Lunar volcanism is one of the most important endogenic processes on the Moon. The final morphology of a lava flow depends on (a) the composition of the magma, which determines its rheology, (b) the effusion rate, controlled by the geometry of the dike transferring the magma to the surface and the overpressure in the magma source, (c) the lava cooling behavior influenced by whether the flow is laminar or turbulent, (d) the total volume of magma erupted, and the topography of the surface onto which the lava flows. Thus, studying the morphology of flows sheds light on their eruption conditions, and has implications for the nature of the magma source region. In this study, we document the effects of topography on a well-preserved Eratosthenian-aged lava flow that most likely originated from the volcanic complex around Euler Crater in Mare Imbrium. We assess how the observations can improve our understanding of previous models of lunar lava flow emplacement and cooling behavior. We find that: 1) the pre-existing topography significantly affected the morphology of the flow; 2) several low wrinkle ridges predating the eruption and controlling the flow path underwent significant tectonic modification after lava emplacement; 3) variations in the extent of lava channel/levee structures along the flow are linked to turbulent/laminar flow modes; 4) the emplacement of the lava flow investigated here was probably completed in about a week, occurring in the very early period of regional wrinkle ridge formation. This lava flow history provides new insight into the interplay of regional volcanism and tectonism in Mare Imbrium and late-stage lunar thermal evolution in general.

Modelling the rheology of mud is intrinsic to studying mudflows in several Earth and planetary science disciplines. Rheological models enable the flow behaviour of mud particle-water suspensions to be understood and predicted with the use of equations relating the shear-stress to the shear-rate, providing insight into subsurface conditions, improving hazard management, and understanding planetary surface conditions on extra-terrestrial bodies like Mars. This review firstly provides an introduction to rheology, then examines and evaluates the importance of mud rheology and its underpinning variables (e.g., particle volume fraction, particle size and shape distribution). We explore how mud rheology is used in different disciplines of Earth and planetary science to understand the dynamics of various natural processes. Rheology models are examined, and we collate data from multiple published studies on mud suspensions. Four of the most commonly used rheology models are presented (Bingham, Herschel-Bulkley, Power Law, and Casson) and we find the Herschel-Bulkley model to provide the best fit to experimental data. The importance of model choice is explored, and we give a direct comparison of mudflow velocity predictions when using the Bingham and Herschel-Bulkley models. Disparities in the calculated velocity are significant, emphasising the challenges of comparing two different model outputs. Furthermore, as these mud suspensions are non-Newtonian (and thus their viscosity depends on the shear-rate applied), we define the shear-rate ranges typical in different environmental settings (e.g., mud volcanoes, drilling, debris flows, and coastal muds), and give subsequent model recommendations depending on the corresponding shear-rate range.

Three anomalously young,-120 Ma old lunar mare pyroclastic beads have recently been reported (Wang et al., 2024) from Chang'e-5 (CE-5 soils, particularly distinguished from impact melt beads by sulfur isotope (34S/32S) composition and correlations with sulfur concentration. We examine lunar pyroclastic eruption theory and candidate eruption conditions in order to locate the vent and assess its geological context, finding that the estimated maximum pyroclast dispersal range from a candidate source vent is likely to be-200 km, placing it within the area of the CE-5-2.0 Ga sampled Em4 unit. The greatest predicted dispersal distances are associated with an explosive eruption from a stalled dike several kilometers below the surface, creating an elongated, multi- km-scale pit crater potentially surrounded by a dark pyroclastic ring. We assessed the Chang'e-5 region for such candidates and found none. This raises the possibility that the-120 Ma pyroclastic beads might have been delivered to the site from an impact crater outside Em4, but the most likely candidates are sufficiently large and at such great distances that they are likely to have reset the ages of any young pyroclastic beads thus delivered. Lacking a clear source for extraordinarily young pyroclastic beads, we reassess the possibility that the-120 Ma beads may be of local impact melt origin. Evidence favoring this hypothesis includes the abundant CE-5 impact glass bead ages in the 100-200 Ma year range previously reported (Long et al., 2022), and the similarities in composition and characteristics of the three beads and those of local impact origin. To address these conundra, further regional searches for a source vent and continued geochemical characterization and dating of CE-5 regolith glass beads should be undertaken.

