Petrogenesis of siliciclastic sediments and sedimentary rocks explored in three-dimensional Al<sub>2</sub>O<sub>3</sub>–CaO<sup>*</sup>+Na<sub>2</sub>O–K<sub>2</sub>O–FeO+MgO (A–CN–K–FM) compositional space
نویسندگان
چکیده
Quantitatively determining the amount of chemical weathering within sedimentary rocks (and profiles) took a major step forward with creation index alteration (CIA) 40 years ago. The CIA relates proportion immobile aluminum to mobile cations calcium, sodium, and potassium is grounded in empirical modeled geochemical data for mineral reactions that occur during hydrolysis. However, should be applied cautiously because it one-dimensional value most complex situations, as clastic rocks, homogenizes compositional inputs source, weathering, sorting, diagenesis. Subsequently developed two-dimensional (2D) ternary diagrams (Al 2 O 3 –CaO * +Na O–K O; Al O+K O–FeO+MgO) permitted capacity explore mineralogical-geochemical pathways sets may separate those inputs, but interpreting complicated they differentiate group certain elements. Here we develop three-dimensional tetrahedral diagram O–FeO+MgO, A–CN–K–FM) incorporates same critical elements permits simultaneous assessment felsic mafic minerals on while retaining ability plagioclase from alkali feldspar monitor post-depositional changes. Using plot, show both positions 2D can generate potentially misleading interpretations without properly budgeting ferromagnesian components parallel. We first how tetrahedron works, then use numerous previously published examples identify competing shape composition source profiles, actively transporting sediment, paleosols, petrogenesis.
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ژورنال
عنوان ژورنال: Canadian Journal of Earth Sciences
سال: 2023
ISSN: ['1480-3313', '0008-4077']
DOI: https://doi.org/10.1139/cjes-2022-0051