Contact Partial Melting of Granitic Country Rock, Melt Segregation, and Re-injection as

• Main Authors: Dikes Ferrar, Dolerite Sills, Mcmurdo Dry, Taber G. Hersum, Bruce D. Marsh, Adam, C. Simony
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Published: 2006
• Subjects: Antarc*
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.617.8620; http://petrology.oxfordjournals.org/content/48/11/2125.full.pdf

Numerous, interconnected, granitic dikes (530 cm in width and hundeds of meters in length) cut Ferrar dolerite sills of the McMurdo DryValleys, Antarctica.The source of the granitic dikes is partial melting of granitic country rock, which took place in the crust at a depth of about 2^3 km adjacent to contacts with dolerite sills. Sustained flow of doleritic magma through the sill generated a partial melting front that propagated into the granitic country rock. Granitic partial melts segregated and collected at the contact in a melt-rich, nearly crystal-free reservoir adjacent to the initial dolerite chilled margin.This dolerite chilled margin was subsequently frac-tured open in the fashion of a trapdoor by the granitic melt, evacuat-ing the reservoir to form an extensive complex of granitic dikes within the dolerite sills. At the time of dike injection the dolerite was nearly solidified. Unusually complete exposures allow the full physical and chemical processes of partial melting, segregation, and dike formation