The deep structure of lunar basins: Implications for basin formation and modification

Bratt, Steven R.; Solomon, Sean C.; Head, J. W.; Thurber, C. H.

doi:10.1029/jb090ib04p03049

Cited by 68 publications

(74 citation statements)

References 30 publications

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“…It is generally assumed that a major part of the negative gravity anomaly of a basin associated with its negative topography is cancelled by the positive gravity anomaly arising from a thick mantle plug at the base [e.g., Bratt et al, 1985b]. This is the model we adopt here in order to determine the thickness of mare filling.…”

Section: Anomaliesmentioning

confidence: 99%

The lunar mascons revisited

Arkani‐Hamed¹

1998

J. Geophys. Res.

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Section: Anomaliesmentioning

confidence: 99%

The lunar mascons revisited

Arkani‐Hamed¹

1998

J. Geophys. Res.

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“…A significant fraction of Ex acts to heat material ejected during basin excavation. To estimate the amount of heat in material thrown beyond the basin rim, we utilize a model for nearside crustal structure derived from gravity and topographic data [Bratt et al, 1985a]. The difference between the assumed pre-impact crustal thickness and the thickness of nonmare crust beneath the youngest basins such as Orientale provides a lower bound on the depth from which material was permanently excavated from the basin.…”

Section: Anelastic Effectsmentioning

confidence: 99%

“…Many of the observed variations likely reflect different degrees of modification of initial basin geometry and structure on time scales long compared to those for cavity excavation and ring formation. The subdued topographic relief of basins formed early in lunar history when the lithosphere was relatively warm is probably a consequence of lateral flow of crustal material over times scales ranging up to millions of years Bratt et al, 1985a]. The infilling of impact basins with mare basalt, on a somewhat greater time scale, led to loading of the lunar lithosphere and consequent subsidence and flexurally-induced tectonic activity [Solomon andHead, 1979, 1980;Comer et al, 1979].…”

Section: Introductionmentioning

confidence: 99%

The evolution of impact basins: Cooling, subsidence, and thermal stress

1985

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Potentially important contributors to the topography and tectonics of multi-ring impact basins are the thermal contraction and thermal stress that accompany the loss of heat emplaced during basin formation. Heat converted from impact kinetic energy and contributed from the uplift of isotherms during cavity collapse are important components in the energy budget of a newly-formed basin. That the subsequent cooling may have been an important factor in the tectonic evolution of the Orientale basin is suggested by the deep central depression and by a surrounding region of extensive fissuring. To test these concepts, we develop models for the anomalous temperature distribution immediately following basin formation, and we calculate the resulting elastic displacement and stress fields that then would accompany cooling of the basin region. All models predict subsidence of the basin floor and a near-surface stress field consistent with fissuring. In addition, the rates of cooling and of accumulation of thermal stress are in agreement with the inferred timing of fissure formation in Orientale. The sensitivity of the predicted displacements and stresses to the initial temperature field allows us to place bounds on the quantity and distribution of impact heat emplaced during basin formation. In order to be consistent with the observed topography and the distribution of fissures in the Orientale basin, the buried heat deposited during the basin-forming event was between 1032 and 1033 erg. It is likely that most of this heat was concentrated within a distance of 100-200 km from the point of impact.

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“…After a giant impact, according to one scenario, the extensive excavation of lunar material resulted in crater relaxation, a strong thermal anomaly, and high amounts of stress within the crust (16 ). The heating and weakening of the crust allowed an upwelling of denser mantle material, resulting in excess mass near the center of the basin (17)(18)(19). This mantle rebound resulted in uplift of the crust-mantle boundary (or Moho) and the formation of a dense mantle "plug."…”

mentioning

confidence: 99%

Improved Gravity Field of the Moon from Lunar Prospector

Konopliv

Binder

Hood

et al. 1998

Science

251

188

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An improved gravity model from Doppler tracking of the Lunar Prospector (LP) spacecraft reveals three new large mass concentrations (mascons) on the nearside of the moon beneath the impact basins Mare Humboltianum, Mendel-Ryberg, and Schiller-Zucchius, where the latter basin has no visible mare fill. Although there is no direct measurement of the lunar farside gravity, LP partially resolves four mascons in the large farside basins of Hertzsprung, Coulomb-Sarton, Freundlich-Sharonov, and Mare Moscoviense. The center of each of these basins contains a gravity maximum relative to the surrounding basin. The improved normalized polar moment of inertia (0.3932 ± 0.0002) is consistent with an iron core with a radius of 220 to 450 kilometers.

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The deep structure of lunar basins: Implications for basin formation and modification

Cited by 68 publications

References 30 publications

The lunar mascons revisited

The lunar mascons revisited

The evolution of impact basins: Cooling, subsidence, and thermal stress

Improved Gravity Field of the Moon from Lunar Prospector

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