Dataset: Biomass-derived and Free Biomarker Concentrations in Cores U1545, U1546, and U1547 from R/V JOIDES Resolution IODP Expedition 385 Guaymas Basin Tectonics and Biosphere between September and November 2019

Samples were collected by the IODP Expedition 385 Scientific Party aboard the drilling ship JOIDES Resolution. Samples were obtained from IODP cores U1545, U1546, and U1547, which are 52, 51, and 27 kilometers northwest of the axial graben of the northern Guaymas Basin. We analyzed samples from three depth horizons (5-10 mbsf, 26-30 mbsf, and 54-57 mbsf) from U1545 and U1547. Samples from U1546 only contained two depth horizons (26-30 mbsf and 54-57 mbsf).

Cores were drilled using an advanced piston corer (APC) and half-length APC and sectioned by the science party (Teske et al., 2021). Samples were handled and preserved anoxically according to best practices for microbiological studies and stored at -80 degrees Celsius (C) in clean glass jars. After being transferred to the laboratory, frozen samples were thawed and extracted using a modified Bligh and Dyer solvent extraction to account for water content and to preserve intact lipid structures. All extractions were performed with cleaned glassware (combusted at 450 degrees C) or in cleaned Teflon bottles (pre-extracted with solvents). Extracts were separated into three polarity fractions using silica gel chromatography to remove intact polar lipids from the other compound classes. All extracts were then transesterified and re-separated into a fine scale chromatography scheme with 10 polarity fractions to allow for high-resolution analysis.

An Agilent 8890 gas chromatograph (GC) was used with 5977C MSD for identification and a FID for quantification. Samples were injected twice to analyze with both detectors. The GC was equipped with He carrier gas with either an Agilent 60m DB-5ms Ultra Inert column or a Thermo TR-FAME column for each compound class.