Lunar igneous intrusions revealed from Apollo 10 and 11 flight photograph

El-Baz, F.

English

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LUNAR IGNEOUS INTRUSIONS 
December 3 ,  1 9 6 9  
.. .................... 
https://ntrs.nasa.gov/search.jsp?R=19700009439 2020-03-12T01:05:13+00:00Z
ELLCOMM, I N C .  
Washington, D. C. 20024 
LUNAR IGNEOUS INTRUSIONS 
December 3 ,  1969 
TR-69-340-5 
Farouk El-Baz 
Work performed for Manned Space Flight, National Aeronautics and 
Space Administration under Contract NASW-417. 
BELLCOMM, INC.  TR- 6 9- 3 4 0- 5 
ABSTRACT 
Apollo 10 and 11 photographs reveal a number of 
probable igneous intrusions, including three probable dikes 
that crosscut the wall and floor of an unnamed 75 km crater 
on the moon's farside. These intrusions are distinguished 
by their setting, textures, structures, and brightness 
relative to the surrounding materials. Recognition of these 
probable igneous intrusions in the lunar highlands augments 
the many indications of the heterogeneity of lunar materials 
and the plausibility of intrusive igneous activity, in addition 
to extrusive volcanism, on the moon. 
B E L L C O M M ,  I N C .  
LUNAR IGNEOUS INTRUSIONS 
TR- 6 9- 3 4 0- 5 
The Apollo 10 and 11 missions photographed a number 
of interesting regions on the moon's farside. Previous 
photographic coverage of these regions was provided by the 
unmanned Luna and Lunar Orbiter spacecraft. However, the 
resolution, sun angle, and viewing direction of Apollo 
photography helped delineate features and structures not 
evident in previous photography. 
One of these regions includes an unnamed*, generally 
round, partly crenulated, relatively young, large crater, about 
75 km in diameter (Figure 1). The crater, whose center is at 
approximately 4'N 120'E on the Lunar Farside Chart (LFC-l), 
is situated in as yet undivided highland materials in the general 
area previously known as the "Soviet Mountains" It exhibits 
a raised, wavy and sculptured rim, and terraced interior walls 
which suggest, although not unequivocally, an impact origin. 
It is not clear from the photographs whether or not the crater 
is rayed: the presence of an extensive ray system is held by 
most as a strong criterion for the impact origin of the 
younger lunar craters. 
The crater is a few kilometers deep and the depth 
of its floor in relation to the rim crest varies with the 
amount of fill. The crater wall is terraced, up to six 
levels, and the highest terrace is steeper than most: a 
feature common to craters of similar size. The floor of the 
crater displays a prominent central peak which is forked. 
It forms a unique Y shape (Figures 1 and 21, with the right 
arm trending nearly due north. 
Apollo 10 and 11 photographs of this crater are 
oblique views, taken at high sun illumination with a hand- 
held Hasselblad camera from an altitude of about 110 km above 
the lunar surface. On Apollo 10, both the 80 mm lens (frames 
4470-4474) and the 250 mm lens (frames 4349-4364) were used. 
Similarly, the Apollo 11 mission photographed the crater in 
medium resolution (frames 5419-5422, 6540-6543, and 6271) and 
in high resolution (frames 6448-6449). Both missions provided 
excellent stereoscopic coverage of the crater and its environs. 
*The crater is given the number 211 by the International 
Astronomical Union as indicated on the (G) Lunar Farside Chart 
(LFC-l), 1967 Edition. 
ELLCOMM,  INC. - 2 -  
Distinct layering is displayed along the crater walls, 
where rock ledges protrude at several levels within the wall 
terraces. At the rim crest, the first ledge of rock is in 
evidence along the crenulations, as in the middle of the 
right hand edge of Figure 2 (Apollo 10 frame 4350). At 
lower levels on the wall, discontinuous rock ledges could 
be traced for distances of 10 km or more, These ledges are 
indicative of horizontal bedding and are different in their 
setting and textural characteristics from material produced 
by slumping and mass wasting along the walls. 
In the northern segment of the crater wall one 
encounters at least four different rock types (Figure 2). 
These are distinguished by their setting, textures, structures, 
and relative brightness. The first rock type is exposed in 
the area marked A in Figure 2. It represents a mantle of 
relatively young material of low albedo. This material appears 
identical to that which can be seen in a pool-like depression 
beyond the rim crest of the crater ( A ' ) .  The latter is part 
of an extensive unit that covers a region of more than several 
thousand square kilometers as previously seen in the Apollo 8 
photography ( 2 )  . 
this unit are reminiscent of those exhibited by terrestrial 
lava flows. Wrinkles on its surface are common, especially 
at the lower parts of a given topographic level. The flow 
fronts are convex downslope and appear to be the result of a 
gentle or slow flow of molten material which has moved from 
higher to lower ground. There is also evidence of collapsed 
pool surfaces as in the upper left edge of Figure 2. An 
alternative interpretation of this mantling material would 
be that it is a debris flow or rock glacier. However, the 
aforementioned criteria supporting an extrusive volcanic 
origin, i.e., a lava flow, are quite strong. 
The textures and structures displayed by 
The second rock type (area marked B in Figure 2 )  
is characterized by a very high albedo. Its texture is 
