Apatite in the Sudbury Igneous Complex, Ontario : monitor of fractionation, degassing, and a metamorphic overprint

• Main Author: Warner, Stephen.
• Other Authors: Martin, Robert F. (advisor)
• Format: Others
• Language: en
• Published: McGill University 1996
• Subjects: Mineralogy.
• Online Access: http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=24046

Apatite occurs as an accessory phase throughout the Sudbury Igneous Complex (SIC), Ontario, as well as in the overlying tuffaceous rocks of the Onaping Formation (OF). This investigation was designed to characterize the textural development and composition of apatite. Representative samples were taken from three traverses: the NW suite is the most pristine. Apatite is found primarily as a post-cumulus (or intergranular) phase, but becomes a cumulus mineral in the quartz gabbro. The apatite is F-rich; Cl and OH contents decrease from the base of the complex upward. Apatite in the OF has higher inferred levels of OH. In the SIC, Cl and OH decreased relative to F upon vapour saturation of the evolving melt. The concentrations of LREE, up to 2 wt% La$ rm sb2O sb3+Ce sb2O sb3+Nd sb2O sb3,$ are higher in apatite near the base of the complex. The chondrite-normalized REE patterns, and $ sp{87}$Sr/$ sp{86}$Sr ratios (0.707-0.708), are similar in apatite from each rock type of the Main Mass. The SIC evolved normally by fractional crystallization of a single batch of basic magma, which likely resulted from an impact-generated crustal melt. Apatite from the SW section and, to a lesser extent, the NE section, has significantly lower levels of Cl and LREE; the $ sp{87}$Sr/$ sp{86}$Sr ratio has also been reset (up to 0.739). Local recrystallization during metamorphism thus led to remobilization of these elements from apatite.