The moon

, Volume 15, Issue 3–4, pp 241–273

Floor-fractured lunar craters

  • Peter H. Schultz
Article

Abstract

Numerous lunar craters (206 examples, mean diameter = 40km) contain pronounced floor rilles (fractures) and evidence for volcanic processes. Seven morphologic classes have been defined according to floor depth and the appearance of the floor, wall, and rim zones. Such craters containing central peaks exhibit peak heights (approximately 1km) comparable to those within well-preserved impact craters but exhibit smaller rim-peak elevation differences (generally 0–1.5km) than those (2.4km) within impact craters. In addition, the morphology, spatial distribution, and floor elevation data reveal a probable genetic association with the maria and suggest that a large number of floor-fractured craters represent pre-mare impact craters whose floors have been lifted tectonically and modified volcanically during the epochs of mare flooding. Floor uplift is envisioned as floating on an intruded sill, and estimates of the buoyed floor thickness are consistent with the inferred depth of brecciation beneath impact craters, a zone interpreted as a trap for the intruding magma. The derived model of crater modification accounts for (1) the large differences in affected crater size and age; (2) the small peak-rim elevation differences; (3) remnant central peaks within mare-flooded craters and ringed plains; (4) ridged and flat-topped rim profiles of heavily modified craters and ringed plains; and (5) the absence of positive gravity anomalies in most floor-fractured craters and some large mare-filled craters. One of the seven morphologic classes, however, displays a significantly smaller mean size, larger distances from the maria, and distinctive morphology relative to the other six classes. The distinctive morphology is attributed, in part, to the relatively small size of the affected crater, but certain members of this class represent a style of volcanism unrelated to the maria - perhaps triggered by the last major basin-forming impacts.

Preview

Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.

