Geological Evidence of a Planet‐Wide Groundwater System on Mars

Post by Dr. F. Salese, Marie Curie Postdoctoral Fellow, Faculty of Geoscience, Utrecht University.

Groundwater had a greater role in shaping the Martian surface and may have sheltered primitive life forms as the planet started drying up. Observations in the northern hemisphere show evidence of a planet‐wide groundwater system. The elevations of these water‐related morphologies in all studied basins lie within the same narrow range of depths below Mars datum (Image 1) and notably coincide with the elevation of some ocean shorelines proposed by previous authors. 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.

Figure 1

Image 1: Morphologies inside several basins. a) Crater #15 shows the presence at the same time of delta, sapping valleys, debris and hummocky terrain. The basin floor is flat. b) Crater #12 shows stepped delta, terraces, shorelines and flow structures at about the same topographic elevations. c) Sapping valley and related stepped delta in crater #18. d) Sapping valley and related stepped delta along with fan and exhumed channels in crater #12. e) Crater #16 shows well-preserved outcrops of debris flow. f) Sapping valley with related delta at -4100m inside crater #22.

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Tufa mounds on Earth and Mars

Post by Dr. Rogelio Linares1 and Dr. Alexis Rodríguez2,3

1Department of Geology- GATA, Autonomous University of Barcelona, Spain . 2 Planetary Science Institute, Tucson, AZ 85719, USA. 3State key Laboratory of Information Engineering on Surveying, Mapping and Remote Sensing, Wuhan University, China.

Tufa or travertine deposition at spring discharges often produce mounded landforms. They are one of the least understood calcareous landforms on Earth. Most documented mounds correspond to thermogene travertine. build-up associated with geothermal springs (where the carbon dioxide comes from thermally generated sources). See May 2009  image of the month. In contrast, work on meteogene mounds (where the carrier carbon dioxide originates in the soil and epigean atmosphere) are quite scarce (Linares et al, 2010).

Image 1

Image 1 (A) Shaded relief view of the Tremp Basin. (B) Geologic map of the study region in Isona area. (C) Electrical resistivity cross-sectional view of the central part of a tufa mound (inset in panel B). Note the cistern-like geometry of the pool facies and the overhanging upflow side of the rimstone. Number 1-2 respectively correspond to Rimstone and Rimstone with crescentic geometry.

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LayeLayered sediments in Martian craters: Crommelin Crater, Mars

Post by Angelo Pio Rossi

Although rocks of volcanic origin are the most common type on Mars, complex sedimentary sequences do occur, often with enormous thickness and lateral extent. Arabia Terra, in particular, hosts several large craters with extensive outcrops of sedimentary or sedimentary-like rocks (Malin and Edgett, 2000). The sedimentary rocks in this area are thought to be very old and some date back to the Noachian Era (from about 4.6 to about 3.7 billion years ago).

Crommelin Crater, Mars

Image 1: Perspective view of Crommelin central bulge. The image is centered at about 350° E, 5° N. The image consists of a mosaic of Mars Reconnaissance Orbiter (MRO) Context (CTX) images (P01_001401_1846_XI_04N010W, P02_002021_1848_XI_04N010W, P02_001876_1852_XI_05N010W, P06_003432_1852_XI_05N009W) draped over High Resolution Stereo Camera (HRSC) Stereo-derived Digital Elevation Model obtained from Mars Express (MEX) orbits: 2108, 3253, 3264, 5091. The width of the scene is about 50 km. The perspective view is north-pointing (see image 3). Vertical exaggeration is 2x.

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