Martian Ocean Research Articles

Characterizing biofilms and their associated biosignatures in an Arctic hypersaline cold spring Mars analog

The last surface-level aqueous environments on Mars were likely sulfurous brines that formed as the climate cooled and large bodies of water receded during the transition from the wet Noachian to the dry Hesperian (4.1 – 3.0 Gya). To understand the diversity of microorganisms that could have inhabited such environments and their associated biosignatures, we turn to analogous environments on Earth. Here we investigated biofilm communities and their associated biosignatures at Gypsum Hill, (GH), a perennial cold spring system located at nearly 80°N on Axel Heiberg Island in the Canadian high Arctic. The biofilms develop during the summer months alongside the oligotrophic and sulphur rich GH brines and spread out along the flood plains formed by meltwater and spring run-off. Our objective was to link the microbial community structure of the biofilms to geochemical changes across the GH site as an analog to the micro-niches that could have formed during the recession of an ancient Martian Ocean. We collected 14 morphologically distinct biofilms over two field season and found that minor variations in chemistry between proximal sites impacted community structure. 16S amplicon sequencing revealed that biofilms closest to outflow channels were dominated by sulfur oxidizing bacteria, suggesting that primary production may be driven by chemolithoautotrophy. The community structure shifted towards more heterotrophic and phototrophic populations the further the biofilms appeared from a spring source. Microbial eukaryotes at the GH site were investigated for the first time through 18S sequencing with diatoms and photoautotrophic algae dominating all biofilms. Lastly, we linked the biofilm communities to potential biosignatures by examining lipid profiles to help guide the search and identification of potential remnants of hypothetical ancient Martian life.

A giant volcanic island in an early Martian Ocean?

Tracking early oceans on Mars has fundamental climatic and exobiological implications but requires unambiguous datable markers. Here we show that the Olympus Mons giant volcano shares morphological similarities with active volcanic islands on Earth where major constructional slope breaks systematically occur at the sea-air transition in response to sharp lava viscosity contrasts. We propose that the upper rim of the 6-km high concentric main escarpment surrounding Olympus Mons most likely formed by lava flowing into liquid water when the edifice was an active volcanic island during the late Noachian - early Hesperian. Similar features on the northern flank of the 1800 km-distant Alba Mons volcano further support an extended early Ocean initially occupying Martian lowlands. Abnormal current shoreline heights imply major surface uplift promoted by internal dynamics during the main phase of development of the Tharsis Bulge at some time during the Hesperian. After ocean retreat, the uplifted shorelines were partly blanketed by late sub-aerial activity during the Amazonian. The newly proposed volcanic shorelines can be dated by radiometric methods, constituting exceptional targets to track early liquid water at key temporal steps and provide valuable insights into the timing and fate of Martian Oceans.

Aqueous alteration of the Vastitas Borealis Formation at the Tianwen-1 landing site

The Vastitas Borealis Formation is a Hesperian-aged sedimentary unit that mainly covers the Martian northern plains. Its environment of formation is uncertain but may be related to an ancient Martian ocean, outflow channel deposits, compaction and drainage activities, or subsurface ice-related processes. Here we investigate the geological evolution of the Vastitas Borealis Formation using geochemical and mineralogical data acquired by the Mars Surface Composition Detector on board the Zhurong rover at the Tianwen-1 landing site. We find that the fine-grained soil is very similar to the ubiquitous surface dust at other landing sites on Mars but mixed with calcium-rich and magnesium-poor local materials. These materials are mostly igneous minerals mixed with allophane and imogolite/opal and appear to have a low degree of chemical alteration. We suggest that these deposits likely formed by alteration of extensive volcaniclastic soils in limited or ephemeral water under cold conditions, which largely supports the hypotheses of a frozen ocean and sublimation.

