Generalized Global Stratigraphy of Venus and Implications for Geologic Evolution
Explore the source record for details and available documents.
impact craters Venus stratigraphic scheme Venusian↗
SEARCH · Search NASA
Results for “STRATIGRAPHY”
Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
Clay Bearing Units in the Region around Mawrth Vallis: Stratigraphy, Extent, and Possible Alteration Fronts
The largest exposure of phyllosilicates on Mars occurs on the highland plains around Mawrth Vallis. This exposure extends for about 300 km southward from the edge of the dichotomy boundary, covering an area greater than 200 x 300 kilometers over an elevation range of approximately 2000 meters. At least two different types of hydrated phyllosilicates (Fe/Mg-rich and Al-rich phyllosilicates) have been identified in OMEGA data based on absorption bands near 2.3 and 2.2 micrometers, respectively. These clay-bearing units are associated with layered, indurated light-toned units with complex spatial and stratigraphic relationships, and are unconfomably overlain by a darker, indurated, more heavily cratered unit. Ongoing analysis of OMEGA (approximately 1 kilometer/pixel) and CRISM multi-spectral (MSP, 200 meters/pixel) data reveal hydrated minerals with absorptions at approximately 2.2 or 2.3 micrometers in locations up to 300 kilometers away from the borders of the previously identified extent of clay-bearing units. We seek to: 1) further constrain the mineralogy of the hydrated species identified in [5], and 2) understand spatial and stratigraphic relationships between the different hydrated minerals and the cratered plains units in which they are found. In this work we perform mineralogical and stratigraphic comparisons between units to test whether these extended units may be related, in order to establish a broad zone of alteration.
Dobrea, E. Z. Noe↗
Stratigraphy of the Upper Martian North Polar Layered Deposits from Radar, Visible and Topographic Data
No abstract available
radargrams↗
Huygens Crater: Insights into Noachian Volcanism, Stratigraphy, and Aqueous Processes
Huygens crater is a well preserved peak ring structure on Mars centered at 13.5 deg S, 55.5 deg E in the Noachian highlands between Terras Tyrrhena and Sabaea near the NW rim of Hellas basin. With a diameter of approximately 470 km, it uplifted and exhumed pre-Noachian crustal materials from depths greater than 25 km, penetrating below the thick, ubiquitous layer of Hellas ejecta. In addition, Huygens served as a basin for subsequent aqueous activity, including erosion/deposition by fluvial valley networks and subsurface alteration that is now exposed by smaller impacts. Younger mafic-bearing plains that partially cover the basin floor and surrounding intercrater areas were likely emplaced by later volcanism.
Ackiss, S. E.↗
The Stratigraphy and Evolution of Lower Mt. Sharp from Spectral, Morphological, and Thermophysical Orbital Datasets
No abstract available
Fraeman, A.A.↗
A Fresh Look at the Stratigraphy of Northern Australe
The roughly circular collection of mare deposits centered at ~38.9°S, 93°E is often re- ferred to as Mare Australe. It is located outside of the Procellarum KREEP Terrain. The circular arrangement of Australe’s mare patches has suggested an ancient, heavily degraded or relaxed impact basin roughly 900 km in diameter. The mare deposits are generally thought to have erupted into smaller post- basin craters. The type, volume, and distribution of mare eruptions potentially resembles the early stages of basin-filling mare events, but which are preserved in Australe and some farside locations. Gravity data suggest that if there was a basin, it is much smaller than originally proposed (now ~600 km) and located in the northern part of Mare Australe, between Humboldt, Milne, and Jenner craters. As a whole, Mare Australe lacks the topography typically associated with a basin; however, northern Australe has a slight topographic depression that roughly corresponds to the basin-like Bouguer gravity signature in the same area. The compositions exposed in Humboldt crater suggest that a preexisting basin might have excavated deeper crustal material. However, the underlying cause of the circularity of Mare Australe’s deposits, particularly those extending outside of the potential impact basin setting, is not yet understood. Thus, Australe may preserve fundamental information about mare volcanism potentially uncoupled from basin formation and structure. The objectives of this study are to use new high- resolution data (images, gravity, topography, and com- position) to reassess Australe’s mare deposits, deter- mine the timing and style of volcanism, identify discrete basalt deposits, and to further characterize the evolution of magmatism and subsurface structure in this area. Here, we focus on the northern Australe deposits (between Humboldt, Jenner, and Milne). As originally noted by Whitford-Stark (1979), Humboldt crater and its ejecta make an excellent stratigraphic marker that can be traced across much of the Australe region. The ejecta serves as a stratigraphic constraint for absolute model ages (AMAs) derived from crater size-frequency distributions (CSFDs).
