%0 Journal Article
%A Martinius, A.W.
%A Geel, C.R.
%A Arribas Mocoroa, José
%T Lithofacies characterization of fluvial sandstones from outcropgamma-ray logs (Loranca Basin, Spain): the influence of provenance
%D 2002
%@ 1354-0793
%U https://hdl.handle.net/20.500.14352/59246
%X Natural gamma spectral (NGS) log motifs and cluster analysis wereused to characterize outcropping sandstone bodies formed in braided and highsinuositystreams of the Tertiary Tórtola fluvial system of the Loranca Basin (Spain).Five coarse-grained lithofacies comprise these deposits and determine distinct NGSlog motif. Cross-plots and cluster analysis of NGS log data of the lithofacies suggestthree distinct clusters. These clusters reflect distinct values for sandstones with smallsets of ripple lamination, cross-stratification, and conglomerates and pebbles.Ripple-laminated sandstones show the most variability in NGS signature, whereasconglomeratic sandstones show the most uniform signature. Such cluster analysismay be used to assign NGS log data points of unknown origin to a specific fluviallithofacies under conditions of equal rock provenance and diagenetic history. Asedimentaclastic (i.e. sedimentary parent rock) origin of sediments appears to be themain control on detrital composition that, in turn, varies with grain size.
%~