In this paper, lunar mare domes (LMDs) are classified according to morphologic and morphometric (primarily diameter) characteristics, and consideration is given to their origin and role in lunar surface processes. In general, they occur either as low, flat, circular structures with convex shapes, slopes less than about 5 deg, and display summit craters, or as irregular structures often adjacent to highland regions and rarely containing summit craters. It is found that LMDs originate through extrusion of lavas through vents to produce low lava shields, or through flooding and draping of preexisting topography to produce kipukas and irregular domes. Smooth, vent-related mare domes range from about 3-17 km in diameter and up to several hundred meters in elevation; they are similar in morphology to small terrestrial lava shields.

Lunar Mare Domes: Classification and Modes of Origin

On December 1, 2020, China's first lunar sample return mission, Chang'e-5 (CE-5), landed at 43.06°N, 51.92°W (Wang et al., 2021) in Northern Oceanus Procellarum, ∼170 km northeast of Mons Rümker (Figure 1a), within the Procellarum-KREEP-Terrain (Jolliff et al., 2000). Rima Sharp, the longest lunar sinuous rille (∼566 km; Hurwitz et al., 2013) extends across the eastern part of the landing region, approaching within ∼15 km of the landing site (Figure 1a).

The Long Sinuous Rille System in Northern Oceanus Procellarum and its Relation to the Chang'e-5 Returned Samples

The pāhoehoe—‘a‘ā morphological transition involves a change in the rheological response of the magmatic suspension from pure viscous to complex rheological behavior, resulting in the development of tear-apart features. Here, we present a suite of concentric cylinder experiments aimed at studying the effects of cooling and shear rates on the rheology of a phonotephrite melt in response to crystallization. Experiments were conducted at: (a) isothermal subliquidus temperatures of 1,167–1,189°C and shear rates of 1–3 s−1; (b) constant cooling rates of 1–10°C/min and shear rates of 1–20 s−1. We defined the viscosity-temperature-time window of lava solidification, as well as the transition from coherent flow to shear localization and physical separation (i.e., viscous rupture). Through this approach, we mapped the processes and timescales affecting pāhoehoe—‘a‘ā transition in natural lavas at variable cooling and shear rates. Under disequilibrium conditions, as the cooling rate increases, both crystallization onset and viscous rupture occur at lower temperature and earlier in time. Moreover, the time to reach the crystallization onset and viscous rupture also decreases with increasing shear rate. Both increasing cooling and shear rate reduces the critical crystallinity required for viscous rupture, a consequence of the non-linear interplay between temperature, crystallization kinetics, and melt viscosity. This outcome expands our knowledge on compositional, thermal, and rheological changes in phonotephritic systems. In addition to shear rate and apparent viscosity, comparison with previous measurements on basaltic systems indicates that the pāhoehoe—‘a‘ā transition is sensitive to the composition and cooling path of lavas.

