Tectonism and volcanism on Mercury

Abstract

Mercury appears to have a tectonic framework and diastrophic history not found on other terrestrial planets explored to date (earth, Mars, and the moon). On the part of the planet viewed by Mariner 10, only two localized areas show evidence of tensional stresses, both of which are apparently associated with the Caloris basin. Lobate scarps occur in the remainder of the explored region and appear to be primarily reverse or thrust faults which have resulted from compressive stresses acting on a global scale. The period of compression represented by these scarps occurred during the final phase of heavy bombardment on Mercury and was probably caused by crustal shortening due to a small decrease in the planet's radius. Stratigraphic, volumetric, and albedo considerations together with distribution indicate that the majority of smooth plains on Mercury were produced by volcanism which occurred at the close of the period of late heavy bombardment similar to that on the moon and Mars. Several generations of plains are evident; the oldest may have resulted in part from an early differentiation of the planet.

Depth of faulting and ancient heat flows in the Kuiper region of Mercury from lobate scarp topography

“…4). The radar profile across the S_K3 scarp is relatively symmetric, whereas lobate scarps are usually asymmetric in cross-section (Strom et al, 1975;Watters et al, 2001;Watters and Nimmo, 2010); this could indicate complex fault geometry beneath the S_K3 scarps. Because of this symmetric profile, even lower error values provide unacceptably poor fits to the topography.…”

“…The most representative tectonic features of Mercury are lobate scarps, which are characterized by a steeply rising scarp face, a gently declining back scarp and a trailing syncline (Strom et al, 1975;Cordell and Strom, 1977;Melosh and McKinnon, 1988;Watters et al, 2001, Watters andNimmo, 2010), and were mostly formed in the Tolstojan and Calorian periods (Watters and Nimmo, 2010), corresponding to an age between 3.2 and 4 Gyr (e.g., Tanaka and Hartmann, 2008). Lobate scarps are interpreted to be the sUlface expressions of thrust faults formed by planetary cooling and con traction (e.g., Strom et al, 1975 ) and estimates of their depth of faulting suggest that they defonned the crust down to the brittle ductile transition (BDT) depth at the time of fault formation, providing important clues about the geological and thermal history of Mercury (Watters et al, 2002;Nimmo and Watters, 2004).…”

“…Lobate scarps are interpreted to be the sUlface expressions of thrust faults formed by planetary cooling and con traction (e.g., Strom et al, 1975 ) and estimates of their depth of faulting suggest that they defonned the crust down to the brittle ductile transition (BDT) depth at the time of fault formation, providing important clues about the geological and thermal history of Mercury (Watters et al, 2002;Nimmo and Watters, 2004). Watters et al (2002) E-mail address: isaegea@iaa.es (I. Egea-Gonzalez).…”

Some aspects of core formation in Mercury

“…Because of the detection of an apparently intrinsic magnetic field in the planet Mercury (Ness et al, 1974;1975a;b) and in light of several deductions about Mercury's history made after study of Mariner lU photographs of the planet's surface (Murray et al, 1974a(Murray et al, , b, 1975Trask and Guest, 1975;Strom et al, 1975), several questions dealing with the nature and history of any large metallic core in Mercury need to be asked. Does Mercury have a core?…”

Radar altimetry of Mercury: A Preliminary analysis

“…0148-0227/86/005 B-5488 $05.00 subdued topography measured by earth-based radar, Mariner 10 carried no altimeter and quantitative altimetry was limited to shadow measurements of high-relief features such as craters and scarps [Gault et al, 1975;Strom et al, 1975] and a few photoclinometry results [e.g., Hapke et al, 1975]. In addition, many of the Mariner 10 images were obtained at unfavorable illumination angles and one entire hemisphere (the dark side at the times of encounter) was not imaged at all.…”