Title: Collaborative Research in Origins (CRiO)
Introduction: The crustal platform of silicate+metal worlds such as Earth; those with a rocky crust, convecting silicate mantle, Fe-Ni core, liquid water hydrosphere and dynamical atmosphere, serves as the ultimate physical-chemical template for life’s origin and subsequent evolution. If the origin of life is the origin of Darwinian evolution , then a plausible corollary would be that the origin of evolution is the origin of inheritable information. To understand this evolution, we need to better understand the physical and chemical regimes of a young planet. To understand the planet we must study rocks. Our aim is to overcome the foremost paradox that plagues all Origins of Life studies: No clear, specific and modern synthesis exists of the actual physical-chemical conditions which prevailed in the Hadean. As a consequence of this, confusion reigns over the genuine conditions under which origins experiments should be performed. The CRiO program will do something that is a bit out of the ordinary, we will seek to RULE OUT those scenarios for life’s origins which do not comport with the geological record. To accomplish this task, CRiO will coordinate and promote research to define the manner in which life appeared and evolved in the context of the geology, age, origin and transformation of the primordial Earth’s crust from actual rock samples from the first billion years. Output from this research will be a modern synthesis of our knowledge of the Hadean, and thus provides the direct input parameters for experiments seeking a chemical pathway to life. The key themes of this proposal specifically explore the paradox that although we seek to design experiments that mimic the natural world, perilously little about what we know of the earliest conditions are invoked.
Scientific Objectives: The starting point is the notion that the conditions at the surface and interior of the Hadean Earth that modulated the origin of life were very different from those at present, but for reasons that are as yet poorly understood. Circumstantial evidence exists that life appeared in the Hadean eon, before about 3.85 Gyr ago . The Hadean Sun was dimmer, mantle hotter, bombardment by asteroids and comets commonplace [3,4] and atmosphere anoxic, but we do not know how such differences influenced the way the Earth functioned. Rates of heat production were higher in the Hadean mantle, but uncertainty over the timing of the appearance of the first crust means that we are unsure about the availability of dry land, pH value, temperature and volume of oceans, or much else about the environment in which life appeared and later evolved. Two commonly cited settings for life’s cradle are oceanic hydrothermal springs and tidal flats on the early continents. What we know about the first scenario is based on studies of modern ocean floor hydrothermal vents, but there is reason to believe that their Hadean counterparts were very different. Hadean oceanic crust probably was much thicker than modern crust  and the thermal gradient across this crust would have been low; temperatures in the shallow interior of Hadean oceanic crust may have been lower than those in modern crust, not higher as is commonly assumed . Hadean volcanic rocks were more Mg-rich that their modern counterparts and Hadean ocean water more reducing (e.g. rich in Fe2+). How did these differences influence conditions in Hadean hydrothermal springs and what was their influence on then appearance and early evolution of life? Our knowledge of emergent (dry) land is even more rudimentary. The survival of ca. 4.3 Gyr old zircons [e.g. 7] from before the Late Heavy Bombardment or “LHB” [8,9] tells us that granitic crust formed very early on, and that this “continental” crust stayed at the surface throughout the Hadean and later into the Archean [10-13]. Eoarchean (ca. 3.8 Gyr old) sediments from West Greenland (Isua, Akilia) and northern Canada (Nuvvuagittuq) tell us that this crust was exposed to weathering and erosion. Some emergent Hadean land may have been similar to that of today, but we need to find the rocks to verify this. Vast exposed volcanic plateaux composed of basaltic and komatiitic (ultra-high Mg-rich) volcanic rocks could have existed as low albedo “melano-continents”. The best modern analogue these land surfaces might be the shores of a “tropical Iceland” under a dense CO2 atmosphere. It may also be that the volume of ocean water was greater than today’s. Was the Hadean a Waterworld in which a few small landmasses breached the ocean surface? Or did higher mantle temperatures produce emergent volcanic mountains along the mid-ocean ridges? The objectives of CRiO will be to provide answers to these and other questions, all of which are crucial to our understanding of the environment for the origin of life.
Field studies, sample collection & techniques: Our research will focus on samples collected from new field excursions funded by this grant to the ca. 3.92 Gyr old Acasta Gneiss Complex (Northwest Territories) in Canada , and the recently discovered >3.9 Ga Ukalik supracrustal belt (Quebec, Canada); the latter could host Hadean rocks of marine sedimentary origin which overlap in age with the height of the bombardment (LHB) epoch . We will employ 235,238U-207-206Pb zircon geochronology on selected rock samples collected in this work along with 176Lu-177Hf and 146-147Sm-142-143Nd isotope systematics applied to the same samples. We have previously shown that the union of these different analytical geochemistry methods yields powerful insights into the age and timing of the appearance of crust of different kinds (mafic “basaltic” vs. felsic “granitic”) in Earth’s earliest history. Results will be used to explore the materialization of the granite-basalt dichotomy that typifies the contemporary continent-ocean system. The primordial crust interacted with the hydrosphere to define the gross physical-chemical habitat for life on our planet, and we need to understand the sedimentary products of this interaction. Metamorphosed rocks of sedimentary protolith (a.k.a. paragneisses) locked in granitoid gneiss terranes are our only achievable archive of the early biosphere [16-19]. Templeton Foundation support would cover the expensive field- and analytical costs necessary to interrogate this archive. Training: A Postdoctoral scholar and a Ph.D. graduate student will be trained in the techniques cited above by working directly with leaders in the field (Table 1). Data from the program will serve to define topics for discussion at our semi-annual workshops, and form the basis for Ph.D. theses and postdoctoral projects supported by this grant. Manuscripts arising will be prepared for publication in peer-reviewed journals. A new suite of graduate-level courses on these topics will also be created at the University of Colorado. Owing to the fact that the CRiO project will yield a large suite of new rock samples from our collective field work, it is important to note that these will become available to the world’s research community on request. Explorations of the planetary conditions for life should not be limited by sample availability.
Scope: The program will be managed at the University of Colorado at Boulder and directed by Prof. Mojzsis. A graduate student, and a postdoctoral scholar, will be supported and based at CU. Aside from this, we will also fund field studies and coordinate exchange visits between participating laboratories of scientists (Table 1). CRiO will sponsor semi-annual workshops and organize topical sessions at congresses to promote origins research. Participants in CRiO include university departments and government-sponsored research agencies. Although most of our collaborative is in the earth sciences, through our association with multidisciplinary institutes such as NASA’s Solar System Exploration Research Virtual Institute (SSERVI) and Astrobiology Institute (NAI), Earth Life Science Institute (ELSI) in Japan, and the Lyon Institute of Origins (LIO) in France, we will interact with scientists from other disciplines. We will also coordinate our activities with domestic and international programs in Early Earth studies and Geobiology.
Summary: The emphasis here is to understand the conditions at or near the surface on the Hadean Earth. The chief goal is to provide a new, modern and coherent synthesis of environmental conditions that prevailed on the Hadean Earth. Our approach is based firmly in the Earth Sciences and will thus be distinguished from other complementary projects in which the stress is entirely on molecular biology, genetics, organic chemical and isotopic biomarkers, and pre-biotic chemical syntheses. By focusing on the first billion years of Earth history, we will be distinguished from those many researchers that dwell mainly on life in modern extreme environments. Our proposed CRiO program involves ~37 collaborating scientists from 24 different participating institutions in nine countries. We are pleased to highlight the fact that with the participation of our national and international collaborating researchers, substantial cost-sharing with our research partners is built into the proposed program.
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Templeton Origins Pre-Proposal fFame
Principal Investigator (Mojzsis, Stephen, Ph.D.)