On geological processes on venus: Analysis of the relationship between altitude and degree of surface roughness

Bazilevski, A. T.; Bobina, N. N.; Shashkina, V. P.; Shkuratov, Yu. G.; Kornienko, Yu. V.; Usikov, A.; Stankevich, D. G.

doi:10.1007/bf00941558

Cited by 7 publications

(3 citation statements)

References 7 publications

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“…Mars is divided into cratered highlands covering most of the southern hemisphere and resurfaced lowlands in the northern hemisphere [ Aharonson et al , 2001]. The surface of Venus can be divided, in its turn, into the following three main regions according to elevation: highlands characterized by volcanic and strongly tectonized structures, mesolands dominated by large extensional fracture belts and several volcanic features, and lowlands mainly shaped through volcanism [ Bazilevski et al , 1982; Price and Suppe , 1995]. Taking into account the clear differentiation in morphological structures as a function of their elevation, an analysis of the global topography based on measures that mix several heights could jumble different features.…”

Section: Introductionmentioning

confidence: 99%

Fractal properties of isolines at varying altitude revealing different dominant geological processes on Earth

Baldassarri¹,

Montuori²,

Prieto-Ballesteros³

et al. 2008

J. Geophys. Res.

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[1] Geometrical properties of landscapes result from the geological processes that have acted through time. The quantitative analysis of natural relief represents an objective form of aiding in the visual interpretation of landscapes, as studies on coastlines, river networks, and global topography, have shown. Still, an open question is whether a clear relationship between the quantitative properties of landscapes and the dominant geomorphologic processes that originate them can be established. In this contribution, we show that the geometry of topographic isolines is an appropriate observable to help disentangle such a relationship. A fractal analysis of terrestrial isolines yields a clear identification of trenches and abyssal plains, differentiates oceanic ridges from continental slopes and platforms, localizes coastlines and river systems, and isolates areas at high elevation (or latitude) subjected to the erosive action of ice. The study of the geometrical properties of the lunar landscape supports the existence of a correspondence between principal geomorphic processes and landforms. Our analysis can be easily applied to other planetary bodies.

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Section: Introductionmentioning

confidence: 99%

Fractal properties of isolines at varying altitude revealing different dominant geological processes on Earth

Baldassarri¹,

Montuori²,

Prieto-Ballesteros³

et al. 2008

J. Geophys. Res.

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“…At least four hypotheses have been put forht to account for the Ishtar Terra highlands: (1) that Lakshmi Planum is an uplifted plateau of lowland plains (Basilevsky et al, 1982); (2) that Ishtar Terra is an ancient remnant of crustal material possibly formed by tectonic processes no longer active on Venus (Phillips et al, 1981); (3) that Ishtar Terra is formed and dominated by 'hot spot' activity associated with Colette and Sacajawea, and tectonic activity is related to this Pronin, personal communication), and (4) that Ishtar Terra is dominated by horizontal compressional deformation, crustal thickening, uplift, and that volcanic activity is associated with this (Campbell et al, 1983;Crumpler et al, 1986;Head, 1986). The relatively young age of the surface of Lakshmi Planum and the distinctive difference in detailed morphology and volcanic style between Lakshmi and the lowland plains argue against the first two hypotheses.…”

Section: Originofthe Highlandsmentioning

confidence: 99%

Geology of the southern Ishtar Terra/Guinevere and Sedna Planitae region on Venus

Stofan

Head

Campbell³

1987

Earth Moon Planet

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Recent high resolution, high incidence angle Arecibo radar images of southern Ishtar Terra and flanking plains of Guinevere and Sedna on Venus reveal details of topographic features resolved by Pioneer Venus. The high incidence angles of Arecibo images favor the detection of surface roughnessrelated features, and complement recently obtained low incidence angle Venera 15/16 images in which changes in surface topographic slope are well portrayed. Four provinces have been defined on the basis of radar characteristics in Arecibo images and topography. Volcanism and tectonism are the dominant processes in the mapped area, which has an average age of about 0.5-1.0 billion years (Ivanov et al., 1986). These processes vary in relative significance in the mapped provinces and it is likely that geologic activity has occurred simultaneously in all four provinces. On the basis of stratigraphic evidence, however, a general sequence is proposed which represents the major activity in each area. The low predominantly volcanic plains of Guinevere and Sedna Planitiae are the relatively oldest terrain. A major region of complex tectonic deformation, the Southern Ishtar Transition Zone, postdates much of the low plains and delineates the steep-sloped flanks of Ishtar Terra. Lakshmi Planum is characterized by a distinctive volcanic style (large low edifices, calderas, flanking plains) and at least in part postdates the Southern lshtar Transition Zone. Relatively recent plains-style volcanism occurs locally in Sedna Planitia and embays the Southern lshtar Transition Zone. Compressional deformation appears to dominate the mountains of the Ishtar plateau, but the nature of the tectonic deformation in the Southern Ishtar Transition Zone is very complex and likely represents a combination of extension, compression and strikeslip deformation.Arecibo data reveal additional coronae in the lowlands, suggesting that corona formation is an even more widespread process than indicated by the Venera data.