Megatsunamis and microbial life on early Mars

AbstractIt is currently believed that early Mars had a vast and shallow ocean, and microbial life may have formed in it, albeit for a short geological time. The geological evidence indicates that during the existence of this ocean, large collisions occurred on the surface of Mars, which led to the formation of megatsunamis in its palaeo-ocean. Previous research has reported on the effects of tsunami waves on microbial ecosystems in the Earth's oceans. This work indicates that tsunami waves can cause changes in the physico-chemical properties of seawater, as well as tsunami-affected land soils. These factors can certainly affect microbial life. Other researchers have shown that there are large microbial communities of marine prokaryotes (bacteria and archaea) in tsunami-induced sediments. These results led us to investigate the impact of tsunami waves on the proposed microbial life in the ancient Martian ocean, and its role in the preservation or non-preservation of Martian microbial life as a fossil signature.

Constraints on the uncertainty, timing, and magnitude of potential Mars oceans from topographic deformation models

Proposed ocean paleoshorelines on Mars have faced criticism over their genetic interpretation and because they deviate significantly from an expected equipotential surface (by many kilometers). Multiple geophysical deformation models have been proposed to explain this large topographic range and deviation including true polar wander and direct Tharsis-induced deformation. Yet, the application of these models is potentially flawed as there exists no consensus on exactly where these proposed paleoshorelines are located. Here, we apply these models to proposed maps and mappings of the putative martian ocean shorelines and show that even when considering deformation due to the rise of Tharsis and its associated true polar wander, the observed deviation within each Arabia level's paleotopography precludes them as past equipotential surfaces. Additionally, we compute best-fit ages for all proposed paleoshorelines relative to the rise of Tharsis and the ages span nearly the entire period of Tharsis construction. Assessment of the paleoelevations of open basin deltas and valley network termini also suggests disagreement with the timing of such features with a paleoocean. Overall, we find that these geophysical deformation models are unable to explain the large elevation ranges observed in the putative shoreline data and that the long-wavelength trends may simply be the result of mismapped features along the topographic dichotomy which itself may have been modified by Tharsis and/or true polar wander.

MOSCOW INTERNATIONAL SYMPOSIA ON SOLAR SYSTEM RESEARCH (10M-S3 AND 11M-S3) REPORTS REVIEW. Part 1. Mars exploration

A review of the reports of the last two Moscow International Symposia on Solar System Research has been completed. In the first part of the review, 43 reports of the main session of the "Mars" section are considered. The works of leading experts in the field of planetary science cover a wide range of scientific and applied problems - from the study of the geological history and climate of Mars, the search for traces of life and subsurface water reserves, to new technologies in planetary research, mission planning, as well as monitoring solar activity and radiation conditions in the interplanetary space, orbit and the surface of Mars. The data obtained in the last two decades has made it possible to significantly advance in understanding the nature of Mars, but many unresolved questions remain regarding the climate in the early era, the existence of the Martian oceans in the past, biological and geological activity. The scientific results obtained by unmanned spacecraft should be fully taken into account in the development of manned deep space exploration programs. Key words: Solar system, planetology, international symposium, deep space, automatic interplanetary stations, Mars, Moon, reports review

Evidence for an Ancient Sea Level on Mars

Abstract Mars shares many similarities and characteristics to Earth including various geological features and planetary structure. The remarkable bimodal distribution of elevations in both planets is one of the most striking global features suggesting similar geodynamic processes of crustal differentiation on Earth and Mars. There also exists much evidence, based on geographic features resembling ancient shorelines, for the existence of an ancient Martian ocean in the northern hemisphere that covers nearly one-third of the planet’s surface. However, the interpretation of some features as ancient shorelines has been thoroughly challenged, which left the existence of a primordial Martian ocean controversial. Moreover, if oceans were formerly present on Mars, there is still significant ambiguity about the volume of water with the estimations ranging over 4 orders of magnitude. Here we map the Martian sea level problem onto a percolation model that provides strong evidence that the longest isoheight line on Mars that separates the northern and southern hemispheres acts as a critical level height with divergent correlation length and plays the same role as the present mean sea level does on Earth. Our results unravel remarkable similarities between Mars and Earth, posing a testable hypothesis about the level of the ancient ocean on Mars that can be answered experimentally by the future investigations and spacecraft exploration.

Scientists Float a New Theory on the Medusae Fossae Formation

Pumice-like rafts of lightweight material could have carried volcanic debris across an ancient Martian ocean to build one of the most puzzling features on the Red Planet.

