LTILTI-RD?G BASIBS OlJ THE MOON,fiKRS AID IUCRCURY. Zh. 3. Rodionova, T.P. Skobeleva., Sternberg State Astronomical Institute, ldoscow 11 7234. In this paper only concentric basins tha? have inside distinct ring rim are considered in contrast to (1,2). 12 such basins with diameters from 280 to 960 km were found on the Moon Eare ring basins such as Mare Imbrium, Nare Serenitatis and ets that were marked on the maps (3) as multi-ring basins were not put on our list becouse their inner rings have been not well preserved. I,ieasurements of multi-ring basins diameters were carried out on the complete map of the ELoon by scale 1: 5 000000 (4). In the table are given names, coordinates and diameters of concentric basins. A ratio of outer and inner rings is 2:l. Triple ring basins (hiare Orientale, Xare Ilectaris , Uare liosco- viense) have one more ring between inner and outer ones. In this case a diameters ratio is 2:l,5:l. Lunar concentric basins are located,mainly, on the high- land of the far side or" the 1.loon and most of them are antipo- des of mare formations of the near side of the Moon. On Edercury 21 formations with two concentric ridges mere discovered in the region, surveyed by IJariner 10 (45% of the whole surface). The diameters measurements were carried out on the map of the (6) at the scale It5 000 000. It follows from the table that the diameters of basins when measuring on an outer ridge are twice as much as when measuring on inner ring,except three for- mation: , Boethius, Ida Chin Yan. Caloris Basin seems to be reffered to triple ring basins. 70% of all concentric basins on Llercury are located in marginal zones between plains and highlands. Martian concentric basins are located in marginal zones of plains. Only 8 multi-ring basins were found on the preliminary map of Mars(7) scale 1:5 000 000. Probably using the photoes with better resolution we shall succeed in discovery some other concentric basins. The tables shows that the ratio of dimensions are also 2:l. The morphology of concentric basins are rather various. The common caracteristics of them are: 1. the presence of chains and valleys, that are located near basins or inside them; 2. an outer ridge, as a rule, is better presemed than inner one; 3. a surface of an inner depression is covered with a fewer number of craters than a surface between an inner and outer ridges and this one,in its turn, are overlaped with craters than a surrounding surface; 4. there is a linear relationship between dimensions of an inner and outer ridges and it can be discribed with the equation: d= 0.50D -1.60 , where d - a diameter of an inner ridge, D - a diameter of an outer ridge. The cornparision of concentric basins dimensions with radii and masses of the Loon, and !;ims shows that with the increasing of the radii and masses these bodies concentric

0 Lunar and Planetary Institute Provided by the NASA Astrophysics Data System WTI-RING BASIEJS OI? !THE MOON, MARS AND UERCURY. Bodionova 2h.F. et. al.

basins become smaller in their dimensions and their diapason get narrower (Figel). The locations and dimensions of concent- ric basins on the hioon, Hercury and Mars that were conditiona- ly plotted on the same net of meridians and parallels at the Mercator projection (Fig. 2). In a western hemisphere where there is an information about Mercury as well we can single out two regions of the most concentration of multi-ring basins: I. a region near equator restricted mith meridians 74°-1800 ; 2. a region, stretched from south-west to north-east. Kulti- ring basins are concentrated in the regions on the Noon as well as on Uercury and Mars. It is rather interesting that the first region contains volcanoes of Nars, domes and rilles. The second region shows that concentric basins of Uercury are located in the direction EN-132 at the angle SO0 to equator. Mare Imbriun, Mare Serenitatis and Eare Humorum are also in this region. We would like to express our gratitute to Dr. G.A. Leykin for the discussion of the paper. References: (1) Bood,C.and ~ead,J. (1976) LS VII, 950-952; (2) - Head,J.(lg78) LS IX, 495-497. (3) Vilhelrns,D adLc.Cauly,J. (1371) Geologic Uap of the 3Tear Side of the bioon;(4) (1969) The Complete Nap of the bioon;Nauka; (5) Lipsgiy Yu, and Rodionova Zh.(lg77) The Soviet-Bmericzn Conf. on Cosmochemistry of the Koon and , 755-761: (6).(1977) Atlas of Nercury,USGS; (7) (1975) Atlas of Mars, USW.

1 2 2 2. UlrlU RINS EZ3 INNER RINGS

ONrnMOOBI * VOLCAKOES OFW 4 D Zm, Jm, am 0 a& cy af5 0 ON MERCURY . ':. Cl RCULAR MARE Radii ~QSWJ(%=I) ''... Fig. ? ON k[ARS , ONTHE MOON Fig2. I

0 Lunar and Planetary Institute Provided by the NASA Astrophysics Data System UUL'PI-RING BBSIITS ON TH2 B1001J , IdARS AlVD iG2RCURY . Rodionova Zh. F. et. al.

THE MOON

Bert zspmmg Apollo Bailly Korolev U-Khwariemi Without naine Hare Humboldtisnum Mare Moecoviense Mare Nectarie Poincare Schrodinger Mare Oriesltale

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lithout -0 Liu Hsin NaDsen Lowell Qoi; Becquezcl Kepldr Without name

0 Lunar and Planetary Institute Provided by the NASA Astrophysics Data System