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“…It is quite probable that weathering rates (at least in the plains) are low[McGill et al, 1983], that mechanical abrasion is almost insignificant, and that some interparticle cementation does occur. As the distribution of p does not depend on latitude or on spatial associations with highlands, an examination of the correlation of p with elevation is warranted.CORRELATION OF REFLECTIVITY AND ELEVATIONThe PV reflectivity and elevation data sets have been corre lated by means of a three-dimensional scatter diagram (Figure 3); this approach was used byBasilevsky et al [1982] in their analyses of roughness, topographic slope, and elevation for various distinct regions (e.g., Beta and Ishtar). Garyin et al[1983, 1984b] used this technique when they correlated the global roughness data for Venus with elevation.…”

mentioning

confidence: 99%

Venus global radar reflectivity and correlations with elevation

Garvin¹,

Head²,

Pettengill³

et al. 1985

J. Geophys. Res.

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The global distribution of the reflectivity of the surface of Venus as determined by the Pioneer Venus orbital radar instrument has been analyzed in a geological context and statistically correlated with elevation. In addition, a comparison between the reflectivity and rms slope (roughness) correlations with elevation permits radar-geologic topographic zones to be identified. The radar reflectivity p at normal incidence and at a wavelength of 17 cm (1.76 GHz) is a rfiodel-dependent measure of the bulk dielectric constant • of surfaces dominated by dry rocks and soils and depends on surface material properties such as porosity and conductivity. Only the quasi-specular component of the radar echo was used in determining the reflectivity values analyzed in this study, and for very rough surfaces the absolute magnitude of p may be underestimated by 10-15%. Empirically derived relationships between p, to, and bulk density 7 are used to interpret geologically the p distribution. The global mean p of 0.13 is significantly greater than the average lunar and typical martian values of •0.07, suggesting the absence of a continuous soil mantle on Venus. The p distribution is well described by a two-stage Gaussian distribution with modes at 0.11 and 0.14. The close proximity of these modes suggests that there is no fundamental dichotomy of surfaces on Venus insofar as their p properties, in contrast with roughness. Less than 15% of Venus has p values low enough to indicate a major soft component on the surface. Approximately 27% of the surface is dominated by low-porosity materials such as bedrock, and less than 15% is enriched in high dielectrics. The rest of the surface (43%) is most simply envisioned as partially mantied bedrock, perhaps an extension of the types of terrain viewed by the Venera 10 and 13 landers. The most plausible model for the highest p (and thus highest •,-) materials requires enrichment in Ti and Fe (e.g., minerals such as futile, ilmenite, and magnetite). High-titanium basalts such as those found on the moon would produce the required enrichment, as would pyrites. Since surface geochemical measurements demonstrate that there are basalts in the Venusian plains, a model in which high-titanium basalts are exposed at the highest elevations (Maxwell, Theia, Aria, Ovda) is favored. Possible weathering of ilmenite in such basalts to produce futile could explain the high-•c materials in less elevated regions. When correlated with elevation, p exhibits a complex nonmonotonic trend in which both decreases and increases are observed. A major decrease in p of ---0.02 km -• in the upper plains contrasts with the almost 1 ø rms km-• increase in surface roughness over the same interval and may be an expression of increased soil production, perhaps due to enhanced breakdown of silicates into carbonates in the lower highlands. Alternately, the decrease could be due to increased centimeter scale toughening, perhaps caused by the increase in regional slope in the highlands. A major increase in p (0.05 km-•) in the midd...

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On geological processes on venus: Analysis of the relationship between altitude and degree of surface roughness

Cited by 7 publications

References 7 publications

Fractal properties of isolines at varying altitude revealing different dominant geological processes on Earth

Fractal properties of isolines at varying altitude revealing different dominant geological processes on Earth

Geology of the southern Ishtar Terra/Guinevere and Sedna Planitae region on Venus

Venus global radar reflectivity and correlations with elevation

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