Gale Crater is filled by sedimentary deposits including a mound of layered deposits, Aeolis Mons. Using orbital data, we mapped the crater infillings and measured their geometry to determine their ...origin. The sediment of Aeolis Mons is interpreted to be primarily air fall material such as dust, volcanic ash, fine‐grained impact products, and possibly snow deposited by settling from the atmosphere, as well as wind‐blown sands cemented in the crater center. Unconformity surfaces between the geological units are evidence for depositional hiatuses. Crater floor material deposited around Aeolis Mons and on the crater wall is interpreted to be alluvial and colluvial deposits. Morphologic evidence suggests that a shallow lake existed after the formation of the lowermost part of Aeolis Mons (the Small yardangs unit and the mass‐wasting deposits). A suite of several features including patterned ground and possible rock glaciers are suggestive of periglacial processes with a permafrost environment after the first hundreds of thousands of years following its formation, dated to ~3.61 Ga, in the Late Noachian/Early Hesperian. Episodic melting of snow in the crater could have caused the formation of sulfates and clays in Aeolis Mons, the formation of rock glaciers and the incision of deep canyons and valleys along its flanks as well as on the crater wall and rim, and the formation of a lake in the deepest portions of Gale.
Key Points
Aeolis Mons is interpreted to be primarily air fall and aeolian sediment
Morphologic clues suggest periglacial processes with a permafrost environment
A lake may have existed after the deposition of the lowest sediment of the mound
Abstract
The Middle Devonian Epoch, ~ 393–383 million years ago, is known for a peak in diversity and highest latitudinal distribution of coral and stromatoporoid reefs. About 388 million years ago, ...during the late Eifelian and earliest Givetian, climax conditions were interrupted by the polyphased Kačák Episode, a short-lived period of marine dys-/anoxia associated with climate warming that lasted less than 500 kyr. Reconstruction of the seawater temperature contributes to a better understanding of the climate conditions marine biota were exposed to during the event interval. To date, conodont apatite-based paleotemperatures across the Eifelian–Givetian boundary interval have been published from Belarus, France, Germany and North America (10–36° S paleolatitude). Here we provide new δ
18
O
apatite
data from the Carnic Alps (Austria, Italy) and the Prague Synform (Czech Republic). For better approximation of the paleotemperature record across the Kačák Episode, a latitude-dependent correction for Middle Devonian seawater δ
18
O is applied. Because δ
18
O
apatite
data from shallow marine sections are influenced by regional salinity variations, calculated mean sea surface temperatures (SST) are restricted to more open marine settings (22–34° S paleolatitude). Water temperatures reach ~ 34 °C in the Prague Synform and ~ 33 °C in the Carnic Alps and suggest that SSTs of the southern hemisphere low latitudes were ~ 6 °C higher than previously assumed for this time interval.
•First detailed morphometric characterization of Martian mounds interpreted as putative mud volcanoes/spring mounds throughout extensive DTM analysis in well-studied areas of Firsoff ...crater.•Algorithm for automatic extraction of mounds within three Martian craters (Firsoff, Kotido, unnamed).•Fractal clustering analysis of mounds distribution: the fluid source feeding mounds through interconnected fracture network is placed between 3.3–4.2 km below Martian surface.•Fluid pressurization is triggered by impacts, and the created fracture network is used to pipe fluids to the surface.•Fluid resurgence can be expected in several other Martian craters with inner bulges.
Arabia Terra is a region of Mars where signs of past-water occurrence are recorded in several landforms. Broad and local scale geomorphological, compositional and hydrological analyses point towards pervasive fluid circulation through time. In this work we focus on mound fields located in the interior of three casters larger than 40 km (Firsoff, Kotido and unnamed crater 20 km to the east) and showing strong morphological and textural resemblance to terrestrial mud volcanoes and spring-related features. We infer that these landforms likely testify the presence of a pressurized fluid reservoir at depth and past fluid upwelling. We have performed morphometric analyses to characterize the mound morphologies and consequently retrieve an accurate automated mapping of the mounds within the craters for spatial distribution and fractal clustering analysis. The outcome of the fractal clustering yields information about the possible extent of the percolating fracture network at depth below the craters. We have been able to constrain the depth of the pressurized fluid reservoir between ∼2.5 and 3.2 km of depth and hence, we propose that mounds and mounds alignments are most likely associated to the presence of fissure ridges and fluid outflow. Their process of formation is genetically linked to the formation of large intra-crater bulges previously interpreted as large scale spring deposits. The overburden removal caused by the impact crater formation is the inferred triggering mechanism for fluid pressurization and upwelling, that through time led to the formation of the intra-crater bulges and, after compaction and sealing, to the widespread mound fields in their surroundings.