Mare domes (interpreted to be a type of shield volcano) represent one important endmember of a variety of volcanic edifices occurring across the volcanic plains on the Moon, whereas Ring-Moat Dome Structures (RMDSs) are interpreted to reflect the thermodynamic behavior of plain-forming mare flows during their emplacement and cooling. A comprehensive study of the direct association between mare domes and RMDSs can not only provide deep insights into their formation mechanisms but also yield key information on the nature of mantle sources. We characterized a total of 200 mare domes and more than 6,400 RMDSs within Mare Tranquillitatis using multiple sets of imagery and topography data. RMDS-bearing domes (80 out of 200) are on average larger than those hosting no RMDSs (average diameter 10.2 vs. 5.5 km) and have lower height/diameter (H/D) ratios (0.01 vs. 0.02) and flank slopes (1.2 degrees vs. 2 degrees). We attribute the presence of RMDSs on some domes to be due to relatively higher effusion rates forming longer thinner flows, producing favorable conditions for the formation of RMDSs. The average diameter of the RMDSs on mare domes (226 m, n = 1,027) appears to be slightly smaller than those located in mare plains (256 m, n = 527). This may be due to slope effects and that the relatively thicker off-dome part of flows undergoes a relatively higher degree inflation process, producing slightly larger RMDSs. We adapt the RMDS-formation theoretical model to shallow subcrustal magma reservoir model to account for the Tranquillitatis dome-RMDS associations. Ring-moat dome structures (RMDSs) are common features across a large expanse of the lunar mare surface, but their nature is poorly understood. A key recent observation is that RMDSs have a close relationship with mare dome-style volcanism, which represents a typical eruption style on the Moon, providing a useful window into the composition and geophysical evolution of the lunar interior. In this study, a total of 80 mare domes in Mare Tranquillitatis were found to be superimposed by varying numbers of RMDSs on their tops and flanks. RMDSs were also found in the maria surrounding these domes. The nature, correlation, and morphologic properties of the RMDSs and their host mare domes were measured. Based on new observations, a basalt flow emplacement scenario for the formation of both mare domes and associated volcanic features (e.g., RMDSs) related to dike-closing in the late stages of eruptions is reviewed and updated to account for these observed associations. The presence of RMDSs on some mare domes is attributed to be due to relatively higher effusion rates forming longer thinner flows Dike-fed volcanic eruptions from the shallow subcrustal magma reservoirs are likely to favor the production of domes around the vent The Tranquillitatis dome-RMDS association can be explained by adapting the RMDS theoretical model to the shallow subcrustal magma reservoir model

High-resolution investigations of Late Amazonian volcanic landforms provide previously unrevealed insights into the dynamics of Martian volcanic eruptions. On Earth, the formation of vent-proximal accumulations of spatter deposits is attributed to low-intensity lava fountaining episodes representing eruptions on the very edge of explosive activity. Martian spatter deposits form small-scale volcanic landforms that are rarely reported, and thus the dynamics of Martian mafic explosive eruptions are still not fully constrained. We conducted high-resolution Context Camera-based mapping coupled with a stereo-pair-generated digital elevation model to reconstruct the eruptive history of a fissure system and its associated products south of Ascraeus Mons, Mars. The studied volcanic fissure clearly demonstrates both explosive and effusive deposits and, in addition, is spatially associated with a lava channel. For the first time, these observations allowed us to conduct a comparative analysis of vent-proximal volcanic products and reconstruct the late-stage eruption dynamics of a fissure system. We found that the spatial distribution of the pyroclastic (spatter) rampart along the fissure vent is heterogeneous and generated using dynamic eruption processes. Moreover, the lava channel fed from the fissure vent shows evidence of successive lava overspills whose emplacement was topographically controlled. These observations suggest that, in contrast to the general inference that Amazonian-age volcanism mainly involves effusive eruptions, explosive-origin landforms might have been overlooked. Therefore, we argue that high-resolution mapping of pyroclastic deposits may provide critical insights into understanding the dynamic nature of Martian fissure eruptions and explosive-associated volatile release during the last stages of eruptions. Although it is widely accepted that Martian volcanism has mainly involved widespread lava effusion, the increased acquisition of high-resolution satellite images is challenging this viewpoint and providing new insights into the dynamics of volcanic eruptions. A better understanding of the small-scale volcanic landforms on Mars increases our understanding of volcanism in general. As Tharsis, the largest volcanic province on Mars, hosts hundreds of volcanic fissure vents and associated landforms, it constitutes the best natural laboratory for the investigation of volcanic products deposited near the vent. Here, we conducted high-resolution mapping of the near-vent accumulations of fragmented lava, called spatter deposits, which allows us to reconstruct the eruption dynamics during the waning stages. Our observations suggest that the spatter deposits are attributed to low-intensity lava fountaining of explosive origin, whereas the adjacent lava flow channels are rimmed by successive lava overspills. These observations suggest that Martian fissure systems experienced two eruptive styles simultaneously. However, to date, on Mars, the explosive-origin landforms associated with fissure vents have been overlooked. Overall, our study indicates the importance of conducting detailed studies of small-scale volcanic landforms that record complex and previously undiscovered dynamics of Martian volcanic systems. Investigation of vent-proximal volcanic products allowed the eruption dynamics of a fissure system to be reconstructed The spatial distribution of spatter rampart deposits along the fissure vent is heterogeneous and related to dynamic eruption processes Amazonian-aged basaltic volcanism involves both effusive activity and low-intensity explosive eruptions

