There are no large-scale sedimentation and erosion processes on Venus, therefore the observed deformation must be formed on the surface or close to it, and in the ellipsoids of stresses one of the main axes must be perpendicular to the surface. According to the deformation visible on photography from Venera-15, 16, the orientations of the ellipsoids of stresses are established in the different sections of the Montes Maxwell and the northern parquet. A geological model is established, according to which the Montes Maxwell is an arched vault and the region to the south a conjugate bend, separated by a shift zone

Ronka, L. B.

English

NASA Technical Reports Server

NASA TECHNICAL MEMORANDUM 
/I+" 9/ 
467%/ 
NASA TM-88509 
STRESS ON THE SURFACE OF VENUS: 
ANALYSIS OF DATA PROVIDED BY VENERA-15 AND VENERA-16 
L.B. Ronka 
Trans1 a t i  on of "0 Napryazheniyakh na Poverkhnos t e  Venery: Isucheniye Dannykh 
Venery-15 i Venery-16, I N :  Geotektonika, No. 4, July-August 1986, "Nauka" /J 
Press, Moscow, pp.  54-59 
{hASA-TM-88509) ,CT&ESS Cii T E E  S U R F A C E  OF N87-15146 
V E N U S :  A N A L Y S I S  CE D A l A  E L C V I L E I :  I i Y  
V E N E R E - 1 5  A N D  VEEIhA-10 { l a t i c n a l  
Aeronautics a n d  SFace Admiriistratioa) 1 I p un c 1 a s I 
CSCL 84B 5 3 / 9 1  43665 
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION 
Washington D.C. 20546 OCTOBER 1986 
https://ntrs.nasa.gov/search.jsp?R=19870005713 2020-03-20T12:27:31+00:00Z
. 
I 14. ) 0 e n a o d n j  A:*ncy CoCe I National Aeronautics and Space Administration, Washington D.C. 20546 
IS. L ; ; ~ a r . . n t c # ,  ~ o t r a  
trans1 a t i  on of "0' Napryazheniyakh na Poverkhnosti Venery: Isucheniye 
Dannykh Venery-15 i Venery-16, Geotektonika, No. 4 ,  July--August 1986, 
"Nauka" Press, Moscow, pp. 54-59 (ISSN 0016-853X) ( U D C  551.24+523.4.42) I 
16' A > i * , d ; t  
There are  no large-scale sedimentation and erosion processes on Venus, 
therefore the observed deformation must be formed on the surface or 
close t o  i t ,  and i n  the e l l ipsoids  of s t resses  one of the main axes must 
be perpendicular to the surface. According t o  the deformati gn v i  si 61 e 
on the pictures of "Venera-15, 16",  the orientations o f  the el l ipsoids  
of s t resses  are eitablished i n  the different sections of the Montes 
Maxwell and the northern parquet. A geological model i s  established, 
according t o  which- the Montes Maxwell i s  an arched v a u l t  and the region 
to the south a conjugate bend, separated by a shif t  zone. 
STRESS ON THE SURFACE OF VENUS: 
ANALYSIS OF DATA P R O V I D E D  BY VENERA-15 AND V E N E R A - 1 6  
L . B .  Ronka 
Introduction 
In radar images, obtained w i t h  the "Venera-15 and 16" s ta t ions ,  no c lear  /54* -
indications may be found of the presence of erosion-sedimentary processes on 
Venus (1). This does not indicate t h a t  there are no such processes a t  a l l ,  i n  
as much as the i r  character is t ics  were detected by previous "Venera" s ta t ions (4-6). 
I t  i s  possible tha t  erosion and sedimentary processes on Venus take place only 
on lower scales than the resolutions of the radar pictures of the "Venera-15 and 
16" s ta t ions (1-2 km). 
The type of tectonic deformations on the surface of Venus i s  related to  
these character is t ics .  Whereas on the earth tectonic deformations are usual l y  
observed arising i n  depth and l a t e r  uncovered by erosion, the deformations on 
Venus should be formed on the surface. E.M. Anderson (9 )  showed tha t  the sur- 
face of the planet must be considered as a plane through which no shear region 
s t resses  pass ( i n  as much as distances of several hundred of kilometers the 
curvature of the surface and the unevennesses of the re l ie f  may be disregarded). 
If  the material on the surface and close to  i t  is  homogeneous enough, the s t resses  
(forces per u n i t  of area) may be represented i n  the idealized form as e l l ipsoids  
of s t resses .  The el l ipsoids  of stresses must not be confused w i t h  e l l ipsoids  
of deformations, which re f lec t  dislocations, and n o t  forces. I n  as much as the 
surface of the planet i s  a plane through which no shear region s t resses  pass, 
i t  may be shown, that  one of the axes of the el l ipsoid of s t resses  should be 
ver t ical .  
served on the surface of Venus. 
