Palaeoclimate Controls on Spectral Gamma-Ray Radiation from Sandstones

  1. Richard H. Worden3 and
  2. Sadoon Morad4
  1. A. H. Ruffell1,
  2. R. H. Worden3 and
  3. R. Evans1,†

Published Online: 17 MAR 2009

DOI: 10.1002/9781444304336.ch4

Clay Mineral Cements in Sandstones

Clay Mineral Cements in Sandstones

How to Cite

Ruffell, A. H., Worden, R. H. and Evans, R. (2009) Palaeoclimate Controls on Spectral Gamma-Ray Radiation from Sandstones, in Clay Mineral Cements in Sandstones (eds R. H. Worden and S. Morad), Blackwell Publishing Ltd., Oxford, UK. doi: 10.1002/9781444304336.ch4

Editor Information

  1. 3

    Department of Earth Sciences, University of Liverpool, Brownlow Street, Liverpool L69 3GP, UK

  2. 4

    Department of Earth Sciences, Uppsala University, Villa vägen 16, S-752 36 Uppsala, Sweden

Author Information

  1. 1

    School of Geography, Queen's University, Belfast BT7 1NN, UK

  2. 3

    Department of Earth Sciences, University of Liverpool, Brownlow Street, Liverpool L69 3GP, UK

  1. Reservoir Management Ltd, 7 Bon Accord Square, Aberdeen AB11 6DJ, UK

Publication History

  1. Published Online: 17 MAR 2009
  2. Published Print: 7 OCT 1999

ISBN Information

Print ISBN: 9781405105873

Online ISBN: 9781444304336

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Keywords:

  • palaeoclimate controls on spectral gamma-ray radiation from sandstones;
  • spectral gamma-ray (SGR) variation;
  • K, U and Th hosts and mobility in sandstones;
  • spectral gamma-ray radiation of sandstones;
  • K mobility in carboniferous feldspathic sandstones from northeast Ireland;
  • unconformity leaching of K in Jurassic Arkosic reservoir sandstones;
  • Triassic Sherwood sandstone group

Summary

Spectral gamma-ray data from borehole logs or outcrop measurements are cheap and quick to access, providing useful information for reservoir geologists, sequence stratigraphers, petrographers and now palaeoclimatologists. Potassium (K), uranium (U) and thorium (Th) are the three most abundant radioactive elements found in rocks and are thus considered to be the likely sources of gamma-ray variation detected both at outcrop and in the subsurface. The spectral gamma-ray (SGR) variation shown by these three elements in rocks has been considered to reflect: grain sorting at flooding surfaces; U concentration during anoxia; Th dilution in carbonates and changes in the weathering regime of sediment source-lands. Potassium is routinely assumed to reflect clay-mineral, feldspar, glauconite and evaporite abundance during wireline log interpretation. This study makes an assessment of the interpretation of spectral gamma-ray data in sandstones in terms of palaeoclimate influence. The different hosts and mobility of K, U and Th can provide interpretative data on palaeoclimates. The content and weathering of K-feldspars, heavy minerals and clays or micas, when observed in conjunction with facies analysis and petrography, all provide palaeoclimatic information. We document three case studies where SGR data in clay-bearing sandstones have yielded valuable palaeoclimatic and reservoir quality information. These are: Cretaceous greensands (southern England); Carboniferous feldspathic ganisters (north of Ireland); and Jurassic feldspathic reservoir sandstones (North Sea). We also document and discuss the reasons why one case study using SGR data failed to reveal significant palaeoclimatic information.