which are believed to be compressional features formed virtually the end of the menses of vulcanism, are seen in many of the maria.

The lunar maria are found primarily on the earth side of the moon. One possible physical caption for the unequal distribution is that the maria formed in accordance with hydrostatic equilibrium: the moon's center of mass is closer to the world's side and the chaff on the farside is thus thicker.

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The Moon

Stuart Ross Taylor , in Encyclopedia of the Solar Arrangement (2nd Edition), 2007

vii.1 Mare Basalt Ages

The oldest ages for returned lunar mare basalts are from Apollo xiv breccias; aluminous low-Ti basaltic clasts in these breccias range in age from 3.9 to four.3 billion years. The oldest basalt from a visible maria is Apollo sample number 10003, a low-K basalt from Mare Tranquilitatis with an age of iii.86 ± 0.03 billion years. This gives a younger limit for the age of the Imbrium standoff because the lavas of Mare Tranquilitatis overlie the Imbrium ejecta blanket.

The youngest dated sample is number 12022, an ilmenite basalt with an age of iii.08 ± 0.05 billion years, although some doubtful younger ages are in the literature. Depression-Ti basalts are generally younger than high-Ti basalts. Stratigraphically younger flows, some of which announced to embay young ray craters, may exist as young every bit one billion years but are of very limited extent. The most voluminous menstruation of eruption of lavas appears to have been between about three.8 and three.1 billion years ago. Isotopic measurements evidence that the mare basalt source regions formed at about four.iv billion years, and this historic period must correspond the solidification of much of the magma ocean.

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Lunar Rocks

Arden 50. Albee , in Encyclopedia of Physical Science and Technology (3rd Edition), 2003

II.D Mare Volcanism

Four of the Apollo missions landed on the mare plains and returned samples of mare volcanic rocks. The lunar mare rocks are basalts like in texture and chemic limerick to volcanic basaltic rocks on the world. The lunar basalts consist importantly of the silicates—clinopyroxene ([Ca,Fe,Mg]SiO₃), anorthitic plagioclase (CaAl₂Si₂O₈), olivine ([Mg,Fe]₂SiO_four)—and the iron–titanium oxides, ilmenite and spinel. The mineralogy is generally like to that on world except for the very low content of sodium in the plagioclase, the loftier abundance of ilmenite, and the total absence of hydrous alteration minerals. Textures range from fine-grained and partially glassy, such as might be expected in a basalt that chilled quickly at the surface of a flow, to coarser-grained, interlocking textures that result from slower cooling within a menstruum.

Terrestrial basalts are formed past partial melting in the olivine and pyroxene-rich rocks of earth's mantle. Every bit melting occurs, the early on formed silicate cook has the composition of basalt, and it separates and rises to the surface. The detailed limerick of a basalt provides a probe into the temperature, depth, and composition of the source; basalt can be readily dated, and the textures provide information on the cooling and crystallization history. Mare basalts differ from terrestrial basalts in some detailed elemental abundances. Lunar basalts (1) contain no detectable H_iiO; (2) are low in alkalis, especially Na; (3) are high in TiO₂; (4) are low in Al_iiO₃ and SiO_two; (5) are high in FeO and MgO; and (half-dozen) are extremely reduced. Lunar basalts contain no trivalent Atomic number 26, and the reduced ions (Fe metal, trivalent Ti, and divalent Cr) may be present.

The petrologic and chemical variation within the lunar basalts of the various missions is summarized in Fig. half-dozen; their isotopic ages fall between 3.xv and 3.96 Gy. The samples tin be divided into two broad groups: an older, high-titanium grouping (ages 3.55–iii.85 Gy; TiO₂, nine–14%) and a younger, low-titanium group (ages 3.15–three.45 Gy; TiO_ii 1–5%). Laboratory experiments indicate that the high-titanium mare basalts could be derived from partially-melted titanium-rich cumulates at depths of nigh 100 km and that low titanium basalts could be produced by fractional melting of olivine and pyroxene-rich rock at depths of 200–400 km.