In the central area of the South Pole-Aitken (SPA) basin, an intermediate albedo, mafic compositional anomaly (SPA Compositional Anomaly, SPACA) has been documented by previous studies, but its origin remains uncertain. We conducted an investigation of stratigraphic units defined based on morphology and composition and their relative ages, and placed these in the context of basin topography and the observed sequence of geological events, all helping to distinguish between SPACA origins from: (a) SPA impact melt, (b) volcanism induced by the SPA event and (c) lunar cryptomaria. We conclude that SPACA represents extensive traditional cryptomare deposits overlying the SPA impact melt. We interpret the basin center to be filled with cryptomare deposits at least one km thick (>1 x 10(5) km(3) in volume) with ages not younger than Early Imbrian. We attribute the relatively high albedo of SPACA to lateral mixing of ejecta from nearby highlands craters and basins, and conclude that the cryptomaria basalts are likely to be very similar to basalts on the nearside. Our findings imply a 0.5%-1.8% increase in the total volume of global lunar mare and cryptomare deposits. These results show that mare volcanism was common only in areas of thinnest crust on the lunar farside, a factor important in understanding lunar nearside-farside asymmetries. Despite this significant increase in total cryptomare volume in the SPA basin center, SPA remains underfilled relative to nearside mascon basins. Return of mare basalts from the SPA region by Chang'E-6 will help determine potential mantle source region differences and petrogenetic pathways.

AbstractLunar mare basalts represent melting of mantle material, buoyant ascent in dikes, and eruption onto <20% of the surface. Global mare distribution is distinctly asymmetrical, with a paucity on the farside, plausibly interpreted to be related to thicker farside low‐density crust inhibiting buoyant magma rise to the surface. Challenging this hypothesis is the presence of the huge, ancient farside South Pole‐Aitken (SPA) basin, site of the thinnest crust and deepest depression observed on the Moon. We hypothesize that an oblique impact stripped the farside crust within the SPA basin, permitting early mare basalt emplacement as cryptomaria due to thin/absent crust. However, removal of the SPA thermally insulating megaregolith/crust accelerated lithosphere thickening beneath the basin. This deepening rheological barrier inhibited buoyant rise of mantle diapirs below SPA, resulting in early abatement of mare basalt extrusions compared to the nearside, and retention of the deep, underfilled SPA impact basin observed today.

We apply basic principles of magma ascent from deep source regions and its eruption into a low-gravity vacuum environment to develop a theoretical treatment of the fluid dynamics and thermodynamics of mare basalt lava flow emplacement and evolution on the Moon. The vacuum conditions influenced the release of volatiles in magma passing through lava fountains, thus controlling the syn- and post-emplacement vesicularity of the resulting deposits. To explain observed lengths and volumes of Mare Imbrium–type flows, high (10 ^6 –10 ^5 m ^3 s ^−1 ) initial magma eruption rates were needed. Combined with low lunar magma viscosity, these caused flows to be initially turbulent. Resulting high radiative heat loss and consequent high crystallization rates caused rapid non-Newtonian rheological evolution and suppression of turbulence at tens of kilometers from vents. Slower cooling rates in the subsequent laminar parts of flows imply distinctive crystal growth rate histories. In a four-phase sequence, (i) initial transient dike-tip gas release followed by (ii) Hawaiian fire fountain activity with efficient volatile loss (iii) transitioned to (iv) Strombolian explosions in a lava lake. Late-stage lava now able to retain volatiles intruded and inflated existing flow deposits after flow front advance ceased. Volatiles forced out of solution by second boiling as lava cooled caused additional inflation. Low gravity and lack of atmospheric pressure commonly produced very vesicular lava. Escape of such lava through cracks in flow crusts is a possible source of ring-moat dome structures; collapse of such lava may explain irregular mare patches.

