thumbnail

Genesis of a regionally widespread celadonitic chert ironstone bed overlying upper Lias manganese deposits, Hungary

Journal of the Geological Society

By:
, , , , , , and
DOI: 10.1144/0016-76492008-132

Links

Abstract

Mineralogy and chemical composition are presented for a chert-ironstone bed that overlies the ??rk??t Mn deposit. This bed is mottled green-brown in its lower and upper parts, which are composed of quartz, goethite and celadonite. These parts of the bed are interpreted to be strongly altered tuffs, reflecting oxidic, low-temperature alteration of a hydrated, Fe-rich, Al-poor tuff, and K and Mg uptake from seawater. The middle part of the bed is a mineralized bacterial mat (quartz, goethite). Textures resembling bacterial cells and colonies are common, with wavy, bulbous laminations composed of mounds overlying a mesh-work stromatolite-like texture constructed of micrometre-size Fe oxides. This bed is concordant with the underlying Mn deposit and marks the termination of Mn accumulation. Although no genetic connection exists between the two, the rocks adjacent to the contact record the oceanographic and bottom-water conditions extant when accumulation of one of the major Mn deposits of Europe ended, when the Transdanubian Range was located in the middle of the Adria-Apulian microcontinent between the Neotethys and Atlantic-Ligurian seaways. A pyroclastic origin for part of the bed has significance for the Toarcian of Central Europe because evidence of volcanism occurring at that time is otherwise sparse. ?? 2010 Geological Society of London.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Genesis of a regionally widespread celadonitic chert ironstone bed overlying upper Lias manganese deposits, Hungary
Series title:
Journal of the Geological Society
DOI:
10.1144/0016-76492008-132
Volume
167
Issue:
2
Year Published:
2010
Language:
English
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
Journal of the Geological Society
First page:
313
Last page:
328
Number of Pages:
16