Basaltic lava flows are common on the surface of the Earth and other terrestrial bodies. However, inflation—including a combination of initially rapid molten core thickening and gradual crustal growth—must be accounted for to enable accurate reconstructions of eruption parameters from observed lava flow morphologies. The shape of an inflated lava flow can change significantly over time. Therefore, incorrectly attributing the flow's final thickness to its dimensions in an initially fully molten state will yield excessively high flow rates, erroneous rheological properties, and unreasonably short eruption durations. To develop improved criteria for identifying inflated lava flows, we examined the McCartys lava flow field in New Mexico, USA. This locality provides an example of how pāhoehoe‐like lava lobes can coalesce and coinflate to form interconnected lava‐rise plateaus with internal inflation pits. These structures were examined using a combination of field observations, low‐altitude kite‐based imaging, and quantitative geomorphology using high‐resolution (1.47 cm/pixel) orthomosaics and stereo‐derived digital terrain models. These observations were used to identify characteristics and diagnostics of inflation, thereby facilitating the interpretation of comparable landforms on other planetary surfaces. Lava‐cooling models were also used to estimate the lava emplacement duration of the ~20‐m‐thick flows by demonstrating that the ~8‐m‐thick upper crust exposed within inflation clefts in the southern part of the McCartys lava flow field would have required 1.2–2.5 years of continuous lava supply to form. This places a minimum bound on the total eruption duration, and implies that comparably thick inflated flows on Mars required years to form.

Integrated analyses of Thermal Emission Imaging System (THEMIS) IR, Context Camera (CTX), and Mars Orbiter Laser Altimeter (MOLA) data sets have been used to characterize the western flank of the Martian volcano Alba Mons, which hosts a prominent population of lava tube systems. Identification and mapping of lava tube systems is based on both morphologic and topographic analyses, including the presence of chains of collapse depressions and elongate, sinuous ridges. Lava tubes and adjacent tabular lava flows with lengths of 100⁺ km form an extensive lava flow field. Analyses of topographic data sets, including slope maps, suggest continuity of the radial flow field pattern across the full western flank. Concurrent surface activity across the western flank is consistent with age constraints from geologic mapping and crater size‐frequency distributions that indicate Early Amazonian ages. The mapped population of 331 lava tube systems in the western flank geologic map quadrangle has a mean length of 36.2 km and a total length of ∼12,000 km. Individual lava tube systems extend up to ∼400 km. Orientation and slope data for lava tube systems show small deviations compared to regional values in 50‐km grid cells defined by the MOLA Digital Elevation Model, suggesting a strong coupling of lava tubes to the current slopes of Alba Mons. Mapping of lava tube systems documents segments both showing collapse and with no collapse, indicating the potential for extensive subsurface cavities that would be important astrobiological targets.

Premise: TagSeq is a cost‐effective approach for gene expression studies requiring a large number of samples. To date, TagSeq studies in plants have been limited to those with a high‐quality reference genome. We tested the suitability of reference transcriptomes for TagSeq in non‐model plants, as part of a study of natural gene expression variation at the Santa Rita Experimental Range National Ecological Observatory Network (NEON) core site.Methods: Tissue for TagSeq was sampled from multiple individuals of four species (Bouteloua aristidoides and Eragrostis lehmanniana [Poaceae], Tidestromia lanuginosa [Amaranthaceae], and Parkinsonia florida [Fabaceae]) at two locations on three dates (56 samples total). One sample per species was used to create a reference transcriptome via standard RNA‐seq. TagSeq performance was assessed by recovery of reference loci, specificity of tag alignments, and variation among samples.Results: A high fraction of tags aligned to each reference and mapped uniquely. Expression patterns were quantifiable for tens of thousands of loci, which revealed consistent spatial differentiation in expression for all species.Discussion: TagSeq using de novo reference transcriptomes was an effective approach to quantifying gene expression in this study. Tags were highly locus specific and generated biologically informative profiles for four non‐model plant species.

We examine the morphology and chemistry of the Vikrahraun basaltic eruption emplaced at Askja Volcano, Iceland, from Oct. 26–Dec. 17, 1961. The eruption had three eruptive events, initiating with aʻa and followed by alternating aʻa and pahoehoe lava flow emplacement. We determine that while the eruption is chemically homogenous (Fe/Mg = 1.9–2.2, 47–52 wt.% SiO2), it demonstrates transitions from high to low viscosity lava flow morphologies. Aʻa flows have a total crystallinity (phenocryst and microlite abundance by area) ranging from 85–100%, which increases by 1% per km from the vents, while pahoehoe flows range from 55–86% and increase at a higher rate of 5% per km. Vesicularity systematically decreases with distance from the vent by 3% per km. Pahoehoe and vent samples have calculated temperatures 50 °C higher than aʻa samples, which we interpret to be due to the difference between tube fed pahoehoe and open channel aʻa lavas. The homogenous nature of the Vikrahraun lava makes it an excellent testbed to study the effects of observational scale and satellite resolution on the interpretation of surficial textures. Festoons, which are downslope pointed convex ridges from 1 to 5 m high and ~ 10 m long, are observed in event 2 aʻa lavas in satellite imagery and topographic profiles. Features of this scale have previously only been documented in terrestrial rhyolitic lavas, leading planetary researchers to infer that festooned lava flows on Venus and Mars may be silicic. The diverse morphologies and homogenous composition make Vikrahraun an important planetary analog, where morphological complexity is over-attributed to chemical variation and suggests the need to re-evaluation planetary lava flow interpretations. Graphical Abstract

Apparent thermal inertia (ATI) is a remote sensing-based thermophysical approximation used to estimate surface properties such as particle size or soil moisture, but is subject to oversimplifications if uniform surface materials are assumed. Geological surfaces realistically contain multiple types of materials that are represented by mixed pixels in a digital image that can dramatically affect the derived thermal response. Thus, the current surface uniformity assumption can lead to erroneous calculations. To define how these mixed particle size surfaces affect ATI, a multi-instrument, multi-spectral study was conducted at the North Coulee rhyolite flow, Mono Domes (California). This flow is compositionally homogenous with particle sizes ranging from silt size to boulders, making it an ideal location to understand the relationship between particle size distributions and ATI. Multispectral data from orbital sensors with increasing spatial resolutions were analyzed in combination with samples, GPS, and photogrammetry data collected in the field. The surface particle size characteristics divided into three broad categories (fine, moderate, and coarse) were mapped based on WorldView-2 visible data and field observations. Broad categories were validated using a 3-dimensional point cloud derived from structure-from-motion (SfM) methods using field photographs. The areal percentage of each category within an ATI pixel was derived to populate a lookup table (LUT) with the corresponding ATI values to quantify the effect of mixed pixels. Lower ATI values are dominated by fine particles (sand and dust) as expected, however, surfaces with the highest values were predominately moderate-sized cobbles. Pixels with a high areal percentage of coarse sizes display an intermediate ATI value, suggesting that either self-shadowing or trapping of fines lowers the ATI value. Alternatively, areas with a majority of moderate particle sizes have less shadowing and efficient vertical sorting of smaller material, as seen in field data, leaving a thermal derived response indicative of the dominating particle size. This study demonstrates how a uniform property assumption can cause erroneous derived thermal modeling, particularly over surfaces with a high percentage of boulders and large particle sizes. Future thermophysical studies of Earth or other planetary surfaces can greatly benefit from a multi-sensor approach combined with a higher spatial resolution visible dataset.