Introduction: Irregular Mare Patches (IMPs) [1] have a rough floor unit (FU) and meniscus-like mounds (MD). Initial Ina CSFD measurements produced ages of ~59 Ma; but Ina is closely associated with an ~3.5 Ga edifice [2]. Could IMP mounds be formed by extrusion of ancient highly vesicular magmatic foams causing impacts to be smaller by ~3X due to formation in compressible magmatic foam [2-3]. Our goal The goal is to distinguish among IMP formation theories [4] by assessing the nature, physical properties, stratigraphic relationships, and ages of Ina units (Fig. 1). Major origin/age questions?: 1) Nature of superposed impact craters?: Formation mode, sampling depth, substrate effects on energy partitioning/subsequent degradation, influence on CSFD ages. 2) Predicted and observed regolith thicknesses?: ~59 Ma lava flows impact-generated regolith should be 5 m. We focus on an extremely fresh ~75m-diameter crater (Fig. 1) on the border between Ina floor and mound units. Nature of Fresh Crater (FC): The 75 m crater rim crest outline is circular where it intersects the mound to the N-NW, slightly indented to the S-SW, and significantly indented to the SE (Fig. 1a). The crater is characterized by a central floor mound ~1-3 m high, and ranges from MD ~2-15 m deep (max d/D of 0.2, typical of small fresh mare craters) to SW FL, ~2 m deep (d/D 0.0266). The crater floor/lower walls/rim are littered with m-scale boulders. Relative and Absolute: Boulders superposed on the main MD, the floor unit and the small SE MD indicates that the crater postdates formation of all these features and initial formation of Ina interior FL and MD units. The median survival time of lunar meter-scale ejecta boulders [5], is ~40-80 Ma, and ~150-300 Ma for ~99% of m-scale blocks. The crater absolute age is clearly in the younger range, placing one of the youngest craters in Ina close to, or greater than the ~59 Ma AMA [1]. Stratigraphy of Target Substrate: The main mound is ~10-13 m above the floor, sloping down to the E. An apparent boundary between the mound and underlying more coherent FL material is seen along the lower crater wall where boulders are exceptionally abundant. Extending adjacent floor unit topographic level laterally into the main mound, we interpret the FL unit to stratigraphically underlie the MD unit. Characteristics of Ejecta Deposit of the Young Crater: Pre-impact target reconstruction suggests the impact point was centered on the NW MD-FL unit boundary; expanding transient cavity intersected the main MD to NW, the FL to SW and the small MD to SE, offering insights into substrate properties, regolith thicknesses/post-impact degradation. FC shows little evidence of typical fresh young maria craters ejecta deposits. Physical Properties of Impacted Substrate: Abundance of crater rim/lower interior boulders, presence of central mound suggest that the crater excavated down into a coherent substrate [13] at 0-13 m depth across the sloping mound surface: this value exceeds both regolith thickness model estimates. The nature of the major mound surface and upper crater wall, particularly along the major mound (NNW) wall, suggest a much more incoherent, regolith-like substrate ranging up to ~13 m thick, but retarded excavation on SW FL unit (d/D = 0.0266). Post-Formation Modification of Main Mound and Crater: A similar-sized degraded crater is observed on the main MD just W of the FC. Its shallow depth (~2 m) and lack of circum-rim boulders suggest that it is >several 100 Ma [5]. Initial analysis of the small SE MD (Fig 1a) appears to indicate that it embays the FC to its NW, indenting its rim circularity, making its formation stratigraphically younger than FC, despite its clearly higher crater density/scattered superposed surface FC boulders. Detailed examination of opposite-side imaging/DTMs, however, reveals a convex-outward topographic mound indentation consistent with FC circularity, exposed boulders along its base, and evidence for mass-wasting of SW mound material down into the FC. Tentative Conclusions About Ina Age/Mode of Origin: There are multiple contradictions in implied ages of the FL/MD units/stratigraphic relationships: 1) FL regolith thickness (thin; 5 m) and optical maturity suggest very ancient age: yet the stratigraphic relationships indicate the MD overlie and are stratigraphically younger than the FL, and CSFD AMAs on both units indicate an extremely young age (~58 Ma). 2) MD appears composed of friable regolith-like material throughout its 0-13 m thickness. 3) Both unit fresh craters lack typical distinctive fresh mare crater ejecta. 4) Distribution of fresh crater boulders suggest a young age; possibly as old as several hundred Ma [5], clearly >58 Ma [1]. 5) Extremely degraded mound crater NW of FC much too degraded to have formed

