Multiple peer-reviewed scientific studies indicate that early Mars experienced clement epochs, liquid water activity, and sedimentary features similar to those found on Earth.
Biomarkers in geological samples are products derived from biochemical (natural product) precursors by reductive and oxidative processes (e.g., cholestanes from cholesterol). Generally, lipids, pigments and biomembranes are preserved best over longer geological times and labile compounds such as amino acids, sugars, etc. are useful biomarkers for recent times. Thus, the detailed characterization of biomarker compositions permits the assessment of the major contributing species of extinct and/or extant life. In the case of the early Earth, work has progressed to elucidate molecular structure and carbon isotropic signals preserved in ancient sedimentary rocks. In addition, the combination of bacterial biochemistry with the organic geochemistry of contemporary and ancient hydrothermal ecosystems permits the modeling of the nature, behavior and preservation potential of primitive microbial communities. This approach uses combined molecular and isotopic analyses to characterize lipids produced by cultured bacteria (representative of ancient strains) and to test a variety of culture conditions which affect their biosynthesis. On considering Mars, the biomarkers from lipids and biopolymers would be expected to be preserved best if life flourished there during its early history (3.5-4 x 10(9) yr ago). Both oxidized and reduced products would be expected. This is based on the inferred occurrence of hydrothermal activity during that time with the concomitant preservation of biochemical
Mudstone-rich lacustrine strata at Gale Crater, Mars, dominate the Mt. Sharp sedimentary succession. The Gale crater strata provide the oppor-tunity to test hypotheses regarding past climate shifts early in the planets history [1, 2], a key motivator for selecting Gale Crater as a landing site for the Curiosity rover.At the base of the Mt. Sharp succession, at Pahrump Hills, mudstones with sedimentary features and geo-chemical attributes occur that suggest that these rocks accumulated in an underfilled lake basin. Lake waters were saline to hypersaline, and lake levels, shorelines, and salinities fluctuated greatly at various temporal scales [3, 4, 5].Laminated mudstones, characterized by alternating softer and harder (cemented) layers and apparent evaporite pseudomorphs [4, 5] associated with the lat-ter, dominate the Pahrump succession. They show multiple textural similarities to evaporitic lacustrine strata on Earth [3]. Although indications of evaporitic conditions have been reported from higher in the sec-tion [6], laminated evaporitic mudstones of the type seen at Pahrump Hills were not been observed for the next 400 m of Mt. Sharp stratigraphy since leaving Pahrump Hills.During the recent ascent from the clay trough to-wards the Sulfate bearing unit, rocks resembling the Pahrump Hills evaporitic mudstones were again en-countered at elevations above -4030 m. Examples of these laminated mudstones are compared to textural equivalents from Pahrump Hills.
We are proposing a model for the delivery of volatiles to the inner planets by icy planetesimals (comets). Laboratory studies of the trapping of gases in ice forming at low temperatures simulate the formation of comet nuclei at various distances from the Sun in the solar nebula. The total gas content as well as the relative proportions of gases trapped in the ice are strong functions of temperature. As they trap N2 inefficiently, all planetesimals formed interior to Neptune are deficient in nitrogen, acquiring values of C/N resembling those found in the inner planet volatile inventories. A mixture of three basic types of comets appears capable of accounting for the observed volatile inventories on Venus, Earth, and Mars, with the caveat that impact erosion is necessary to explain the present condition of the martian atmosphere. The model includes the possibility of several epochs of clement conditions on early Mars. Some tests of these ideas are suggested, including measurements in Jupiter's atmosphere by the Galileo probe.
Abstract Two areas on Mars in the old Thaumasia region were analysed, where interaction between fluvial and tectonic landforms provided conditions to improve age estimation for valley network formation. An Earth analog terrain was also involved in this work at Villany Hills (Hungary) for reference and to see the relations in tectonic-fluvial interaction. On Mars such interaction was observed by morphology (parallel curvatures of neighbour valleys) and by the comparison of statistical analyses of the fluvial and tectonic lineaments’ azimuthal orientation. While in the case of Mars the fluvial network elements’ distribution closely follows that of the tectonic elements’ distribution, in the case of the Earth the connection is weaker. The comparison gives an interesting example for tectonic landforms controlling fluvial valley orientations, occasionally producing resembling features in valley tracks, influencing the sediment transport and the locations of deposits. Because the tectonic faults crossed a much larger area than the fluvial valleys they influenced, crater size frequency distribution based ages could be better measured with them. Using this approach, we found the minimal age of the fluvial network formation to be around 3.7 Ga (or up to 3.9 Ga). This result demonstrates that the small, scattered, and poorly integrated valleys might also have formed at the same period as the larger, branching systems with well determined ages: around the Noachian/Hesperian transition.
The success of recent spacecraft from the U.S.A. and the U.S.S.R. has given us a wealth of new data about the planets in our solar system. We can now develop a much better rationale for the reasons that abundant life is only found on our planet. Mars, smaller and more distant from the Sun, may nevertheless hold clues to the early development of Earth's atmosphere. The origin of life on Mars early in that planet's history cannot be ruled out. Titan offers a contemporary example of extremely primitive conditions, where chemical reactions resembling those that preceded the development of life on Earth may be occurring today. Venus and Jupiter illustrate the need for a planet to be the right size and the right distance from the sun if chemical evolution leading to the origin of life is to occur.
Manganese plays a crucial role as a paleo-environmental and geological indicator due to its sensitivity to redox potential and pH variations in the environment. On Earth, the association between the rise of atmospheric oxygen during the Great Oxidation Event and the presence of Mn in the sedimentary rock record underscores its significance. Here, in this study, we reexamined ChemCam targets from the first 600 sols of the Mars Science Laboratory mission, focusing on identifying instances of above-average Mn within these targets. These elevated-Mn targets were categorized into distinct geologic classes, revealing a pattern linking heightened Mn levels with diagenetically altered materials, such as calcium-sulfate veins and concretions, as well as clay minerals within the same targets, indicating a compelling relationship between Mn enrichment and diagenetic processes. High concentrations of Mn were observed in chemically altered targets, suggesting the occurrence of multiple fluid events: the first to alter the material and the second to deposit Mn. The observed patterns suggest multiple diagenetic events and redox cycling that facilitated the deposition and transport of Mn subsequent to the initial dissolution of basaltic materials. This research sheds light on the complexity of martian diagenetic processes and their implications for the planet’s environmental evolution.
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