Physical Properties of Sediment Collected during India's National Gas Hydrate Program NGHP-02 Expedition in the Krishna-Godavari Basin Offshore Eastern India, 2015

Deployment sample collection: All specimens were collected from the working half of split cores collected from 20150428 – 20150731. Specimens were stored in heat-sealed plastic specimen bags and refrigerated during the expedition. Depth below seafloor was determined from centimeter scales running alongside the cores during processing, then tied to the continuous downhole depth log using both the IODP standard depth terminologies, which are each based on drilling records of the drill pipe length: CSF-A (total depth from seafloor to target sediment, including gas expansion gaps in the core, if present) and CSF-B (total depth from seafloor to target sediment, after all gas expansion gaps have been removed). The seafloor depth reference (mudline) determined from a combination of noting when the drill string contacts the seafloor and increases the measured weight-on-bit, and visual verification of the drill bit position using an ROV.

After the specimens were shipped in coolers with cold packs to the WHCMSC, they were subsampled for grain size. Specimens of ~20 grams were sealed in plastic specimen bags and shipped to PCMSC for analysis.

Samples used for particle size determination were placed into a 1000 ml beaker filled with 200-500 ml of deionized water. Organics were removed by adding 5-10 ml of 30weight percent hydrogen peroxide and allowing the sample to oxidize overnight.  Following the oxidation the samples were heated to drive off excess hydrogen peroxide.  Samples were than washed twice via centrifugation in order to remove all solubles and excess organic material.  Following washing the samples were wet sieved to segregate them into three broad size fractions: Coarse/Gravel (greater than 2mm); Intermediate/Sand (2.00 mm - 0.063mm); and Mud (silt and clay) composed of the material greater than 0.063mm.
The gravel fraction was sized with sieves binned at 1/4phi intervals.  The sand and mud fractions were sized with a Beckman Coulter LS 13-320 laser diffraction particle size analyzer at 1/4 phi size intervals.  The particle size data were then combined and processed with the PCMSC proprietary software called pcSDSZ. The pcSDSZ software determines the particle size distribution according to graphical statistics using the formulas of Folk (1966, 1974); Folk and Ward (1957), Inman (1952), and Trask (1930, 1932), as well as Moment Measures (Collias and others 1963; Jaquet J.-M., Vernet J.-P., 1976).
Collias, E.E., Rona, M.R., McManus, D.A., and Creager, J.S., 1963, Machine processing of geological data: Univ. Washington Tech. Rept. 87, 119 pp.
Folk, R.L., 1966, A review of grain-size parameters, Sedimentology, 6, p. 73-93.
Folk, R.L., 1974, Petrology of Sedimentary Rocks, Hemphill, Austin, TX, p. 1-159.
Folk, R.L., and Ward, W.C., 1957, Brazos River bar - a study in the significance of grain size parameters: Journal Sedimentary Petrology, 27, p. 3-26.
Inman, D.L., 1952, Measures for describing the size distribution of sediments: Journal of Sedimentary Petrology, 22, p. 125-145.
Jaquet J.-M., Vernet J.-P., 1976, Moment and graphic size parameters in sediments of Lake Geneva (Switzerland): Journal of Sedimentary Petrology, 46, p. 305–312.
Trask, P.D., 1930, Mechanical analysis of sediments by centrifuge: Economic Geology, 25, p. 581-599.
Trask P.D., 1932, Origin and Environment of Source Sediments of Petroleum: Gulf Publishing Company, Houston, Texas, 323 pp.
Wentworth, C.K., 1922, A scale of grade and class terms for clastic sediments: Journal of Geology, v. 30, p. 377-392.

Data archiving: Microsoft Excel version 15.33 was used to gather all data in a spreadsheet. Specimen locations (latitude/longitude) and depth below seafloor is added to the compiled tabular results spreadsheet. Results spreadsheet is exported to a comma-separated values (csv) file format.

Added keywords section with USGS persistent identifier as theme keyword.