The other natural gases ([[delta].sup.13][C.sup.1] ranging from -50[per thousand] to -37[per thousand]) were recognized as thermal genetic gases or mixtures of thermal genetic gases and abiogenic
gas and/or secondary cracking gas.
However, the central and peripheral zones of the concretion formed from C[O.sub.2] generated by abiogenic
thermal decomposition of organic matter at greater depths (< ~500 m).
There is also, however, a controversial theory which one of us (JMS) does not wish to exclude, that the carbon may have been abiogenic
in ultimate origin, (10) with the vanadium provided by vanadium-porphyrin complexes.
that demonstrates there are so many ways to make hydrocarbons in an abiogenic
setting." The largest barrier to making the complex, sulfur- and nitrogen-bearing molecules characteristic of living organisms is creating long-chain hydrocarbon precursors like those found in the Lost City fluids, he says.
The serious problems of abiogenic
synthesis of monomers, polymers, and complex functioning systems are discussed with a continuing emphasis on the increasing degree of complexity required as one moves toward systems that might be considered living.
Methane is also released during the abiogenic
process of biomass burning.
The discussion on abiogenic
origins of oil, gas, and coal and the consequences for public policy if the theory is right (Ehrlich thinks it is) alone are worth the price of the book to anyone who teaches earth sciences, environmental sciences, energy issues--or who is trying to decide what kind of car to buy.
Textural signatures in the alteration products of certain rocks suggest that up to 75% of the uppermost crust is microbially altered (Furnes and Staudigel, 1999), whereas such features in other samples suggest that most alteration is probably abiogenic
(Alt and Mata, 2000).
At the same time, the information gained through this research has implications for fundamental science--demonstrating that abiogenic
reactions that may have generated prebiotic organic molecules in the early earth continue to play a significant role in the production of hydrocarbons in Precambrian Shield crystalline rocks.
The trend observed in the [Cl.sup.-]depleted sample of Kulo Lasi was very similar to the ones attributed to an abiogenic
origin in the Precambrian shields or in the Lost City hydrothermal field [69,70].
These issues include: i) the potential for abiogenic
production of organic matter and the significance of this to our understanding of the timing of life's origins; ii) the timing of oxidation of earth's atmosphere; and iii) the continued expansion of our understanding of the capabilities and limits of microbial fife.
Barbara Sherwood Lollar, a geologist at the University of Toronto, says the new study provides "excellent scientific evidence" of the formation of abiogenic
hydrocarbons in the mantle.
The former is the common growth morphology of abiogenic
aragonite and often results in extensive lateral inter-growth, producing fanlike aggregates of misaligned needles.