Some aspects of lunar and Martian volcanism as examined with spectral, topographic, and morphologic data derived from spacecraft images.

摘要

Utilizing newly calibrated Mariner 10 color images (Chapter 2), the titanium abundances of lunar mare soils on the eastern limb and farside are examined. These maria are found to have TiO{dollar}sb2{dollar} contents in the range of {dollar}<{dollar}2 to 5%. The existence of cryptomare deposits northeast of Mare Marginis is confirmed. This leads to the prediction that no high TiO{dollar}sb2{dollar} ({dollar}>{dollar}8 wt%) mare basalt soils will be found in regions with thickened crust (most of the lunar farside) that are yet to be examined with spectrometers, due to the greater density of high titanium magma.; Utilizing Viking Orbiter and Mariner 9 data, the martian volcanoes Biblis Patera, Ceraunius Tholus, Jovis Tholus, Ulysses Patera, Uranius Patera, and Uranius Tholus are analyzed (Chapter 3). Specifically, morphologic and topographic features indicative of the eruption style (effusive vs. explosive) that formed each edifice are examined. From new digital mosaics of these volcanoes, both effusive and explosive deposits are found. It is proposed that the initial period of activity for some martian volcanoes was dominantly explosive (driven by juvenile gases), whereas later activity was mostly effusive. In support of this hypothesis, an analysis of the martian volcano Apollinaris Patera is presented (Chapter 4). Using digital images, thermal inertia data, and a new topographic model, the chronology of Apollinaris Patera is determined to have been dominated early on by explosive activity, followed by later effusive eruptions. From the topographic data, its volume is estimated to be {dollar}sim{dollar}10{dollar}sp5{dollar} km{dollar}sp3.{dollar} The volcano may have been active for {dollar}sim{dollar}10{dollar}sp7{dollar} yrs, based on its volume and an inferred rate of eruption of {dollar}1.5 times 10sp{lcub}-2{rcub}{dollar} km{dollar}sp3{dollar} yr{dollar}sp{lcub}-1{rcub}.{dollar} It is proposed that at least {dollar}2 times 10sp{lcub}15{rcub}{dollar} kg of juvenile water was added to the martian atmosphere as a consequence of these eruptions.; Detailed examination of a multi-temporal series of Viking Orbiter color images of the Apollinaris Patera region (Chapter 5) shows, that, for a given area on the surface, the red over violet ratio varies from 2.9 to 3.4, and the albedo ranges from 21% to 16%. These changes are interpreted to be predominately due to variations in the amount of atmospheric condensates.