Water-related Features Research Articles

A probable ancient nearshore zone in southern Utopia on Mars unveiled from observations at the Zhurong landing area

The Chinese Mars rover Zhurong successfully landed in southern Utopia Planitia on Mars in May 2021. Previous research suggested a Hesperian ocean may have existed in the northern lowland on Mars. Recent research observed water-related features at the Zhurong landing site from in situ data. In this study, we conducted a comprehensive geomorphological analysis of the landing area using remote sensing data, supplemented by in situ observations, and unveiled features consistent with the existence of a nearshore zone in southern Utopia. Different types of water-related geomorphological features were separated by specific topographic contours, suggesting different types of marine environments. The area was subdivided into a foreshore highland-lowland transition unit, a shallow marine unit and a deep marine unit. In situ observations including sedimentary deposit rocks, water-related lamination features, and subsurface sedimentary layers, also indicate past water activities. Results suggested an evolution scenario of the nearshore zone in southern Utopia: (1) Flooding of the Utopia Planitia in Late Noachian around 3.65–3.68 Ga reached the foreshore unit; (2) formation of the shallow and deep marine units after the flooding was completed by about 3.5 Ga and 3.42 Ga in Early Hesperian, respectively; (3) gradual loss of subsurface volatiles during the Amazonian epoch.

Enhancing the explanation of household water consumption through the water-energy nexus concept

Estimating household water consumption can facilitate infrastructure management and municipal planning. The relatively low explanatory power of household water consumption, although it has been extensively explored based on various techniques and assumptions regarding influencing features, has the potential to be enhanced based on the water-energy nexus concept. This study attempts to explain household water consumption by establishing estimation models, incorporating energy-related features as inputs and providing strong evidence of the need to consider the water-energy nexus to explain water consumption. Traditional statistical (OLS) and machine learning techniques (random forest and XGBoost) are employed using a sample of 1320 households in Beijing, China. The results demonstrate that the inclusion of energy-related features increases the coefficient of determination (R2) by 34.0% on average. XGBoost performs the best among the three techniques. Energy-related features exhibit higher explanatory power and importance than water-related features. These findings provide a feasible modelling basis and can help better understand the household water-energy nexus.

A chemistry-based explainable machine learning model based on NIR spectra for predicting wood properties and understanding wavelength selection

ABSTRACT A chemistry-based explainable machine learning (ML) approach was used to predict wood properties using near infrared (NIR) spectral data collected from rough and smooth surfaces, and to provide better understanding of the role of important NIR wavelengths (features) in the performance of ML models. NIR spectra collected from western hemlock (Tsuga heterophylla) and coastal Douglas-fir (Pseudotsuga menziesii) boards with rough and smooth surfaces were fed into random forest and TreeNet; a gradient boosting machine algorithm, for predicting wood density, modulus of elasticity (MOE) and modulus of rupture (MOR). The TreeNet model could predict the MOE, MOR, and density with R2 of 0.66, 0.64, and 0.64 using spectra collected from rough surface and R2 of 0.54, 0.46, and 0.46 using spectra collected from smooth surface. TreeNet outperformed the random forest, and for both ML algorithms higher R2 and lower error were obtained using NIR data collected from rough surfaces. This suggested that for Douglass fir and western hemlock, NIR spectra could be collected on a sawn surface prior to surface planing. However, it is difficult to generalize the impact of surface roughness on the performance of predictive model as different factors (e.g. what constitutes a smooth or rough surface, variability of data set in terms of wood properties) impact the success of predictive models. NIR features having the greatest influence on TreeNet models were examined and consistently had wood chemistry specific band assignments. The most important features occurred in the O-H first overtone, and C–H second overtone regions and a narrow zone (approximately 2400–2500 nm) of the C–H stretch C–C stretch combination region. Important features also differed by property and with surface roughness. Explaining ML model performance using the relative importance of the NIR features showed the importance of wood chemistry related information when developing models, however MOE and MOR TreeNet models based on smooth surface NIR spectra showed an increased importance of water related features. Overall, the chemistry-based explainable machine learning model approach allows for identification of important NIR features, and regions, and aids in understanding how they contribute to the performance of NIR-based wood property predictive models.

