The Cauchy 5 Small, Low-Volume Lunar Shield Volcano:Evidence for Volatile Exsolution-Eruption Patterns and Type 1/Type 2 Hybrid Irregular Mare Patch Formation

The lunar shield volcano Cauchy 5, sitting at the low diameter‐height‐volume end of the population, is the only known example containing two different types of Irregular Mare Patches (IMPs) in very close association: (1) the pit crater interior Type 1 IMP composed of bleb‐like mounds surrounded by a hummocky and blocky floor unit and (2) Type 2 IMPs, small, often optically immature pits less than ~5 m deep, located on the generally block‐deficient shield flanks. A four‐phase lunar magma ascent/eruption model predicts that during a relatively brief eruption, low magma rise rates maximize volatile exsolution in lava filling the pit crater. Bubble‐rich magmas overtop the pit crater and form extremely vesicular flows on the shield flanks. Exposure of the flanking flows to vacuum produces a fragmental layer of exploded glassy bubble walls. Subsequent second boiling upon cooling of the flanking flow interiors releases additional volatiles which migrate and collect, forming magmatic foams and gas pockets. As magma rise rates slow, trapped gas and magmatic foam build up below the cooling pit crater floor. Magmatic foams are extruded to form Type 1 IMP deposits. Type 2 IMPs on the flanks are interpreted to be due primarily to subsequent impacts causing collapse of the flow surface layer into the extremely vesicle‐ and void‐rich flow interior. Anomalously young pit crater floor/shield flank crater retention ages compared with surrounding maria ages may be due to effects of Cauchy 5 substrate characteristics (extreme micro‐ and macroporosity, foamy nature, and glassy auto‐regolith) on superposed crater formation and retention

A tensile deformation model for in-situ dendrite/metallic glass matrix composites

In-situ dendrite/metallic glass matrix composites (MGMCs) with a composition of Ti46Zr20V12Cu5Be17 exhibit ultimate tensile strength of 1510 MPa and fracture strain of about 7.6%. A tensile deformation model is established, based on the five-stage classification: (1) elastic-elastic, (2) elastic-plastic, (3) plastic-plastic (yield platform), (4) plastic-plastic (work hardening), and (5) plastic-plastic (softening) stages, analogous to the tensile behavior of common carbon steels. The constitutive relations strongly elucidate the tensile deformation mechanism. In parallel, the simulation results by a finite-element method (FEM) are in good agreement with the experimental findings and theoretical calculations. The present study gives a mathematical model to clarify the work-hardening behavior of dendrites and softening of the amorphous matrix. Furthermore, the model can be employed to simulate the tensile behavior of in-situ dendrite/MGMCs

Lunar Irregular Mare Patches:Classification, Characteristics, Geologic Settings, Updated Catalog, Origin, and Outstanding Questions

One of the most mysterious lunar features discovered during the Apollo era was Ina, a ~2 × 3-km depression composed of bleb-like mounds surrounded by hummocky and blocky terrains. Subsequent studies identified dozens of similar features in lunar maria, describing them as Irregular Mare Patches (IMPs). Due to the unusual and complex characteristics of IMPs, their specific formation mechanism is debated. To improve our understanding of the nature and origin of IMPs, we undertook an updated search and geological characterization of all IMPs and established a classification approach encompassing the full spectrum of IMPs. We present an updated catalog of 91 IMPs and survey the detailed characteristics of each IMP. We find that the majority of IMPs occur in maria emplaced over three billion years ago, contemporaneous with the peak period of global lunar volcanism. We utilized geologic context information and characteristics to establish two classification schemes for lunar IMPs: (1) geologic context: IMPs are categorized into (a) small shield volcano summit pit floor and flank, (b) linear/sinuous rille interior and adjacent exterior, and (c) typical maria; (2) characteristics: IMPs are classified into (a) “mound + floor” and (b) “pit only” types. We showed the range of characteristics of lunar IMPs was consistent with the waning-stage magmatic foam formation and extrusion scenario in different environments. Our updated catalog and classification raise several outstanding questions concerning the nature and origin of lunar IMPs. Assessing these questions will improve our knowledge of lunar thermal and geologic evolution. ©2020. American Geophysical Union. All Rights Reserved

Mare Domes in Mare Tranquillitatis:Identification, Characterization, and Implications for Their Origin

