The Cuatro Cienegas Bolson in Coahuila, Mexico: an astrobiological Precambrian park
1Instituto de Ecología, Universidad Nacional Autonoma de Mexico, CU, Coyoacan 04510, Mexico; 2Department of Statistics, Rice University, Houston Texas, USA; 3School of Life Sciences, Arizona State University, Tempe, Arizona, USA
The Cuatro Cienegas Bolson (CCB) is a rare oasis in the Chihuahuan desert in the state of Coahuila, Mexico. It has a biological endemism equal to the Galapagos, it presents anomalous elemental stoichiometry, and its spring-fed ecosystems are dominated by living microbial mats and stromatolites. CCB is a reasonable proxy for the late Precambrian, it is an extant ecological “time machine” to study the evolutionary processes that structure of earth-based life.
Geochemical Cycles of Bio-essential Elements on Early Earth
NASA Astrobiology Institute and The Pennsylvania State University, United States of America
Many scientists have assumed that before ~2.4 Ga, the oceans were rich in Fe, but poor in O2 and many other bio-essential elements (BEEs). We have discovered that the 3.46 Ga jaspers and submarine basalts from Australia possess essentially the same geochemical characteristics as those affected by O2-rich deep-ocean water at MORs today. This suggests that the geochemistry of most BEEs in the 3.46 Ga oceans was basically the same as today’s oceans to promote the divergence of organisms.
Availability of O2 and H2O2 on the Pre-photosynthetic Earth
Pennsylvania State University, United States of America
Old arguments that free O2 must have been available at Earth’s surface prior to the origin of photosynthesis have been revived by a new study that shows that aerobic respiration can occur at dissolved oxygen concentrations much lower than had previously been thought, perhaps as low as 0.05 nM. Numerical models of atmospheric photochemistry indicate that this “early respiration” hypothesis might be physically reasonable.
First direct evidence of photosynthesis in a 3.3 Ga-old microbial mat
Photosynthesis on the primitive Earth (3.5-3.3 Ga) was previously hypothesised on the basis of circumstantial structural and carbon isotopic data. We present the first direct in situ evidence for photosynthesis, based on contemporaneous calcification, related to SRB activity, of a 3.3 Ga-old microbial mat from the Barberton greenstone belt in South Africa.
Quantifying the biological damage of Gamma-Ray Bursts on the Earth and rocky planets
1IAG/USP, Brazil; 2UCLV, Santa Clara, Cuba; 3Centro de Investigaciones de Ecosistemas Costeros, Cuba; 4IMEDEA, Esporles, Spain
We present a full account on the effects of a gamma-ray burst (GRB) incidence onto the Earth, occurring at high rates in the early galaxy. We address the UV flash at the surface, the ozone depletion and their biological effects for atmospheres with oxygen levels ranging from 10-5 to 1 of the present atmospheric, using biologically weighted fluxes to address the response of cells to the retransmitted and enhanced solar flux. A calculation of the sudden phytoplankton biomass reduction yields from 10% up to 25 %.
Environmental Constraints on the Distribution, Diversity, and Activity of Biological Nitrogen Fixation in the Yellowstone Geothermal Complex
1Montana State University, United States of America; 2Astrobiology Biogeocatalysis Research Center
Biological nitrogen fixation is a keystone process and fundamental to the evolution of life. 15N2 incorporation assays suggest the presence of active diazotrophy in high temperature acid springs. These studies provide insight into the environmental constraints of the diversity and activity of diazotrophs, extend the upper temperature limit for diazotrophy in terrestrial environments, and may represent the most extreme environmental conditions that support diazotrophic growth determined to date.
Biogeochemical study of Silurian and Precambrian cherts : reassessing the use of EPR for the dating of kerogen in Precambrian cherts
1Bioemco, Paris, France; 2Ecole Nationale Supérieure de Chimie de Paris, Paris, France; 3ENS, Paris, France; 4Institute of Paleobiology, Warsaw, Poland; 5CBM, Orléans, France; 6LEME, Paris, France
Cherts are sedimentary siliceous rocks that contain the oldest biological record on Earth. It is therefore crucial to study the syngeneity of their kerogen and chert formation. The present study aims at decoupling the effects of age and metamorphism on kerogen maturation. We demonstrate that for cherts older than 600Ma, the age controls the maturity of the kerogen and EPR is the most suitable analysis technique, giving information on the age of the kerogen and therefore, on its syngenicity.