I f  this is  true,  then only def in i te  types of deformations may be ob- 
*Numbers i n  the margin indicate pagination i n  the foreign text.  
3 
Usually the radii of the ell ipsoid are proportional to the s t resses  (forces 
per u n i t  of area) directed towards the center of the el l ipsoid (compression for- 
ces) .  
speaking, can not appear on the scale of radar images, b u t  may be assumed s t a r t -  
i n g  from the different ia l  decrease of the compression forces, which was described 
i n  the publication by D. Griggs and G. Handin ( 7 ) .  
B u t  i n  tectonics, they often talk of forces of extension, which s t r i c t l y  
Figure 1 shows sections of ell ipsoids of s t resses  and cracks, which may be 
expected. I t  i s  the convention t o  assume tha t  G1 i s  the direction of the max- 
imum s t r e s s ,  d2 of the intermediate s t ress  and d3 m i n i m u m .  
of  compression, i f  we ta lk  o f  visible s t resses  of extension, t he i r  dis t r ibut ion 
is inverse: dl i s  the m i n i m u m  extension, d3 is  maximum. 
All these are s t resses  
The simplest type of deformations which m a y  be expected on the scale of radar 
images are ruptures. 
only three orientations w i l t h  regard to  the el l ipsoid of  stresses.  
two are represented by two symmetrical planes perpendicular t o  'the planes w Y t h  
61 and d3 and w i t h  angles less t h a n  45' w i t h  regard to  hl. In this connec- 
tion usually movements occur, causing relat ive la teral  shift  i n  d i f ferent  d i r -  
ections o f  the rupture. 
t o  which direction of the s t resses  i s  vertical  ( dl ,L2 ,  d 3 ) .  
mation takes place i n  bo th  planes, the ruptures arising are called conjugate. 
The t h i r d  type of ruptures may appear along the plane perpendicular to  d,. 
this connection there are no la teral  movements or  the small, and the ruptures 
are called cracks of extension. 
Theoretically i n  a homogeneous material ruptures may have 
The f i r s t  
/E. 
As a resul t  force, up  thrusts and shifts occur according 
If the rupture for- 
In  
Theoretically the deformations may also occur i n  folds. On the earth with 
a few exceptions, the folding usually takes place i n  depth, b u t  i t  i s  impossible 
to  establish this for the moment for Venus. I f  the folds are located on this 
surface, then i t  may be assumed that the horizontal traces of the i r  axial planes 
are perpendicular to  6,. 
Observations and Analysis 
The above indicated considerations were used for  a region extending eas t  o f  
4 
li ' the Montes Maxwell, where the northern parquet extends 
(figures 9,11,12 i n  ( 2 ) ) .  
for other regions (4) .  
Studies are be ing  planned 
1 
61 Q n % n f  I t  is  eas ies t  to  detect the deformations which 
V 
are called conjugate ruptures: two networks of rup- 
tures, which do not in te rsec t  under d i rec t  angles, 
and of which neither of the networks intersects  the 
i n  certain sections of l inear  structures eas t  of the 
Montes Maxwell and i n  the northern parquet. As was 
shown above basic directions of s t resses  are c lear ly  
established i n  t h i s  connection. 
tain indications on the bl/d3 ra t io ,  by measuring the 
angles between the conjugate ruptures , which decrease 
w i t h  the increase of  dl/d3. 
orientation o f  the ruptures corresponds to  the orien- 
V 
2 62+@-$+@-+62 
Q6, 06, other consecutively. Such con jugate ruptures are found 062 $2 
3 63+-9-$3;p-+63 
I t  i s  possible to  ob- 
6, 0 62 
6.& Z -963 
I t  i s  assumed tha t  the 4 ap 06 
Fig'1' Cross sections Of  
the e l l ipsoid of tensions tations o f  vectors connecting the centers of the e l l i p -  
and corresponding rup- soids w i t h  places of  interaction of the e l l i p se  w i t h  
tures. The wide 
indicate the maximum com- the circle of circumference equal to  i t  (conditions 
pression forces, the dot- o f  "hydrostatic s t r e s s " ) .  On figures 2 and 3 the black - - 
ted 'line Ones,  
v i  si bl e extending s t resses  out lines show the orientations and forms of e l l ipsoids ,  
(see text) and the double 
arrows are the direction 
of s h i f t  along the r u p t  
tures. The hor i  zontal In  certain regions such as the Montes Maxwell, 
bu i l t  up according to the conjugate ruptures. 
no conjugate ruptures are vis ible ,  and deformations cross sections are: 1-shifts, 2-UP thrusts ,  
3-poles, -4-cracks. are represented by a network in one direction (see 
f i g . 2 ,  B - E ) .  
the above considerations, they are e i ther  fa l se  (61 i s  ver t ica l )  or upthrusts 
(63 ver t ica l ) .  
and the absence of open cracks make i t  possible to  assume the decrease o f  the 
area and consequently the presence o f  up thrusts.  I f  the observed structures 
are poles, the orientation of the ell ipsoids remains the same as the four. 