clearly different from that displayed by the rest of the 
crater wall. The latter represents a third rock type, a 
typical segment of which is marked C in the same figure. 
The brightest segment of the wall (area B) is characterized 
by a great number of massive domical hills. These are 
separated by shallow furrows filled by darker, probably 
fine-grained debris material. These features strongly 
ELLCOMM,  INC. -. 3 - 
indicate that this segment of the crater wall is made of 
a rock type which is dissimilar to that exposed elsewhere 
along the crater wall. The bright material may represent an 
exposure of intrusive, probably batholithic rock mass 
* 
It must be stated that the unusually high albedo 
of this intrusive material.is not due to a mantle of bright 
material. Bright rays from the crater Giordano Bruno (located 
at 37.7ON 102.5OE on LFC-1: barely seen on Lunar Orbiter V 
frame M-181 and best seen on Apollo 8 frame 22091,  which were 
erroneously interpreted from Luna I11 photogranhs as the 
"Soviet Mountains I' are evident in the vicinity of the 
crater. The characteristics of these bright rays are easily 
distinguishable from those of what is here interpreted as an 
intrusive rock mass. 
Two major zones of extremely dark rocks within the 
bright segment of the northern wall of the crater represent the 
fourth rock type. The one to the left, marked D in Figure 2,  
displays fine, closely-spaced, discontinuous, linear outcrops 
of dark rock, which crosscut the wall material. The outcrops 
are localized in a zone 2 km long with an average width of 
about 0.5 km. This zone, which trends in a northwesterly 
direction, is texturally different and is much darker than 
the enclosing wall materials. By earth analogy this zone 
most probably represents a dike and is,here so interpreted. 
An alternative explanation would be that it is a segment of 
the layered wall material which has rotated through slumping 
to stand on edge. However, the appearance of this rock and 
its setting support the interpretation as a dike. 
**  
Farther east, to the right of this dike, is another 
zone of the crater wall which displays a similar dark color. 
In this case, the first ledge below the top is nearly black. 
"Batholithic, meaning that it may be part of a mass of 
igneous intrusive rock which crystallized beneath the crust 
and whose diameter and depth are unknown. In support of this 
interpretation is the fact that this bright mass of rock displays 
steep contacts. The exposed portion of the rock mass appears 
to dip outward from the crater wall. 
**A dike is a wall-like tabular body of igneous rock that 
cuts across the structure of adjacent materials. 
B E L L C O M M ,  INC. - 4 -  
A dark zone about 2 km wide extends for a short distance beyond 
the rim crest of the crater. This zone includes a linear 
structure that may also represent a dike (D' in Figure 2 ) .  
One also encounters the dark layers overlying the lower wall 
terraces in this area. The latter occurrence however, probably 
represnts a shedding from the upper rock mass. 
A slightly arcuate and discontinuous line of rock 
that outcrops within the crater floor represents a third 
probable dike (D"). The outcrops are similar to the exposed 
rocks of the aforementioned probable intrusions. Here 
again, the rocks are texturally different from the enclosing 
material. The discontinuous outcrops stand above the sur- 
rounding terrain and appear much darker than it. 
Outcrops of dark rock are also evident on top of 
the central peaks, especially along the sides of the right 
arm of the Y-shaped chain of mountains. These occurrences 
of dark material on the central peaks may be related to the 
intrusive rock material. They represent either extensions of 
the same material or a similar rock type that was brought to 
the surface by the cratering event. Additional photography 
at higher resolutions on future Apollo missions would help 
delineate these relationships. 
The Flamsteed P ring in Oceanus Procellarum has 
been interpreted as a ring dike(3). 
one of the central peaks of the crater Copernicus has also 
been interpreted as a possible lunar dike'l). 
of this new locality of probable igneous intrusions in the 
farside highlands is strong evidence for the heterogeneity of 
lunar materials. It lends additional support to the 
plausibility of intrusive igneous activity, in addition to 
extrusive volcanism, on the moon. 
A prominent zone within 
The recognition 
2015-FEB-kmj 
Attachments 
References 
Figures 
BELLCOMM, INC.  
REFERENCES 
1. E. A. Whitaker, Comparison with Luna I11 Photographs, 
In: "Analysis of Apollo 8 Photography and Visual 
Observations," U. S .  Gov't. Print. Off. (1969; in press). 
2. H. G. Wilshire and Farouk El-Baz, "Possible Volcanic Features- 
Landforms," ibid; and D. E. Wilhelms, D. E. Stuart-Alexander, 
and K. A. Howard, "Lunar Farside," ibid. 
3. J. A. O'Keefe, P. D. Lowman, JY., and W. S .  Cameron, 
Science 155, 3758 (1967) p. 77-79. 
4. Farouk El-Baz, "Geologic Characteristics of the Nine Lunar 
Landing Mission Sites Recommended by the Group for Lunar 
Exploration Planning," Bellcomm Technical Report, TR-68-340-1, 
(1968). 
FIGURE 1 
PART OF LUNAR ORBIT I FRAME M-136 SHOW1NG CRATER 211 NEARLY IN THE CENTER. NOTE THE Y-SHAPED 
CENTRAL PEAKS. A DETAIL OF THE MARKED AREA IS SHOWN IN FIGURE 2. 
VERIAL WHICH 
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Lunar igneous intrusions

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