Frontal Aureole Deposit on Acheron Fossae ridge as evidence for landslide-generated tsunami on Mars

The recurrent failures of the 8 to 10-km high basal scarp of the Olympus Mons volcano on Mars has resulted in enormous landslides merging into a composite deposit known as the aureole. The largest of these landslides, the western (W) aureole, appears as a hummocky and extensive tongue reaching the distance of 700 ​km from the present Olympus Mons edge. Totalizing a volume of 106 Km3, the W aureole was created by a single, 100°-wide sector collapse of the Olympus Mons flank between north and west directions. Whereas the western segment of the landslide fell onto the flat area of Amazonis Planitia, the northern section came across the gently sloping ridge of Acheron Fossae after 550 ​km of travel, and subsequently rose against slope for some additional 50–80 ​km.Analysis of imagery on Acheron Fossae ridge beyond the front of the landslide shows a peculiar deposit and associated morphologies. Termed here Frontal Aureole Deposits (FAD), it occurs in two units: a smooth, uniform deposit immediately beyond the aureole terminus, followed in the distal part by distinct lobes directed against slope. These deposits are interpreted as the remnants of debris-rich sandy and muddy waves thrust by the W aureole landslide that inundated the Acheron Fossae ridge. Numerical and analytical calculations set up to study the dynamics of inundation show that the length of the deposits was in the reach of water thrust by a fast-travelling landslide. A possible explanation for the presence of water is that the front was travelling across an outlet of the ancient Martian ocean which, consequently, must have persisted when the landslide event took place. According to this hypothesis, FAD represents the remnant of a giant tsunami deposit similar, albeit at a much larger scale, to those that occur on Earth.

A New Way to Analyze Evidence of Martian Oceans

Mars’s aqueous past holds the answers to many questions about the Red Planet. A new study provides a tool for scouring planetary surfaces for ancient shorelines.

Geological Evidence of Planet-Wide Groundwater System on Mars.

The scale of groundwater upwelling on Mars, as well as its relation to sedimentary systems, remains an ongoing debate. Several deep craters (basins) in the northern equatorial regions show compelling signs that large amounts of water once existed on Mars at a planet‐wide scale. The presence of water‐formed features, including fluvial Gilbert and sapping deltas fed by sapping valleys, constitute strong evidence of groundwater upwelling resulting in long term standing bodies of water inside the basins. Terrestrial field evidence shows that sapping valleys can occur in basalt bedrock and not only in unconsolidated sediments. A hypothesis that considers the elevation differences between the observed morphologies and the assumed basal groundwater level is presented and described as the “dike‐confined water” model, already present on Earth and introduced for the first time in the Martian geological literature. Only the deepest basins considered in this study, those with bases deeper than −4000 m in elevation below the Mars datum, intercepted the water‐saturated zone and exhibit evidence of groundwater fluctuations. The discovery of these groundwater discharge sites on a planet‐wide scale strongly suggests a link between the putative Martian ocean and various configurations of sedimentary deposits that were formed as a result of groundwater fluctuations during the Hesperian period. This newly recognized evidence of water‐formed features significantly increases the chance that biosignatures could be buried in the sediment. These deep basins (groundwater‐fed lakes) will be of interest to future exploration missions as they might provide evidence of geological conditions suitable for life.

New Evidence of an Ancient Martian Ocean From the Global Distribution of Valley Networks

AbstractWe examine the connection between true polar wander (TPW) and the evidence for an ancient ocean on Mars. Previous studies have investigated the plausibility of a Mars ocean by examining the topography of possible ancient sea level markers on the planet's surface. One such study argued that features interpreted as ancient shorelines display long‐wavelength topographic variations consistent with postformational TPW (Perron et al., 2007, https://doi.org/10.1038/nature05873). In contrast, a second study argued that the elevations of possible ancient deltaic deposits associated with an ocean on early Mars are not consistent with the TPW scenario (di Achille & Hynek, 2010, https://doi.org/10.1038/ngeo891). Herein we revisit this issue by examining another marker of ancient shorelines—fluvial valley networks observed on the surface of Mars. Our results support the existence of an ancient Martian ocean and that long‐wavelength deformation of related surface features (ancient shorelines and valley networks) was driven by some combination of TPW and surface loading associated with the formation of the Tharsis volcanic province.