If  they are ruptured, then according to  
The presence i n  th is  region of such structures as curved ridges, 
5 
Fig .2 .  Scheme of the Montes Maxwell. The l e t t e r s  indicate the sections indi- 
cated i n  the text.  
sentative sections. 
61 (on the large axis)  and63 (on the small a x i s ) .  
approximately proportional t o  B 1/63, according to  the description i n  the text. 
The dotted l ines indicate e l l ipses  i n  the places of proposed up thrusts ,  w i t h  
61 on the large axis and 6 2  on the small one. 
trary.  The arrows indicate the sh i f t s  and the shear regions (a solid l ine  the 
The e l l ipses  show the d i s t r i b u t i o n  of s t resses  on the repre- 
The e l l ipses  indicated by sol id  l ines ,  indicate the s t resses  
The ra t io  of the axes i s  
The ra t io  o f  the axes is  arbi- 
re la t ively rel iable  ones, the dotted l ines ,  the assumes ones). 
I f  t h i s  analysis i s  correct,  then the differences between the Montes Maxwell /z 
and the section of  the northern parquet (see fig.2,C) are not very large. 
diagram i l l u s t r a t ing  th i s  i s  shown on f i g .  4. 
of the s t resses  i s  in la t i tude ,  b u t  i f  on the Montes Maxwell the intermediate 
s t resses  are directed horizontally, in the meridional direction, then i n  the 
not-thern parquet the vector of  the intermediate s t resses  i s  ver t ical .  
The 
In bo th  regions the main direction 
A different  type of deformation is  observed on the planes west o f  the Montes 
Maxwell (right of the l e t t e r  A, see f ig .2) .  
bent open cracks, expanding towards the south .  
I t  i s  represented by a system of 
With steady observation i t  i s  
6 
apparent t h a t  i f  the cracks are t h i n ,  they are interrupted and bridges ex is t .  
The edges of the cracks are not smooth, b u t  jagged. 
s t ructures ,  based on the theory o f  ell ipsoidal s t resses ,  i s  shown i n  fig.5. 
These cracks are considered as cracks of extension (perpendicular to  6,) and 
shifts (perpendicular t o  planes w i t h  
by a rotation of the el l ipsoid i n  the southern direction. 
The interpretation of these 
and d3) whose formation was accompanied 
A new type of deformation appears fur ther  to  the eas t  on the northern parquet. 
Here we see i r regular  spot of a smooth region (see l e t t e r s  G,F and H on f ig .3) .  
Although rel iable  character is t ics  of their origin are not known, they may be re- 
la ted w i t h  the cracks of extension (perpendicular t o  d3)¶ f i l l e d  l a t e r  w i t h  
1 avas . 
/58. -
Fig .  3. 
indicated in the text.  
corresponding sections w i t h  
Scheme of the northern parquet. The l e t t e r s  indicate smooth sections, 
The 
The el l ipses  indicate the distribution of s t resses  i n  the 
of  the large axis and 1 3  of the small one. 
ra t io  of the axes i s  approximately proportional to  cil/G3. 
7 
6 7  
Fig. 4. 
and on the parquet ( fa l l s )  and on the parquet (conjugate ruptures) and cor- 
responding orientations of the ellipsoids of stresses. 
Block diagram of the deformations i n  the Montes Maxwell (upthrusts) 
F i g .  5. Model of the shear reg 
between the extended blocks are 
on southwest of the Montes Maxwel . The limits 
shifts ,  and the gaps between them are formed 
On the le f t  the planimetric scheme of such a by uncovering in the extension. 
sp l i t  i s  shown (the southern por t ion  i s  enlarged). The orientation of the el-  
i s  shown. 1 i pses of stresses 
In terpreta t i  on 
To understand the stresses responsib e for the occurrance of  deformations, 
i s  only a f i r s t  step t o  understanding the entire geological picture. 
step may be the interpretation o f  the geo ogical structure leading t o  the under- 
standing of local and overall tectonics. 
application t o  one region; the author hopes t h a t  this method can be used as a 
f i r s t  step. 
The next 
This study proposes a method and i t s  
8 
The overall geological structure of the studied region i s  fo r  the moment 
Nevertheless one of the possible interpretations is  given here, f o r  unclear. 
the study of which one must turn t o  the region south of the Montes Maxwell (see 
l e t t e r  D on f ig .  2 ) .  
depression. 
cracks are visible.  
because this region i s  located as on a hinge on the edge of a buckling region. 
