Physics – Geophysics
Scientific paper
Jan 1997
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1997lpico.922...49r&link_type=abstract
Large Meteorite Impacts and Planetary Evolution, p. 49
Physics
Geophysics
Impact Melts, Lunar Maria, Topography, Lunar Craters, Selenology, Meteorite Craters, Clementine Spacecraft, Gravity Anomalies, Breccia, Moon
Scientific paper
The Serenitatis Basin was recognized in the early 1960s as a multiring impact basin. Poikilitic impact melt breccias collected on the Apollo 17 mission, generally inferred to be Serenitatis impact melt, precisely define its age as 3.893 +/- 0.009 Ga. On the topographic map produced from Clementine data, the basin has a well-defined, circular structure corresponding closely with mare fill. In the review by , this circular structure has a diameter of 620 km (Taurus ring). The main rim is deemed to have a diameter of 920 km (Vitruvius ring). Thus Serenitatis is both the oldest and the largest basin in the solar system to which we can confidently assign samples. The central flooded part of the Serenitatis Basin displays a mascon gravity anomaly. Gravity and topographic studies by Neumann, correcting for the mascon, indicate that the crust was thinned to about 30 km compared to a surrounding thickness of about 55 km. The rim has a slightly thickened crust. The Apollo 17 landing site lies between the Taurus and the Vitruvius rings. Remote studies show that the Taurus highlands differ in chemical composition from those around the Crisium and Nectaris Basins. They are consistently lower in alumina and higher in Fe and radioactive elements: the highlands are the noritic, rather than the anorthosite, stereotype of the ancient highlands. Tracks show that many of the poikilitic impact melt breccias rolled from high in the massifs, possibly from ledges. They vary in grain size and texture. Larger boulders display sharp contacts between texturally different units, which differ slightly big significantly in composition. They have about 18% Al2O3 and incompatible elements of about 100x chondrites. The breccias contain lithic clasts. Feldspathic granulitic breccias are the most common, but these do not form any significant component of the melt composition itself. Other lithic components are mainly plutonic igneous rocks such as norite and troctolite. Ferroan anorthosites and mare basalts are absent. Mineral fragments suggest similar but more diverse mafic lithologies. The evidence from rocks, remote sensing, and geophysics suggests that the target for the Serenitatis impact was a noritic one and consisted largely of pristine igneous mafic rocks rather than a megabreccia. As the melt moved out, it first picked up heavily comminuted mineral fragments similar to the target and later picked up larger fragments of such material. Finally, it picked up feldspathic granulitic breccias when the melt was too cool to dissolve them significantly into the melt. The melt finally came to rest in a location that, following slumping, formed the Taurus highlands.
No associations
LandOfFree
Serenitatis: The Oldest, Largest Impact Basin Sampled in the Solar System does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Serenitatis: The Oldest, Largest Impact Basin Sampled in the Solar System, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Serenitatis: The Oldest, Largest Impact Basin Sampled in the Solar System will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-1808835