Geological Evidence of Planet‐Wide Groundwater System on Mars Salese, Francesco; Pondrelli, Monica; Neeseman, Alicia ...
Journal of geophysical research. Planets,
February 2019, 2019-Feb, 2019-02-00, 20190201, Volume:
124, Issue:
2
Journal Article
Peer reviewed
Open access
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.
Plain Language Summary
Most previous studies on Mars relevant groundwater have proposed models, but few have looked at the geological evidence of groundwater upwelling in deep closed basins in the northern hemisphere equatorial region. Geological evidence of groundwater upwelling in these deep basins is a key point that will help to validate present‐day models and to better constraint them in the future. Observations in the northern hemisphere show evidence of a planet‐wide groundwater system on Mars. The elevations of these water‐related morphologies in all studied basins lie within the same narrow range of depths below Mars datum and notably coincide with the elevation of some ocean shorelines proposed by previous authors.
Key Points
Geological evidence supporting Martian planet‐wide groundwater upwelling
Water‐saturated zone intercepted by basins reaching more than ‐4000m below the Mars DATUM
Putative relations between groundwater‐saturated level (groundwater‐fed lakes) and the ocean shorelines around ‐4000m below the DATUM
In the Carnic Alps there are four sections exposing rocks across the Devonian–Carboniferous boundary: the Grüne Schneid and the Kronhofgraben sections in Austria, the Plan di Zermula A and the ...Sentiero per Cresta Verde sections in Italy. All of them are mainly composed of limestone and span from the late Famennian through the Tournaisian. In the Kronhofgraben and Plan di Zermula A sections, the limestone sedimentation is interrupted by black shales interpreted as equivalent of the Hangenberg Black Shales. The Grüne Schneid and the Sentiero per Cresta Verde sections are two of the few sections worldwide, where the calcareous sedimentation is continuous. The main extinction event registered at the end of the Devonian is testified not only in the sections where the calcareous sedimentation was replaced by black shales sedimentation but also in the Grüne Schneid and in the Sentiero per Cresta Verde sections. Data on conodont biostratigraphy and biofacies, the content in ammonoids, and trilobites and geochemistry patterns from all sections are here summarised and reviewed. These data-set allow to conclude that the four Carnic Alps sections positively test the suitability of the timeline proposed by the DCB working group for the definition of the revised Devonian–Carboniferous boundary.
Southern highlands of Mars have experienced regional to global scale deformations in the history of its evolution. Deformational structures originated from impact-induced stresses and later viscous ...relaxation of the impact basin to cooling related global contraction. Here in this study, we investigated an Early Hesperian (Eo-Archean / Paleo-Archean equivalent to the Earth) aged lobate scarp i.e., surface signature of thrust fault, possibly originated because of global contraction. We used ‘offset crater perimeter’ measurement technique using high-resolution data (both image and DTM) to execute most precise estimation of fault plane slope and length–displacement relationship. The derived range of fault plane slope is much narrower (21°–29°) than the previously cited 20° to 35° range. Displacement–length ratio (4.51 × 10−3) is also unique and lower than the previously evaluated values of lobate scarps from other region (mainly from dichotomy boundary) of Mars. The newly derived results from the morphometric analysis are due the differential stress pattern and the distinct basement rock rheology. Our results highlight the need for more high-resolution estimation of lobate scarps from several regions with the methodology employed in this study to better understand the global Martian early tectonic scenario.
•Morphometric analysis of a Hesperian aged compressional structure.•Precise estimation of fault plane slope using new technique.•Derived length-displacement relation using high-resolution data.•Derived data could impact on further stress/strain estimation.