The depression i s  f i l l e d  w i t h  some material, probably lavas. 
of the northern border of the region w i t h  the Montes Maxwell has a c lear  and 
sharp appearance, as i n  the case of normal f a l l s .  
Maxwell , the conjugate ruptures on the parquet on the depressions and the f a l l s  
to the north of this depression may be interpreted as shown on f i g .  6. 
Judging by the radar altimetry, this region i s  a deep 
In the eastern and southeastern sections of this depression open 
They may be cracks of extension, created by s t resses  arising 
The western section 
The upthrusts i n  the Montes 
F i g .  6. Simplified diagram of the proposed s t ructure  o f  the Montes Maxwell and 
depressions t o  the south  of them. I t  is  assumed t h a t  l a t i t u d e  s t resses  cause: 
1-the raising of  the Montes Maxwell and the upthrusts (these processes are not 
distinguished on the diagram) ; 2-the occurrance of zones of shearing; 3-the for- 
mation of a depression (for simplicity i t i s  shown i n  the form of a synclinal , 
b u t  ruptures are also possible i n  this connection). The cross structures i n  the 
r i g h t  hand portion indicate conjugate ruptures on the parquet. The l e t t e r s  cor- 
respond to  sections on f i g .  2 indicated i n  text .  
The proposals on the structure o f  the eastern section of the northern par- 
quet has an even weaker foundation. 
middle of t h i s  region a boundary may ex i s t ,  separating the e l l ipses  w i t h  l a t i tude  
orientations from the meridional ones. 
change i n  the direction of  forces, determining the s t resses .  These forces may 
be directed everywhere i n  la t i tude,  b u t  i n  the eas t  they appear i n  the form of 
Figure 3 shows t h a t  approximately i n  the 
This does n o t  necessarily indicate a 
9 
compression (along d l )  and i n  the west i n  the form o f  extension (along d3). The 
conditions of extension fo r  the western portion may be assumed both according to  
the orientation of the el l ipsoid,  and according to  the presence of the dense 
sections. 
The l a s t  s tep i n  the construction of the related geological picture must be 
By analogy w i t h  the earth we may assume 
the determi nation of the tectonic mechanisms creating the observed structures.  
Unfortunately this  i s  n o t  possible now. 
t ha t  the determining forces were caused by asthenospheric flows, interacting w i t h  /E. 
the lithosphere. 
variables: 1-the geometry and the philosophy of the asthenospheric flows; 2-the 
nature of interaction between the asthenosphere and the lithosphere; 
ness, temperature and composition of the lithosphere. 
The s t resses  i n  the lithosphere may be determined by several 
3-the thick- 
‘10 
REFERENCES 
1. Barsukov V . L . ,  Bazilevskiy A.T., Kuz 'min  R . D .  e t  a1 ,"Geology of Venus 
According t o  the Results of the Analysis of the Radar Images, Obtained 
by the Stations "Venera-15" and "Venera-16" (Preliminary Data)': ,Geokhimiy 
1984, no. 12 ,  pp. 1811-1820. 
2 .  Barsukov V . L . ,  Sukhanov A.P . ,  Akim A . L . ,  e t  a l ,  "Geological and Mortholo- 
gical Characteristics of the Northern Region of Venus ,I' Geotektoni ka, 1986, 
no. 4, pp.4-25. 
3. Anderson E.M. The Dynamics o f  Faulting,(Oliver and Boyd, Ed inburg ) ,  1951. 
206 pp. 
4. Basilevsky A.T. , Kuzmin R.O. b Nikoraeva O . V . ,  e t  a1 ."The Surface o f  Venus 
as Revealed by the Venera Landings: Part 11," Geol. SOC. Amer.Bull., 1985, 
V .  96, pp.137-144. 
5. Florensky K . P . ,  Ronca L . B . ,  Basilevsky A.T., "Geomorphic Degradation on the 
Surface of Venus," Science, 1977, v.  196, p.  869-870. 
6. Florensky K.P. , Basilevsky A.T.,  Kryuchkov V.P . ,  e t  a l ,  "Sedimentary Rocks 
on Venus?" Science, 1983, v.221, pp. 57-59. 
7. Hobbs B . E . ,  Means W . D . ,  Williams P . F . ,  An Outline o f  Structural Geology, 
N.Y. :  John Wiley and Sons, 1976, 571 pp. 
Recf&ed by Edi tors  November 10, 1985 Vine University, U.S.A. 


Stress on the surface of Venus: Analysis of data provided by Venera-15 and Venera-16

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