Supplementary Data for Marine chemical sedimentary protoliths determined for ca. 3.71 Ga calc-silicate schists and quartzites from the Isua Supracrustal Belt

Located here are the isotopic (Si, S, O) and major - trace metal data to accompany the publication, "Marine chemical sedimentary protoliths determined for ca. 3.71 Ga calc-silicate schists and quartzites from the Isua Supracrustal Belt."

To put this data in context foliated calc-silicate schists and quartzites from a ca. 3.71 Ga domain within the northeastern part of the Isua Supracrustal Belt (southern West Greenland) may be interpreted as either deformed layered “metasedimentary” rocks, or the metasomatic fluid alteration products of a deformed mafic igneous precursor (i.e., basaltic protolith).

To determine the protolith, we used correlated mineralogical, outcrop- and regional-scale structural, and in situ major-, minor- and trace-element geochemical analyses coupled with high spatial resolution Si, O, and S isotope measurements. We conclude the protoliths were sedimentary chemical precipitates with a minor detrital clay fraction. This interpretation is bolstered by the low levels of generally immobile elements (Zr, Cr, Y, Ti, and P) which rule out either a purely igneous or clastic sedimentary origin. Further evidence for a sedimentary origin includes heterogeneous Si and O isotopes and mass-independent S isotope values (Δ33S>0, S-MIF), along with rare earth element (REE + Y) signatures that show light REE-depletion in PAAS normalized REE patterns and seawater-like Y/Ho.