Radar Echo Reconstruction in Oceanic Area via Deep Learning of Satellite Data

A conventional way to monitor severe convective weather is using the composite reflectivity of radar as an indicator. For oceanic areas without radar deployment, reconstruction from satellite data is useful. However, those reconstruction models built on a land dataset are not directly applicable to the ocean due to different underlying surfaces. In this study, we built reconstruction models based on U-Net (named STR-UNet) for different underlying surfaces (land, coast, offshore, and sea), and evaluated their applicability to the ocean. Our results suggest that the comprehensive use of land, coast, and offshore datasets should be more suitable for reconstruction in the ocean than using the sea dataset. The comprehensive performances (in terms of RMSE, MAE, POD, CSI, FAR, and BIAS) of the Land-Model, Coast-Model, and Offshore-Model in the ocean are superior to those of the Sea-Model, e.g., with RMSE being 5.61, 6.08, 5.06, and 7.73 in the oceanic area (Region B), respectively. We then analyzed the importance of different types of features on different underlying surfaces for reconstruction by using interpretability methods combined with physical meaning. Overall, satellite cloud-related features are most important, followed by satellite water-related features and satellite temperature-related features. For the transition of the model from land to coast, then offshore, the importance of satellite water-related features gradually increases, while the importance of satellite cloud-related features and satellite temperature-related features gradually decreases. It is worth mentioning that in the offshore region, the importance of satellite water-related features slightly exceeds the importance of satellite cloud-related features. Finally, based on the performance of the case, the results show that the STR-UNet reconstruction models we established can accurately reconstruct the shape, location, intensity, and range of the convective center, achieving the goal of detecting severe convective weather where a radar is not present.

Layer by Layer: A Mortar with Charcoal from the Costești-Blidaru Cistern

"The aim of this article is to present the characteristics of a mortar layer from the floor of the cistern discovered by C. Daicoviciu and his team underneath Costeşti-Blidaru fortress. This investigation is based on the published information, on data from the excavation records and on the results of a recent mineralogic analysis of a sample from the layer in question. I compared the layer and the cistern with water related features and structures from the Mediterranean area, in an effort to identify the origins of the techniques that were used during the cistern's construction. Additionally, the recourse to ancient literary sources allowed me to discuss the practices of hydraulic engineers in classical times, in order to assess the validity of C. Daicoviciu’s appreciation, according to which the cistern was built by following ""Vitruvian recipes"". The final part of the paper contains some observations regarding the chronology of the cistern, based on the techniques that were used and on the chronology of the fortress and its related structures. Keywords: mortar, charcoal, undercoat, cistern, Vitruvius "

Analysis of Corn Yield Prediction Potential at Various Growth Phases Using a Process-Based Model and Deep Learning.

Early and accurate prediction of grain yield is of great significance for ensuring food security and formulating food policy. The exploration of key growth phases and features is beneficial to improving the efficiency and accuracy of yield prediction. In this study, a hybrid approach using the WOFOST model and deep learning was developed to forecast corn yield, which analysed yield prediction potential at different growth phases and features. The World Food Studies (WOFOST) model was used to build a comprehensive simulated dataset by inputting meteorological, soil, crop and management data. Different feature combinations at various growth phases were designed to forecast yield using machine learning and deep learning methods. The results show that the key features of corn's vegetative growth stage and reproductive growth stage were growth state features and water-related features, respectively. With the continuous advancement of the crop growth stage, the ability to predict yield continued to improve. Especially after entering the reproductive growth stage, corn kernels begin to form, and the yield prediction performance is significantly improved. The performance of the optimal yield prediction model in flowering (R2 = 0.53, RMSE = 554.84 kg/ha, MRE = 8.27%), in milk maturity (R2 = 0.89, RMSE = 268.76 kg/ha, MRE = 4.01%), and in maturity (R2 = 0.98, RMSE = 102.65 kg/ha, MRE = 1.53%) were given. Thus, our method improves the accuracy of yield prediction, and provides reliable analysis results for predicting yield at various growth phases, which is helpful for farmers and governments in agricultural decision making. This can also be applied to yield prediction for other crops, which is of great value to guide agricultural production.

