Composition of tephra of the Goldberg volcano (West Eifel, Germany) and search for its dispersion

Abstract

Because of intensive exploitation of the Goldberg volcano (West Eifel Volcanic Field, Germany), in the past three decades, additional information has been obtained on its volcanological history and its products. Two important explosive events are recorded in the stratigraphic pile. An attempt is made to trace tephra of the volcano, by sampling soils in plateau position all around the volcano. However, the sampled sites also contained minerals from the Laacher See tephra that blanketed the area as demonstrated by the occurrence of a layer in the nearby Bragphenn peat bog. We performed electronic microprobe analyses, to discriminate between the pyroxenes from Goldberg and those from the Laacher See. Since the quantities of minerals drop rapidly away from the volcano, the Goldberg tephra cannot be traced beyond some 6 km. Nevertheless the dispersion is more important in westwards so that further discovery of the tephra can be expected especially in Upper Belgium. Our results allow us to shift the minimal age of the eruption from 11.6 ka BP to 25 ka BP.