Robert J. Malcuit

The lunar capture hypothesis revisited

Recent work on planetary formation processes have suggested that ancient planetary bodies could have been warmer and, therefore, more easily deformable soon after formation than at present. By use of the estimates for the elastic parameters believed to be appropriate for a warm ancient Moon and Earth, it is shown that the energy of deformation of the planetary bodies during a close gravitational encounter was sufficient to effect capture.

Differentiation of an andesine-type anorthosite: The San Gabriel Suite

Abstract The San Gabriel anorthosite is an andesine-type anorthosite and has been investigated in order to test a model which postulates that the parental magmas of such anorthosites are andesite. Plagioclase in the anorthosites ranges from An 55 (mol per cent) to An 35 with a mode at An 49 , in the diorites from An 52 to An 24 (mode An 36 ), and in the monzonites/ quartz-monzonites from An 27 to An 9 (mode An 21 ). No hiatus occurs in the compositional spectrum, suggesting that the sequence is derived from a common parent, with anorthosite accumulating first and quartz-monzonite last. The parent magma is constrained by having plagioclase of about An 55 on the liquidus, and by producing an oversaturated residual liquid. The sequence is in accord with published experimental observations on the fractional crystallization of a synthetic quartz-diorite (andesite), and is compatible with a model for the differentiation of andesine-type anorthosites from andesitic magmas.

Use of Fourier Shape Analysis in Zircon Petrogenetic Studies

Zircon morphology has long been an important parameter in the study of petrogenesis in igneous and metamorphic rocks and provenance in sedimentary rocks. Fourier shape analysis is a much more sensitive technique for morphological analysis than the more widely used elongation ratio. Secondly, subtle variations in shape can also be determined by Fourier shape analysis. Zircon populations from three compositionally similar granitic plutons from the Western Intrusive Series of the Sierra Nevada batholith differ significantly in average morphology as determined by Fourier shape analysis. This technique resolves a two-dimensional shape into multiple shape components (harmonics) with each component making an independent contribution to the total shape. Seven of the nine harmonics analyzed are statistically significant in orthogonal comparisons of the zircon populations. Information carried by each harmonic should be of use in determining the significance of zircon morphology in petrogenetic studies and will prove especially useful where differences are subtle.

Some Critical Interpretations and Misinterpretations of Lunar Features

This somewhat lengthy chapter is a series of “vignettes” concerning certain concepts or features of solar system science. A “vignette” for our purposes is defined as “a short literary composition characterized by compactness, subtlety, and delicacy”.

The Origin of the Sun and the Early Evolution of the Solar System

The origin of the Solar System has intrigued scientists for centuries. As recently as five decades ago the models were still very general and were concerned mainly with the collapse of a cloud of stellar dust and gas of roughly solar composition and the transformation of that cloud into a rapidly rotating disk-shaped mass around a proto-sun. The next few decades were dominated by calculations of equilibrium chemical condensation models from a cooling nebula of solar composition based mainly on the temperature and pressure conditions for the solar nebula from Cameron and Pine. Identification of high-temperature condensates [calcium-aluminum inclusions (CAIs)] in the Allende meteorite was a critical event in the development of more sophisticated models for the evolution of the Solar System. After the discovery of CAIs it was important to develop models to explain (a) the origin of chondrules (the main constituent of chondritic meteorites), (b) the origin of CAIs, as well as (c) the origin of the very fine-grained matrix of the chondritic meteorites.

Models for the Origin and Evolution of the Earth-Moon System

The origin of the Moon remains an unsolved problem. In spite of the claims of the ruling paradigm investigators, the GIANT IMPACT MODEL (GIM) is a disappointment when it comes to explaining many of the major features of the Earth and Moon. It appears to be especially inadequate to explain the facts associated with the COOL EARLY EARTH MODEL.

A Prograde Gravitational Capture Model for the Origin and Evolution of the Earth-Moon System

The origin of the Moon is one of the outstanding unsolved problems in the natural sciences. Cursory examination of college-level textbooks in the Earth and Planetary Sciences leaves one with the impression that the Moon is simply a “night lantern” and that the moon effects the Earth in only minor ways, such as controlling the tidal waters on the planet.

Origin and Evolution of the Venus-Adonis System: A Retrograde Gravitational Capture Model

The Earth is the only habitable planet that we know of at present. Thus, we naturally tend to define a habitable zone based on what we know about our planet. In most discussions of the concept of a “habitable zone”, the Earth’s Moon is not even mentioned. In this treatment, I am going to demonstrate that a large natural satellite can have a dramatic, really critical, effect on the habitability of a planet.

Discussion of the Probability of Finding Habitable Planets for Humans Orbiting Sun-Like Stars

Most scientists that are interested in the habitability of planets can agree on the definition of a habitable zone. But from the quotes shown above, it is clear that there is very little agreement for how prevalent life forms are beyond the Earth. We geoscientists know that the Earth has had a complex evolution and that is a large part of the problem. The metazoan life forms on Earth appear to be a result of this complex evolution of the planet. How about the origin of the simpler forms of life? Could a less complex planetary evolution result in less complex life forms? And does this less complex planet evolution scheme make it more probable to find habitable planets in other star-planet systems?

Planet Orbit—Lunar Orbit Resonances and the History of the Earth-Moon System

After reviewing a number of geology and astronomy textbooks, a reader gets the feeling that the Moon is not all that important in the development of our habitable planet. The Moon raises ocean tides on the planet and it serves as a “night lantern” and these features of the Moon have been important for some human endeavors (e.g., in production of food crops in coastal areas and, in some special circumstances, in military campaigns at specific times in human history). But the question posed here is: HAS THE MOON BEEN IMPORTANT IN THE DEVELOPMENT OF PLANET EARTH INTO THE ONLY PLANET THAT WE KNOW OF THAT IS HABITABLE TODAY, AFTER NEARLY 4.6 BILLION YEARS OF GEOLOGICAL EVOLUTION?