Timing of oceans on Mars from shoreline deformation.

Widespread evidence points to the existence of an ancient Martian ocean. Most compelling are the putative ancient shorelines in the northern plains. However, these shorelines fail to follow an equipotential surface, and this has been used to challenge the notion that they formed via an early ocean and hence to question the existence of such an ocean. The shorelines' deviation from a constant elevation can be explained by true polar wander occurring after the formation of Tharsis, a volcanic province that dominates the gravity and topography of Mars. However, surface loading from the oceans can drive polar wander only if Tharsis formed far from the equator, and most evidence indicates that Tharsis formed near the equator, meaning that there is no current explanation for the shorelines' deviation from an equipotential that is consistent with our geophysical understanding of Mars. Here we show that variations in shoreline topography can be explained by deformation caused by the emplacement of Tharsis. We find that the shorelines must have formed before and during the emplacement of Tharsis, instead of afterwards, as previously assumed. Our results imply that oceans on Mars formed early, concurrent with the valley networks, and point to a close relationship between the evolution of oceans on Mars and the initiation and decline of Tharsis volcanism, with broad implications for the geology, hydrological cycle and climate of early Mars.

The Faint Young Sun and Faint Young Stars Paradox

AbstractThe purpose of this paper is to explore a resolution for the Faint Young Sun Paradox that has been mostly rejected by the community, namely the possibility of a somewhat more massive young Sun with a large mass loss rate sustained for two to three billion years. This would make the young Sun bright enough to keep both the terrestrial and Martian oceans from freezing, and thus resolve the paradox. It is found that a large and sustained mass loss is consistent with the well observed spin-down rate of Sun-like stars, and indeed may be required for it. It is concluded that a more massive young Sun must be considered a plausible hypothesis.

Tsunamis Splashed Ancient Mars

Massive meteorites likely slammed into a Martian ocean billions of years ago, unleashing tsunami waves up to 120 meters tall, a close study of a region of the Red Planet's terrain has found.

Tsunami waves extensively resurfaced the shorelines of an early Martian ocean.

It has been proposed that ~3.4 billion years ago an ocean fed by enormous catastrophic floods covered most of the Martian northern lowlands. However, a persistent problem with this hypothesis is the lack of definitive paleoshoreline features. Here, based on geomorphic and thermal image mapping in the circum-Chryse and northwestern Arabia Terra regions of the northern plains, in combination with numerical analyses, we show evidence for two enormous tsunami events possibly triggered by bolide impacts, resulting in craters ~30 km in diameter and occurring perhaps a few million years apart. The tsunamis produced widespread littoral landforms, including run-up water-ice-rich and bouldery lobes, which extended tens to hundreds of kilometers over gently sloping plains and boundary cratered highlands, as well as backwash channels where wave retreat occurred on highland-boundary surfaces. The ice-rich lobes formed in association with the younger tsunami, showing that their emplacement took place following a transition into a colder global climatic regime that occurred after the older tsunami event. We conclude that, on early Mars, tsunamis played a major role in generating and resurfacing coastal terrains.

Boulders of the Vastitas Borealis Formation: Potential origin and implications for an ancient martian ocean

The hypothetical existence of a martian ocean that is based on identification of alleged paleoshorelines has been heavily contested during recent years. Despite the controversy surrounding the paleoshoreline interpretation, additional evidence supporting the idea of a late Hesperian–early Amazonian martian ocean has recently been documented in areas that were potentially covered by this body of water. Most of these observations have been made by the establishment of analogies between martian features within the northern plains and depositional elements from deep-water terrestrial environments (e.g., teardrop-shaped islands, large-scale polygonal terrains, and highalbedo mounds). This paper showcases a new terrestrial, deepwater analogy that also supports the existence of an ancient martian ocean. Boulder-size rocks that are contained within the Vastitas Borealis Formation (VBF) on the northern plains of Mars are compared with boulderand kilometer-scale blocks that have been transported subaqueously as part of mass-transport events in a multitude of terrestrial deep-water environments. These observations suggest that meter-scale rocks that make up part of the VBF might have been emplaced by catastrophic mass-transport events similar to those documented within continental margins on Earth.

