Ether-derived alkanes from sedimentary organic matter

Abstract

Glycerol ether lipids have been detected in the bitumen of DSDP sediments from Sites 467, 440B and 380 and from the Green River Shale. The alkyl side groups of these ethers were determined by conversion into deuteroalkanes. The presence of glycerol ethers produced by methanogenic bacteria was indicated in .the DSDP bitumens by the formation of monodeuterated phytane and dideuterated biphytane. Other ethers were found with novel non-isoprenoidal side groups which may belong to sulfate-reducing or other, probably anaerobic, bacteria. Kerogen-bound alkoxy groups were determined using hydrogen iodide cleavage of the ether link followed by conversion of the iodoalkanes into corresponding deuteroalkanes. For this reaction, the kerogen was not isolated from the rock matrix. The structures so produced were found to include alkyl groups which have known bacterial precursors as well as others that are presently unknown in organisms. The Green River ether biomarker profile is interpreted as possibly indicative of bacterial diagenesis exclusive of biomethanogenesis.