Young, R. A.

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UTILIZATION OF UNIQUE MARE STRATIGRAPHY FOR DETERMINATIONOF LUNAR
SURFACE MATERIAL PROPERTIES AND LOCATION OF SUBSURFACE OPERATIONS FACILITIES;
R. A. Young, Department of Geological Sciences, SUNY, Geneseo, N. Y. 144S4.
Detailed studies of mare crater size-frequency distributions in the
diameter range from 100m to 600m have demonstrated a distinct inverse relation
between total numbers of craters and surface ages in the diameter interval
below 300m (i). This relationship indicates that caution must be exercised
in any theoretical calculations of the particle size distributions of regolith
fragments based on models using measured crater size distributions. Because
the disappearance of small craters in this size interval (<300m) is considered
to be caused by the cumulative effects of seismic vibrations, as well as
impact gardening in the thickening rego!ith, _,_h_ _,,_ are .........
estimate the effect of prolonged impact gardening on the physical nature of
the regolith. The buffering effect of the growth-regulated regolith has
been discussed by Quaide and Oberbeck (2), but additional factors may be of
importance. For example, the subsurface stratigraphy of Mare Serenitatis
(3,4) has produced a conspicuous increase in the size and number of ejecta
fragments around small craters. Additional studies (5) have shown that both
crater-size frequency distributions and crater morphology for craters up to
700m in diameter are measurably affected by the magnitude of impact gardening
and the nature of subsurface discontinuities in individual mare regions.
It would be advantageous to attempt calculations of probable regolith
fragment size distributions for a number of theoretical ages and simple
layered models to explore the economics of various surface mining, stripping,
construction, or processing operations. In this regard, each mare basin or
subregion is probably unique.
Southern Mare Serenitatis (inside the dark annulus) is the most obvious
of those regions where a number of orbital and remote sensing experiments
indicate an older regolith in a widespread subsurface layer that is probably
I00 to 200m beneath relatively coherent surface lavas (4,5). The evidence
for this buried zone can be seen in crater-size frequency distributions, the
morphology of craters <700m in diameter, infrared spectral reflectance data(6),
Lunar Sounder data (7)_ the ejecta of large craters such as Bessel (4), and
rim height/diameter ratios of partially flooded craters (Fig. I).
The presence of this buried zone of regolith and dark mantle (?) material
provides a unique situation for combined subsurface construction, natural
shielding, and access to large quantities of fragmental lunar materials. In
addition, it is possible that the voids in the buried regolith contain mineral-
ized zones, intrusive veins, or vapor phase mineral deposits from events
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UTILIZATIONOFUNIQUEMARESTRATIGRAPHY
Young, R. A.
associated with the emplacementof the younger surface flows and intrusive
mare ridges.
Access to this buried regolith zone is readily provided by fresh craters
less than one km in diameter (Fig. I). The mineralogy of ejecta from these
craters can be studied by remote spectral reflectance from earth or lunar
orbit (6,8). Fresh craters with progressively larger diameters could be
examinedby infrared reflectance to explore below the surface and detect
mineralogical differences, regolith, or dark mantle zones.
Mare Serenitatis has the additional advantage of containing someof the
youngest intrusive mare ridges (4) as demonstrated by flow into numerous
postmare impact craters. These ridges are probably the most coherent surface
exposures of lunar bedrock with a minimumof regolith cover and could provide
solid foundations on the surface for related engineering, scientific, or
launch facilities. The ridges mayalso represent late-stage differentiation
of magmasinjected as residual melts from the earlier widespread mare flooding.
For this reason, they might be the best candidates in the maria for mineral
"prospecting".
References
I. Young, R. A., 1975, Proc. Lunar Sci. Conf. 6th, p. 2645-2662.
2. Quaide, W. and Oberbeck, V., 1975, Moon, 13, p. 27-55.
3. Young, R. A., Brennan, W. J., and Nichols, D. J., 1974, Proc. Lunar Sci.
Conf. 5th, p. 159-169.
4. Young, R. A. and Brennan, W. J., 1976, Final Report NASA Contract
NAS 9-12770, 171 p.
5. Young, R. A., 1976, In "Lunar Science VII, The Lunar Science Institute",
_in press).
6. Johnson, T. V., Matson, D. L., Phillips, R. J., and Saunders, R. S., 1975,
Proc. Lunar Sci. Conf. 6th, p. 2677-2688.
. Phillips, R. J., Adams, G. F., Brown, W. E., Eggleton, R. E., Jackson, P.,
Jordan, R., Peeples, W. J., Porcello, L. J., Ryu, J., Schaber, G., Sill,
W. R., Thompson, T. W., Ward, S. H., and Zelenka, T. S., 1973, Proc.
Lunar Sci. Conf. 4th, p. 2821-2831.
8. McCord, T. B., Charette, M. P., Johnson, T. V., Lebofsky, L. A. and Pieters,
C., 1972, Jour. Geophys. Res., 77, p. 1349-1359.
UTILIZATION OF UNIQUE MARE STRATIGRAPHY
R. A. Young
157
DIAGRAMMATIC CROSS SECTIONS
MARE SERENITATIS
(NOT TO SCALE)
:; TAN FLOWS
BURIED REGOLITH ENTRANCES AREAS
BLUISH LAVA FLOWS
I 1 I I,
FIGURE 1


Utilization of unique mare stratigraphy for determination of lunar surface material properties and location of subsurface operations facilities

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