Isotopic and molecular indicators of origins of organic compounds in sediments

Thesis/Dissertation · Thu Jan 01 00:00:00 EST 1987

OSTI ID:5749494

Takigiku, R

Organic matter preserved in ancient sediments is composed of material of mixed origins. Reconstruction of the specific biological origin of some compounds isolated from ancient sediments is aided by measurement of stable carbon-isotope abundances. It has been shown that the stable isotopic compositions of organic materials can remain unchanged long after sedimentary processes have reworked them, and caused subsequent loss of subtle, structural details that initially distinguish very similar compounds (e.g., chlorophyll a form chlorophyll c). Results of this research indicate that the stable carbon-isotopic composition of chlorophyll-derived geoporphyrins appears to faithfully, and selectively, record the isotopic composition of both recent and ancient primary photosynthetic organic matter. This finding has improved the breadth of information regarding processes associated with organic carbon burial and preservation. Further, the isotopic composition of photosynthetic carbon encodes information about the environment in which it was biosynthesized, and therefore yields information regarding ancient atmospheres and oceans. In this study, specific compounds from several ancient organic carbon-rich sediments were examined and compared to analogous compounds isolated from pure cultures or organisms. These analyses permitted (i) reconstruction of isotopic compositions of organisms at different trophic levels; (ii) identification of specific sources for compounds of previously unknown origin; (iii) recognition that diagenetic processes can significantly alter the isotopic composition of total organic material preserved in ancient sediments; and (iv) inferences about the operation of the global carbon cycles.

• Research Organization: Indiana Univ., Bloomington, IN (USA)
• OSTI ID: 5749494
• Resource Relation: Other Information: Thesis (Ph. D.)
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
GEOLOGIC DEPOSITS
ORGANIC MATTER
ORIGIN
CARBON CYCLE
CARBON ISOTOPES
CLIMATES
DIAGENESIS
GEOLOGIC HISTORY
GLOBAL ASPECTS
ISOTOPE RATIO
PHOTOSYNTHESIS
PORPHYRINS
SEDIMENTS
CARBOXYLIC ACIDS
CHEMICAL REACTIONS
HETEROCYCLIC ACIDS
HETEROCYCLIC COMPOUNDS
ISOTOPES
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PHOTOCHEMICAL REACTIONS
SYNTHESIS
020200* - Petroleum- Reserves
Geology
& Exploration