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 (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.
Posted by megafloods2013 on September 16, 2013
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).
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.
Posted by megafloods2013 on September 11, 2013