Mare domes, small shield volcanoes typically <∼30 km diameter, are part of the spectrum of lunar volcanic features that characterize extrusive basalt deposits. We used new spacecraft data to document these in Mare Tranquillitatis, among the oldest maria and the site commonly interpreted as an ancient degraded non-mascon impact basin. We found 283 known and suspected mare domes, with the majority (n = 229) concentrated on a broad, ∼450 km circular topographic rise in eastern Mare Tranquillitatis. The domes (median diameter 5.6 km, height 68 m, volume 0.7 km3) contain summit pits (74%; median diameter 0.8 km), and exhibit minor compositional variability between domes and surrounding flows, suggesting that domes both supply and are embayed by these flows. Based on their characteristics and associations, we interpret the small shield volcanoes to have been built from individual low-volume (<∼10–100 km3), low volatile content, short duration, cooling-limited eruptions. The ∼450 km broad volcanic rise is ∼920 m high (volume ∼1.6 × 105 km3) and is interpreted to be built from multiple occurrences of small shield eruptions, a shield plains volcanism style. This implies a shallow mantle source region capable of supplying distributed dike-emplacement and eruption events over an area of 1.75 × 105 km2 early in mare volcanism history (∼3.7 Ga). The difference between Mare Tranquillitatis and younger mare-filled mascon basins is attributed to the more ancient thermal state and crustal structure of the viscously relaxed Tranquillitatis basin, and a shallower broad magma source region present in earlier lunar thermal history

Geological Characterization of the Ina Shield Volcano Summit Pit Crater on the Moon:Evidence for Extrusion of Waning-Stage Lava Lake Magmatic Foams and Anomalously Young Crater Retention Ages

Ina, a distinctive ~2 × 3 km D-shaped depression, is composed of unusual bulbous-shaped mounds surrounded by optically immature hummocky/blocky floor units. The crisp appearance, optical immaturity, and low number of superposed impact craters combine to strongly suggest a geologically recent formation for Ina, but the specific formation mechanism remains controversial. We reconfirm that Ina is a summit pit crater/vent on a small shield volcano ~3.5 billion years old. Following detailed characterization, we interpret the range of Ina characteristics to be consistent with a two-component model of origin during the waning stages of summit pit eruption activities. The Ina pit crater floor is interpreted to be dominated by the products of late-stage, low-rise rate magmatic dike emplacement. Magma in the dike underwent significant shallow degassing and vesicle formation, followed by continued degassing below the solidified and highly microvesicular and macrovesicular lava lake crust, resulting in cracking of the crust and extrusion of gas-rich magmatic foams onto the lava lake crust to form the mounds. These unique substrate characteristics (highly porous aerogel-like foam mounds and floor terrains with large vesicles and void space) exert important effects on subsequent impact crater characteristics and populations, influencing (1) optical maturation processes, (2) regolith development, and (3) landscape evolution by modifying the nature and evolution of superposed impact craters and thus producing anomalously young crater retention ages. Accounting for these effects results in a shift of crater size-frequency distribution model ages fro

Revisiting the Bs(∗)B^{(*)}_s-Meson Production at the Hadronic Colliders

The production of heavy-flavored hadron at the hadronic colliders provides a challenging opportunity to test the validity of pQCD predictions. There are two mechanisms for the $B^{(*)}_s$ hadroproduction, i.e. the gluon-gluon fusion mechanism via the subprocess $g+g\rightarrow B^{(*)}_s+b+\bar{s}$ and the extrinsic heavy quark mechanism via the subprocesses $g+\bar{b}\to B^{(*)}_s +\bar{s}$ and $g+s\to B^{(*)}_s +b$, both of which shall have sizable contributions in proper kinematic region. Different from the fixed-flavor-number scheme (FFNS) previously adopted in the literature, we study the $B^{(*)}_s$ hadroproduction under the general-mass variable-flavor-number scheme (GM-VFNS), in which we can consistently deal with the double counting problem from the above two mechanisms. Properties for the $B^{(*)}_s$ hadroproduction are discussed. To be useful reference, a comparative study of FFNS and GM-VFNS is presented. Both of which can provide reasonable estimations for the $B^{(*)}_s$ hadroproduction. At the Tevatron, the difference between these two schemes is small, however such difference is obvious at the LHC. The forthcoming more precise data on LHC shall provide a good chance to check which scheme is more appropriate to deal with the $B^{(*)}_s$-meson production and to further study the heavy quark components in hadrons.Comment: 18 pages, 8 figures, 4 tables. To match the published version. To be published in Eur.Phys.J.

Detection of inconsistencies in geospatial data with geostatistics

Almost every researcher has come through observations that “drift” from the rest of the sample, suggesting some inconsistency. The aim of this paper is to propose a new inconsistent data detection method for continuous geospatial data based in Geostatistics, independently from the generative cause (measuring and execution errors and inherent variability data). The choice of Geostatistics is based in its ideal characteristics, as avoiding systematic errors, for example. The importance of a new inconsistent detection method proposal is in the fact that some existing methods used in geospatial data consider theoretical assumptions hardly attended. Equally, the choice of the data set is related to the importance of the LiDAR technology (Light Detection and Ranging) in the production of Digital Elevation Models (DEM). Thus, with the new methodology it was possible to detect and map discrepant data. Comparing it to a much utilized detections method, BoxPlot, the importance and functionality of the new method was verified, since the BoxPlot did not detect any data classified as discrepant. The proposed method pointed that, in average, 1,2% of the data of possible regionalized inferior outliers and, in average, 1,4% of possible regionalized superior outliers, in relation to the set of data used in the study