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D.E. Stuart-Alexander

Publications and source records attributed to D.E. Stuart-Alexander.

7 recordsLinked to original sources
USGS1978

Geologic map of the central far side of the Moon

This map is one of a series of geologic maps t hat will cover the entire Moon at a scale of 1:5,000,000. The geology of the central far side is compiled largely from NASA Lunar Orbiter and Apollo photographs and Soviet Zond photographs; the discussion and interpretation of geologic units incorporate the geochemical and geophysical data obtained from orbiting s p acecraft. Geologic units are based on the stratigraphic framework established by Shoemaker and Hackman (1962) as subsequently revised (summarized by McCauly , 19 67 ; Wilhelms , 1970; Mutch , 1972; Stuart-Alexander and Wilhelms , 1975). Description of map units is brief because they largely follow units described on the nearside 1:5,000,000 map of Wilhelms and McCauley (1971). The reader unfamiliar with lunar maps, mapping principles, and terminology is referred to that map. Only new units and features or units whose origins are still much in doubt are discussed here.

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USGS1972

Geologic map of the Fracastorius Quadrangle of the Moon

The multi-ringed Nectaris basin ( Hartmann and Kuiper, 1962) dominates the Fracastorius quadrangle. The basin is 840 km across as measured from the outermost ring and lies athwart four quadrangles. Frac astorius , the southeastern quadrangle , straddles the three rings of the basin (fig. 1 ). In this quadrangle most pre- Imbri an structures and many depositions were formed by the Nectaris impact. Furthermore, the emplacement of many younger deposi ts was controlled by basin structures and locally by probable multi-ring structures related to the Fecunditatis basin center ed northeast of the quadrangle. Other geologic features in the area include diverse mantling deposits and both primary impact craters and secondary impact craters produced by ejecta from distant impacts .

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USGS1971

Geologic map of the Rheita Quadrangle of the Moon

Photographs returned by unmanned Lunar Orbiters have contributed greatly to the current lunar geologic mapping program. This is particu larly true for quadrangles near the limbs, such as Rh eita in the southeast earthside quadrant. The new data and revised in terpretations amend the geologic framework established by earlier workers (Shoemaker (1962) and Shoemaker and Hackman (1962) applied basic stratigraphic principles to set up a lunar time scale; McCauly (1967) summarized changes made in he next five years of study; Wilhelms (1970) compiled all the telescopic refinements and additions to the original framework) . Detailed studies of crater morphologies from Lunar Orbiter photographs ( Pohn and Offield , 1970) permit the placement of most craters within the time- stratigraphic systems ( Offield and Pohn , 1970 : Offield , 1971). Other advances in understanding lunar processes included establishing the sequence of formation and features of large, multiringed basins ( McCauly , 1968; Stuart-Alexander and Howard, 1970) and criteria for distinguishing between impacts and possible volcanic craters (McCauly,1968).

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USGS1970

Lunar Maria and circular basins-a review

Lunar Orbiter data make it possible to examine the distribution and relations of maria and large circular basins over the entire Moon. The restricted distribution and age of the maria are in marked contrast to the apparently random distribution in time and place of the circular basins, some of which contain mare fillings. The circular basins are believed to be impact scars, and the maria to be volcanic fills which in each case are younger than the structures they fill. Twenty-nine circular basins 300 km wide or wider are recognized. They are placed in an age sequence because successive stages of degradation can be recognized from the fresh Orientale basin to the almost obliterated basin containing Mare Australe. The maria were emplaced during a short span of lunar history, although some light plains of the highlands may be older maria lightened through age. The present maria are topographically low, tend to be associated with large circular basins, and lie in a crude global belt of regional concentrations; 94% are on the hemisphere facing the Earth. Possible explanations offered for these patterns of mare distribution include impact-induced volcanism, volcanic extrusion to a hydrostatic level, isostatic compensation, lateral heterogeneity in the lunar interior, subcrustal convection, and volcanism due to disruption by Earth's gravity.

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