3f1e4b2d-dbdd-47ea-bde8-18447fd8bf10 urn:uuid eng UTF-8 nonGeographicDataset nonGeographicDataset 2025-10-16T05:28:54 creation ISO 19115 2016 Outcrop and drill core gamma-ray logging integrated with sequence stratigraphy: examples from Proterozoic sedimentary successions of northern Australia 3f1e4b2d-dbdd-47ea-bde8-18447fd8bf10 Outcrop and core gamma-ray logs have been successfully used to correlate Proterozoic units in northern Australia. This paper highlights the benefits of integrating gamma-ray data and traditional sedimentology for defining large-scale depositional cycles and depositional geometry. Gamma-ray logs of outcrop and cored intervals provide excellent stratigraphic and sedimentological information for areas where conventional down-hole geophysical surveys are lacking. Both total count (scintillometer) gamma-ray profiles and spectral gamma-ray profiles enable recognition of subtle changes in lithology and sedimentary cyclicity that might have been missed during customary section measuring. Lithofacies described from measured sections and core may be characterised by their gamma-ray signatures, and the signatures may then be used as proxies for down-hole gamma-ray logs obtained from the subsurface where direct lithological information is sparse or absent. The integration of traditional lithostratigraphic descriptions with surface and subsurface gamma-ray logs results in a more robust and sophisticated stratigraphic framework than either data set can yield independently. Use of sequence stratigraphic principles enables gamma-ray log trends and their stacking patterns to be interpreted as part of larger sedimentary cycles that reflect changes in sediment supply and relative sea level. Abrupt shifts in gamma-ray values occur at important stratigraphic surfaces that define sedimentary sequences of various scales. Systematic variations in sedimentary thickness and gamma- ray stacking patterns between areas are related to changes in depositional geometry of sequences. Regional mapping of stratigraphic surfaces and sequences by the correlation of vertical gamma-ray profiles and corresponding descriptive logs allows a predictive chronostratigraphic framework to be constructed for a region. Earth Sciences GA Publication Journal Published_External Journal article (pdf) documentDigital Journal article (pdf) PDF Unnamed resource documentDigital HTML