Sulfur isotopic evidence for sources of volatiles in Siberian Traps magmas

The Siberian Traps flood basalts transferred a large mass of volatiles from the Earth's mantle and crust to the atmosphere. The eruption of the large igneous province temporally overlapped with the end-Permian mass extinction. Constraints on the sources of Siberian Traps volatiles are critical for determining the overall volatile budget, the role of crustal assimilation, the genesis of Noril'sk ore deposits, and the environmental effects of magmatism. We measure sulfur isotopic ratios ranging from -10.8 parts per thousand to +25.3 parts per thousand Vienna Canon Diablo Troilite (V-CDT) in melt inclusions from Siberian Traps basaltic rocks. Our measurements, which offer a snapshot of sulfur cycling far from mid-ocean ridge and arc settings, suggest the delta S-34 of the Siberian Traps mantle melt source was close to that of mid-ocean ridge basalts. In conjunction with previously published whole rock measurements from Noril'sk, our sulfur isotopic data indicate that crustal contamination was widespread and heterogeneous-though not universal-during the emplacement of the Siberian Traps. Incorporation of crustal materials likely increased the total volatile budget of the large igneous province, thereby contributing to Permian-Triassic environmental deterioration. (C) 2014 Elsevier B.V. All rights reserved.