Earth-based telescopic spectra signal that a wide multifariousness of volcanic flows cover the maria, only a third of which were sampled by the Apollo missions. Further, the multispectral images from Clementine suggest that the high Ti basalts, so arable in the returned samples, encompass just a small fraction of the surface lava flows on a global basis.

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The Solar Organisation at Ultraviolet Wavelengths

Amanda R. Hendrix , ... Deborah Fifty. Domingue , in Encyclopedia of the Solar Organisation (Second Edition), 2007

4.viii. The Moon and Mercury

The first UV observations of the Moon were made at FUV wavelengths using the instrument aboard the Apollo 17 orbiter. Information technology was noted in these measurements that the lunar maria regions, darker than the highlands at visible wavelengths, are brighter than the highlands in the FUV. This was the first indication of the so-chosen spectral reversal, which was also detected at EUV wavelengths using measurements by the EUVE. This phenomenon is attributed to the concept that FUV measurements probe simply the outer layers of the grains (surface scattering, as opposed to volume handful measured at longer wavelengths), and that space weathering processes may cause the lunar grains to exist covered with a fine coating. Lunar samples measured in the laboratory support this idea: Lunar soils (presumably more than weathered) show the spectral reversal, while ground-upwards lunar rocks (presumably less weathered) exercise not. Galileo UVS measurements in the NUV showed that the maria are darker than the highlands and that the spectral reversal must occur at a wavelength shorter than ∼2200 Å. The HUT measurement of the lunar surface (a region about Flammarion-C, a border expanse betwixt mare and highlands) at FUV wavelengths indicated an albedo of ∼4% with a slight increase in effulgence toward shorter wavelengths. Because of the different spectral behavior at UV versus visible wavelengths, ratio images of UV to visible color images and visible reflectance spectra are used to map spectral trends related to opaque mineral abundance and the combined effects of FeO content and soil maturity. From the Apollo samples, it is known that the dominant opaque mineral is ilmenite, which is high in Ti content. Thus, UV/visible ratio images have been used to map Ti content variation in the lunar mare basalts.

The Mariner 10 spacecraft carried a color imager that included a near UV filter (3550 Å). Mercury image ratios (UV/visible) have been used to map spectral trends associated with geologic features, using similar methods every bit used on lunar images. A lower UV/visible ratio suggests more FeO, or more mature soil. Spectrally neutral opaque minerals (such as ilmenite) tend to lead to a higher UV/visible ratio. Mercurian regions believed to be volcanic in origin have been found to have FeO amounts slightly less than average, consistent with aboriginal lava flows.

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Planetary Satellites, Natural

Bonnie J. Buratti , in Encyclopedia of Physical Science and Technology (3rd Edition), 2003

4.A.iii Early History of the Moon

Soon after the Moon accreted information technology heated up due to the reasons outlined in Section II.B . The result was the melting and eruption of basaltic lava onto the lunar surface between 3.viii to almost two.8 billion years ago to form the lunar maria. This lava was highly fluid under the weaker gravitational field of the Moon and spread over vast distances.

Earlier Soviet and American spacecraft explored the Moon, in that location was considerable debate over whether the craters on the Moon were of impact or of volcanic origin. Morphological features, such as bright rays and ejecta blankets, around large craters show that they were formed past impacts.

The ringlike structures that delineate the maria are the outlines of impact basins, which filled in with lava. The maria are not as heavily cratered as the uplands because the lava flows which created them obliterated preexisting craters.

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The Apollo program

Eric A. Jerde , in Sample Render Missions, 2021

two.8.4 Basalt – after volcanism

Lunar basalts bear witness a wide variation in compositions, and a wider range in ages. On Globe, basalts represent fractional melts from the pall, and thus provide constraints on the drapery'due south composition. Although volumetrically small (< 1 per centum of the crustal volume – Head and Wilson, 1992), the lunar mare basalts provide significant data about the lunar interior limerick during a 2d era of melting and igneous action that began shortly before the end of activity related to the magma body of water crystallization. The lavas were very depression in water contents, and this, forth with mostly depression SiO_two contents and high temperatures, means that lunar mare basalts had very depression viscosities. The result was that the basalts formed highly effusive flows that filled large swaths of impact basins very quickly.

