Introduction: The geologic mapping of Vesta

Williams, D. A.; Yingst, R. A.; Garry, W. B.

doi:10.1016/j.icarus.2014.03.001

Cited by 46 publications

(41 citation statements)

References 94 publications

(98 reference statements)

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“…Detailed discussion of the basemap and supplemental materials used to make the quadrangle maps of Vesta, as well as the techniques and tools used, is given in the introductory paper (Williams et al, 2014). Briefly, we conducted iterative mapping of the Av-8 Marcia quadrangle using successively higher spatial resolution Framing Camera image mosaics obtained during the Survey ($260 m/pixel), High Altitude Mapping Orbit (HAMO, $70 m/pixel), and LAMO ($25 m/pixel, Fig.…”

Section: Methodsmentioning

confidence: 99%

The geology of the Marcia quadrangle of asteroid Vesta: Assessing the effects of large, young craters

Williams¹,

Denevi²,

Mittlefehldt³

et al. 2014

Icarus

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a b s t r a c tWe used Dawn spacecraft data to identify and delineate geological units and landforms in the Marcia quadrangle of Vesta as a means to assess the role of the large, relatively young impact craters Marcia ($63 km diam.) and Calpurnia ($53 km diam.) and their surrounding ejecta field on the local geology. We also investigated a local topographic high with a dark-rayed crater named Aricia Tholus, and the impact crater Octavia that is surrounded by a distinctive diffuse mantle. Crater counts and stratigraphic relations suggest that Marcia is the youngest large crater on Vesta, in which a putative impact melt on the crater floor ranges in age between $40 and 60 Ma (depending upon choice of chronology system), and Marcia's ejecta blanket ranges in age between $120 and 390 Ma (depending upon choice of chronology system). We interpret the geologic units in and around Marcia crater to mark a major vestan time-stratigraphic event, and that the Marcia Formation is one of the geologically youngest formations on Vesta. Marcia crater reveals pristine bright and dark material in its walls and smooth and pitted terrains on its floor. The smooth unit we interpret as evidence of flow of impact melts and (for the pitted terrain) release of volatiles during or after the impact process. The distinctive dark ejecta surrounding craters Marcia and Calpurnia is enriched in OH-or H-bearing phases and has a variable morphology, suggestive of a complex mixture of impact ejecta and impact melts including dark materials possibly derived from carbonaceous chondrite-rich material. Aricia Tholus, which was originally interpreted as a putative vestan volcanic edifice based on lower resolution observations, appears to be a fragment of an ancient impact basin rim topped by a dark-rayed impact crater. Octavia crater has a cratering model formation age of $280-990 Ma based on counts of its ejecta field (depending upon choice of chronology system), and its ejecta field is the second oldest unit in this quadrangle. The relatively young craters and their http://dx

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Section: Methodsmentioning

confidence: 99%

The geology of the Marcia quadrangle of asteroid Vesta: Assessing the effects of large, young craters

Williams¹,

Denevi²,

Mittlefehldt³

et al. 2014

Icarus

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“…The chronology function is calculated using a vestan impact probability of Main Belt asteroids and the lunar chronology (Schmedemann et al, in preparation). This method, similar to the chronologies for Mars (e.g., Ivanov, 2001;Hartmann and Neukum, 2001), is briefly reviewed in Williams et al (2014a). The lunar chronology itself relies on radiometrically dated samples and crater counts on the lunar surface (e.g., Stöffler and Ryder, 2001;Neukum et al, 2001;Hiesinger et al, 2012).…”

Section: Datasets and Methodsmentioning

confidence: 99%

“…The lunar chronology itself relies on radiometrically dated samples and crater counts on the lunar surface (e.g., Stöffler and Ryder, 2001;Neukum et al, 2001;Hiesinger et al, 2012). We have chosen to use these functions rather than the alternative Vesta chronology of O'Brien (in preparation) and production function used by Marchi et al (2012), and discussed in Williams et al (2014a). The reason for this choice is that the chronology and production functions of Schmedemann et al (in preparation) are based on lunar observations (CSFD and lunar samples) scaled to the Vesta conditions, in contrast to a chronology based on Main Belt dynamics (O'Brien, in preparation) and a production function based on a model of the size-frequency distribution of Main Belt objects (Marchi et al, 2012).…”

Section: Datasets and Methodsmentioning

confidence: 99%

Geologic map of the northern hemisphere of Vesta based on Dawn Framing Camera (FC) images

Ruesch

Hiesinger

Blewett

et al. 2014

Icarus

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a b s t r a c tThe Dawn Framing Camera (FC) has imaged the northern hemisphere of the Asteroid (4) Vesta at high spatial resolution and coverage. This study represents the first investigation of the overall geology of the northern hemisphere (22-90°N, quadrangles Av-1, 2, 3, 4 and 5) using these unique Dawn mission observations. We have compiled a morphologic map and performed crater size-frequency distribution (CSFD) measurements to date the geologic units. The hemisphere is characterized by a heavily cratered surface with a few highly subdued basins up to $200 km in diameter. The most widespread unit is a plateau (cratered highland unit), similar to, although of lower elevation than the equatorial Vestalia Terra plateau. Large-scale troughs and ridges have regionally affected the surface. Between $180°E and $270°E, these tectonic features are well developed and related to the south pole Veneneia impact (Saturnalia Fossae trough unit), elsewhere on the hemisphere they are rare and subdued (Saturnalia Fossae cratered unit). In these pre-Rheasilvia units we observed an unexpectedly high frequency of impact craters up to $10 km in diameter, whose formation could in part be related to the Rheasilvia basin-forming event. The Rheasilvia impact has potentially affected the northern hemisphere also with S-N small-scale lineations, but without covering it with an ejecta blanket. Post-Rheasilvia impact craters are small (<60 km in diameter) and show a wide range of degradation states due to impact gardening and mass wasting processes. Where fresh, they display an ejecta blanket, bright rays and slope movements on walls. In places, crater rims have dark material ejecta and some crater floors are covered by ponded material interpreted as impact melt.

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“…The map was prodeced from data about spectral reflectivity of the surface, collected by Dawn Mission. The most ancient and heavily cratered regions are brown; areas modified by the Veneneia and Rheasilvia impacts are purple (the Saturnalia Fossae Formation, in the North) and light cyan (the Divalia Fossae Formation, equatorial), respectively; the Rheasilvia impact basin interior (in the South) is dark blue, and neighboring areas of Rheasilvia ejecta (including an area within Veneneia) are light purple-blue; areas modified by more recent impacts or mass wasting are yellow/orange or green, respectively (Williams et al 2014).…”

Section: Figure 11mentioning

confidence: 99%

Asteroids

Andreić¹

2016

MGPB

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Asteroids are the largest minor bodies in the Solar System. Nowadays they are in the research focus due to several facts about them: first, a subclass of asteroids can collide with Earth, and consequences of such a collision are dramatic. Second, they are now seen as source of materials that are becoming scarce on Earth, and they will be needed in future space constructions anyway. Third, they are holding clues about the origin and evolution of the Solar System. In this article, a short overview of current knowledge about asteroids is presented. Last, but not least, as several Croatian scientists were recently honored by naming an asteroid after them, a short overview of the naming process is given.

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Introduction: The geologic mapping of Vesta

Cited by 46 publications

References 94 publications

The geology of the Marcia quadrangle of asteroid Vesta: Assessing the effects of large, young craters

The geology of the Marcia quadrangle of asteroid Vesta: Assessing the effects of large, young craters

Geologic map of the northern hemisphere of Vesta based on Dawn Framing Camera (FC) images

Asteroids

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