Wind blowing over sand on Earth produces decimeter-wavelength ripples and hundred-meter— to kilometer-wavelength dunes: bedforms of two distinct size modes. Observations from the Mars Science ...Laboratory Curiosity rover and the Mars Reconnaissance Orbiter reveal that Mars hosts a third stable wind-driven bedform, with meter-scale wavelengths. These bedforms are spatially uniform in size and typically have asymmetric profiles with angle-of-repose lee slopes and sinuous crest lines, making them unlike terrestrial wind ripples. Rather, these structures resemble fluid-drag ripples, which on Earth include water-worked current ripples, but on Mars instead form by wind because of the higher kinematic viscosity of the low-density atmosphere. A reevaluation of the wind-deposited strata in the Burns formation (about 3.7 billion years old or younger) identifies potential wind-drag ripple stratification formed under a thin atmosphere.
For ~500 Martian solar days (sols), the Mars Science Laboratory team explored Vera Rubin ridge (VRR), a topographic feature on the northwest slope of Aeolis Mons. Here we review the sedimentary ...facies and stratigraphy observed during sols 1,800–2,300, covering more than 100 m of stratigraphic thickness. Curiosity's traverse includes two transects across the ridge, which enables investigation of lateral variability over a distance of ~300 m. Three informally named stratigraphic members of the Murray formation are described: Blunts Point, Pettegrove Point, and Jura, with the latter two exposed on VRR. The Blunts Point member, exposed just below the ridge, is characterized by a recessive, fine‐grained facies that exhibits extensive planar lamination and is crosscut by abundant curvi‐planar veins. The Pettegrove Point member is more resistant, fine‐grained, thinly planar laminated, and contains a higher abundance of diagenetic concretions. Conformable above the Pettegrove Point member is the Jura member, which is also fine‐grained and parallel stratified, but is marked by a distinct step in topography, which coincides with localized meter‐scale inclined strata, a thinly and thickly laminated facies, and occasional crystal molds. All members record low‐energy lacustrine deposition, consistent with prior observations of the Murray formation. Uncommon outcrops of low‐angle stratification suggest possible subaqueous currents, and steeply inclined beds may be the result of slumping. Collectively, the rocks exposed at VRR provide additional evidence for a long‐lived lacustrine environment (in excess of 106 years via comparison to terrestrial records of sedimentation), which extends our understanding of the duration of habitable conditions in Gale crater.
Plain language summary
The primary goal of the Mars Science Laboratory Curiosity rover mission is to explore and assess ancient habitable environments on Mars. This requires a detailed understanding of the environments recorded by sedimentary rocks exposed at the present‐day surface in Gale crater. Here we review the types of sedimentary rocks exposed at a location known as Vera Rubin ridge. We find that the rocks at Vera Rubin ridge record an ancient lake environment and are a continuation of underlying lake deposits. Ancient lake deposits are highly desirable targets in the search for habitable environments, due to their ability to concentrate and preserve organic matter. This study significantly expands the duration of habitable conditions that can be confirmed through ground truth of sedimentary rocks and provides a framework for interpreting strata that lie ahead as Curiosity continues to explore Aeolis Mons.
Key Points
Six sedimentary facies were identified at and just below Vera Rubin ridge and comprise three members of the Murray formation
Vera Rubin ridge records deposition in a lacustrine environment, which expands the duration of habitable conditions observed in Gale
The facies and stratigraphy identified here serve as a framework for interpreting strata within the Glen Torridon region and beyond
This paper provides an overview of the Curiosity rover's exploration at Vera Rubin ridge (VRR) and summarizes the science results. VRR is a distinct geomorphic feature on lower Aeolis Mons ...(informally known as Mount Sharp) that was identified in orbital data based on its distinct texture, topographic expression, and association with a hematite spectral signature. Curiosity conducted extensive remote sensing observations, acquired data on dozens of contact science targets, and drilled three outcrop samples from the ridge, as well as one outcrop sample immediately below the ridge. Our observations indicate that strata composing VRR were deposited in a predominantly lacustrine setting and are part of the Murray formation. The rocks within the ridge are chemically in family with underlying Murray formation strata. Red hematite is dispersed throughout much of the VRR bedrock, and this is the source of the orbital spectral detection. Gray hematite is also present in isolated, gray‐colored patches concentrated toward the upper elevations of VRR, and these gray patches also contain small, dark Fe‐rich nodules. We propose that VRR formed when diagenetic event(s) preferentially hardened rocks, which were subsequently eroded into a ridge by wind. Diagenesis also led to enhanced crystallization and/or cementation that deepened the ferric‐related spectral absorptions on the ridge, which helped make them readily distinguishable from orbit. Results add to existing evidence of protracted aqueous environments at Gale crater and give new insight into how diagenesis shaped Mars' rock record.