One of the peradventure surprising discoveries about lunar basalts is that these compositions appear to be unique to the Moon. There are no terrestrial basalts that are similar in composition to those on the Moon, which are college in FeO and MgO, and lower in CaO, Al₂O_iii, and Na_twoO. Indeed, meteoritic samples of basalt (fifty-fifty those from Mars) are also very different from lunar basalts. The low Na₂O probable reflects the general depletion in the Moon of volatile elements (Taylor, 1982), but the significantly lower CaO and Al_iiO₃ reflect a mantle source that is unusual. The flotation of calcium-rich plagioclase to form the lunar crust would have removed calcium and aluminum from the residua of the magma bounding main. Given this Lunar Magma Body of water image, the mare basalts are viewed every bit having formed non by melting of a archaic lunar mantle, but by secondary melting of the mafic-rich residua of magma sea crystallization (Shearer et al., 2006).

The bulk of mare basalts occupy the major impact basins on the Moon. The ages of the basalts and highlands rocks accept permitted the development of meteoroid flux models for the Moon, which then provide for the determination of ages for the diverse basin-forming events. This work resulted in the determination that nearly large basins formed between 4.0 – 3.8 Ga. Whether this represents simply the tail end of the Solar Arrangement accretion procedure (e.g., Neukum et al., 2001), or an actual increase in large impacts to course a "cataclysmic bombardment" (e.k., Cohen et al., 2000) is still an open question.

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Mercury

Robert G. Strom , in Encyclopedia of the Solar System (2d Edition), 2007

6.1.four SMOOTH PLAINS

The younger smoothen plains cover almost 40% of the total area imaged past Mariner 10. About 90% of the regional exposures of smoothen plains are associated with large impact basins. They also fill up smaller basins and large craters. The largest occurrence of smooth plains fill and surround the Caloris Basin (Fig. 7 ), and occupy a big circular surface area in the n polar region that is probably an former bear on bowl (Borealis Basin). They are similar in morphology and way of occurrence to the lunar maria. Craters within the Borealis, Goethe, Tolstoy, and other basins have been flooded past smooth plains ( Fig. fourteen). This indicates the plains are younger than the basins they occupy. This is supported past the fact that the density of craters superimposed on the smooth plains that surround the Caloris Basin is substantially less than the density of craters superimposed on the floors of all major basins including Caloris. Furthermore, several irregular rimless depressions that are probably of volcanic origin occur in polish plains on the floors of the Caloris and the Tolstoy basins. The smooth plains' youth relative to the basins they occupy, their great areal extent, and other stratigraphic relationships suggest they are volcanic deposits erupted relatively late in Mercurian history. Mariner ten enhanced color images bear witness the boundary of smooth plains inside the Tolstoy Basin is also a color purlieus, further strengthening the volcanic interpretation for the polish plains. Based on the shape and density of the size/frequency distribution of superimposed craters, the polish plains probably formed near the finish of tardily heavy battery. They may take an boilerplate age of about iii.viii billion years as indicated by crater densities. If so, they are, in general, older than the lava deposits that constitute the lunar maria.

Three big radar-bright anomalies accept been identified on the unimaged side of Mercury. They are designated as A (347° W longitude, −34° latitude), B (343° W longitude, 58° longitude), and C (246° Due west longitude, eleven° N latitude). All features are relatively fresh touch on craters with radar-bright ejecta blankets and/or rays similar to Kuiper crater (60 km diameter) on the imaged portion of Mercury. Characteristic A is 85 km in diameter with an extensive ray system and a crude radar-bright floor, consistent with a fresh impact crater (Figure xv). Feature B is 95 km diameter with radar-brilliant rays and a radar-dark floor (Figure 15). Unlike feature A, the radar-dark flooring indicates it is shine at the 12.six cm wavelength of the image. Feature C is a fresh crater near 125 kilometers in diameter. Water-rich comets or asteroids responsible for i or more of these craters could be the source of the polar water-ice deposits.