Coastal toponyms of Iran

Abstract While the domain of toponymy has great research potential, it has so far gained little attention in Iran. The present paper is a typological study on a sample group of toponyms from two different provinces of Gilan (a northern coastal province next to the Caspian Sea) and Bushehr (a southern coastal province beside the Persian Gulf) within the framework of the Australian National Placenames Survey typology proposed by Tent and Blair. The two regions in question are similar in terms of adjacency to a major water body but different in language, culture, and geography. To determine whether the Australian proposed typology is applicable to Iranian toponyms, we collected 60 coastal placenames from Gilan and Bushehr and classified them according to their Specifics and Generics based on Tent and Blair’s (2009, 2011) typology. Further, we compared placenaming motivations and processes in the two regions. The results show that although the Iranian placenames differ from the Australian ones in terms of their structure, they fit well into the typology. Water-related features are among the top motivations for local namers in both Gilan and Bushehr. Nevertheless, Bushehr namers are more motivated by natural features while those from Gilan, in most cases, are non-naturally motivated.

Extracting water-related features using reflectance data and principal component analysis of Landsat images

ABSTRACTThis study aimed to map water features using a Landsat image rather than traditional land cover. We involved the original bands, spectral indices and principal components (PCs) of a principal component analysis (PCA) as input data, and performed random forest (RF) and support vector machine (SVM) classification with water, saturated soil and non-water categories. The aim was to compare the efficiency of the results based on various input data. Original bands provided 93% overall accuracy (OA) and bands 4–5–7 were the most informative in this analysis. Except for MNDWI (modified normalized differenced water index, with 98% OA), the performance of all water indices was between 60 and 70% (OA). The PCA-based approach conducted on the original bands resulted in the most accurate identification of all classes (with only 1% error in the case of water bodies). We therefore show that both water bodies and saturated soils can be identified successfully using this approach.

Participatory mobile- and web-based tools for eliciting landscape knowledge and perspectives: introducing and evaluating the Wisconsin geotools project

Despite synergistic goals across a wide breadth of fields and modalities, coastal landscape conservation projects that engage the lay public and integrate narratives of place remain elusive. This paper addresses these needs by introducing and evaluating the Wisconsin Geotools, an integrated pair of mobile-and web-based applications that allow users to generate and share spatially defined multimedia observations — including photos, short textual descriptions (or journals), and audio and video clips — of their surrounding bioregional landscapes. We followed a participatory, user-centered design process to develop a mobile application that uses GPS capabilities to geolocate multimedia observations of landscapes and feed them into a web-based application, which displays content through the structure of an interactive story map. The applications were piloted with coastal community user groups in Green Bay (Lake Michigan), Wisconsin, USA. Over 800 observations were recorded by participants in our study area. Results from a user evaluation survey indicate the geotools effectively engaged participants in learning about and exploring their surrounding coastal landscapes. A spatial analysis revealed participants’ affinity for water-related features in landscapes. We close by suggesting a variety of ways in which these tools can support future projects and existing methodologies that are advancing transdisciplinary approaches to engaging the public in coastal conservation.

Polygonal ridge networks on Mars: Diversity of morphologies and the special case of the Eastern Medusae Fossae Formation

