Igneous processes of the early solar system

Abstract

Experimental, petrographic and numerical methods are used to explore the igneous evolution of the early solar system. Chapters 1 and 2 detail the results of petrographic and experimental studies of a suite of primitive achondritic meteorites, the ureilites. The first chapter presents data that reveal correlations between mineral modal proportions and mineral chemistry that are used to guide experiments and models of ureilite petrogenesis. Chapter 2 details and applies the experimental results to describe ureilite petrogenesis as the result of progressive heating of a primitive carbon-rich body. The experiments place temperature and depth constraints on uteilite formation of 1100 to 13000C and 5 to 13 MPa - equivalent to the central pressure of an asteroid with a radius of 130 km. Chapter 3 reports the results of melting experiments of Allende carbonaceous chondrite at temperatures and pressures that would be expected on small bodies in the early solar system (up to 1300⁰C and 2.5 to 15 IPa) heated by decay of short lived isotopes. The results are then applied to ureilite petrogenesis and assembly of larger planetary bodies. The final chapter is an experimental study to test a hybridized source region for the high titanium lunar ultramafic glasses. Two models are presented that invoke either a heterogeneous source region or sinking and reaction of an ultramafic, titanium rich magma with underlying mantle regions.