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Planets and Moons

B.A. Ivanov , W.1000. Hartmann , in Treatise on Geophysics, 2007

10.06.4.1 Hartmann Product Function

To stand for the crater SFD found on the terrestrial planets, Hartmann uses the log-incremental SFD representation with a standard $\sqrt{ii}$ diameter bin size. Figure 4 in Hartmann (2005) is a proper illustration of the process of averaging of individual mare counts. We call his upshot the 'Hartmann product function', or HPF. The number of craters per square kilometers hither is calculated for craters in the bore bin D₅₀ < D < D _R, where D _L and D _R are the left and correct bin boundary and the standard bin width is D _R/D _L = 2^i/2.

The tabulated HPF is an aggregation of data selected by Hartmann to present the production function for one specific moment of time – the boilerplate time of lunar mare surface formation. For larger craters (D > 4 km), he used an exhaustive itemize of individual crater-by-crater diameters, measured past Arthur et al. (1963, 1965a, 1965b, 1966). Here the condition to have a fresh surface is satisfied by the fact that most lunar mare basalt samples have a narrow range of ages (due east.thou., 3.2–3.6 Gy; Stöffler and Ryder, 2001). Usage of the cratering chronology, discussed later in this chapter, helps to estimate the rate of accumulation of mare basalt flows (Hiesinger et al., 2003). Using figure 13 from Hiesenger et al., we plot the estimated cumulative book of mare basalts, accumulated with historic period, in Figure 7 . The median book fraction (50%) of basalt flooding was reached ∼iii.4 Ga while the interval from 0.ii to 0.8 fraction occupied the model historic period interval from ∼2.8 to ∼three.5 Ga. This fourth dimension interval may exist used as an figurer of the 'fourth dimension slit width' for Hartman's crater counts for an 'boilerplate mare' surface.

The tabulated HPF has been constructed by starting with a lunar curve that combines and averages crater counts in different mare areas. These lunar counts included data from the meticulous Arthur catalog which tabulated frontside lunar craters of D > four km. Table 1 lists these Hartmann'due south mare crater counts in each bore bin together with Hartmann'southward scaled estimates of the Martian Neukum production part (NPF) (Hartmann, 2005). The full number of largest craters ( Table 1 ) illustrates that during the last 3.5 Ga the Moon experienced ∼ten impacts, creating craters 64–128 km in bore, while ∼100 craters larger than this diameter take been formed on the whole of Mars. The corresponding average altitude betwixt these craters is approximately 2000 km on the Moon and 1200 km on Mars. One can state that in the last iii.5 Ga the Moon and Mars have accumulated relatively sparse populations of largest craters.