Polygonal ridge networks, also known as boxwork or reticulate ridges, are found in numerous locations and geological contexts across Mars. Distinguishing the morphologies and geological context of the ridge networks sheds light on their potential as astrobiological and mineral resource sites of interest. The most widespread type of ridge morphology is characteristic of the Nili Fossae and Nilosyrtis region and consists of thin, criss-crossing ridges with a variety of heights, widths, and intersection angles. They are found in ancient Noachian terrains at a variety of altitudes (between -2500 and 2200m) and geographic locations and are likely to be chemically altered fracture planes or mineral veins. They occur in the same general areas as valley networks and ancient lake basins, but they are not more numerous where these water-related features are concentrated, and can appear in places where th morphologies are absent. Similarly, some of the ridge networks are located near hydrated mineral detections, but there is not a one-to-one correlation. Smaller, light-toned ridges of variable widths have been found in Gale Crater and other rover sites and are interpreted to be smaller versions of the Nili-like ridges, mostly formed by the mineralization of fractures. This type of ridge is likely to be found in many other places on Mars as more high-resolution data become available. Sinus Meridiani contains many flat-topped ridges arranged into quasi-circular patterns. The ridges are eroding from a clay-rich unit, and could be formed by a similar process as the Nili-type ridges, but at a much larger scale and controlled by fractures made through a different process. Hellas Basin is host to a fourth type of ridge morphology consisting of large, thick, light-toned ridges forming regular polygons at several superimposed scales. While still enigmatic, these are most likely to be the result of sediment-filled fractures. The Eastern Medusae Fossae Formation contains large swaths of a fifth, previously undocumented, ridge network type. The dark ridges, reaching up to 50m in height, enclose regular polygons and erode into dark boulders. These ridge networks are interpreted to form as a result of lava flow embayment of deeply fractured Medusae Fossae Formation outcrops.

The role of porous matrix in water flow regulation within a karst unsaturated zone: an integrated hydrogeophysical approach

Some portions of the porous rock matrix in the karst unsaturated zone (UZ) can contain large volumes of water and play a major role in water flow regulation. The essential results are presented of a local-scale study conducted in 2011 and 2012 above the Low Noise Underground Laboratory (LSBB – Laboratoire Souterrain a Bas Bruit) at Rustrel, southeastern France. Previous research revealed the geological structure and water-related features of the study site and illustrated the feasibility of specific hydrogeophysical measurements. In this study, the focus is on hydrodynamics at the seasonal and event timescales. Magnetic resonance sounding (MRS) measured a high water content (more than 10 %) in a large volume of rock. This large volume of water cannot be stored in fractures and conduits within the UZ. MRS was also used to measure the seasonal variation of water stored in the karst UZ. A process-based model was developed to simulate the effect of vegetation on groundwater recharge dynamics. In addition, electrical resistivity tomography (ERT) monitoring was used to assess preferential water pathways during a rain event. This study demonstrates the major influence of water flow within the porous rock matrix on the UZ hydrogeological functioning at both the local (LSBB) and regional (Fontaine de Vaucluse) scales. By taking into account the role of the porous matrix in water flow regulation, these findings may significantly improve karst groundwater hydrodynamic modelling, exploitation, and sustainable managementme portions of the porous rock matrix in the karst unsaturated zone (UZ) can contain large volumes of water and play a major role in water flow regulation. The essential results are presented of a local-scale study conducted in 2011 and 2012 above the Low Noise Underground Laboratory (LSBB – Laboratoire Souterrain a Bas Bruit) at Rustrel, southeastern France. Previous research revealed the geological structure and water-related features of the study site and illustrated the feasibility of specific hydrogeophysical measurements. In this study, the focus is on hydrodynamics at the seasonal and event timescales. Magnetic resonance sounding (MRS) measured a high water content (more than 10 %) in a large volume of rock. This large volume of water cannot be stored in fractures and conduits within the UZ. MRS was also used to measure the seasonal variation of water stored in the karst UZ. A process-based model was developed to simulate the effect of vegetation on groundwater recharge dynamics. In addition, electrical resistivity tomography (ERT) monitoring was used to assess preferential water pathways during a rain event. This study demonstrates the major influence of water flow within the porous rock matrix on the UZ hydrogeological functioning at both the local (LSBB) and regional (Fontaine de Vaucluse) scales. By taking into account the role of the porous matrix in water flow regulation, these findings may significantly improve karst groundwater hydrodynamic modelling, exploitation, and sustainable management.

