Mapping of crustal magnetic anomalies on the lunar near side by the Lunar Prospector electron reflectometer

Lunar Prospector (LP) electron reflectometer measurements show that surface fields are generally weak in the large mare basalt filled impact basins on the near side but are stronger over highland terranes, especially those ly ing antipodal to young large impact basins. Between the Imbrium and Nectari s basins, many anomalies correlate with the Cayley and Descartes Formations . Statistical analyses show that the most strongly magnetic nearside terran es are Cayley-type light plains, terra materials, and pre-Imbrian craters. Light plains and terrae include basin impact ejecta as a major component, s uggesting that magnetization effects from basin-forming impacts were involv ed in their formation. The magnetization of pre-Imbrian craters, however, m ay be evidence of early thermal remanence. Relatively strong, small-scale m agnetic anomalies are present over the Refiner Gamma feature on western Oce anus Procellarum and over the Rima Sirsalis ripe on the southwestern border of Procellarum. Both Apollo subsatellite and LP data show that the latter anomaly is nearly aligned with the ripe, though LP magnetometer and reflect ometer data show that the anomaly peak is actually centered over a fight pl ains unit. This anomaly and the Refiner Gamma anomaly are approximately rad ially aligned with the center of Imbrium, suggesting an association with ej ecta from this basin.