ISSN:
1432-0967
Source:
Springer Online Journal Archives 1860-2000
Topics:
Geosciences
Notes:
Abstract The delay in nucleation of olivine in basaltic melts increases systematically with decreasing degree of supercooling, cooling rate, superheat, olivine content of the melt and with increasing melt viscosity. These findings imply homogeneous nucleation of olivine in melts run in the Pt-wire loop sample container used. Unlike plagioclase nucleation, the appearance of the first olivine crystal in a melt is predictable (to within 0.1–1 h of the event). The ‘metastable region’ (i.e., the minimum degree of supercooling necessary for nucleation) is less than 13 ° C. The cause of the delay in nucleation is discussed in terms of the finite growth rate of embryos and the progressive polymerization of the melt with decreasing temperature and increasing time. At degrees of superheat 〈18 ° the melts are inferred to be more highly disordered than expected. Some implications of the results for petrology and experimental petrology are discussed, including the possibility that continuous zoning may develop under isothermal conditions due to the sluggish attainment of equilibrium of melt structure following a sudden change in temperature.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00375191