Plain Language Summary
Vera Rubin ridge is a feature at the base of Mount Sharp with a distinct texture and topography. Orbiter observations showed hematite, a mineral that sometimes forms by chemical reactions in water environments, was present atop the ridge. The presence of both water and chemical activity suggested the area preserved a past habitable environment. In this paper, we detail how the Curiosity science team tested this and other orbital‐based hypotheses. Curiosity data suggested that most ridge rocks were lain down in an ancient lake and had similar compositions to other Mount Sharp rocks. Curiosity confirmed that hematite was present in the ridge but no more abundantly than elsewhere. Larger grain size or higher crystallinity probably account for the ridge's hematite being more visible from orbit. We conclude Vera Rubin ridge formed because groundwater recrystallized and hardened the rocks that now make up the ridge. Wind subsequently sculpted and eroded Mount Sharp, leaving the harder ridge rocks standing because they resisted erosion compared with surrounding rocks. The implication of these results is that liquid water was present at Mount Sharp for a very long time, not only when the crater held a lake but also much later, likely as groundwater.
Key Points
We summarize Curiosity's campaign at Vera Rubin ridge (Sols 1726–2302) and the high‐level results from articles in this special issue
Vera Rubin ridge formed when diagenesis hardened rocks along the base of Aeolis Mons; wind subsequently etched the feature into a ridge
Results add evidence for protracted aqueous environments at Gale crater and give new insight into how diagenesis shaped Mars' rock record
The Glen Torridon (GT) region within Gale crater, Mars, occurs in contact with the southern side of Vera Rubin ridge (VRR), a well-defined geomorphic feature that is comparatively resistant to ...erosion. Prior to detailed ground-based investigation of GT, its geologic relationship with VRR was unknown. Distinct lithologic subunits within the Jura member (Murray formation), which forms the upper part of VRR, made it possible to be also identified within GT. This indicates that the strata pass across the geomorphic divide between regions. Furthermore, the cross-bedded lower part of the overlying Knockfarril Hill member (Carolyn Shoemaker formation) also occurs within both VRR and GT. Correlation of both units demonstrates that the strata form a continuous stratigraphic succession regardless of large-scale geomorphic expression. The lithologic change from mudstone (Jura member) to cross-bedded sandstone (Knockfarril Hill member) heralds a significant shift in paleoenvironment from lacustrine to fluvial. The upper part of the Knockfarril Hill member consists of interbedded mudstone and sandstone that transitions to the overlying finely laminated mudstone of the Glasgow member, and a return to lacustrine deposition. In GT, the Stimson formation unconformably overlies the Glasgow member, where it demarks the southern boundary of GT. Contacts for each stratigraphic unit were defined and transferred to a high-resolution image base to make a geologic map and cross sections perpendicular to the NE strike. Stratal dips cannot exceed 2° NW to retain the positions of stratigraphic units in the locations they are exposed throughout GT.
Wave modeling and analysis of sedimentary structures were used to evaluate whether four examples of symmetrical, reversing, or straight‐crested bedforms in Gale crater sandstones are preserved wave ...ripples; deposition by waves would demonstrate that the lake was not covered by ice at that time. Wave modeling indicates that regardless of atmospheric density, winds that exceeded the threshold of aeolian sand transport could have generated waves capable of producing nearshore wave ripples in most grain sizes of sand. Reversing 3‐m‐wavelength bedforms in the Kimberley formation are interpreted not as wave ripples but rather as large aeolian ripples that formed in an atmosphere approximately as thin as at present. These exhumed bedforms define many of the ridges at outcrops that appear striated in satellite images. At Kimberley these bedforms demonstrably underlie and therefore predate subaqueous beds, suggesting that a thin atmosphere existed at least temporarily before subaqueous deposition ceased in the crater. The other three candidate wave ripples (Square Top, Hunda, and Voe) are consistent with modeled waves, but other origins cannot be excluded. The predominance of flat‐laminated (non‐rippled) beds in the lacustrine Murray formation suggests that some aspect of the lake was not conducive to formation or preservation of recognizable wave ripples. Water depths may generally have been too deep, lakebed sediment may have been too fine‐grained, the lake may have been smaller than modeled, or the lake may have been covered by ice.
Plain Language Summary
Wave modeling and analysis of sedimentary structures were used to evaluate whether ancient lake deposits in Gale crater contain ripples formed by waves on the surface of the lake. Deposition by waves would show that the lake was not covered by ice at that time. Modeling shows that regardless of atmospheric density, winds capable of moving sand on land would generally have been strong enough to form waves that would produce ripples near shore. Large bedforms in the Kimberley formation are interpreted as ripples formed by the wind in an atmosphere similar to that of Mars today. These bedforms underlie and are older than other beds deposited in water, thereby showing that a thin atmosphere existed at least temporarily before deposition in water ceased in the crater. Three other candidate wave ripples are consistent with modeled waves, but other origins are possible. Thick sequences of sedimentary rock in Gale crater are flat‐laminated rather than rippled, suggesting that some aspect of the lake was not favorable for their formation or preservation. Much of the lake may have been too deep or ice‐covered, or the lake may have been smaller than modeled or had sediment too fine to form easily observed ripples.
