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Equatorial Layered Deposits (ELDs) reveal aspects of past depositional environments useful for timing climatic and geological events on Mars. However, their formation has several contending hypotheses which reflect a diverse range of possible environments. To better constrain their formation mechanism, we analyzed the stratigraphic and mineralogical characteristics and mapped the distribution of ELDs within three close craters, Sera, Jiji, and an unnamed crater in central Arabia Terra. Analyses of craters' geology allowed us to reconstruct the paleo‐environments where ELDs have been deposited. Thinning and thickening sequence trends show shared and repeated variations in the depositional environment, reflecting sediment accumulation strongly controlled by a regional groundwater reservoir. Layered deposits are characterized by monohydrated and polyhydrated sulfate signatures implying an interaction between water and rock in acidic conditions. Our study contributes to the understanding of regional geological processes in Arabia Terra revealing long‐term aqueous activity. Plain Language Summary: Despite years of orbital observations of the surface of Mars, mid‐to low‐latitude layered deposits (LD) in Arabia Terra are not yet fully understood. These deposits record an important geological sequence of the early Martian history, but their exact formation, specifically the putative role of the water in their formation and preservation, remains an unanswered question. This study helps in further understanding these processes by comparing and contrasting LD present in craters in very close proximity to each other. In this way, proposed hypotheses benefit from having a control that is not limited to a singular crater or location. Our study contributes to the understanding of regional geological processes in Arabia Terra revealing long‐term aqueous activity. Results combine various analyses, including measurements of layer thickness and attitudes, orbital spectroscopy, basin geometry, and morphologies aimed at reconstructing the geological evolution of the area. In particular, we interpreted that LD were emplaced in a depositional environment reflecting sediment accumulation strongly controlled by a regional groundwater reservoir in acidic conditions. Key Points: Regional groundwater fluctuations influenced the deposition, mineralogy, and preservation of Equatorial Layered Deposits (ELDs) in Arabia TerraFour different stratigraphic sequences of layered deposits have been identified on the basis of strata thickness and attitudeMineralogical analyses of ELDs suggest the presence of different levels of hydration of sulfates [ABSTRACT FROM AUTHOR]

The formation of layered mounds on Mars remains a major topic of debate, with the relationship between their deposition and chemical alteration a major aspect still to be constrained. The association these deposits have with hydrated minerals indicates aqueous processes were active in their past, however the extent and duration of this aqueous period has yet to be fully realized. We studied compositional, stratigraphical, and structural characteristics of two separate layered deposits within Becquerel crater, Arabia Terra, to constrain their origins and the intensity of past aqueous activity. We find that due to key differences in composition, layering, and deformation between the two deposits, the timing of important depositional changes within Becquerel can be identified. We propose a scenario involving differences in fluid expulsion intensity and water level between the two layered deposits, in which diverse depositional and post‐depositional environments were able to form. Furthermore, internal collapsing and deformation of the main mound might reflect that fluid upwelling persisted below the mound after formation. Determining the relationship between these two deposits is an important step in unraveling the past climate of Arabia Terra, and more broadly Mars. The evidence of protracted fluid expulsion represents a unique opportunity for future missions searching for signs of past life. Plain Language Summary: Becquerel crater is located in the Arabia Terra region (Mars), and it is characterized by the occurrence of a large layered mound. We used spectral reflectance to study mineralogy within the layered mound, finding hydrated sulfates, minerals which formed in the presence of water. In addition, we noticed that not far from the mound, there are separate layered deposits within a smaller interior crater on the floor of Becquerel crater. This interior crater creates nearly a kilometer difference in elevation between the large layered mound and the separate layered deposits, leaving the separate layered deposits mostly isolated from the rest of Becquerel. The layered deposits within the interior crater were found to have unique clay lithologies. We compared these separate layered deposits with those of the large layered mound to determine their relationship and we concluded that their origins might be related to fluid expulsion which exploited weak areas of the crater floor from the intersections of impact related radial faults and a pre‐existing regional fault. Due to the abundance of fluvial related structures and hydrated mineral assemblages, Becquerel might be considered an optimal place to search for signs of past life. Key Points: Spectral and morphologic analyses highlight multiple events related to water activity within Becquerel craterWidespread faulting suggests the internal collapse of a layered mound, possibly due to fluid expulsion from belowDifferences in elevation reflect different mineralogies and layer thicknesses between two layered deposits [ABSTRACT FROM AUTHOR]

