Chalk Talk - Natural nuclear reactors as a case study for coupled thermodynamic feedback and organic synthesis in geological systems- Zachary Adam (EPS - Knoll Group)


Thursday, April 2, 2015, 9:00am


Naito Laboratory, Room 205, 12 Oxford Street

Abstract:  Energy dissipation processes in abiotic systems is typically unidirectional, ranging from the gentle rain of sunshine to the explosive release of an impactor. Though these and other dissipation processes have served as invaluable prebiotic synthesis scenarios, the thermodynamics of such systems are inherently problematic for origins of life studies. Mass transport, thermal and chemical gradients converge and interact on short systemic scales to freeze reactants into organic matter, but work and information flow rarely result in stable circulatory patterns that link chemical outcomes to energy inputs. Here I will introduce a geologic and engineering model of natural nuclear reactor formation on the early Earth to demonstrate how the feedback parameters of reactor operation would have created cyclic temperature oscillations comparable to polymerase chain reaction (PCR) thermal profiles along reactor margins. Simultaneously, gamma radiolysis of simple C1 reactants would have produced nucleobase precursors (pyrimidines, purines and sugars) within these volumes. Experimentation with organically cooled and moderated reactors and comparative analysis of organic-rich and organic-poor reactor cores in Gabon, Africa has demonstrated that the chemical products of each period of reactor activity have the potential to shape future reactor power production via neutron moderation and redox state alteration. Natural nuclear reactors may thus serve as an instructive scenario for investigating how abiotic energy feedback mechanisms can serve as a thermodynamic template for the simultaneous production and organization of organic matter. A search for thermodynamic feedback in other naturally-occurring organic synthesis systems and geologic settings, and the incorporation of feedback analogs into laboratory experiments, may prove an insightful avenue for future origins of life studies. 

Zachary Adam
Postdoctoral Fellow - Dept. of Earth & Planetary Sciences (Andy Knoll Group)

Harvard University

See also: Chalk Talks