New multi-dimensional diagrams for tectonic discrimination of siliciclastic sediments and their application to Precambrian basins

•We present the first multi-dimensional diagrams for silicic sedimentary rocks.•These are the first diagrams for discrimination of three tectonic settings.•These diagrams are based on coherent statistical treatment of compositional data.•Only major elements are required for their use in deciphering tectonic setting.•The existing diagrams do not perform well and should be replaced by these new ones.

Siliciclastic sediments owe their origin mainly to land sources. New discriminant-function-based major-element diagrams for the tectonic discrimination of siliciclastic sediments from three main tectonic settings: island or continental arc, continental rift, and collision, have been constructed for the tectonic discrimination of high-silica [(SiO2)adj = 63%-95%] and low-silica rocks [(SiO2)adj = 35%-63%], where (SiO2)adj refers to the SiO2 value obtained after volatile-free adjustment of the ten major-elements to 100 wt.%. These diagrams are based on worldwide examples of Neogene-Quaternary siliciclastic sediments from known tectonic settings, loge-ratio transformation of ten major-elements with SiO2 as the common denominator, and linear discriminant analysis of the loge-transformed ratio data. The success rates of these diagrams as judged from the original data varied from 84.5% to 93.6%. These diagrams were successfully tested on Neogene to Quaternary rocks not included in the original database. These discriminant diagrams were also successfully applied on older high-silica and low-silica sandstones and shales of Paleoarchean-Ediacaran age. Finally, these diagrams were shown to be useful against chemical changes related to analytical errors, weathering, recycling and post-depositional processes.

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