Table ane. HPF for the Moon and Mars

D _L	D _R	The Moon			Mars
D _L	D _R	Mare counts Northward _H per ikm ²	Global number of large craters	N _H, 3.5Ga	Global number of large craters	N _H, 3.fiveGa	Due north _H, iGa
iii.90 g	5.52 m			2.31 (4) ^b		1.24 (4) ^b	4.04 (3) ^b
five.52 m	7.81 m			1.33 (four) ^b		seven.14 (3) ^b	2.33 (three) ^b
7.81 m	11.0 chiliad			6.53 (3) ^b		three.50 (3) ^b	1.14 (iii) ^b
11.0 m	15.six m	7.33 ± 0.29 (one) ^a		two.62 (three) ^b		ane.41 (iii) ^b	4.58 (2) ^b
15.vi m	22.1 one thousand	two.42 ± 0.12 (1)^a		i.09 (three) ^b		5.85 (2) ^b	1.91 (ii) ^b
22.1 m	31.ii grand	1.57 ± 0.ten (1)^a		iii.81 (2)		two.04 (2)	6.66 (1) ^b
31.ii m	44.ii m	5.82 ± 0.48 (0)^a		1.37 (2)		7.35 (1)	two.iv (1) ^b
44.two g	62.5 m	three.13 ± 0.35 (0)^a		v.40 (ane)		2.90 (two)	nine.44 (0) ^b
62.5 k	88.3 k	ane.87 ± 0.27 (0)^a		1.89 (ane)		1.01 (1)	iii.3 (0) ^b
88.3 m	125 chiliad	ane.84 ± 0.17 (0)^a		6.95 (0)		3.73 (0)	1.22 (0) ^b
125 m	176 m	i.06 ± 0.thirteen (0)^a		two.l (0)		i.34 (0)	4.37 (−one) ^b
176 chiliad	250 chiliad	8.08 ± 0.55 (−i)^a		8.40 (0)		4.51 (−)	1.47 (−ane) ^b
250 k	353 grand	5.79 ± 0.52 (−1)^a		2.69 (−one)		one.44 (−i)	4.seventy (−2) ^b
353 grand	500 m	1.04 ± 0.06 (−1)		7.91 (−two)		4.24(−two)	1.38(−two)
500 m	707 m	3.23 ± 0.fourteen (−two)		2.thirty (−2)		1.23(−ii)	4.02(−iii)
707 thou	ane km	1.14 ± 0.05 (−2)		6.sixty (−iii)		iii.54(−iii)	ane.15(−three)
1 km	1.41 km	1.64 ± 0.09 (−3)		1.76 (−3)		9.44(−4)	three.08(−4)
1.41 km	ii km	5.74 ± 0.46 (−4)		7.32 (−4)		3.93(−four)	i.28(−4)
two km	2.83 km	2.82 ± 0.25 (−4)		3.92 (−4)		2.10(−4)	vi.85(−5)
2.83 km	iv km	1.21 ± 0.11 (−4)		two.10 (−4)		1.13(−4)	3.67(−5)
4 km	5.66 km	eight.31 ± 0.37 (−5)		one.thirteen (−4)		6.06(−5)	1.98(−5)
five.66 km	viii km	5.10 ± 0.29 (−5)		vi.05 (−5)		three.25(−5)	1.06(−5)
8 km	11.3 km	2.56 ± 0.21 (−5)		3.24 (−five)		one.74(−v)	5.68(−6)
11.3 km	xvi km	one.67 ± 0.18 (−iv)		ane.74 (−5)		9.33(−6)	3.04(−six)
16 km	22.six km	5.51 ± 1.06 (−6)		9.29 (−half dozen)		four.98(−six)	one.62(−6)
22.six km	32 km	4.29 ± 0.94 (−6)		4.98 (−6)		two.67 (−half dozen)	8.71 (−7)
32 km	45.iii km	2.24 ± 0.68 (−6)		two.67 (−6)		1.43 (−6)	4.67 (−7)
45.3 km	64 km	two.04 ± 0.72 (−6)	∼77	1.37 (−6)	∼200	7.35 (−7)	2.4 (−7)
64 km	90.five km	two.14 ± ii.14 (−7)	∼8	6.38 (−seven)	∼92	iii.42 (−7)	1.12 (−7)
90.5 km	128 km	2.14 ± 2.xiv (−seven)	∼8	2.98 (−7)	∼43	1.60 (−vii)	v.21 (−8)
128 km	181 km	ane.00 (−7)^c	∼four	1.39 (−vii)	∼xx	7.46 (−8)	2.43 (−8)
181 km	256 km	four.69 (−8)^c	∼2	6.48 (−8)	∼9	3.48 (−viii)	1.13 (−eight)
256 km	362 km	2.18 (−8)^c	∼1	3.02 (−8)	∼4	1.62 (−8)	5.28 (−ix)
362 km	512 km			ane.41 (−8)	∼2	7.56 (−ix)	ii.47 (−9)
512 km	723 km			6.58 (−9)	∼1	3.53 (−9)	1.xv (−9)
723 km	1024 km			3.07 (−nine)	<1	ane.65 (−ix)	v.37 (−10)

a: Density of craters is in the equilibrium state below the production function.
b: These values are for the production role estimates.