Research Article| December 01, 2023 Lunar Mare Basaltic Volcanism: Volcanic Features and Emplacement Processes James W. Head; James W. Head Department of Earth, Environmental and Planetary Sciences, Brown University, Providence, RI 02912, USA Search for other works by this author on: GSW Google Scholar Lionel Wilson; Lionel Wilson Lancaster Environment Centre, Lancaster University, Lancaster, LA1 4YQ, UK Search for other works by this author on: GSW Google Scholar Harald Hiesinger; Harald Hiesinger Institut für Planetologie, Westfälische Wilhelms-Universität, Wilhelm-Klemm-Str. 10, 48149 Münster, Germany Search for other works by this author on: GSW Google Scholar Carolyn van der Bogert; Carolyn van der Bogert Institut für Planetologie, Westfälische Wilhelms-Universität, Wilhelm-Klemm-Str. 10, 48149 Münster, Germany Search for other works by this author on: GSW Google Scholar Yuan Chen; Yuan Chen Key Laboratory for Lunar and Deep Space Exploration, National Astronomical Observatories, Chinese Academy of Sciences, 20A Datun Road, Chaoyang District, Beijing 100101, China Search for other works by this author on: GSW Google Scholar James L. Dickson; James L. Dickson Division of Geological and Planetary Science, California Institute of Technology, 1200 E California Blvd, MC 150–21. Pasadena, CA, 91125, USA Search for other works by this author on: GSW Google Scholar Lisa R. Gaddis; Lisa R. Gaddis Lunar and Planetary Institute, 3600 Bay Area Boulevard, Houston, Texas 77058, USA Search for other works by this author on: GSW Google Scholar Junichi Haruyama; Junichi Haruyama Institute of Space and Astronautical Science, JAXA, Japan (3–1-1 Yoshinodai, Chuo-ku, Sagamihara, Kanagawa 252–5210, Japan) Search for other works by this author on: GSW Google Scholar Erica R. Jawin; Erica R. Jawin Smithsonian Institution National Museum of Natural History, Department of Mineral Sciences, PO Box 37012, Washington, DC 20013–7012, USA Search for other works by this author on: GSW Google Scholar Lauren M. Jozwiak; Lauren M. Jozwiak Johns Hopkins Applied Physics Laboratory, 11100 Johns Hopkins Rd, Laurel, MD 20723, USA Search for other works by this author on: GSW Google Scholar Chunlai Li; Chunlai Li Key Laboratory for Lunar and Deep Space Exploration, National Astronomical Observatories, Chinese Academy of Sciences, 20A Datun Road, Chaoyang District, Beijing 100101, China Search for other works by this author on: GSW Google Scholar Jianzhong Liu; Jianzhong Liu Center for Lunar and Planetary Sciences, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China Search for other works by this author on: GSW Google Scholar Tomokatsu Morota; Tomokatsu Morota Department of Earth and Planetary Science, University of Tokyo, Bunkyō-ku, Tokyo, Japan Search for other works by this author on: GSW Google Scholar Debra H. Needham; Debra H. Needham National Aeronautics and Space Administration Headquarters, Washington, D.C. 20546, USA Search for other works by this author on: GSW Google Scholar Lillian R. Ostrach; Lillian R. Ostrach US Geological Survey Astrogeology Science Center, 2255 N. Gemini Drive, Flagstaff, AZ USA Search for other works by this author on: GSW Google Scholar Carle M. Pieters; Carle M. Pieters Department of Earth, Environmental and Planetary Sciences, Brown University, Providence, RI 02912, USA Search for other works by this author on: GSW Google Scholar Tabb C. Prissel; Tabb C. Prissel Astromaterials Research and Exploration Science Division, NASA Johnson Space Center, Houston, TX 77058 USA Search for other works by this author on: GSW Google Scholar Yuqi Qian; Yuqi Qian Planetary Science Institute, China University of Geosciences, Wuhan, 430074, China Search for other works by this author on: GSW Google Scholar Le Qiao; Le Qiao Institute of Space Science, Shandong University, Weihai, 264209, China Search for other works by this author on: GSW Google Scholar Malcolm R. Rutherford; Malcolm R. Rutherford Department of Earth, Environmental and Planetary Sciences, Brown University, Providence, RI 02912, USA Search for other works by this author on: GSW Google Scholar David R. Scott; David R. Scott Department of Earth, Environmental and Planetary Sciences, Brown University, Providence, RI 02912, USA Search for other works by this author on: GSW Google Scholar Jennifer L. Whitten; Jennifer L. Whitten Department of Earth and Environmental Sciences, Tulane University, New Orleans, LA 70118 USA Search for other works by this author on: GSW Google Scholar Long Xiao; Long Xiao Planetary Science Institute, China University of Geosciences, Wuhan, 430074, China Search for other works by this author on: GSW Google Scholar Feng Zhang; Feng Zhang National Space Science Center, No. 1 Nanertiao, Zhongguancun, Haidian District, Beijing, China Search for other works by this author on: GSW Google Scholar Ouyang Ziyuan Ouyang Ziyuan Key Laboratory for Lunar and Deep Space Exploration, National Astronomical Observatories, Chinese Academy of Sciences, 20A Datun Road, Chaoyang District, Beijing 100101, China Search for other works by this author on: GSW Google Scholar Author and Article Information James W. Head Department of Earth, Environmental and Planetary