Premium
Stratigraphy and evolution of basalts in Mare Humorum and southeastern Procellarum
Author(s) -
Hackwill Terence,
Guest John,
Spudis Paul
Publication year - 2006
Publication title -
meteoritics and planetary science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.09
H-Index - 100
eISSN - 1945-5100
pISSN - 1086-9379
DOI - 10.1111/j.1945-5100.2006.tb00475.x
Subject(s) - basalt , impact crater , lunar mare , geology , volcano , geochemistry , lava , lithosphere , stratigraphy , mineralogy , paleontology , astrobiology , tectonics , physics
— We have studied the mare basalts of Mare Humorum and southeastern Procellarum (30°W–50°W, 0°–40°S). One hundred and nine basaltic units have been identified from differences in their FeO wt% and TiO 2 wt% content, and variations in crater densities. Crater counting and reference to isotopically dated Apollo samples have provided an age for 33 major units. Some evidence for three distinct periods of volcanic activity has been found. We found that the large unit in the middle of Mare Humorum is the oldest in the basin. This supports the suggestion that the oldest central unit sank causing the lithosphere to bend and create dykes through which lava flowed to produce the outer units. No evidence of a trend in FeO wt% and TiO 2 wt% content against time is found within Mare Humorum. There appears to be no lateral trend of basalts in terms of FeO and TiO 2 wt% over the entire area with time. An increase in FeO content with time is found in the 33 major units and there is some evidence for an increase in TiO 2 in the same units. A correlation between FeO wt% and TiO 2 wt% content is evident when all 109 units are compared. A notable feature of this correlation is a sharp increase in gradient of TiO 2 wt% content when the FeO wt% content rises above about 17%.