The north polar basal unit of Mars: An Amazonian record of surface processes and climate events

Nerozzi, S.; Ortiz, M. R.; Holt, J. W.

doi:10.1016/j.icarus.2021.114716

Cited by 11 publications

(13 citation statements)

References 56 publications

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“…At lower elevations, the NPLD grades into the basal Cavi (ABbc) unit that is hypothesized to have formed during the Middle to Late Amazonian period (Nerozzi et al., 2022; Tanaka et al., 2012). ABbc is marked by low albedo aeolian cross‐strata of water ice‐cemented sandy material, hypothesized to be an ancient polar dune field, which are inter‐bedded with bright pure ice layers that may be remnants of ancient polar caps (Fishbaugh & Head, 2005; Nerozzi & Holt, 2019; Tanaka et al., 2008).…”

Section: Composition Of Geologic Units Within the Npldmentioning

confidence: 99%

“…The Rupes (ABbr) unit, once a 'paleo-plateau', forms most of the basal unit and contains the oldest north polar sediments (Tanaka et al, 2008). Early to Late Hesperian in age, Rupes is over a kilometer in thickness and composed of layers of ice and fine-grained material that is hypothesized to have been eroded and transported from the Scandia region (Nerozzi et al, 2022;Tanaka et al, 2008Tanaka et al, , 2012. Lacking dark sandy surficial mantle, the sampled surface is likely a sublimation lag of fine-grained materials comprising Rupes, whose spectra appear dust and ice free, with a broad and symmetric absorption band at 1.1 μm and negligible absorption at 2 μm, most consistent with glass (Type 4; s4).…”

Section: Composition Of Geologic Units Within the Npldmentioning

confidence: 99%

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Sediments Within the Icy North Polar Deposits of Mars Record Recent Impacts and Volcanism

Sinha

Horgan

2022

Geophysical Research Letters

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The North Polar Layered Deposits (NPLD) of Mars are ice‐rich sedimentary layers that formed under the influence of Mars' modern climate and thus record the recent climatic history of Mars, analogous to terrestrial ice sheets. The 2013–2023 Planetary Science Decadal Survey recommends a lander mission to sample the NPLD for climatic records; however, linking the geologic record to the climatic history will require quantitative dating of the NPLD. In this study we use orbital reflectance spectroscopy to show for the first time that dateable mafic lithics are present throughout the NPLD. We find significant glass as well as diverse crystalline minerals, which suggests that surface processes like impacts and volcanism were active during the late Amazonian and transported sediments from across the planet to the north pole. In situ investigation of the NPLD will thus provide critical quantitative constraints on both the recent geologic and climatic histories of Mars.

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Section: Composition Of Geologic Units Within the Npldmentioning

confidence: 99%

Section: Composition Of Geologic Units Within the Npldmentioning

confidence: 99%

Sediments Within the Icy North Polar Deposits of Mars Record Recent Impacts and Volcanism

Sinha

Horgan

2022

Geophysical Research Letters

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“…Using the same inline and crossline grid-mapping approach, we delineated a reflector within the cavi unit in Planum Boreum that was mapped in SHARAD 2D profiles by Nerozzi et al (2022) and interpreted as the contact between the cavi and rupēs geologic units (Tanaka & Fortezzo 2012). We then compared the extent of our mapping to the previous map of this contact.…”

Section: Bu Analysismentioning

confidence: 99%

“…The reflector is mostly horizontal, except for gentle downward slopes in its northern and eastern reaches (blue and white areas in Figure 4(a)). The large lateral extent makes this reflector one of the most extensive within the cavi unit (Nerozzi & Holt 2019;Nerozzi et al 2022).…”

Section: Basal Unitsmentioning

confidence: 99%

“…The new data volume allowed us to greatly expand the mapping of the reflector first delineated by Nerozzi et al (2022) and interpreted by them as the contact between the cavi and rupēs units (Figure 5). In particular, we found that the contact can be traced further to the southeast toward Gemina Lingula and that a similar reflector appears toward the southwest close to Olympia Cavi.…”

Section: Basal Unitsmentioning

confidence: 99%

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New Views of the Internal Structure of Planum Boreum from Enhanced 3D Imaging of Mars Reconnaissance Orbiter Shallow Radar Data

et al. 2022

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We present first results from a new 3D radargram produced from 3399 Mars Reconnaissance Orbiter (MRO) Shallow Radar observations of the north polar region of Mars. While incorporating an additional 5 yr of observations relative to the prior 3D radargram, we employed surface-clutter simulations to improve the coregistration of the input data and thereby enhance the effective vertical resolution of features. Combining those improvements with the geometric corrections and an increase in signal-to-noise ratio afforded by the 3D imaging process, this data product provides new details about the interior of Planum Boreum, the Martian north polar cap. We assess the overall characteristics and compare portions of the new 3D radargram to results from prior studies that used either the prior 3D radargram or sets of 2D radargrams from individual MRO orbits. We find that the new 3D radargram has recovered essentially all of the vertical resolution inherent to the input data, and the increased coverage density has substantially reduced artifacts while enabling much greater detail in the imaging of subsurface layering and structures. These improvements extend throughout the 3D radargram, from the basal units to the shallowest subsurface layering in Planum Boreum, and out into the surrounding plains. Subsurface features such as a buried chasma, other layering structures and unconformities, and trough-bounding surfaces that offset shallow layering are now visible in unprecedented detail. A thorough analysis of this new 3D radargram and its implications for the geologic and climate history of Planum Boreum will extend over many years.

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Glacial deposits, remnants, and landscapes on Amazonian Mars: Using setting, structure, and stratigraphy to understand ice evolution and climate history

Koutnik,

Butcher,

Soare

et al. 2024

Ices in the Solar System

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The north polar basal unit of Mars: An Amazonian record of surface processes and climate events

Cited by 11 publications

References 56 publications

Sediments Within the Icy North Polar Deposits of Mars Record Recent Impacts and Volcanism

Sediments Within the Icy North Polar Deposits of Mars Record Recent Impacts and Volcanism

New Views of the Internal Structure of Planum Boreum from Enhanced 3D Imaging of Mars Reconnaissance Orbiter Shallow Radar Data

Glacial deposits, remnants, and landscapes on Amazonian Mars: Using setting, structure, and stratigraphy to understand ice evolution and climate history

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