Organic metamorphism in Middle Ordovician carbonates, Lebanon Valley nappe, Pennsylvania

An assemblage of highly brecciated organic fragments at the contact of the Middle Ordovician Annville and Myerstown Formations in the Lebanon Valley n appe, Lebanon County, Pennsylvania, was found to have maximum reflectances generally exceeding 8% R, with the highest values approaching 13% R. Such r eflectance values are consistent with greenschist facies metamorphism, the latter supported by metamorphic mineral assemblages. Brecciation and metamo rphism of the organics probably occurred at the time of the emplacement of the nappe during the Ordovician Taconic orogeny. (C) 2000 Elsevier Science B.V. All rights reserved.