Sciences, Brown University, Providence, RI 02912, USA Lionel Wilson Lancaster Environment Centre, Lancaster University, Lancaster, LA1 4YQ, UK Harald Hiesinger Institut für Planetologie, Westfälische Wilhelms-Universität, Wilhelm-Klemm-Str. 10, 48149 Münster, Germany Carolyn van der Bogert Institut für Planetologie, Westfälische Wilhelms-Universität, Wilhelm-Klemm-Str. 10, 48149 Münster, Germany Yuan Chen Key Laboratory for Lunar and Deep Space Exploration, National Astronomical Observatories, Chinese Academy of Sciences, 20A Datun Road, Chaoyang District, Beijing 100101, China James L. Dickson Division of Geological and Planetary Science, California Institute of Technology, 1200 E California Blvd, MC 150–21. Pasadena, CA, 91125, USA Lisa R. Gaddis Lunar and Planetary Institute, 3600 Bay Area Boulevard, Houston, Texas 77058, USA Junichi Haruyama Institute of Space and Astronautical Science, JAXA, Japan (3–1-1 Yoshinodai, Chuo-ku, Sagamihara, Kanagawa 252–5210, Japan) Erica R. Jawin Smithsonian Institution National Museum of Natural History, Department of Mineral Sciences, PO Box 37012, Washington, DC 20013–7012, USA Lauren M. Jozwiak Johns Hopkins Applied Physics Laboratory, 11100 Johns Hopkins Rd, Laurel, MD 20723, USA Chunlai Li Key Laboratory for Lunar and Deep Space Exploration, National Astronomical Observatories, Chinese Academy of Sciences, 20A Datun Road, Chaoyang District, Beijing 100101, China Jianzhong Liu Center for Lunar and Planetary Sciences, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China Tomokatsu Morota Department of Earth and Planetary Science, University of Tokyo, Bunkyō-ku, Tokyo, Japan Debra H. Needham National Aeronautics and Space Administration Headquarters, Washington, D.C. 20546, USA Lillian R. Ostrach US Geological Survey Astrogeology Science Center, 2255 N. Gemini Drive, Flagstaff, AZ USA Carle M. Pieters Department of Earth, Environmental and Planetary Sciences, Brown University, Providence, RI 02912, USA Tabb C. Prissel Astromaterials Research and Exploration Science Division, NASA Johnson Space Center, Houston, TX 77058 USA Yuqi Qian Planetary Science Institute, China University of Geosciences, Wuhan, 430074, China Le Qiao Institute of Space Science, Shandong University, Weihai, 264209, China Malcolm R. Rutherford Department of Earth, Environmental and Planetary Sciences, Brown University, Providence, RI 02912, USA David R. Scott Department of Earth, Environmental and Planetary Sciences, Brown University, Providence, RI 02912, USA Jennifer L. Whitten Department of Earth and Environmental Sciences, Tulane University, New Orleans, LA 70118 USA Long Xiao Planetary Science Institute, China University of Geosciences, Wuhan, 430074, China Feng Zhang National Space Science Center, No. 1 Nanertiao, Zhongguancun, Haidian District, Beijing, China Ouyang Ziyuan Key Laboratory for Lunar and Deep Space Exploration, National Astronomical Observatories, Chinese Academy of Sciences, 20A Datun Road, Chaoyang District, Beijing 100101, China Publisher: Mineralogical Society of America First Online: 04 Dec 2023 Copyright © 2023 by the Mineralogical Society of AmericaMineralogical Society of America Reviews in Mineralogy and Geochemistry (2023) 89 (1): 453–507. https://doi.org/10.2138/rmg.2023.89.11 Article history First Online: 04 Dec 2023 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn Email Permissions Search Site Citation James W. Head, Lionel Wilson, Harald Hiesinger, Carolyn van der Bogert, Yuan Chen, James L. Dickson, Lisa R. Gaddis, Junichi Haruyama, Erica R. Jawin, Lauren M. Jozwiak, Chunlai Li, Jianzhong Liu, Tomokatsu Morota, Debra H. Needham, Lillian R. Ostrach, Carle M. Pieters, Tabb C. Prissel, Yuqi Qian, Le Qiao, Malcolm R. Rutherford, David R. Scott, Jennifer L. Whitten, Long Xiao, Feng Zhang, Ouyang Ziyuan; Lunar Mare Basaltic Volcanism: Volcanic Features and Emplacement Processes. Reviews in Mineralogy and Geochemistry 2023;; 89 (1): 453–507. doi: https://doi.org/10.2138/rmg.2023.89.11 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyReviews in Mineralogy and Geochemistry Search Advanced Search Volcanism is a fundamental process in the geological evolution of the Moon, providing clues to the composition and structure of the mantle, the location and duration of interior melting, the nature of convection and lunar thermal evolution. Progress in understanding volcanism has been remarkable in the short 60-year span of the Space Age. Before Sputnik 1 in 1957, the lunar farside was unknown, the origin of the dark lunar maria was debated (sedimentary or volcanic), and significant controversy surrounded the question of how the multitude of craters on the surface formed. 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This dataset contains the areal extents of the SPA central cryptomaria analyzed in Wang et al. (2023), as shown in Figure 8. The data is in 'shafile' format and can be opened directly in ArcGIS software. The data is in the stereographic projection centered at the center of SPA (191.1°E, 53.2°S; Garrick-Bethell and Zuber, 2009). MinExt_SPACC=Minimum areal extent of the SPA central cryptomaria; MaxExt_SPACC=Maximum areal extent of the SPA central cryptomaria.