The type-Silurian Cellon section in the Carnic Alps in Austria underpins much of the current Silurian conodont zonations, forming the basis for the Silurian timescale. However, the Silurian record of ...the Cellon section lacks radiometric and astrochronological age constraints, making it difficult to gain insights into the processes pacing Silurian (anoxic) events. To attain age constraints and investigate the pacing Silurian (anoxic) events by astronomical cycles, a cyclostratigraphic study was conducted on high-resolution pXRF (CaO, Al 2 O 3 , and Fe 2 O 3 ) and induration records spanning the Ludlow and Pridoli parts of the Cellon section. Astronomical cycles ranging from precession to the 405-kyr eccentricity cycle were first recognised visually in the field and in proxy records. The visual detection of astronomical cycles served as an input for the WaverideR R package, enabling the tracking of the 405-kyr eccentricity period in each proxy’s continous wavelet transform scalograms. These tracked period curves were combined with external age controls through multiple Monte Carlo simulations, generating an (absolute) age model. This age model is used to assign ages and durations and their respective uncertainties to a hiatus in the Ludfordian, conodont zones, lithological units, geochronological units and events, yielding new ages for Silurian stage boundaries (e.g., Gorstian-Ludfordian boundary at 425.92 ± 0.65 Ma, the Ludfordian-Pridoli boundary at 423.03 ± 0.53 Ma, the Silurian-Devonian boundary at 418.86 ± 1.02 Ma), and new durations for the Ludfordian at 2.89 ± 0.35 Myr and Pridoli at 4.24 ± 0.46 Myr. Furthermore, the imprint of astronomical cycles in the Cellon section itself indicates that the Linde, Klev and Silurian-Devonian boundary events all occur after a 2.4-Myr eccentricity node, indicating pacing by astronomical forcing, similar to other Devonian and Cretaceous anoxic events. The Lau event, however, does not appear to coincide with a 2.4-Myr eccentricity node.
Large-scale spring deposits on Mars? Rossi, Angelo Pio; Neukum, Gerhard; Pondrelli, Monica ...
Journal of Geophysical Research - Planets,
August 2008, Volume:
113, Issue:
E8
Journal Article
Peer reviewed
Open access
We present a large‐scale spring hypothesis for the formation of various enigmatic light‐toned deposits (LTDs) on Mars. Layered to massive LTDs occur extensively in Valles Marineris, chaotic terrains, ...and several large craters, in particular, those located in Arabia Terra. Most of these deposits are not easily explained with either a single process or multiple ones, either in combination or occurring sequentially. Spring deposits can have a very wide range of internal facies and exhibit complex architectural variations. We propose the concept of large‐scale spring deposits for explaining LTDs on Mars. Stable volcano‐tectonic settings, such as the ones typical on Mars, are compatible with a large‐scale, long‐term, multistage formation of spring deposits. The large‐scale spring deposit model can explain the formation of LTDs with a common process, although active in different times and locations, compatible with coeval local or regional processes and deposits, such as volcaniclastic ones. LTDs, if formed as spring deposits derived from subsurface fluids, could potentially offer favorable conditions both to life and to the fossilization of past life forms.
Aeolis Dorsa is a topographic depression, ∼800 km east of Gale Crater, located along the Mars' dichotomy boundary. This area hosts a set of fluvial sedimentary rocks displaying an exceptional record ...of depositional environments and fluvial channels patterns that suggest the presence of a large amount of surface and/or subsurface water. We interpreted the plain as an ancient waterlogged environment, a sedimentary basin passing into distal depositional environments. Regional mapping of the area revealed the presence of a large-scale fluvial system that points to a long-term and extensive hydrological cycle. A significant wet period with changing environmental conditions in Hesperian/Amazonian occurred in the study area diverging from the present-day climate. Our map (
Main Map
) contributes to the understanding of past climatic conditions on Mars. Moreover, it provides an interesting perspective for future missions looking for evidence of present-day and/or past extraterrestrial organisms as the life as we know it needs liquid water.
Ares Vallis is one of the greatest outflow channels of Mars. Using high-resolution images of recent missions to Mars (MGS, 2001 Odyssey, and Mars Express), we investigated Ares Vallis and its valley ...arms, taking advantage of 3-dimensional analysis performed using the high-resolution stereo capability of the Mars Express High Resolution Stereo Camera (HRSC). In our view, Ares Vallis is characterized by catastrophic flood landscapes partially superimposed by ice-related morphologies. Catastrophic flood landforms include erosional terraces, grooved terrains, streamlined uplands, giant bars, pendant bars, and cataract-like features. Ice-related morphologies include probable kame features, thermokarstic depressions, and patterned grounds. Our investigations outline that throughout the Hesperian age, Ares Vallis and its valley arms had been sculpted by several, time-scattered, catastrophic floods, originating from Iani, Hydaspis and Aram Chaos. Geomorphological evidence suggests that catastrophic floods were ice-covered, and that climatic conditions of Mars at this time were similar to those of the present day. At the end of each catastrophic flood, ice masses grounded, forming a thick stagnant dead-ice body. Each catastrophic flood was followed by a relatively brief period of warmer-wetter climatic conditions, originated as a consequence of catastrophic flooding. During such periods thermokarstic depressions originated, liquid water formed meandering channels, and ice-contact deposits were emplaced by ice-walled streams. Finally, the climate turned into cold-dry conditions similar to the present-day ones, and ice masses sublimated.
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