Igneous rocks thermal history

Evolved extraterrestrial materials are generally igneous rocks, which according to their thermal history can be discnssed analogonsly to terrestrial samples. To this category belong planetary bodies, differentiated asteroids, and achondritic meteorites. 

Because D increases with increasing temperature (the Arrhenius equation 1-73), time-dependent D is often encountered in geology because an igneous rock may have cooled down from a high temperature, or metamorphic rock may have experienced a complicated thermal history. If the initial and boundary conditions are simple and if D depends only on time, the diffusion problem is easy to deal with. Because D is independent of x. Equation 3-9 can be written as... 

In particular, consider a thermal history of monotonic cooling (such as an igneous rock, especially a volcanic rock) represented by the asymptotic cooling model (Equation 2-41) ... 

Shortly after the condensation of the first minerals to form within the Solar System, thermal processing of refractory inclusions began. The overall processing of these materials into igneous rocks was short-lived, perhaps only 100000 years (Bizzarro et al. 2007). The critical constraints on the thermal histories of these objects is essentially limited to Type-B CAIs (Connolly Desch 2004), which have been generated by the experimental reproduction of these objects in the laboratory. Type-B CAIs are composed mostly of melilite, anorthite, aluminous spinel, and a titanium-rich pyroxene known in the parlance as fassaite (for a summary of minerals common to the Solar System see Appendix 1). The general consensus is... 

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