Nonmare volcanism on the Moon: Photometric evidence for the presence of evolved silicic materials

Clegg-Watkins, R. N.; Jolliff, Bradley L.; Watkins, M. J.; Coman, E. O.; Giguere, T. A.; Stopar, J. D.; Lawrence, S. J.

doi:10.1016/j.icarus.2016.12.004

Cited by 19 publications

(15 citation statements)

References 38 publications

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“…Their unique surface morphologies suggest the lava flows that produced the domes were highly viscous (Hagerty et al, ; Head & McCord, ). Lunar Prospector Gamma ray spectrometer (GRS) data and Clementine multispectral data show that these domes are relatively low in FeO (6–8 wt %) and high in Th contents (43 ± 3 ppm for Gruithuisen Gamma and 17 ± 6 ppm for Gruithuisen Delta, Hagerty et al, ), and photometric observations and Diviner spectral data confirm that these domes have intermediate silicic compositions (Clegg‐Watkins et al, ; Glotch et al, ). Relevance to Science Themes S.2: Samples from this site would play a major role in filling in our understanding of crustal petrogenesis.…”

Section: Overview Of Individual Landing Sitesmentioning

confidence: 97%

“…Materials such as andesite or dacite, which have never been sampled on the Moon, may be present at some of the larger domes (Clegg‐Watkins et al, ). Multiple lines of evidence support the existence of unusual pyroclastic compositions (including OH and spinel) at the complex (Bhattacharya et al, ; Clegg‐Watkins et al, ; Petro et al, ; Pieters et al, , ; Wilson et al, ). Relevance to Science Themes S.2: Samples from this site would play a major role in filling in our understanding of crustal petrogenesis.…”

Section: Overview Of Individual Landing Sitesmentioning

confidence: 98%

“…Lunar Reconnaissance Orbiter Diviner data show evidence for silicic composition corresponding to the CBVC, and rock types such as granite or rhyolite are likely present (Jolliff et al, ). Materials such as andesite or dacite, which have never been sampled on the Moon, may be present at some of the larger domes (Clegg‐Watkins et al, ). Multiple lines of evidence support the existence of unusual pyroclastic compositions (including OH and spinel) at the complex (Bhattacharya et al, ; Clegg‐Watkins et al, ; Petro et al, ; Pieters et al, , ; Wilson et al, ).…”

Section: Overview Of Individual Landing Sitesmentioning

confidence: 99%

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Lunar Science for Landed Missions Workshop Findings Report

Jawin

Valencia

Clegg-Watkins

et al. 2019

Earth and Space Science

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The Lunar Science for Landed Missions workshop was convened at the National Aeronautics and Space Administration Ames Research Center on 10–12 January, 2018. Interest in the workshop was broad, with 110 people participating in person and 70 people joining online. In addition, the workshop website (https://lunar-landing.arc.nasa.gov) includes video recordings of many of the presentations. This workshop defined a set of targets that near‐term landed missions could visit for scientific exploration. The scope of such missions was aimed primarily, but not exclusively, at commercial exploration companies with interests in pursuing ventures on the surface of the Moon. Contributed and invited talks were presented that detailed many high priority landing site options across the surface of the Moon that would meet scientific goals in a wide variety of areas, including impact cratering processes and dating, volatiles, volcanism, magnetism, geophysics, and astrophysics. Representatives from the Japan Aerospace Exploration Agency and the European Space Agency also presented about international plans for lunar exploration and science. This report summarizes the set of landing sites and/or investigations that were presented at the workshop that would address high priority science and exploration questions. In addition to landing site discussions, technology developments were also specified that were considered as enhancing to the types of investigations presented. It is evident that the Moon is rich in scientific exploration targets that will inform us on the origin and evolution of the Earth‐Moon system and the history of the inner Solar System, and also has enormous potential for enabling human exploration and for the development of a vibrant lunar commercial sector.

