Geomorphometric Characterization,Composition,and Geological Evolution Of Volcanic Cones In The Marius Hill,the Moon

Volcanism is one of the major internal dynamic geological processes of the Moon.Studying the geological characteristics of lunar volcanic formation is of significant scientific values to provide important insights into geological and thermal evolution history of the Moon.The characteristics of volcanic landform are result of long-term complex evolution.Under the interpretation of dike propagagtion model,the diversity of volcanic landform often indicates different volcanism.Among them,the lunar volcanic cone is the product of explosive volcanic activity,which corresponds to the terrestrial Strombolian-type eruption.Previously,due to the influence of data accuracy,the research on small-scale volcanic construction such as lunar volcanic cone was insufficient.However,newly-obtained multi-source and high-precision data can effectively realize geomorphic survey and material detection of lunar volcanic cone.Based on the above situation,we have carried out the research of lunar volcanic cone from the two aspects of morphological characteristics and material composition,which is of great significance for understanding the characteristics of lunar volcanism,including tectonic background,magma composition and flow,eruption mode and climate conditions.In this work,we focus on the Marius Hills region,a volcanic plateau in south Oceanus Procellarum,which hosts the most abundant volcanic cones on the Moon,along with other volcanic features.In terms of data method,we used LROC WAC and Kaguya TC image to identify the topographic and geomorphic features of volcanic cone,and distinguishes the reliability and shape of the recognition results.Using Kaguya MI to achieve the inversion of Fe and Ti content of volcanic cone.The Dinviner data are used to calculate the Si content and rock abundance of volcanic cone.And the mineral inversion is realized by M3 data.The study found that 360 volcanic cones and 22 volcanic domes were identified in the Marius Hills.Following detailed morphological characterizations,the volcanic cones show various morphology types,including C-shaped,elliptical-shaped,elongated-shaped,irregular-shaped cones and roundedshaped.The cones(median basal width～2.7 km,height～115 m,volume 0.25 km3)contain summit pit craters(15%;median width～358 m),exhibiting smaller basal widths and summit pit crater widths compared with lunar mare domes.The mean slope(3.5°-15.6°)and rock abundance(0.3%-3.8%)of volcanic cones in Marius Hills are larger than those of mare dome,suggesting different eruption mechanisms.Marius Hills cones also show larger basal widths and smaller height/width ratios than terrestrial volcanic cones,which are attributed to multiple factors,including subaerial environment,volatile content of magma,eruption rate and lava viscosity.In terms of material composition,the Fe content of volcanic cone in Marius Hills is uniform at a high level(18-21 wt.%).There are great differences in Ti content among individuals,and a considerable number of volcanic cones have an average Ti content of more than 10 wt.%.There is no significant difference between Si content and surrounding mare units;The mineral composition is dominated by pyroxene rich in Fe and Ca.There is no obvious difference in mineral composition of volcanic cones with different shapes,which excludes the possibility that magmatic composition leads to different shapes of volcanic cone.The joint study of morphology and material composition of volcanic cone in Marius Hills carried out in this paper updates and supplements the relevant morphological parameters of volcanic cone,and provides certain constraints on lunar volcanism in combination with the results of material composition.Through the comparison with terrestrial volcanic cone,we discussed the similarities and differences between terrestrial volcanism and lunar volcanism.At the same time,it also provides a certain reference for the systematic study of lunar volcanic cones from multiple angles using multi-source data in the future.