KEY OBJECTIVES: POROUS MINERAL FORMATIONS NEAR SUBSEA ALKALINE HYDROTHERMAL VENTS EMBED CHEMICALLY RICH MICROENVIRONMENTS MAKING THEM POTENTIAL HOT SPOTS FOR PREBIOTIC MACROMOLECULAR SYNTHESIS. BUT SYNTHESIS OF LONG-CHAIN MOLECULES NEEDED TO SUPPORT HIGHER ORDER FUNCTIONS IN LIVING SYSTEMS (E.G. POLYPEPTIDES PROTEINS NUCLEIC ACIDS) AND THEIR SUBSEQUENT ENCAPSULATION WITHIN LIPID MEMBRANE PROTOCELLS CANNOT OCCUR WITHOUT ENRICHMENT OF CHEMICAL PRECURSORS PRIOR TO INITIATING POLYMERIZATION AND VESICULAR PACKAGING. IDENTIFICATION OF A SUITABLE ENRICHMENT MECHANISM HAS THEREFORE BECOME ONE OF THE KEY UNANSWERED QUESTIONS IN THE ORIGIN OF LIFE. OUR TEAM HAS RECENTLY DISCOVERED HOW 3D CHAOTIC THERMAL CONVECTION--FLOW PHENOMENA THAT NATURALLY PERMEATE HYDROTHERMAL PORE NETWORKS--SUPPLY A ROBUST MECHANISM FOR FOCUSED CHEMICAL ACCUMULATION AT DISCRETE TARGETED SURFACE SITES [PNAS 114 (2017): 1275-1280]. WE PROPOSE FUNDAMENTAL RESEARCH THAT BUILDS ON THESE NEW DISCOVERIES TO FULLY ELUCIDATE HOW SYNCHRONIZATION OF INTERFACIAL ENRICHMENT WITH BULK HOMOGENIZATION OF CHEMICAL SPECIES TWO DISTINCT PROCESSES THAT ARE SEEMINGLY OPPOSED CAN SYNERGISTICALLY ACCELERATE REACTION KINETICS BY SEVERAL ORDERS OF MAGNITUDE. METHODS AND TECHNIQUES TO ACCOMPLISH: WE WILL PERFORM FUNDAMENTAL COORDINATED EXPERIMENTAL AND COMPUTATIONAL STUDIES TO SYSTEMATICALLY CHARACTERIZE MICRO-SCALE 3D FLOW CHEMICAL SPECIES TRANSPORT ENRICHMENT BIOCHEMICAL REACTION AND VESICULAR ASSEMBLY PROCESSES WITHIN HYDROTHERMAL PORE ENVIRONMENTS. A STATE-OF-THE-ART MICRO PARTICLE IMAGE VELOCIMETRY APPROACH WITH THERMALLY INDUCED FLUORESCENT IMAGING WILL BE EMPLOYED TO QUANTITATIVELY MEASURE IN-PORE 3D VELOCITY AND TEMPERATURE DISTRIBUTIONS WITH HIGH SPATIAL AND TEMPORAL RESOLUTION. RESULTS OF THESE STUDIES WILL ENABLE US TO QUANTITATIVELY IDENTIFY COMBINATIONS OF POROSITY THERMAL GRADIENT AND SURFACE REACTIVITY CONDITIONS THAT ARE CONDUCIVE TO PROTOCELL FORMATION AND INTRODUCE A NEW IN-SITU EXPERIMENTAL PLATFORM CAPABLE OF DIRECTLY PROBING THESE PHENOMENA IN MICRO-SCALE ALKALINE PORE-MIMICKING SURROUNDINGS. THESE NEW INSIGHTS WILL LAY A FOUNDATION TO RATIONALLY PREDICT HOW CHAOTIC THERMAL CONVECTION CAN MEDIATE PROTOCELL FORMATION IN THE PREBIOTIC MILIEU. RELEVANCE OF PROPOSED RESEARCH: THIS RESEARCH WILL ESTABLISH A VERSATILE PLATFORM TO EXPLORE THE ROLE OF THERMAL CONVECTION IN PREBIOTIC SCENARIOS INVOLVING SURFACE ADSORPTION CATALYSIS POLYMERIZATION AND ASSEMBLY. OUR PRELIMINARY RESULTS SUGGEST THAT CHAOTIC THERMAL CONVECTION MAY SUPPLY A PREVIOUSLY UNAPPRECIATED DRIVING FORCE TO ORCHESTRATE SYNTHESIS OF PREBIOTIC CHEMICAL PRECURSORS CRITICAL TO THE ORIGIN OF LIFE AND THEIR ENCAPSULATION IN LIPID VESSICLE PROTOCELLS. THESE FINDING ARE PARTICULARLY EXCITING IN LIGHT OF THE RECENT DISCOVERY OF HIGHLY ALKALINE VENT SYSTEMS (E.G. LOST CITY VENT MID-ATLANTIC RIDGE) THAT APPEAR TO PROVIDE IDEAL MICROENVIRONMENTS INHERENTLY RICH IN THE DISSOLVED CHEMICAL SPECIES AND CATALYTICALLY ACTIVE MINERAL SURFACE SITES THAT WOULD HAVE BEEN NEEDED TO FOSTER EMERGENCE OF BIOCHEMICAL COMPLEXITY. THESE PHENOMENA ARE ALSO LIKELY TO PLAY A PIVOTAL ROLE IN EXOBIOLOGICAL SCENARIOS INVOLVING HYDROTHERMAL VENT SYSTEMS (E.G. THE JOVIAN MOON EUROPA AND THE SATURNIAN MOON ENCELADUS). MORE BROADLY THIS RESEARCH PROMISES TO IMPACT A DIVERSE ARRAY OF PROCESSES BEYOND PREBIOTIC BIOCHEMISTRY THAT CAN BE CATALYZED IN HYDROTHERMAL MICROENVIRONMENTS. SUBMARINE IGNEOUS FORMATIONS FOR EXAMPLE PLAY A KEY ROLE IN GEOTHERMAL CONVERSION OF CO2 INTO STABLE CARBONATES AND PARTIAL REDUCTION TO FORMATE CARBON MONOXIDE AND METHANE. THESE REACTIONS ARE ACCELERATED WITHIN THE PORES OF HYDROTHERMAL FORMATIONS SUGGESTING A COMPELLING ROLE FOR THE THERMAL CONVECTIVE PHENOMENA DESCRIBED HERE IN GOVERNING TRANSPORT AND REACTION OF CO2 ALONG PATHWAYS NOT CAPTURED IN EXISTING CLIMATE MODELS.