麻豆传媒

听

The Kinsac Pluton is a porphrytic two mica quartz monzonite of Early Devonian age which intrudes the folded Cambro-Ordivician meguma metasediment complex of mainland Nova Scotia. The present exposure is approximately circular and is completely surrounded by metasediments. Various lines of evidence suggest, however, that it is really an elongate lens-shaped body which at depth widens out, the present outcrop being only the "nose" of a larger intrusive mass which is an extension of the main pluton to the west. The presence of sharp contacts and lack of sedimentary inclusions, as well as the chemical data, all suggest that stoping and assimilation were not methods of intrusion, but rather intrusion seems to have been largely mechanical, pushing apart and deforming the axis of the fold into which it was intruded. In addition the presence of probable secondary muscovite, hydrothermal tourmaline, and iron stained feldspars suggest extensive, probably late stage, hydrothermal effects. These minerals, along with the presence of andalusite in the nearby contact metasediments, suggest a minimum intrusion temperature of 650^oC, and pressures of .5 to 4 Kb., suggesting a lower epizone (410 Km) crustal intrusion at least 369-379 m.y. ago, similar to the quartz monzonites of the main batholith.

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