A GIS-based relational data model for multi-dimensional representation of river hydrodynamics and morphodynamics

The emerging capabilities of the geo-based information systems to integrate spatial and temporal attributes of in-situ measurements is a long-waited solution to efficiently organize, visualize, and analyze the vast amount of data produced by the new generations of river instruments. This paper describes the construct of a river data model linked to a relational database that can be populated with both measured and simulated river data to facilitate descriptions of river features and processes using hydraulic/hydrologic terminology. The proposed model, labeled Arc River, is built in close connection with the existing Arc Hydro data model developed for water-related features to ensure the connection of the river characteristics with their floodplains and watersheds. This paper illustrates Arc River data model capabilities in conjunction with Acoustic Doppler Current Profiler measurements to demonstrate that essential river morphodynamics and hydrodynamics aspects can be described using data on the flow and its boundaries.

Water, Ritual, and Power in the Inca Empire

Archaeological, ethnohistoric, and ethnographic evidence provides ample indication that water was a key symbol in Andean thought. During the late precolumbian era, the attention lavished on waterworks and features by the Inca emphasizes a clear concern with control over water and its movement. This paper examines the way in which specific relations of power and identity were constructed through Inca management of water. To this end, I offer a comparative analysis of water-related features from different sectors of the Empire, representing different moments in its historical development. The intent is to further our understanding of how the manipulation of water figured in the imperializing process and how its use and meaning may have evolved over time. The architectural evidence from the sites included in the study suggests that conspicuous exercise of control over the movement and flow of water may have been more critical to the establishment of Inca hegemony than to its subsequent maintenance.

Landscape aesthetics: Assessing the general publics' preferences towards rural landscapes

The central aim of this study was to gain greater insights into the factors that affect individuals' preferences for a variety of landscape settings. Using a nationally representative survey conducted in the summer of 2010 of 430 individuals living in Ireland, this paper derived dependent variables (based on a factor analysis of respondents mean ratings of 47 landscape images) representing 5 different landscape categories. These variables were then utilised in separate OLS regression models to examine the effect of personal characteristics, residential location and environmental value orientations on landscape preferences. First in terms of visual amenity the results suggest that the general public have the strongest preference for landscapes with water related features as its dominant attribute which was followed by cultural landscapes. Second the results also demonstrate how there is significant heterogeneity in landscape preferences as both personal characteristics and environmental value orientations were found to strongly influence preferences for all the landscape types examined. Moreover the effect of these variables often differed significantly across the various landscape groupings. In terms of land use policy, given the diversity of preferences a one size fits all approach will not meet the general publics' needs and desires.

Impact cratering in H2O‐bearing targets on Mars: Thermal field under craters as starting conditions for hydrothermal activity

Abstract– We present a case modeling study of impact crater formation in H2O‐bearing targets. The main goal of this work was to investigate the postimpact thermal state of the rock layers modified in the formation of hypervelocity impact craters. We present model results for a target consisting of a mixture of H2O‐ice and rock, assuming an ice/water content variable with depth. Our model results, combined with results from previous work using dry targets, indicate that for craters larger than about 30 km in diameter, the onset of postimpact hydrothermal circulation is characterized by two stages: first, the formation of a mostly dry, hot central uplift followed by water beginning to flow in and circulate through the initially dry and hot uplifted crustal rocks. The postimpact thermal field in the periphery of the crater is dependent on crater size: in midsize craters, 30–50 km in diameter, crater walls are not strongly heated in the impact event, and even though ice present in the rock may initially be heated enough to melt, overall temperatures in the rock remain below melting, undermining the development of a crater‐wide hydrothermal circulation. In large craters (with diameters more than 100 km or so), the region underneath the crater floor and walls is heated well above the melting point of ice, thus facilitating the onset of an extended hydrothermal circulation. These results provide preliminary constraints in characterizing the many water‐related features, both morphologic and spectroscopic, that high‐resolution images of Mars are now detecting within many Martian craters.

