RECALIBRATED MARINER-10 COLOR MOSAICS - IMPLICATIONS FOR MERCURIAN VOLCANISM

Recalibration of Mariner 10 color image data allows the identification of distinct color units on the mercurian surface. We analyze these da ta in terms of opaque mineral abundance, iron content, and soil maturi ty and find color units consistent with the presence of volcanic depos its on Mercury's surface. Additionally, materials associated with some impact craters have been excavated from a layer interpreted to be def icient in opaque minerals within the crust, possibly analogous to the lunar anorthosite crust. These observations suggest that Mercury has u ndergone complex differentiation like the other terrestrial planets an d the Earth's moon.