Document Type

Article

Publication Date

5-1982

Abstract

Three lines of evidence indicate that volcanic activlty, predating the basalts now visible in the marla, extensively resurfaced' the lunar nearside highlands; l) Frequency distributions of aliinum, magnesium, titaniun, iron and thorium concentrations from orbital data show a displacement of modes toward more anorthositic rock typeston the far side of the Moon. These compositions are rare on the near side; 2) High resolution Hg/A1- X-ray data over large impact craters (Taruntius, Langrenus and Menelaus), and structurally uplifted basin rings on the near.side imply that the subsurface has more anorthosític composítíons, comparable to the lupar far side; 3) Higher concentrations of magnesiu and lower concentrations of aluminun associated with several different nearside terra units increase- the likelihood that pre-Imbrian and Imbrian age volcanism in highland regions of the near side was common, widespread and varied in composition,

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