We describe a model of the fluid mechanics and thermodynamics of turbulent lava flows capable of thermally eroding sinuous rille channels on bodies without atmospheres. The model assumes Bingham plastic rheology for the lava and shows how the effects of radiant cooling and consequent crystallization change the rheology and control the point at which turbulence ceases. A correlation is found between magma volume eruption rate and the length and width of the eroded rille channel. Thus, simple measurements of rille length and width in images can provide reliable estimates of magma eruption rates. The model also predicts rille floor erosion rates, so that if rille depths are measured, eruption durations and erupted magma volumes can also be found. The model is applied in detail to six well-preserved lunar rilles and more generally to a published catalog of 214 lunar rilles. We find that rille-forming eruptions have magma volume eruption rates of a few times 10 ^4 m ^3 s ^−1 , durations of up to 3 months, and erupted magma volumes up to ∼200 km ^3 , consistent with theoretical predictions of basaltic magma ascent and eruption from deep mantle sources. The key requirement for rille formation, rather than mare lava flow deposit formation, is the turbulent eruption of a sufficiently large volume of low-viscosity magma at a sufficiently low eruption rate.

Much has been discovered about volcanism on Mars over the past fifty years of space exploration. Previous reviews of these discoveries have generally focused on the volcanic constructs (e.g., Olympus Mons and the other volcanoes within the Tharsis and Elysium regions), the analysis of individual lava flows, and how volcanic activity on Mars has evolved over time. Here we focus on attributes of volcanology that have received less attention and build upon characteristics of terrestrial volcanoes to pose new questions to guide future analyses of their Martian equivalents either with existing data sets or with new types of measurements that need to be made. The remarkable lack of exposed dikes at eroded ancient volcanoes attests to an internal structure that is different from terrestrial equivalents. Enigmatic aspects of the origin of the ridged plains (commonly accepted to be volcanic but with few identifiable flow fronts and only rare vents), the style(s) of volcanism during the earliest period of Martian history (the Noachian), and the possible mode(s) of formation of the Medusae Fossae Formation are considered here. Martian meteorites have been dated and are volcanic, but they cannot be correlated with specific geographic areas, or the chronology of Mars derived from the number of superimposed impact craters. Some of these questions about Martian volcanism can be addressed with existing instrumentation, but further progress will most likely rely on the acquisition of new data sets such as high-resolution gravity data, the return of samples from known localities, the flight of a synthetic aperture imaging radar, penetrators sent to the Medusae Fossae Formation, and detailed in situ field observations of selected volcanic sites.

Young on the scene, the field of planetary volcanology has transitioned from a predominantly descriptive science to a quantitative holistic view of the integrated generation, ascent, and eruption of magma under very different planetary sizes, densities, atmospheres, and positions in the Solar System. These multiple settings and conditions, now augmented by thousands of exoplanets, are providing new insights into the nature and history of volcanic processes and the thermal evolution of our own home planet, Earth.

