Tectonic analysis of Mare Humorum on the lunar surface

Morphology and internal structures of surface features of the Mare Humorum area were interpreted from photographs and topographic maps. The postulated origin of certain features is based on analog comparisons with known terrestrial features. The laws of crate ring and a newly developed computer program were applied to two representative classes of craters to determine the possibility of a meteoritic impact origin. Some of the craters formed by meteoritic impact and others, including those with a radius larger than 10 Km, probably resulted from volcanic activity. Mare Humorum formed from centripetal subsidence followed by extensive lava eruptions. Spacially related rilles and gravity faults on the east and west of the Mare are tension fractures resulting from directed radial forces produced by the subsidence. Bending and monoclinal centripetal warping on the north and south of the Mare resulted in inward tilted older craters. Wrinkle ridges of sub-parallel marginal pattern are lava filled fissures and surface highs of lava showing a rough anticlinal form. These and similar fractures were the channelways for the extensive lava eruptions which covered the Mare. An interpretive geologic and tectonic map demonstrated the important structural features of the Mare Humorum area --Abstract, page ii