An Extended Rheological Map of Pāhoehoe—‘A‘ā Transition

Volatile interactions with the lunar surface

Research Article| May 01, 2022 Magma / Suspension Rheology Stephan Kolzenburg; Stephan Kolzenburg Department of Geology University at Buffalo 126 Cooke Hall Buffalo, NY 14260-4130, USADepartment of Earth and Environmental Sciences Ludwig-Maximilians-University Munich Theresienstr. 41 / III 80333, Munich, GermanyDepartment of Earth and Planetary Sciences McGill University 3450 University Street Montreal, H3A 0E8, Quebec, Canada stephank@buffalo.edu Search for other works by this author on: GSW Google Scholar Magdalena O. Chevrel; Magdalena O. Chevrel Laboratoire Magmas et Volcans, Université Clermont Auvergne, CNRS, IRD, OPGC, 6 Avenue Blaise Pascal f-63000, Clermont-Ferrand, France oryaelle.chevrel@ird.fr Search for other works by this author on: GSW Google Scholar Donald B. Dingwell Donald B. Dingwell Department of Earth and Environmental Sciences Ludwig-Maximilians-University Munich Theresienstr. 41 / III 80333, Munich, Germany dingwell@lmu.de Search for other works by this author on: GSW Google Scholar Author and Article Information Stephan Kolzenburg Department of Geology University at Buffalo 126 Cooke Hall Buffalo, NY 14260-4130, USADepartment of Earth and Environmental Sciences Ludwig-Maximilians-University Munich Theresienstr. 41 / III 80333, Munich, GermanyDepartment of Earth and Planetary Sciences McGill University 3450 University Street Montreal, H3A 0E8, Quebec, Canada Magdalena O. Chevrel Laboratoire Magmas et Volcans, Université Clermont Auvergne, CNRS, IRD, OPGC, 6 Avenue Blaise Pascal f-63000, Clermont-Ferrand, France Donald B. Dingwell Department of Earth and Environmental Sciences Ludwig-Maximilians-University Munich Theresienstr. 41 / III 80333, Munich, Germany stephank@buffalo.edu oryaelle.chevrel@ird.fr dingwell@lmu.de Publisher: Mineralogical Society of America First Online: 01 May 2022 Copyright © 2022 by the Mineralogical Society of AmericaMineralogical Society of America Reviews in Mineralogy and Geochemistry (2022) 87 (1): 639–720. https://doi.org/10.2138/rmg.2022.87.14 Article history First Online: 01 May 2022 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Stephan Kolzenburg, Magdalena O. Chevrel, Donald B. Dingwell; Magma / Suspension Rheology. Reviews in Mineralogy and Geochemistry 2022;; 87 (1): 639–720. doi: https://doi.org/10.2138/rmg.2022.87.14 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 When considering the rheology of a suspension the fundamental physical aspect to be quantified is the redistribution of strain between the deformable matrix fraction of the physical mixture and the suspended phase or phases. For the case of solid particle suspensions in magma and lava the suspended crystalline phases will generally be devoid of significant internal strain during flow. With some exceptions (Cordonnier et al. 2009; Kendrick et al. 2017), the stresses driving the magmatic deformation and flow, are generally not high enough to induce significant crystal deformation (see however below). Thus, the primary task becomes one... You do not have access to this content, please speak to your institutional administrator if you feel you should have access. 

Magma / Suspension Rheology

Formation and dispersal of pyroclasts on the Moon: Indicators of lunar magma volatile contents

Many of the grand challenges in volcanic and magmatic research are focused on understanding the dynamics of highly heterogeneous systems and the critical conditions that enable magmas to move or eruptions to initiate. From the formation and development of magma reservoirs, through propagation and arrest of magma, to the conditions in the conduit, gas escape, eruption dynamics, and beyond into the environmental impacts of that eruption, we are trying to define how processes occur, their rates and timings, and their causes and consequences. However, we are usually unable to observe the processes directly. Here we give a short synopsis of the new capabilities and highlight the potential insights that in situ observation can provide. We present the XRheo and Pele furnace experimental apparatus and analytical toolkit for the in situ X-ray tomography-based quantification of magmatic microstructural evolution during rheological testing. We present the first 3D data showing the evolving textural heterogeneity within a shearing magma, highlighting the dynamic changes to microstructure that occur from the initiation of shear, and the variability of the microstructural response to that shear as deformation progresses. The particular shear experiments highlighted here focus on the effect of shear on bubble coalescence with a view to shedding light on both magma transport and fragmentation processes. The XRheo system is intended to help us understand the microstructural controls on the complex and non-Newtonian evolution of magma rheology, and is therefore used to elucidate the many mobilization, transport, and eruption phenomena controlled by the rheological evolution of a multi-phase magmatic flows. The detailed, in situ characterization of sample textures presented here therefore represents the opening of a new field for the accurate parameterization of dynamic microstructural control on rheological behavior.

Cerith Morgan

Papers

Formation and dispersal of pyroclasts on the Moon: Indicators of lunar magma volatile contents

Quantifying Microstructural Evolution in Moving Magma