Lithology and diagenesis of the poorly consolidated Cambrian siliciclastic sediments in the northern Baltic Sedimentary Basin

Authors

  • Valle Raidla Institute of Geology, University of Tartu, Vanemuise 46, EE-51014 Tartu, Estonia
  • Kalle Kirsimäe Institute of Geology, University of Tartu, Vanemuise 46, EE-51014 Tartu, Estonia
  • Liidia Bityukova Institute of Geology, Tallinn University of Technology, Ehitajate tee 5, Tallinn 19086, Estonia
  • Argo Joeleht Institute of Geology, University of Tartu, Vanemuise 46, EE-51014 Tartu, Estonia
  • Alla Shogenova Institute of Geology, Tallinn University of Technology, Ehitajate tee 5, Tallinn 19086, Estonia
  • Saulius Sliaupa Institute of Geology, T. Sevčenkos 13, LT2600 Vilnius, Lithuania

Keywords:

Cambrian, Baltic Sedimentary Basin, siliclastic sediments, diagenesis, clay minerals, compaction

Abstract

The present study discusses lithology and diagenetic characteristics of the siliciclastic Cambrian and the enclosing Ediacaran and Ordovician deposits in the northern Baltic Sedimentary Basin (BSB). The Neoproterozoic and Lower Palaeozoic sediments are despite their age unconsolidated with primary porosity of 20-25% for both shales and sandstones. The sparse Fe-dolomite cementation of arenitic and subarenitic sandstones and siltstones occurs mainly at lithological contacts with the massive Ediacaran and Lower Cambrian claystones and is probably related to ions released during illitization. In contrast to weak mechanical and chemical compaction of sandstone, the clay mineral diagenesis of Cambrian deposits is well advanced. The highly illitic (80-90%) nature of illite-smectite (I-S) suggests evolved diagenetic grade of sediments which conflicts with shallow maximum burial and low compaction. Smectite-to-illite transformation has resulted in formation of diagenetic Fe-rich chlorite in claystones. Some porosity reduction of sandstones is due to formation of authigenic kaolinite at the expense of detrital mica or K-feldspar.

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Published

2010-03-27

Issue

Vol. 50 No. 4 (2006)

Section

Articles

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