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1 GSA Data Repository Das et al., 2017, In situ peridotitic diamond in Indus ophiolite sourced from hydrocarbon fluids in the mantle transition zone: Geology, doi: /g Figure DR1. A: Geological map of the Nidar ophiolite and associated lithologic units in the Indus Suture Zone, Indian Himalaya; inset shows the location of the Nidar ophiolite in India. B: Digital elevation model of the Nidar ophiolite and adjacent litho units. C: Pseudo stratigraphic reconstruction of the Nidar ophiolite based on geological mapping (done along AB of Fig. B) showing the location of the studied peridotite bodies 1M1 and 1NU27.

2 Figure DR2. A: Inclusions in an orthopyroxene porphyroclast of 1M1 peridotite are studied. B: From the same grain, coesite and clinoenstatite assemblage were reported (Das et al., 2015). Hematites (α Fe 2 O 3 ) occur as inclusions in the orthopyroxene porphyroclast. C: Some of the α Fe 2 O 3 bear inclusions of silicate minerals. Point 1 and 2 are the spots for Laser Raman analyses of both α Fe 2 O 3 and its inclusions respectively. C1: Raman spectrum confirms the opaque phase as α Fe 2 O 3 or hematite. C2: The silicate mineral in α Fe 2 O 3 is characterized as clinoenstatite (Cen). With the Cen, sharp peak of methane (at cm -1 ) also found.

3 Figure DR3. A: In peridotite 1NU27, granular opaque precipitations of α Fe 2 O 3 are found in some of the olivines. B: α Fe 2 O 3 precipitates are also noticed with the Cr Spinel exsolution needles in host olivine. B1: Raman spectrum of opaque precipitates, spot 1 in Fig DR3A, confirms the phase as α Fe 2 O 3.

4 Figure DR4. A: Clinoenstatite (Cen) lamella in orthoenstatite (Oen) from peridotite 1NU27 (Das et al., 2015). Point 1 is the spot of Laser Raman analyses shown in A1. A1: The Raman spectrum of point 1 showing presence of methane with Cen.

5 DR5 Analytical Methods Four thin sections from the two ultramafic units of the Nidar Ophiolite were used in this study. Thin section preparation and petrographic study were done initially at the Wadia Institute of Himalayan Geology (WIHG), Dehradun, India. The thin sections were studied optically under transmitted and reflected light using a Nikon Eclipse LV 100 POL microscope and image analyses were performed using NIS-Elements software. Majority of the Raman spectra and mapping were obtained with the aid of a Thermo Scientific DXRxi Raman imaging spectroscope in the Department of Earth and Environmental Science, University of Texas at Arlington, USA. Spectra were generated using a 50X objective and 532 nm laser. The laser spot size at the time of analyses were ~ 2 µm. The operating conditions were 1 5 sec acquisition time, 1 5 accumulations and 4 6 mw laser power. The Raman maps were made in standard 2D mode along the XY plane of a thin section. The accuracy of the Raman peak positions was generally considered to be < 1 cm -1. The maps display the geometrical distribution of phases in detail, more importantly where mixed phases are concerned. The maps allow to search new phases in selected fluid inclusions (or selected area) if some phases were missed by single point analysis. Though the DXRxi Raman imaging microscope is calibrated through autoalignment, Si (520.5 Cm -1 peak) is used to recheck the calibration. Laser Raman spectroscopy was also performed in WIHG by a LabRAM HR-Horiba Jovin Yuvon instrument. Spectra were generated at room temperature with the nm Ar laser and detected with a charge-coupled detector array through Olympus 50 and 100 objective lenses. The laser spot on the surface had a diameter of approximately 1 2 µm and a power of mw. The real-time display exposure times for the minor mineral phases were selected between 1

6 and 40 sec with an exposure time of 1 15 sec and an accumulation number of The Raman spectroscope was calibrated with a synthetic Si standard (at cm -1 ). DR6 Summary of the observations Peridotite sample no Olivine Orthopyroxene 1NU27 Hematite precipitations Diamond with nitrogen Cr spinel exsolution needles Methane with high pressure clinoenstatite C H and H 2 Graphite pseudomorphs after diamond 1M1 Hematite inclusion with clinoenstatite and methane