An extensive distribution of water‐altered equatorial layered deposits (ELDs) characterizes the densely cratered terrain of Arabia Terra (AT), Mars. The majority of these deposits reside within craters and are easily identified by laterally continuous layering. The processes that led to their formation have been widely investigated, but remain unresolved. Furthermore, their precise spatial distribution as a whole, as well as their relationship to one another individually, has yet to be fully appreciated. This work examines 1,013 craters and emphasizes 45 that were observed to contain ELDs within the eastern half of AT. We present the statistical relationships between crater characteristics (e.g., location, diameter, depth), as well as evidence supporting a southeast‐northwest facies change. The 30–2,000‐m range of measured deposit thicknesses, accompanied with individual layer thicknesses, correlate with crater elevation either due to water level differences within craters, or a proximal‐distal relationship to the source. Air fall or fluid expulsion appear to stand out among all the prevailing depositional hypotheses, however the volume required to fill these craters in an ash fall scenario is in opposition with the locations of known volcanic provinces and the volume of ash that volcanic eruptions produce. This new evidence of a regional facies change provides a unique opportunity to better understand past climate and sedimentary processes on Mars, as well as the putative groundwater level in ancient AT. Ultimately, our results do not agree well with a unified depositional method for these deposits and the possibility of mixed origins should be taken seriously. Plain Language Summary: Layer thicknesses of equatorial layered deposits (ELDs) within craters in western Arabia Terra (AT) show a regional NW‐SE thickening, correlating with both elevation and latitude. The trend does not correlate with locations of established volcanic provinces or proposed locations of nearby calderas. Additionally, the volume necessary to completely fill craters may be problematic in an ash fall scenario. The discrepancy of ELD size between craters is problematic and requires specialized erosional intensities unique to each crater. Fluctuating water level might create a proximal‐distal effect either from the putative ocean to the northwest which hinders thicker ELD formation, or fluid expulsion focused at Meridiani Planum which aids thicker ELD formation. Thinning and thickening sequences in individual craters suggests repeated changes from low to high energy environments. Low to moderate layer attitudes are indicative of compaction or draping during deposition over pre‐existing topography, whereas steeply dipping layers suggests post‐depositional deformation in specific craters. This implies post‐depositional histories are often unique to individual craters. Observations demonstrate that determining the depositional method requires a regional overview to establish the controls that create these unique characteristics. Thus, a unifying depositional theory does not fit all characteristics of ELDs in AT and multiple or mixed origins should be considered. Key Points: Geological evidence supporting a SE‐NW facies change within intracrater layered deposits in western Arabia TerraMeasurements of deposit thickness and individual layer thickness decrease with elevation and latitudeThe volume required to fill these craters in an air fall scenario is in opposition with the locations of known volcanic provinces and the volume of ash volcanic eruptions produce [ABSTRACT FROM AUTHOR]

Understanding the origin of the Hesperian‐aged sulfate‐bearing Equatorial Layered Deposits (ELDs) is crucial to infer Mars' climatic conditions during their formation and to assess their habitability potential. We investigated well‐exposed ELDs in Kotido crater (Arabia Terra) and produced a detailed geological map of the crater infill, distinguishing different units within the ELDs based upon their morphological and sedimentological characteristics. The ELDs consist of interbedded light‐toned, darker‐toned deposits and mounds, associated with possible fissure ridges. Although heavily eroded by younger eolian processes, we interpret these deposits and their associated morphologies as remnants of depositional features and propose that they are the result of fluid, gas, and sediment expulsion processes sourced from the groundwater. The textural characteristics, their depositional geometry, the associated morphologies, and the inferred composition of the light‐toned deposits suggest an evaporitic origin, whereas the darker‐toned deposits might reflect clastic sedimentary processes, related or not to fluid expulsion and/or residual deposition following dissolution of the evaporites. The relative ratio of fluids, salts, and clasts controlled the depositional process, analogous to what happens in terrestrial playas. The controls on fluid expulsion is interpreted to depend on groundwater emplacement and fluctuations, possibly related to climatic changes, and to the interactions with the fractures related to the crater formation, which allowed the actual upwelling from a pressurized aquifer. Plain Language Summary: Light‐toned layered deposits rich in sulfates are widespread on Mars in several locations. Understanding how these deposits formed is crucial to infer the climatic conditions during Martian history and, in light of the fact that potentially similar deposits on Earth have been shown to be conducive to bacterial life, is critical in the search for habitable environments on Mars. We focused on Kotido crater because it shows a remarkable infill and excellent data coverage. We drew a detailed geological map, recognizing subunits interbedded within the layered deposits: light‐toned and darker‐toned layers, subconical mounds, and associated fractures. We interpret these materials to result from episodes of water upwelling sourced from the subsurface: a mixture of fluids, gases, and sediments emerged in Kotido leading to the deposition of the different subunits depending on the relative ratio of the upwelling materials in the different phases. The mounds and fractures would represent the morphological expression of the upwelling process, while the light‐ and darker‐toned material would represent the resulting deposits. The proposed mechanism is identical to that of terrestrial environments such as playa and spring deposition typical of arid settings where bacterial life is well adapted. Key Points: We mapped the Equatorial Layered Deposits of Kotido crater, recognizing their geological variability and stratigraphic relationsFluid expulsion processes controlled by groundwater fluctuations appear to be the driving mechanism on the deposition/preservationThe importance of groundwater control raises issues on the possible lateral relations with other deposits/morphologies in Arabia Terra [ABSTRACT FROM AUTHOR]

Isolates of Penicillium expansum recovered from stored pears were scored for resistance to the fungicide thiabendazole (TBZ) and for pathogenic fitness. Out of 50 isolates, nine were sensitive (S) and 41 resistant (R or RR). Seven of these resistant isolates (RR) germinated with a higher percentage on TBZ-amended medium than on unamended medium. Six S isolates and six RR isolates were chosen at random for further analysis. S and RR isolates had similar in vitro growth fitness, although RR isolates were characterized by higher infection severity on fruits. Laboratory-induced resistant isolates were generated by UV-irradiating S strains, and a similar correlation between the induced TBZ resistance and pathogenic fitness was observed. The β-tubulin gene of RR and S isolates was amplified and sequenced; mutations correlating with TBZ resistance were identified at residues Phe 167 and Glu 198. Analogous mutations were detected in the laboratory-induced resistant isolates. [ABSTRACT FROM AUTHOR]

A severe decline of apricot trees, present in Austria for several years, has recently reached notifiable levels. Initial symptoms on affected trees resemble deficiencies in water and nutrient supplies, expressed as leaf rolling, chlorosis and early reddening, leading to sudden dieback during the growing season. Small, wilted fruit and dried leaves may also persist during the autumn. Phytoplasmas belonging to the 16SrX-B subgroup of European stone fruit yellows (ESFY) were identified by nested polymerase chain reaction/restriction fragment length polymorphism analysis in a high percentage of affected trees from two different regions of Austria. [ABSTRACT FROM AUTHOR]