IRTF spectra for 17 asteroids from the C and X complexes: A discussion of continuum slopes and their relationships to C chondrites and phyllosilicates

In order to gain further insight into their surface compositions and relationships with meteorites, we have obtained spectra for 17 C and X complex asteroids using NASA’s Infrared Telescope Facility and SpeX infrared spectrometer. We augment these spectra with data in the visible region taken from the on-line databases. Only one of the 17 asteroids showed the three features usually associated with water, the UV slope, a 0.7 μm feature and a 3 μm feature, while five show no evidence for water and 11 had one or two of these features. According to DeMeo et al. (2009), whose asteroid classification scheme we use here, 88% of the variance in asteroid spectra is explained by continuum slope so that asteroids can also be characterized by the slopes of their continua. We thus plot the slope of the continuum between 1.8 and 2.5 μm against slope between 1.0 and 1.75 μm, the break at ∼1.8 μm chosen since phyllosilicates show numerous water-related features beyond this wavelength. On such plots, the C complex fields match those of phyllosilicates kaolinite and montmorillonite that have been heated to about 700 °C, while the X complex fields match the fields for phyllosilicates montmorillonite and serpentine that have been similarly heated. We thus suggest that the surface of the C complex asteroids consist of decomposition products of kaolinite or montmorillonite while for the X complex we suggest that surfaces consist of decomposition products of montmorillonite or serpentine. On the basis of overlapping in fields on the continuum plots we suggest that the CI chondrites are linked with the Cgh asteroids, individual CV and CR chondrites are linked with Xc asteroids, a CK chondrite is linked with the Ch or Cgh asteroids, a number of unusual CI/CM meteorites are linked with C asteroids, and the CM chondrites are linked with the Xk asteroids. The associations are in reasonable agreement with chondrite mineralogy and albedo data.

IDENTIFICATION OF MAGNETITE IN B-TYPE ASTEROIDS

Spectrally blue (B-type) asteroids are rare, with the second discovered asteroid Pallas being the largest and most famous example. We conducted a focused, infrared spectroscopic survey of B-type asteroids to search for water-related features in these objects. Our results show that the negative optical spectral slope of some B-type asteroids is due to the presence of a broad absorption band centered near 1.0 micron. The 1-micron band can be matched in position and shape using magnetite (Fe3O4), which is an important indicator of past aqueous alteration in the parent body. Furthermore, our observations of B-type asteroid (335) Roberta in the 3-micron region reveal an absorption feature centered at 2.9 micron, which is consistent with the absorption due to phyllosilicates (another hydration product) observed in CI chondrites. The new observations suggest that at least some B-type asteroids are likely to have incorporated significant amounts of water ice and to have experienced intensive aqueous alteration.

Motivation, development and validation of a new spectral greenness index: A spectral dimension related to foliage projective cover

A method is presented for the development of a regional Landsat-5 Thematic Mapper (TM) and Landsat-7 Enhanced Thematic Mapper plus (ETM+) spectral greenness index, coherent with a six-dimensional index set, based on a single ETM+ spectral image of a reference landscape. The first three indices of the set are determined by a polar transformation of the first three principal components of the reference image and relate to scene brightness, percent foliage projective cover (FPC) and water related features. The remaining three principal components, of diminishing significance with respect to the reference image, complete the set.The reference landscape, a 2200 km2 area containing a mix of cattle pasture, native woodland and forest, is located near Injune in South East Queensland, Australia. The indices developed from the reference image were tested using TM spectral images from 19 regionally dispersed areas in Queensland, representative of dissimilar landscapes containing woody vegetation ranging from tall closed forest to low open woodland. Examples of image transformations and two-dimensional feature space plots are used to demonstrate image interpretations related to the first three indices. Coherent, sensible, interpretations of landscape features in images composed of the first three indices can be made in terms of brightness (red), foliage cover (green) and water (blue). A limited comparison is made with similar existing indices. The proposed greenness index was found to be very strongly related to FPC and insensitive to smoke. A novel Bayesian, bounded space, modelling method, was used to validate the greenness index as a good predictor of FPC. Airborne LiDAR (Light Detection and Ranging) estimates of FPC along transects of the 19 sites provided the training and validation data. Other spectral indices from the set were found to be useful as model covariates that could improve FPC predictions. They act to adjust the greenness/FPC relationship to suit different spectral backgrounds. The inclusion of an external meteorological covariate showed that further improvements to regional-scale predictions of FPC could be gained over those based on spectral indices alone.

