Accretionary lapilli in Cambrian “adinoles” of the Příbram area

 

Ferry Fediuk

Geoscience Research Reports 37, 2004 (GRR for 2003), pages 22–23
Map sheets: Březnice (22-12)

Full text (PDF, 0.08 MB)

 

Abstract

The terrigenous Lower Cambrian sandstones and subgreywackes of the Holšin-Hořice Formation in the Barrandian Příbram-Jince Basin of Central Bohemia contain several layers of highly silicious, light greenish grey coloured cherty rocks known since the 19th century as adinoles. Later, they were recognized as silicified fine ashy rhyodacitic tuffs. In one of their frequent but mostly not very thick occurrences, on the northern slope of the Dubová hora hill (el. 626.5) 4 km WNW from the centre of the old mining town Příbram, numerous and well preserved accretionary lapilli, formerly mistaken for ooids, occur. They amount up to 250 000 corpuscules per one m3 of the rock. It is the first discovery of this volcanic structure in pre-Tertiary rocks of the Czech Republic.