Redeposited zeolitic rocks from the NE Rhodopes, Bulgaria

Abstract

The redeposited zeolitic rocks of Early Oligocene age in the NE Rhodopes, Bulgaria, are composed of zeolitic rock fragments. Material for the study was collected from four sections situated to the north of the Arda river, Haskovo district. These rocks occurred in a rhythmic series of sediments, occupying the interval between the products of two episodes of acidic volcanism (Lower Oligocene). They consist predominantly of subangular to subrounded clinoptilolitic rock fragments in which are preserved the specific relict textures of earlier zeolitized volcanic glass shards. The clinoptilolite content, which has been determined both under the microscope and by X-ray diffraction, varies between 10% and 80% but is usually about 50% by volume. Implications for the paleogeographic and tectonic regime of the area are considered.