How long was Meridiani Planum wet? Applying a jarosite stopwatch to determine the duration of aqueous diagenesis

Research Article| July 01, 2009 How long was Meridiani Planum wet? Applying a jarosite stopwatch to determine the duration of aqueous diagenesis Megan E. Elwood Madden; Megan E. Elwood Madden 1School of Geology and Geophysics, University of Oklahoma, 100 E. Boyd Street, Suite 810, Norman, Oklahoma 73019, USA Search for other works by this author on: GSW Google Scholar Andrew S. Madden; Andrew S. Madden 1School of Geology and Geophysics, University of Oklahoma, 100 E. Boyd Street, Suite 810, Norman, Oklahoma 73019, USA Search for other works by this author on: GSW Google Scholar J. Donald Rimstidt J. Donald Rimstidt 2Department of Geosciences, Virginia Tech, 4044 Derring Hall, Blacksburg, Virginia 24061, USA Search for other works by this author on: GSW Google Scholar Geology (2009) 37 (7): 635–638. https://doi.org/10.1130/G25639A.1 Article history received: 04 Nov 2008 rev-recd: 03 Mar 2009 accepted: 08 Mar 2009 first online: 02 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Megan E. Elwood Madden, Andrew S. Madden, J. Donald Rimstidt; How long was Meridiani Planum wet? Applying a jarosite stopwatch to determine the duration of aqueous diagenesis. Geology 2009;; 37 (7): 635–638. doi: https://doi.org/10.1130/G25639A.1 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGeology Search Advanced Search Abstract Jarosite dissolution rates can be used to determine the duration of water at Meridiani Planum and other environments containing this ephemeral, metastable ferric sulfate salt. The maximum duration of aqueous fluids in the region is calculated based on the dissolution rate of jarosite under varying temperature and ionic strength conditions. Jarosite lifetimes predicted in this study range from 1.5 a in warm dilute environments to 100 ka in NaCl-saturated brines at 250 K. The preservation of jarosite within rocks at Meridiani Planum requires that aqueous fluids were active over a small fraction of the billions of years since jarosite formed or was deposited in the region, limiting the probability of life being established in such a temporally restricted system. In addition, water-related features such as hematite spherules and crystal molds must have formed relatively quickly during this geologically short period of aqueous diagenesis. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.

Spatial distribution of putative water related features in Southern Acidalia/Cydonia Mensae, Mars

Many putative water-related features exist in the northern lowlands of Mars. These features may provide clues to the abundance and timing of water or ice that existed there in the past. The Cydonia Mensae and Southern Acidalia area was chosen as the study area owing to the abundance of two of these features: giant polygons and pitted cones. In addition a section of the Deuteronilus shoreline is located there. The abundance and close proximity of the features makes this area an excellent place to study the spatial relationships between these landforms, as well as the morphological characteristics of pitted cones. The features were mapped into a GIS for spatial analyses. The highest densities of pitted cones and giant polygons are adjacent but distinctly separated by a knobby ridge that is surrounded by the Deuteronilus putative shoreline. Pitted cones were measured and examined to determine if a classification by morphology is possible, but the results were inconclusive. Statistical tests on pit-to-cone diameter ratios and tests of surface temperatures of cone material suggest, but do not verify, a single cone origin. The various shapes, sizes, and putative ages of pitted cones may be attributed to temporal variation in emplacement and spatial variation in material properties. Among the possible scenarios put forth for pitted cone genesis on Mars two are likely candidates in Cydonia Mensae: (1) the sublimation of a cold-based glacier, and (2) a buried lens of methane and/or CO2 clathrates.