Wherever effusive volcanism has occurred, there is usually also evidence of explosive volcanism. The boundaries between these two kinds of eruption are blurred, because even the sources of lava flows, regarded as the classic effusive landform, may exhibit explosive activity. In the absence of an atmosphere, the expansion of gas (derived from volatiles either dissolved in or encountered by the magma) is uninhibited once any bubbles have burst, and explosively ejected particles of all sizes follow ballistic trajectories once they are clear of any gas jet. An atmosphere impedes bubble expansion, decelerates smaller ballistic particles preferentially compared with larger ones, and introduces the possibility of a convective plume (i.e., an eruption column) able to loft fine particles to much greater heights than would be possible ballistically. Atmospheres also enable the formation of ground-hugging pyroclastic density currents that have no equivalents on airless bodies.

From April to August 2018, Kīlauea volcano, Hawai'i, experienced the largest lower East Rift Zone eruption and caldera collapse in at least 200 years. This activity included the destruction of the Halema'uma'u and Pu'u 'Ō'ō lava lakes, up to 500 m of collapse of the floor of Kīlauea caldera, the opening of 24 different fissure approximately 40 km from the summit at Leilani Estates, and the production of numerous high-volume lava flows that ultimately reached the ocean. Many attributes of this activity have analogs to volcanic landforms and processes found on other planetary bodies, and so provide the potential for greater insight into caldera collapse, lava lakes, and pit craters on the Moon, Mars, Venus, Io, and elsewhere. Observations of the Kīlauea eruption also demonstrate the need for caution when using the preserved morphology of planetary lava flows to estimate mass eruption rates and duration between eruptions. Further, lava flows from Leilani Estates entering the ocean produced copious volumes of volcanic haze "laze" (a dense hydrogen chloride mist), and may provide a new explanation for the elevated chlorine levels detected by gamma ray spectrometers in Mars orbit.

Understanding magma-ice interaction processes is critical for mitigation of the hazards generated by subglacial explosive volcanism, including large flowrate meltwater floods and fine-grained volcanic ash. We propose and evaluate a subglacial eruption mechanism with potential for rapid ablation of the overlying ice that involves the impact of pyroclasts on the ice surfaces of depressurised, vapour dominated ice cavities that surround subglacial vents. Such impacts are likely to cause considerable fracturing and mechanical fragmentation of the ice and thus increase the heat transfer area available for ice-melt. This mechanism has not, to our knowledge, been explored previously in the literature, but we find that published experimental work on impact cratering of icy solar system bodies can be used to predict fragmentation damage by pyroclast impact. Our principal conclusions are as follows. (1) Ice ablation rates of order 100 m h-1 are predicted, for typical pyroclast velocities, provided that the mechanism is sustained. (2) The thermal energy of the eruption, together with the size of the ice fragments produced, is sufficient to prevent accumulation of fractured ice within the cavity. (3) Upward ablation of the ice cavity roof results in a progressive decrease in pyroclast impact velocity that is partly compensated by downward movement of the roof by ductile ice flow. (4) This ice ablation mechanism is likely common during subglacial eruptions on the relatively steep slopes of ice-covered stratovolcanoes, where steepness of slope and ice thickness are favourable for rapid drainage of meltwater by gravity and consequent depressurisation of the cavity.

Abstract More than 50 years of solar system exploration have revealed the great diversity of volcanic landscapes beyond Earth, be they formed by molten rock, liquid water, or other volatile species. Classic examples of giant shield volcanoes, solidified lava flows, extensive ash deposits, and volcanic vents can all be identified, but except for eruptions seen on the Jovian moon Io, no planetary volcanoes have been observed in eruption. Consequently, the details of the processes that created these landscapes must be inferred from the available spacecraft data. Despite the increasing improvement in the spatial, temporal, compositional, and topographic characteristics of the data for planetary volcanoes, details of the way they formed are not clear. However, terrestrial eruptions can provide numerous insights into planetary eruptions, whether they are effusive eruptions resulting in the emplacement of lava flows or explosive eruptions due to either volatiles in the magma or the interaction between hot lava and water or ice. In recent decades, growing attention has been placed on the use of terrestrial analogs to help interpret volcanic landforms and processes on the rocky planets (Mercury, Venus, the Moon, and Mars) and in the outer solar system (the moons of Jupiter and Saturn, and the larger asteroids). In addition, terrestrial analogs not only provide insights into the geologic processes associated with volcanism but also can serve as test sites for the development of instrumentation to be sent to other worlds, as well as provide a training ground for crewed and uncrewed missions seeking to better understand volcanism throughout the solar system.