Stopar, J. D.↗
Re-examination of the Population, Stratigraphy, and Sequence of Mercurian Basins: Implications for Mercury’s Early Impact History and Comparison with the Moon
Mercury has one of the best preserved impact records in the inner Solar System due to the absence of an atmosphere, but it has much higher rates of surface modification than on the Moon. The earliest geological mapping of the planet revealed a variety of important differences from the Moon, regarding the impact basin (D ≥ 300 km) and cratering record, as well as the extensive volcanic plains of Mercury [1-3]. It has been shown [3] that the bombardment history of the terrestrial planets is lunar-like and linked in terms of impactor population(s) and impact rates. Recent studies suggest that Mercury and the Moon had the same early impactor populations based on the similarity of their crater size-frequency distributions (CSFD), however the impact rates on Mercury are higher than on the Moon. Catalogued and characterized the basin population on Mercury using early optical data obtained by the MESSENGER spacecraft and found 46 certain and probable impact basins, as well as 41 tentative.
Orgel, C.↗
An Impact Crater Origin for the InSight Landing Site at Homestead Hollow, Mars: Implications for Near Surface Stratigraphy, Surface Processes, and Erosion Rates
The InSight mission to Mars landed within Homestead hollow on an Early Amazonian lavaplain. The hollow is a 27‐m‐diameter, 0.3‐m‐deep quasi‐circular depression that shares morphologic and sedimentologic characteristics to degraded impact craters. Unlike the intercrater plains outside of the hollow, the interior lacks cobbles and is dominated by loose sand, granules, and pebbles. Fresher craters near the landing site exhibit meter‐scale bedforms in their ejecta and on their floors due to sediment trapping.The sedimentology of the interior fill of Homestead hollow suggests similar trapping. The hollow falls along amorphologic continuum that requires low rates of rim degradation and fill. Crater degradation rates (rim erosion plus filling) in the landing site decline nonlinearly through time from 10−2to 10−4m/Myr as craters evolve to a hollow‐like form. Rim erosion rates are lower initially, at 10−3m/Myr, but converge with degradation rates to 10−4m/Myr. This implies that while filling plays an important role soon after crater formation, it is limited in later stages. Crater statistics indicate that the bulk of the fill occurred in the first~50 Myr for Homestead hollow. The estimated maximum age of the hollow is ~400 to 700 Myr. This requires near‐zero fill aggradation and long‐term soil stability for the bulk of the crater's history. Fill stability manifests in Homestead hollow as a ~5‐to 10‐cm‐thick duricrust, formed by exchanges of atmospheric water vapor with soil. The estimated degradation in the hollow requires ~2 to 3 m of sedimentary fill beneath the lander.
Maria Elaine Banks↗
Application of Multi-frequency Tomography Radar Observations for Snow Stratigraphy
UNKNOWN
Shen, Haoran; Zhu, Jiyue; Xu, Haokui; Tsang, Leung↗
Ancient Martian aeolian sand dune deposits recorded in the stratigraphy of Valles Marineris and implications for past climates
Aeolian sediment transport, deposition, and erosion have been ongoing throughout Mars’ history. This record of widespread aeolian processes is preserved in landforms and geologic units that retain important clues about past environmental conditions including wind patterns. In this study we describe landforms within Melas Chasma, Valles Marineris, that occur in distinct groups with linear to crescentic shapes, arranged with a characteristic wavelength; some possess slope profiles analogous to modern sand dunes, yet show evidence for lithification. Based on the features’ dimensions, asymmetry, and spatial patterns relative to modern equivalents, we interpret these landforms to be two classes of aeolian bedforms: decameter-scale mega-ripples and sand dunes. The presence of superposed erosional features and depositional units indicates these landforms were cemented and likely ancient. Melas paleo-dunes are found atop Hesperian-aged layered deposits, but we estimate them to be younger, likely lithified in the Amazonian period. Although a range of degradation was observed, some paleo-dunes are >10 m tall and maintain steep lee sides (>25°), an uncommon scenario for terrestrial examples as other geologic processes lead to dune obliteration. The preserved paleo-bedform geometries are largely consistent with those of modern aeolian indicators, suggesting no major shifts in wind regime or contributing boundary conditions. Finally, we propose their appearance and context require sequential periods of dune migration, stabilization following catastrophic burial, cementation, differential erosion, exposure, and burial. The presence of wholly preserved duneforms appears to be more common on Mars compared to the Earth and may signal something important about Martian landscape evolution. Plain Language Summary Wind-driven sand dunes are common on modern Mars and the presence of certain sedimentary rock layers indicates these landforms occurred there in the past. Here, we explore features in the canyons of Valles Marineris which show characteristics frequently attributed to dunes, yet evidence for their lithification and burial is clear. Their horizontal extent, height, shape, slopes, and collective spatial patterns led to our interpretation of them as lithified dune fields. The heavily eroded appearance along with superposed elements such as craters and boulders led to the conclusion that these are relatively ancient landforms. Despite this erosion This level of preservation is rare for terrestrial sand dunes due to erosion and tectonics, thus providing an opportunity to reconstruct the various factors contributing to their history. Understanding the circumstances that led to the preservation of these ancient duneforms will yield crucial information regarding planetary sedimentary processes and the geologic history of the region.
Matthew Chojnacki↗