The chemical structure of a pronounced series of iso-alkanes in South Oman crudes

Application of Biomarkers and Compound Specific Stable Isotopes for the Assessment of Hydrology as a Driver of Organic Matter Dynamics in the Everglades Ecosystem

“…One additional C 29 MMA (3-methyl octacosane) eluted between the C 28 and C 29 n-alkanes. Generally, the mid-chain methyl-substituted alkane isomers eluted earlier than isomers substituted near the chain terminus (e.g., iso or anteiso), in agreement with previous reports (e.g., Klomp, 1986;Fowler and Douglas, 1987;Lu et al, 2003). A total of 46 MMAs were tentatively identified (Table 3. MMAs.…”

“…Their origin has been debated for years and two major hypotheses have been proposed as either biological or geosynthetic origins. The geosynthetic hypothesis includes (1) diagenetic transformation of functionalized lipid precursors such as common bacteria derived iso-and anteiso-fatty acids (Summons, 1987;Kaneda, 1991), and some bacterial mid-chain branched fatty acids (Summons, 1987;Summons et al, 1988); (2) products of acid clay mineral catalyzed reactions of alkenes (Kissin, 1987); or (3) longterm equilibration products from a limited range of isomers (e.g., Klomp, 1986). …”

Ghaba salt basin province and Fahud salt basin province, Oman; geological overview and total petroleum systems

“…The main geochemical characteristics of the Huqf-type oils, which correlate well with extracts from Huqf source rocks, are high sulfur (1.5-2.0%) content, the presence of a homologous series of long chain, methyl substituted alkanes, the so-called 'X'-branched compounds (Klomp, 1986), high (45-90%) C27 sterane percent, and high-negative (-28 to -33‰) carbon isotope. The geochemical character-istics of North Oman Huqf-type and 'Q'-type oils are summarized in table 1.…”

Biomarker and Pyrolysis Geochemistry of Organic Matter from Argo and Gascoyne Abyssal Plain Sediments, Northeastern Indian Ocean

“…Their elution positions and mass spectra suggest that these are homologous series of branched alkanes, but at present, little is known about either their precise structure or their origin. These branched alkanes have different characteristics from the mid-chain monomethyl alkanes that are prominent in many Proterozoic and lower Paleozoic sediments and petroleums (Jackson et al, 1986;Klomp, 1986;Summons, 1987;. These unidentified hydrocarbons sometimes appear in samples of sedimentary bitumen that have experienced high degrees of thermal alteration (Summons, unpubl.…”