Open AccessCalibration of spectral gamma-ray logs to deltaic sedimentary facies from the Cretaceous Atane Formation, Nuussuaq Basin, West Greenland
Author(s) -
Gunver Krarup Pedersen,
Niels H. Schovsbo,
Henrik NøhrHansen
Publication year - 2013
Publication title -
geological survey of denmark and greenland bulletin
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.652
H-Index - 29
eISSN - 1904-4666
pISSN - 1604-8156
DOI - 10.34194/geusb.v28.4726
Subject(s) - geology , petrophysics , lithology , zircon , glauconite , outcrop , uranium , geochemistry , facies , thorium , feldspar , radiometric dating , mineralogy , sedimentary rock , gamma ray , quartz , structural basin , geomorphology , paleontology , materials science , geotechnical engineering , physics , porosity , astrophysics , metallurgy
Gamma-ray logs are widely used as a lithology indicator in wells as part of standard petrophysical interpretations. In cored wells, gamma-ray logs should always be calibrated to the lithology in order to correct the petrophysical model. Gamma radiation is emitted from three elements, K, Th and U (potassium, thorium and uranium) which occur in minerals such as feldspar, mica, glauconite, clay minerals, zircon, titanite and apatite as well as in organic complexes. Organic-rich mudstones usually have high gamma-radiation values and quartz-rich sandstones low values. In many places, upward-coarsening successions are recognisable from the gamma log. The gamma log records the sum of radiation from K, Th and U, and their relative contributions are measured in a spectral gamma-ray log. The present case study focuses on spectral gamma-ray characterisation of the deltaic Atane Formation which shows well-developed, upward-coarsening delta-front deposits in outcrops (Fig. 1C).