Formation and dissolution of zeolite during burial diagenesis - Examples from glauconitic sandstones in the Palaeogene Siri Canyon, Danish North Sea

TY - CONF

T1 - Formation and dissolution of zeolite during burial diagenesis - Examples from glauconitic sandstones in the Palaeogene Siri Canyon, Danish North Sea

AU - Kazerouni, Afsoon Moatari

AU - Friis, Henrik

AU - Svendsen, Johan B

AU - Weibel, Rikke

PY - 2008

Y1 - 2008

N2 - The Palaeogene Siri Canyon fill consists of hemipelagic and turbidite marl and claystones interbedded with massive and blocky glauconitic sandstones deposited from sandy mass-flows and sandy turbidites. The Palaeogene sediments in the Danish area are rich in siliceous microfossils as well as late Paleocene–early Eocene volcanic ash layers. Zeolites have a hydrated alumosilicate framework with varying amounts of alkali and alkaline earth metals.Authigenic zeolites may be common in deep marine sediments, and in volcanoclastic deposits. They are generally related to dissolution of siliceous fossils or diagenetic alteration of volcanic glass. Authigenic zeolites are uncommon constituents in most sandstones. However, authigenic zeolites are common in some of the glauconitic sandstones from the Siri Canyon, where it is generally associated with thick coatings of opal/microquartz on the detrital framework grains. The remaining open porespace may be filled with berthierine, chlorite, calcite or quartz, together with minor amount of other minerals such alkalifeldspar, siderite or pyrite, but in general, a high porosity (25-32%) is seen. Most occurring zeolites have a void in their central part, most likely reflecting dissolution of an early phase with different chemical composition. In many samples, zeolites have been totally dissolved, leaving impression marks in the opal/microquartz coating. The textural relation demonstrates that zeolite was dissolved after microquartz precipitation. In most case, the dissolution of zeolite has exposed the surface of detrital grains, allowing large syntaxial quartz overgrowths to form in the impression.This paper presents the occurrence and compositional variance of the authigenic zeolites in the Siri Canyon sandstones, and discuss the physico-chemical conditions which prevailed during formation of zeolites, pore water chemistry, composition of mineralogical precursors and the host sediments.

AB - The Palaeogene Siri Canyon fill consists of hemipelagic and turbidite marl and claystones interbedded with massive and blocky glauconitic sandstones deposited from sandy mass-flows and sandy turbidites. The Palaeogene sediments in the Danish area are rich in siliceous microfossils as well as late Paleocene–early Eocene volcanic ash layers. Zeolites have a hydrated alumosilicate framework with varying amounts of alkali and alkaline earth metals.Authigenic zeolites may be common in deep marine sediments, and in volcanoclastic deposits. They are generally related to dissolution of siliceous fossils or diagenetic alteration of volcanic glass. Authigenic zeolites are uncommon constituents in most sandstones. However, authigenic zeolites are common in some of the glauconitic sandstones from the Siri Canyon, where it is generally associated with thick coatings of opal/microquartz on the detrital framework grains. The remaining open porespace may be filled with berthierine, chlorite, calcite or quartz, together with minor amount of other minerals such alkalifeldspar, siderite or pyrite, but in general, a high porosity (25-32%) is seen. Most occurring zeolites have a void in their central part, most likely reflecting dissolution of an early phase with different chemical composition. In many samples, zeolites have been totally dissolved, leaving impression marks in the opal/microquartz coating. The textural relation demonstrates that zeolite was dissolved after microquartz precipitation. In most case, the dissolution of zeolite has exposed the surface of detrital grains, allowing large syntaxial quartz overgrowths to form in the impression.This paper presents the occurrence and compositional variance of the authigenic zeolites in the Siri Canyon sandstones, and discuss the physico-chemical conditions which prevailed during formation of zeolites, pore water chemistry, composition of mineralogical precursors and the host sediments.

M3 - Poster

T2 - Nordic Mineralogical Network Annual meeting

Y2 - 16 June 2008 through 19 June 2008

ER -