Key Points
Wave modeling was used to test the hypothesis that 4 examples of lithified bedforms observed by the Curiosity rover are wave ripples
3‐m‐wavelegnth bedforms are thin‐atmosphere aeolian ripples formed before the last subaqueous deposition ended in Gale crater
Three examples remain viable candidates for wave ripples‐which would indicate a lake that was largely free of ice at time of deposition
This paper provides an overview of the
rover's exploration at Vera Rubin ridge (VRR) and summarizes the science results. VRR is a distinct geomorphic feature on lower Aeolis Mons (informally known as ...Mount Sharp) that was identified in orbital data based on its distinct texture, topographic expression, and association with a hematite spectral signature.
conducted extensive remote sensing observations, acquired data on dozens of contact science targets, and drilled three outcrop samples from the ridge, as well as one outcrop sample immediately below the ridge. Our observations indicate that strata composing VRR were deposited in a predominantly lacustrine setting and are part of the Murray formation. The rocks within the ridge are chemically in family with underlying Murray formation strata. Red hematite is dispersed throughout much of the VRR bedrock, and this is the source of the orbital spectral detection. Gray hematite is also present in isolated, gray-colored patches concentrated toward the upper elevations of VRR, and these gray patches also contain small, dark Fe-rich nodules. We propose that VRR formed when diagenetic event(s) preferentially hardened rocks, which were subsequently eroded into a ridge by wind. Diagenesis also led to enhanced crystallization and/or cementation that deepened the ferric-related spectral absorptions on the ridge, which helped make them readily distinguishable from orbit. Results add to existing evidence of protracted aqueous environments at Gale crater and give new insight into how diagenesis shaped Mars' rock record.
ABSTRACT
Derelict coal mine workings at Apedale in Staffordshire, United Kingdom were the focus for a multi‐disciplinary geophysical and intrusive site investigation. Objectives were to: 1) locate ...the surface entrance to a coal mine access shaft, 2) determine the inclined shaft’s changing depth below present ground level, 3) determine if it was open, partly or fully filled, 4) locate it beneath a known shaft if (1) was unsuccessful and finally 5) compare geophysical mineshaft detection techniques in difficult ground conditions.
After initial site reconnaissance, desktop study and modelling, field work collected surface micro‐gravity and electrical resistivity imaging (ERI) 2D profiles to locate the shaft and entrance area. The made‐ground nature of the site made identification of clear geophysical anomalies challenging. Subsequent intrusive investigations to locate the entrance were unsuccessful. A second phase of fieldwork down a known mineshaft imaged three geophysical anomalies beneath this shaft floor; after comparison with modelled data, subsequent intrusive investigations of the ERI anomaly successfully located the target shaft. Collapsed material was progressively cleared to the surface and a new shaft entrance stabilized.
Surface micro‐gravity 2D profiles surprisingly did not produce clear target anomalies, likely to be due to the target depth below ground level and the variety of above‐ground, relict mine structures present. Surface ERI 2D profiles were less affected by above‐ground structures but investigated anomalies were found to be heterogeneous ground materials. Comparisons of 2D micro‐gravity, ERI and ground‐penetrating radar profiles collected within a mineshaft showed ERI data were optimal. 2D micro‐gravity and ERI modelling were shown to aid geophysical interpretations.
In a 12 month open study of itraconazole in pulmonary aspergilloma nine patients received oral itraconazole 200 mg daily for six months followed by further itraconazole or observation for a further ...six months. There was no change in the serum IgG specific for Aspergillus fumigatus (mean (SE) change -4% (10%)) or symptoms of chronic cough and haemoptysis. In two of the three patients who continued treatment beyond six months symptoms and radiographic appearances improved and a temporary reduction in A fumigatus specific IgG occurred in one patient. Further experience of the effects of longer treatment are needed before oral itraconazole can be recommended for aspergilloma.
IgG antibodies cause inflammation and organ damage in autoimmune diseases such as systemic lupus erythematosus (SLE). We investigated the metabolic profile of macrophages isolated from inflamed ...tissues in immune complex (IC)-associated diseases, including SLE and rheumatoid arthritis, and following IgG Fcγ receptor cross-linking. We found that human and mouse macrophages undergo a switch to glycolysis in response to IgG IC stimulation, mirroring macrophage metabolic changes in inflamed tissue in vivo. This metabolic reprogramming was required to generate a number of proinflammatory mediators, including IL-1β, and was dependent on mTOR and hypoxia-inducible factor (HIF)1α. Inhibition of glycolysis, or genetic depletion of HIF1α, attenuated IgG IC-induced activation of macrophages in vitro, including primary human kidney macrophages. In vivo, glycolysis inhibition led to a reduction in kidney macrophage IL-1β and reduced neutrophil recruitment in a murine model of antibody-mediated nephritis. Together, our data reveal the molecular mechanisms underpinning FcγR-mediated metabolic reprogramming in macrophages and suggest a therapeutic strategy for autoantibody-induced inflammation, including lupus nephritis.
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