Lunar Ring Dikes from Orbiter I

O’Keefe, John A.; Lowman, Paul D.; Cameron, W. S.

doi:10.1126/science.155.3758.77

Cited by 33 publications

(5 citation statements)

References 8 publications

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“…Abundant evidence of settling of mare lava surfaces due to cooling, shrinkage, or withdrawal suggests that circular structures such as these represent draping of cooled or cooling lavas over preexisting structure. Many of these mare ring structures have been attributed to shallow circular igneous intrusions emplaced along ring fractures over larger igneous masses[Strom, 1972;O'Keefe et al, 1967;Cameron and Padgett, 1974]. However, their abundance in the shallower maria and their partial development on craters that adjoin the highlands (Letronne, Lemonnier) argue that the draping hypothesis for the circular structures may represent the dominant mechanism of their formation.…”

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confidence: 99%

Lunar volcanism in space and time

Head

1976

Reviews of Geophysics

334

215

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Lunar volcanic deposits are dominated by areally extensive mare units occurring in regionally low areas predominantly on the lunar near side. Data obtained from lunar orbit and earth‐based observations have been used to extend the detailed characterizations derived from Apollo and Luna sample return missions to other parts of the moon. Mare volcanism occurred over a period of about 1.3 billion years (b.y.), from about 3.8 to about 2.5 b.y. ago, although the absolute age of the youngest flows is not known. An early Ti‐rich mare phase (Apollo 11 and Apollo 17 type basalts) flooded large areas of the eastern portion of the lunar near side in the early Imbrian Period (about 3.5–3.8 b.y. ago). An intermediate age, less Ti‐rich phase (Apollo 12 and Apollo 15 type basalts) flooded widespread areas of the moon predominantly in the middle to late Imbrian Period (about 3.0–3.5 b.y. ago). Finally, a second Ti‐rich phase (unsampled by Apollo and Luna) flooded portions of Mare Imbrium and the western maria in the early Eratosthenian Period (about 2.5–3.0 b.y. ago). Features associated with mare deposits and processes include lobate scarps, sinuous rilles, domes, cones, dark halo craters, collapse craters, kipukas, lava terraces, mare ridges, and volcanic complexes. The very fluid nature of lunar lavas, their voluminous and extensive flows, and the dominance of volcanic landforms of nonexplosive origin all strongly indicate that lunar eruptions and deposits are most similar to terrestrial basaltic flood and Hawaiian eruptions. Volcanic morphologic features, deposit volumes, extrusion rates, and association of many sources with major crustal fractures all suggest that mare lavas originated at subcrustal depths and worked their way to the lunar surface through a passive but fractured lunar crust. Lavas preferentially infilled the existing low regions of the moon, apparently in a hydrostatic mode. Since lunar impact basins produce most of the topographic lows, mare deposits are concentrated in and around these features. The lunar crust acted essentially as a passive platform on which mare lavas were emplaced. Far side mare deposits are patchy but are concentrated on the floors of the largest basins. Thicker far side crust and hydrostatic emplacement of mare lavas may explain the lack of extensive far side deposits even in deep basins. Individual maria had a history of filling largely determined by the geometry and state of degradation of the basins in which they occur. Mare deposits are generally less than about 2 km in thickness but probably approach 6–8 km locally in the center of some mare basins. The process of filling took place over extensive periods of time and produced complex deposits. Although some near‐surface fractionation of mare lavas must have occurred, there is little photogeologic evidence for environments in which extensive fractionation would take place; lavas appear to have erupted at high rates, to have been very fluid, and to have spread out into thin flows; evidence is lacking for shallow magma reservoirs a...

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confidence: 99%

Lunar volcanism in space and time

Head

1976

Reviews of Geophysics

334

215

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“…The second assumption is somewhat betterfounded ;chat the first; even if they were initiated by impact, the mare material and the mare basins are clearly older than the highlands (except for possible isolated extrusions, such as the Flamsteed ring (O'Keefe, et al, 1967). Moreover, all stages between complete burial by mare material and incipient subsidence a r e visible in regions such as Mare Nectaris and Oceanus Procellarum.…”

Section: Large Volumes Of Intermediate To Acidic Magmas Can Form By Pmentioning

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Composition of the lunar highlands: Possible implications for evolution of the Earth's crust

Lowman¹

1969

J. Geophys. Res.

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An alternate implication is that the continents a r e derived from the mantle by some igneous process related to formation of the earth's core in early Precambrian time. A third possibility is that the continents are meteoritic additions to the earth, and that these supposed bodies missed the moon.A basic lunar highland composition would imply that the lower continental crust layer and the main oceanic crust layer may be the original or nearlyoriginal basaltic crust of the earth.

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“…A far-side crater at 1280E,28 S, about 70 km south of Tsiolkovsky, reveals some topographx (shown in the approximiiate cross-sectional profile A'-B'-C'-D', in Fig. 1) on the north and east sides of the cralter floor that seemi.s to be slightly different in extrusive or flow, nature from that near-Flamstead and elsewhere (1). The approxinmate profile between D' and C' crosses a lobalte fr-ont.…”

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confidence: 97%

“…The cosmic ray flux at the top of the atmosphere, due to an explosion occurring a distance R light-years away, for Ecr = 1051 ergs is, F = 9 X 10"/R'ergcm-2 (1) Since cosmic rays are charged particles, they will be affected by the interstellar magnetic field to some extent. However, for the nearby explosions that are of importance here this effect is negligible.…”

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confidence: 99%