Aliphatic and monocyclic saturated hydrocarbons in the molecular fossil record and their paleobiological interpretation
| Biomarker | Biological and/or environmental interpretation | References |
|---|---|---|
| n-alkanes | ||
| outstanding concentrations of n15, n17 and n19 in early Paleozoic rocks | Gloeocapsomorpha prisca, marine phytoplankton of uncertain affinity, probably an alga, identified in Cambrian-Devonian sediments but most prominent in Ordovician. Estonian kukersite is a typical source | Blokker et al., 2001, Fowler, 1992 |
| n-C27 with OEP1 | waxes derived from higher plants, terrestrial input, post-Silurian age | Hedberg, 1968, Tissot and Welte, 1984 |
| n-C40 | predominantly degradation products of aliphatic macromolecules such as algaenan (marine, lacustrine), cutan and suberan (terrestrial, plant derived) | Allard et al., 2002, Killops et al., 2000 |
| Branched alkanes and acyclic isoprenoids | ||
| monomethylalkanes and dimethylalkanes (MMA and DMA) | cyanobacteria both cultured and in mat communities from hypersaline and hydrothermal environments | Dembitsky et al., 2001, Kenig et al., 1995b, Koster et al., 1999, Shiea et al., 1990 |
| 5, 5-diethylalkanes with OEP1 (wrongly reported as 3, 7- or 3,w7-dimethyllkanes) | these structures widely and incorrectly assigned. Chemical synthesis of a 5, 5-diethylalkane indicates this is a major series. Often occurs with other alkanes with quaternary carbon centers (BAQCs). Source organisms not known but commonly found in association with benthic microbial mats. | Arouri et al., 2000a, Arouri et al., 2000b, Kenig et al., 2002, Logan et al., 1999, Logan et al., 2001, Simons et al., 2002 |
| pristane (Pr) and phytane (Ph) | from chlorophylls of cyanobacteria, algae and plants, bacteriochlorophylls a and b of phototrophic bacteria, tocopherols, Ph: archaeal membrane lipids | Peters and Moldowan, 1993 |
| regular acyclic isoprenoids i-21 to i-30 | probable source is halophilic Archaea, abundant in evaporitic environments | Grice et al., 1998b |
| squalane (tail-tail C30 acyclic isoprenoid) | all organisms produce some squalene, most sedimentary squalane probably from Archaea. | Grice et al., 1998b |
| crocetane | archaea (anaerobic methane oxidizers), associated with sub-sea gas, gas hydrate and mud volcanoes | Bian et al., 2001, Thiel et al., 1999 |
| PMI (2,6,10,15,19-pentamethylicosane) | methanogenic and methanotrophic archaea | Elvert et al., 1999, Schouten et al., 1997, Thiel et al., 1999 |
| TMI (2,6,15,19-tetramethylicosane) | only reported from a mid-Cretaceous oceanic anoxic event, nonhyperthermophilic marine Crenarchaeota? | Kuypers et al., 2001 |
| C20, C25, C30 and C35 highly branched isoprenoids | unsaturated and polyunsaturated isoprenoid hydrocarbons are prominent biochemicals in some diatom taxa such as Rhizoselenia and Haslea | Sinninghe Damste et al., 1999a, Volkman et al., 1994, Belt et al., 2000, Rowland et al., 2001 |
| botryococcenes and botryococcanes, cyclobotryococcenes, polymethylsqualenes | the unsaturated, sometimes cyclic, biogenic hydrocarbons and their saturated fossil counterparts are diagnostic markers of the chlorophyte B. braunii and their preferred habitat of fresh to brackish water. | Huang et al., 1988, Metzger and Largeau, 1999, Summons et al., 2002 |
| Monocyclic saturated hydrocarbons | ||
| C42 – C46 cyclopentylalkanes with OEP1 | oils from marine environments, unknown biological source | Carlson et al., 1993, Hsieh and Philp, 2001 |
| C42 – C46 cyclopentylalkanes with no distinct carbon preference | oils from freshwater lacustrine settings, unknown biological source | same as above |
| C42 – C46 cyclopentylalkanes with strong EOP2 | oils from saline lacustrine settings, unknown biological source | same as above |
| cyclohexyl alkanes without predominance | formed during pyrolysis of biopolymers with long aliphatic carbon chains suggesting an origin from acyclic polymethylenic precursors | Gelin et al., 1994 |
| macrocyclic alkanes C15-C34 without preference | bitumens extracted from torbanites containing remains of B. braunii, fresh to brackish water | Audino et al., 2002 |
1 Odd-over-even carbon number preference
2 Even-over-odd carbon number preference