Hartmann's estimates for 1 Ga (the last cavalcade in Table 1 ) were scaled by him to any age younger than ∼iii.iii Ga bold the constant cratering charge per unit.

The HPF may exist presented as a piece-wise three-segment ability law (Ivanov, 2001; Hartmann, 2005):

[20a] $log {Due north}_{H} = - two.198 - 2.20 log D_{50}, D_{L} > 64 km$

[20b] $log N_{H} = - 2.920 - 1.80 log D_{50}, 1.41 km < D_{50} < 64 km$

[20c] $log N_{H} = - two.616 - 3.82 log D_{L}, 0.3 < D_{L} < 1.41 km$

Mare craters reach a saturation equilibrium areal density above D ∼ 300 chiliad and to define the product office for smaller craters one should apply crater counts in areas, much younger than 3.5 Ga. Deriving Mars isochrones, Hartmann (2005) adopted a continuation of the curve past grafting on the shape at the minor-D end of the NPF, discussed below. The NPF uses the –2.9 cumulative gradient (Shoemaker et al., 1970) giving lunar HPF-similar SFD for small craters as:

[20d] $log {North}_{H} = - 2.0 - 2.90 log D_{L}, 0.01 < D < 0.125 km$

Note that Hartmann (2005) includes effects of atmospheric shielding for small Martian affect craters.

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Triton

William B. McKinnon , Randolph L. Kirk , in Encyclopedia of the Solar Organisation (2nd Edition), 2007

6.6 Geological History

It is notable that the volcanic province shown in Effigy 10 is 1 of two similar ones, with the 2nd occurring to the southeast and together stretching beyond 1000 km of Triton'due south surface. The alignments of volcanic vents in both provinces suggest extension and rifting of Triton's relatively strong icy outer beat, or lithosphere. The volcanic plains shown in Effigy ten are as well very sparsely cratered (the largest crater visible is 16 km across), much less cratered than, say, the lunar maria. Estimates of the rate at which comets bombard Triton suggest that these provinces are no more than 300 million years onetime, and possibly much less. A wide region of Triton'south sublithospheric pall was thus hot and partially molten very late in solar organisation history, and probably remains so. Such internal warmth is as well consistent with a deep subsurface sea ( Fig. seven).

The loftier volcanic plains postdate most of the other terrains on Triton. They stratigraphically overlie the terraced plains to the west and the hummocky plains to the east. The terraced plains class into and announced to superpose the cantaloupe terrain. The relative age of the cantaloupe terrain cannot be determined by traditional crater counting methods, because the rugged topography there prevents reliable crater identification in Voyager images. Stratigraphically, however, cantaloupe terrain appears to be the oldest unit on Triton. The linear ridges patently postdate the cantaloupe terrain, all the same some ridges fade into the terraced plains to the east and another is discontinuous as it crosses the hummocky and smooth plains near the equator to the eastward (Figs. one and eleven); no ridges cut the loftier volcanic plains.

The eastern hummocky and smooth plains contain the most heavily cratered region on Triton, and when due account is taken of the concentration of cometary impacts on Triton's leading hemisphere, appears to be somewhat older than the loftier volcanic plains to the north and northwest. The cantaloupe terrain, then, must be even older. The hummocky terrain may be a degraded version of cantaloupe terrain. Indeed, cantaloupe terrain has been suggested to underlie much of Triton's surface. (For example, cantaloupe-similar topography extends well due south into the bright region of the trailing hemisphere.)

