A Proterozoic Lacustrine Interlude from the Zambian Copperbelt

  1. Albert Matter and
  2. Maurice E. Tucker
  1. Harry Clemmey

Published Online: 29 JUN 2009

DOI: 10.1002/9781444303698.ch14

Modern and Ancient Lake Sediments

Modern and Ancient Lake Sediments

How to Cite

Clemmey, H. (2009) A Proterozoic Lacustrine Interlude from the Zambian Copperbelt, in Modern and Ancient Lake Sediments (eds A. Matter and M. E. Tucker), Blackwell Publishing Ltd., Oxford, UK. doi: 10.1002/9781444303698.ch14

Author Information

  1. Department of Earth Sciences, The University of Leeds, Leeds LS2 9JT, UK

Publication History

  1. Published Online: 29 JUN 2009
  2. Published Print: 24 NOV 1978

ISBN Information

Print ISBN: 9780632002344

Online ISBN: 9781444303698

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Keywords:

  • transgression contain a trace fossil fauna indicative of an advanced metazoan benthos.;
  • desiccation cracks;
  • syneresis cracks;
  • Proterozoic lacustrine interlude;
  • Silt/fine sand fades assemblage

Summary

On the Zambian Copperbelt the Orebody Member of the Kitwe Formation is represented by some 30 m of dolomitic and siliciclastic rocks. These meta-sediments illustrate the problems of differentiating between pre-Phanerozoic sediments of lacustrine, lagoonal or epeiric sea origin.

Facies analysis of the sequence indicates a four stage history. First, a marine transgression took place over a dominantly fluvial landscape. The basal sediments of this transgression contain a trace fossil fauna indicative of an advanced metazoan benthos. Secondly, isolation of the sea led to the establishment of lacustrine conditions. Incipient sabkha diagenesis occurred in the lake edge sediments and is indicated by anhydrite crystal lath mush, gypsum crystal mats and nebulitic anhydrite. Thirdly, a return to marine conditions occurred and finally a major regression, documented by a coarsening upward sequence, indicates the advance of alluvial sediments into the area. Siliciclastic sabkhas were developed during this final period. Strontium values lend some support to the facies interpretation, the highest values occurring in the marine stages.

Five major transgressive periods impart a recognizable cyclicity to the sediments. The stratigraphic applications of this cyclicity are of potential economic importance for the major orebodies of the Copperbelt are located within the unit.