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    STUDIA GEOLOGIA - Issue no. 3 / 2003  
         
  Article:   HERCYNITE AND MAGNETITE IN THE HORNFELS XENOLITHS HOSTED BY GRANODIORITE FROM VALEA LUNGII (CLUJ COUNTY, ROMANIA).

Authors:  NICOLAE HAR, RAMONA NĂSTASE.
 
       
         
  Abstract:  Isolated intermediate magmatic bodies of Upper Cretaceous – Paleogene age crops out in the Valea Drăganului – Valea Lungii area (northern part of the Apuseni Mountains, Romania). The petrography is mainly granodioritic, typical for hipabyssic facies. They contain frequently xenoliths from the basement of the area. In the intrusive granodioritic body from Valea Lungii two different types of xenoliths are present: of magmatic (porphyritic granodiorite) and metamorphic (gneiss) origin. The xenoliths are variable in size (up to 30 cm in diameter) and usually dark in color. The study is focused on the xenoliths of metamorphic origin, that have undergone pyrometamorphic transformations under the influence of the host melt. The resulted hornfels preserves the texture of the initial gneiss. Two different varieties of hornfels are present: spinel andalusite and spinel sillimanite hornfels. Both include different amounts of K-feldspar, biotite, phlogopite, magnetite and hercynite.  
         
     
         
         
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