Basalts Through Time — Roy et al. (2026), Communications Earth & Environment

This repository contains the supplementary data accompanying the manuscript:Roy, S., Kamber, B. S., Hayman, P. C. & Murphy, D. T. (2026). Tectonic setting and mantle source evolution reconstructed from deep time analysis of basalt geochemistry. Communications Earth & Environment.The study presents a global deep-time analysis of basalt CIPW normative mineralogy, tracking secular changes in basalt petrology from the Archaean to the present day.Key findings include:- Archaean continental basalts are dominantly quartz-normative (~49%), with striking compositional similarity to Phanerozoic continental flood basalts.- Normative clinopyroxene/orthopyroxene ratios argue against dominant hydrous flux-melting as a petrogenetic mechanism for Archaean basalts.- A progressive secular increase in nepheline-normative (alkali) basalts, with a pronounced step-change near the Precambrian–Phanerozoic boundary, attributed to widespread mantle hybridisation following the onset of sustained, modern-style deep subduction in the Neoproterozoic.- Two lulls in Palaeoproterozoic mafic magmatic activity are identified: the established Tectono-Magmatic Lull (~2,365–2,235 Ma) and a newly recognised lull at ~2,000 Ma.FILES INCLUDEDSupplementary Data 1 — Compiled whole-rock geochemical databaseSupplementary Data 2 — Experimental melt compositionsSupplementary Data 3 — LDA analysis outputsSupplementary Data 4 — MAGEMin fractional crystallisation model outputSupplementary Information — Supplementary figures, tables, notes, and references (PDF)Python scripts for all figures are available at:https://github.com/INDeep-earth/roy-2026-basalt-normative-mineralogy