References

  1. Baldwin, R. B.: 1963,The Measure of the Moon, University of Chicago Press. 488pGoogle Scholar
  2. Brennan, W. J.: 1975, ‘Modification of Premare Impact Craters by Volcanism and Tectonism’,The Moon 12, 449–461.Google Scholar
  3. Cameron, W. S. and Padgett, J. L.: 1974, ‘Possible Lunar Ring Dikes’,The Moon 9, 249–294.Google Scholar
  4. Daneš, Z. F.: 1965, ‘Rebound Processes in Large Craters’, InAstrogeologic Studies, pp. 81–100, U.S. Geol. Survey open file ann. prog. rept., pt. A.Google Scholar
  5. De Hon, R.: 1971, ‘Cauldron Subsidence in Lunar Craters Ritter and Sabine’,J. Geophys. Res. 76, 5712–5718.Google Scholar
  6. Dence, M. R.: 1971, ‘Impact Melts’,J. Geophys Res. 76, 5552–5565.Google Scholar
  7. Gault, D. E., Quaide, W. L., and Oberbeck, V. R.: 1968, ‘Impact Cratering Mechanics and Structures’, InShock Metamorphism of Natural Materials, p. 87–99. B. French and N. Short (eds). Mono Book Corp., Baltimore. 644p.Google Scholar
  8. Greely, R.: 1975, ‘A Model for the Emplacement of Lunar Basin-Filling Basalts’,Lunar Science VI, 309–310. Lunar Science Institute, Houston.Google Scholar
  9. Mason, R., Guest, J. E., and Cooke, G. N.: 1975, ‘An Imbrium Pattern of Grabens on the Moon’,Proc. Geol. Assoc. (in press).Google Scholar
  10. Masursky, H.: 1964, ‘A Preliminary Report on the Role of Isostastic Rebound in the Geologic Development of Lunar Crater Ptolemaeus’, InAstrogeologic Studies, pp. 103–134, U.S. Geol. Survey open file ann. prog. rept., pt A.Google Scholar
  11. Moore, H. J., Hodges, C. A., and Scott, D. H.: 1974, ‘Multiringed Basins — Illustrated by Orientale and Associated Features’, InProc. Fifth Lunar Sci. Conf., Geochem. Cosmochim. Acta, Suppl. 5, Vol. 1, pp. 71–100. Pergamon.Google Scholar
  12. Muller, P. M. and Sjogren, W. L.: 1968, ‘Mascons: Lunar Mass Concentrations’,Science 161, 680–684.Google Scholar
  13. Quaide, W. L., Gault, D. E., and Schmidt, R. A.: 1965, ‘Gravitative Effects on Lunar Impact Structures’, InGeological Problems in Lunar Research, pp. 563–572, Annals N.Y. Acad. Sci.123.Google Scholar
  14. Pike, R. J.: 1968, ‘Meteoritic Origin and Consequent Endogenic Modification of Large Lunar Craters — A Study in Analytical Geomorphology’, Ph. D. thesis, University of Michigan, 404p.Google Scholar
  15. Schultz, P. H.: 1972, ‘A Preliminary Morphologic Study of Lunar Surface Features’, Ph.D. thesis, University of Texas at Austin, 967p.Google Scholar
  16. Schultz, P. H.: 1974, ‘Floor-fractured Lunar Craters’,Lunar Science V, 681–683. Lunar Science Institute, Houston.Google Scholar
  17. Schultz, P. H.: 1976,Moon Morphology, University of Texas Press, Austin.Google Scholar
  18. Schultz, P. H. and Gault, D. E.: 1975, ‘Seismic Effects from Major Basin Formation on the Moon and Mercury’,The Moon,12, 159–177.Google Scholar
  19. Schultz, P. H., Manley, W. D., Jr., and Ingerson, F. E.: 1973, ‘Comparison of Lunar and Martian Crater Floors (abs.)’,Trans. Amer. Geophys. Union 54, 1127.Google Scholar
  20. Sjogren, W. L. and Wollenhaupt, W. R.: 1973, ‘Gravity: Mare Humorum’,The Moon 8, 25–32.Google Scholar
  21. Sjogren, W. L. and Wollenhaupt, W. R.: 1975, ‘Lunar Maria Figure’,Lunar Science VI, Lunar Science Institute, Houston.Google Scholar
  22. Sjogren, W. L., Muller, P. M., and Wollenhaupt, W. R.: 1972, ‘S-Band Transponder Experiment’, InApollo 16 Preliminary Science Report, pp. 24:1–24:7. NASA SP-315.Google Scholar
  23. Sjogren, W. L., Wimberly, R. W., and Wollenhaupt, W. R.: 1974, ‘Lunar Gravity via the Apollo 15 and 16 Subsatellites’,The Moon,9, 115–128.Google Scholar
  24. Smith, R. L. and Bailey, R. A.: 1968, ‘Resurgent Cauldrons’, In R. R. Coats, R. L. Hay, and C. A. Anderson (eds.),Studies in Volcanology, pp. 613–662, Geol. Soc. Amer. Mem. 116.Google Scholar
  25. Whitford-Stark, J. L.: 1974, ‘Internal Origin for Lunar Rilled Craters and the Maria?’,Nature,248, 573–575.Google Scholar
  26. Wood, C. A.: 1974, ‘External Origin for Lunar Rilled Craters and Mare Basins’,Nature 251, 166.Google Scholar
  27. Young, R. A.: 1972, ‘Lunar Volcanism: Fracture Patterns and Rilles in Marginal Premare Craters’, InApollo 16 Preliminary Science Report, pp. 29 : 89–29 : 90. NASA SP-315.Google Scholar

Copyright information

© D. Reidel Publishing Company 1976

Authors and Affiliations

  • Peter H. Schultz
    • 1
  1. 1.Space Science DivisionNASA Ames Research CenterMoffett FieldUSA
  2. 2.Space Science DivisionUniversity of Santa Clara/NASA Ames Research CenterMoffett FieldUSA

Personalised recommendations