Possible erosion marks of bottom oceanic currents in the northern lowlands of Mars

There has been much interest for the hypothetical ancient ocean which might have resided in the northern lowlands of Mars. Hints are the global subdivision of Martian crust, the smooth appearance of the northern terrains, the elevation of river deltas, and the past shorelines. Here it is suggested that water in a sufficiently deep northern ocean would have likely formed water currents similar to those occurring in the ocean on Earth.Numerous furrows in the northern lowlands are interpreted as the erosion marks of former water currents and shown to reasonably match the expected orientation on a rotating planet. The direction of furrows indicates that whereas some of the currents were directed down-slope (being thus driven by slight gravity differences like in a turbidity current of hyperpycnal flow), others were nearly parallel to the contour lines. It is suggested that the latter could correspond to the scars of ancient Martian currents similar to contour currents occurring in the oceans of the Earth, a kind of low-density oceanic flow in which gravity is balanced by the Coriolis force. Contour currents are particularly relevant for assessing the Martian ocean, as they are characteristic of the oceanic environment and cannot be formed by subaerial processes.

Hydrodynamics of impact-induced tsunami over the Martian ocean

Large bodies of liquid water ranging from lakes to oceans have been hypothesized to have occupied the surface of ancient Mars episodically. Such inferences have been founded largely on geomorphological observations of putative shoreline features during the period ranging from the 1980s to the early 2000s. High-resolution satellite images obtained during various Mars missions conducted since the early 2000s have enabled detailed sedimentological studies. One phenomenon that might leave sedimentological traces of the purported Martian paleo-oceans is a bolide impact and consequent generation of large tsunami waves. Numerical modeling of impact-induced tsunami waves on a hypothesized northern plains paleo-ocean was performed to elucidate their potential propagation characteristics on Mars, including the ranges of wave height and velocity. When considering a tsunami triggered by a 50km-diameter impact cratering event, the offshore and shore-zone wave heights respectively reached 40–50m and 120m. In the same test scenario, the tsunami wave velocity reached 20m/s near the crater and 16m/s at the shore zone. The wave height and velocity in highly cratered regions, such as Arabia Terra, tend to be relatively low because tsunami inundation is diffused by impact crater rims existing along the tsunami passage.

Giant Polygons and Mounds in the Lowlands of Mars: Signatures of an Ancient Ocean?

This paper presents the hypothesis that the well-known giant polygons and bright mounds of the martian lowlands may be related to a common process-a process of fluid expulsion that results from burial of fine-grained sediments beneath a body of water. Specifically, we hypothesize that giant polygons and mounds in Chryse and Acidalia Planitiae are analogous to kilometer-scale polygons and mud volcanoes in terrestrial, marine basins and that the co-occurrence of masses of these features in Chryse and Acidalia may be the signature of sedimentary processes in an ancient martian ocean. We base this hypothesis on recent data from both Earth and Mars. On Earth, 3-D seismic data illustrate kilometer-scale polygons that may be analogous to the giant polygons on Mars. The terrestrial polygons form in fine-grained sediments that have been deposited and buried in passive-margin, marine settings. These polygons are thought to result from compaction/dewatering, and they are commonly associated with fluid expulsion features, such as mud volcanoes. On Mars, in Chryse and Acidalia Planitiae, orbital data demonstrate that giant polygons and mounds have overlapping spatial distributions. There, each set of features occurs within a geological setting that is seemingly analogous to that of the terrestrial, kilometer-scale polygons (broad basin of deposition, predicted fine-grained sediments, and lack of significant horizontal stress). Regionally, the martian polygons and mounds both show a correlation to elevation, as if their formation were related to past water levels. Although these observations are based on older data with incomplete coverage, a similar correlation to elevation has been established in one local area studied in detail with newer higher-resolution data. Further mapping with the latest data sets should more clearly elucidate the relationship(s) of the polygons and mounds to elevation over the entire Chryse-Acidalia region and thereby provide more insight into this hypothesis.