Progressive Dynamic Formation of Three States in Life Formation on the Earth-Type Planets
1Yamaguchi University, Japan; 2Ritsumeikan University
Formation of primordial life based on C, H and O elements is based on progressive dynamic activities of the three vapor, liquid and solid states with life developments which are triggered by shock waves in the volcano, ground-quake and asteroids collisions in the Earth-type planets, though fossil minerals should be remained by rapid separation with any shock-wave events with lower temperature.
Evaluation potential of abiotic and biotic methane formation fueled by olivine dissolution.
1Department of Geological Sciences, Stockholm University, S-10691 Stockholm, Sweden; 2Department of Molecular Biology and Fuctional Genomics, S-1069, Stockholm, Sweden; 3Department of Thematic Studies - Water and Environmental Studies, Linköping University, 58183 Linköping, Sweden
In habitable conditions of early Earth, how much methane was contributed from abiotic versus biotic processes? To answer this question, abiotic and biotic experiments of olivine dissolution at 30, 50 and 70°C were used. The experimental results showed that biotic methane formation rate was significantly higher than abiotic one at 70°C. The stable isotope signature showed that methanogens not only survived but also actively formed methane under the minimal conditions in the incubations.
Lightning’s Discharges in Earth’s Early Atmosphere
Institute of Semiconductor Physics, Ukraine
Considering lightnings as an energy source for synthesis of organic compounds, we consider self-evident, that in early atmosphere there was a sufficient thunderstorm activity. The analysis of modern thunderstorm activity enables to formulate a number of conditions for estimation of degree of such activity in the early atmosphere. It is possible that exists two comfortable period for thunderstorm activity: 3…3,5 Ga and 2,5…2 Ga. Hadean, early Archaean and "snowball Earth" are uncomfortable.
Earth’s atmospheric evolution as constrained by sedimentary sulfur deposits
1Virtual Planetary Laboratory; 2University of Washington; 3Penn State University
Understanding conditions on the early Earth is a fundamental astrobiological challenge, both for the origin and evolution of life and for interpreting “Earth-like” exoplanets. Anomalous sulfur isotopes provide the strongest constraints on ancient atmospheric composition, and constrain O2 to trace levels prior to 2.5 billion years ago. We argue that there is more signal in the data, and that the magnitude of the signature can constrain the presence of additional gases in the paleoatmosphere.
Early Ozone Production on the Earth
1islamic azad university, urmia branch, department of science, urmia, Iran; 2young researchers club, islamic azad university, urmia branch, Iran
The early condition which explained in Haldane and Oparin theory (Primordial Soup) was simulated by Miller. According to laboratory production of ozone, incidence of lightening in the water provides a suitable condition to form ozone as a new atmospheric molecule.
3 H2O → O3 + 6 H+ + 6 e− (ΔEo = –1.53 V)
According to early Earth conditions, this reaction has occurred frequently. So, it can be concluded that the ozone layer should be formed before the life began on the Earth.
Mass-independent fractionation of sulfur by SO2 photolysis
1UCLA, United States of America; 2Wellesley College, USA; 3Imperial College, UK
Photolysis of atmospheric SO2 is believed to be the source of sulfur isotope anomalies measured in Archean rocks. Recently measured cross sections at low resolution, and ongoing measurements at high resolution (this work). have yielded very different interpretations for the origin of sulfur MIF. Here we present our latest results on measurements for 32SO2, 33SO2, and 34SO2 made at Imperial College. We compare our results to the previously published measurements, and discuss the implications.
Structures and properties of metal sulfites: possible phases on the early Earth
Diamond Light Source, United Kingdom
We are using synchrotron diffraction to study properties of magnesium sulfite hexahydrate and hannebachite, and to examine structural changes of these phases with pressure and temperature, including thermal expansion, phase transformations and structural distortion. These phases offer a mineralogy between fully reduced (sulfide) and fully oxidised (sulfate) sulfur-bearing minerals, of relevance to the reduced conditions of the early Earth.