Calcite Needles in Syros Marbles

INTRODUCTION The rocks on the Greek island of Syros are part of a suite of high pressure metamorphic rocks which outcrop all across the Cyclades. There is a complex metamorphic history recorded in the rocks here, including a Cretaceous or Eocene high-pressure blueschist event and a Miocene, extension-related greenschist overprint. The Island of Syros is mostly composed of schists , which alternate with north-dipping pure and “impure” marbles, and some smaller outcrops of breccia and metagabbro [Dixon and Ridley 1987]. Calcite in the marbles here shows a needle-like texture. Needles are generally sub-vertical, sub-perpendicular to the marble foliation and range in length from 1 cm to 6cm.The origin of these needles , the significance of their alignment with respect to local structures and answering why these needles might be oriented sub-perpendicular to the foliation makes up the bulk of this study.