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Section: Overview Of Individual Landing Sitesmentioning

confidence: 97%

Section: Overview Of Individual Landing Sitesmentioning

confidence: 98%

Section: Overview Of Individual Landing Sitesmentioning

confidence: 99%

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Lunar Science for Landed Missions Workshop Findings Report

Jawin

Valencia

Clegg-Watkins

et al. 2019

Earth and Space Science

Self Cite

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“…Lunar silicic areas exhibit a range of reflectance values, both within and among the regions, which may have compositional significance. These reflectance variations may be owing to mixing of silicic components, addition of pyroclastic materials, and/or the presence of KREEPy (less silicic) materials (Clegg-Watkins et al, 2017). The reflectance variations are especially evident at the CBVC, where the most reflective regions are small bulges or domes in the central part of the complex.…”

Section: Overview Of Modern Remote Observationsmentioning

confidence: 99%

“…The reflectance variations are especially evident at the CBVC, where the most reflective regions are small bulges or domes in the central part of the complex. Radar data (Chauhan et al, 2015), the presence of OH/H2O absorptions (Bhattacharya et al, 2013), eastward extension of the Th anomaly (Wilson et al, 2015), laboratory spectra of analog materials (Clegg-Watkins et al, 2017), and the offset between the high-reflectance and elevated topography at the CBVC (Jolliff et al, 2011) indicate the presence of silicic pyroclastics within and around the complex, which also contribute to the increased reflectance.…”

Section: Overview Of Modern Remote Observationsmentioning

confidence: 99%

End-member volcanism in the absence of plate tectonics: Silicic volcanism on the Moon

Valencia

Watkins

Richardson

et al. 2021

Bulletin of the AAS

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BackgroundGranites and granitoid rocks are evolved igneous rocks that occur on silicate (i.e., SiO2 bearing) planetary bodies when highly silicic melts (i.e., rich in SiO2) form as residual melts of more mafic parent melts, or by partial melting of "fertile" crustal rocks (Winter, 2014). Owing to the large knowledge gaps that remain about non-basaltic magmatism on the Moon, for this paper we use the broad term "silicic" to include all rocks considerably richer in SiO2 than lunar basalts. Silicic rocks can either be intrusive (i.e., plutonic: diorite, granodiorite, or granite) or extrusive (i.e., volcanic: andesite, dacite, or rhyolite). On Earth, silicic rocks are common and span a large range of compositions. Highly silicic rocks on Earth (i.e., granite/rhyolite) are efficiently created by subduction, which recycles crust and concentrates SiO2 in magma through partial melting and extended fractional crystallization, though other petrogenesis pathways for silicic rocks exist.Unlike Earth, highly silicic rocks are relatively rare on the Moon. While a few fragments of silicic rocks or mineral assemblages were returned by the Apollo missions, none of the Apollo or Luna missions visited a silicic target, thus our knowledge of these enigmatic terrains relies mostly on remote sensing observations. Many of these remotely sensed areas are classified as spectral "red spots" Whitaker (1972) and are characterized by high albedos, strong absorptions in the UV, and morphologic characteristics such as domes with steep flanks, consistent with silicic volcanic constructs (e.g., Hagerty et al., 2006). Morphometric studies of these landforms estimate yield strengths and plastic viscosities that are characteristic of silicic lavas (Wilson and Head, 2003). These remote observations indicate there are significantly large silicic bodies on the Moon, thereby motivating the need for targeted studies of silicic rocks on the Moon including additional remote observations and sample studies (Valencia et al., 2020). Possible Formation Mechanisms of Silicic Rocks on a One-Plate BodyVolcanism on the Moon is hypothesized to be dominated by short-lived, voluminous basalt outpourings from large dikes (Wilson and Head, 2017), owing to the difficulty of sustaining melt in a relatively cool crust and a lack of buoyant forces driving smaller magma bodies toward the surface. These factors make granite formation at colder and/or smaller planets difficult, and we have a poor understanding of the mechanisms through which silicic rocks from. Constraining the conditions under which silicic melts were produced is essential to understanding the thermal evolution of the Moon.There are two leading formation hypotheses for silicic lithologies on the Moon -silicate liquid immiscibility (SLI) and basaltic underplating. SLI occurs when a basaltic magma basaltic magma

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