The youngest surfaces on Triton, naturally, involve the mobile materials of the brilliant terrains. These probably include the zoned maculae of the eastern hemisphere. The geological substrate upon which the brilliant materials reside may of course be older. The walled plains themselves are locally the youngest stratigraphic units. Ruach Planitia and a larger planitia immediately to the west are less cratered than the loftier volcanic plains, admitting with a big statistical uncertainty. The filling of these walled plains may thus stand for the well-nigh recent volcanic activeness on the hemisphere of Triton seen by Voyager.

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Meteorites, Comets, and Planets

Thou.J. Taylor , Due east.R.D. Scott , in Treatise on Geochemistry, 2003

1.18.1 Introduction: The Importance of Mercury

Mercury is an of import part of the solar arrangement puzzle, yet nosotros know less most it than any other planet, except Pluto. Mercury is the smallest of the terrestrial planets (0.05 Earth masses) and the closest to the Sun. Its relatively high density (5.iv k cm⁻³ ) indicates that it has a large metallic core (∼3/4 of the planet's radius) compared to its silicate pall and crust. The existence of a magnetic field implies that the metallic cadre is nonetheless partly molten. The surface is heavily cratered similar the highlands of the Moon, but some areas are smooth and less cratered, possibly similar the lunar maria (simply not as dark). Its surface composition, as explained in the adjacent section, appears to exist depression in FeO (but ∼three wt.%), which implies that either its crust is anorthositic ( Jeanloz et al., 1995) or its mantle is similarly low in FeO (Robinson and Taylor, 2001).

The proximity of Mercury to the Dominicus is particularly important. In one somewhat outmoded view of how the solar arrangement formed, Mercury was assembled in the hottest region shut to the Sun so that virtually all of the iron was in the metallic state, rather than oxidized to FeO (e.one thousand., Lewis, 1972, 1974). If correct, Mercury ought to have relatively a depression content of FeO. This hypothesis also predicts that Mercury should accept high concentrations of refractory elements, such equally calcium, aluminum, and thorium, and low concentrations of volatile elements, such as sodium and potassium, compared to the other terrestrial planets.

Alternative hypotheses tell a much more nomadic and dramatic story of Mercury's birth. In 1 culling view, wandering planetesimals that might take come up from as far away equally Mars or the inner asteroid belt accreted to class Mercury (Wetherill, 1994). This model predicts higher FeO and volatile elements than does the high-temperature model, and like compositions among the terrestrial planets. The accession process might have been accompanied by a awe-inspiring impact that stripped abroad much of the young planet'southward rocky mantle, accounting for the loftier density of the planet (Benz et al., 1988). Well-nigh planetary scientists consider such a giant impact as the most probable hypothesis for the origin of the Moon. A giant impact model could explicate the high density of Mercury if much of the silicate material failed to reaccrete, just it would not explain the low FeO concentration of the planet. Thus, knowing the composition of Mercury is crucial to testing models of planetary accretion.

In this chapter we summarize what we know near the chemic composition of Mercury, with emphasis on assessing the amount of FeO in the majority planet. FeO is a especially useful quantity to evaluate the extent to which Mercury is enriched in refractory elements, because its concentration increases with decreasing temperature in a cooling gas of solar composition (eastward.g., Goettel, 1988). Nosotros then examine models for the composition of Mercury and outline tests that future orbital missions to Mercury will be able to make.

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harrickslefterim.blogspot.com

Source: https://www.sciencedirect.com/topics/physics-and-astronomy/lunar-maria

Harricks Lefterim

When I See You Again Lunar Maria

Lunar Maria

Moon

V.A.2 Maria and Basins

The Moon

vii.1 Mare Basalt Ages

Lunar Rocks

II.D Mare Volcanism

The Solar Organisation at Ultraviolet Wavelengths

4.viii. The Moon and Mercury

Planetary Satellites, Natural

4.A.iii Early History of the Moon

The Apollo program

two.8.4 Basalt – after volcanism

Mercury

6.1.four SMOOTH PLAINS

Planets and Moons

10.06.4.1 Hartmann Product Function

Triton

6.6 Geological History

Meteorites, Comets, and Planets

1.18.1 Introduction: The Importance of Mercury

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