Jacob Elvin Bleacher

Lava tubes are key targets in the search for life on Mars. Their basaltic walls provide protection from radiation and changing environmental conditions, which could enable life or preservation of previous life in an otherwise harsh environment. We can understand the potential for Martian life in lava tubes by studying the habitability of analog environments on Earth. In this study, we present the first characterization of the microbial life inside a pristine Mauna Loa lava tube. This study is the first to combine 16S SSU rRNA sequencing and whole genome shotgun sequencing to map the taxonomic makeup and functional potential of any lava tube community in Hawaii, enabling a deep understanding of the types of microbes that thrive in this unique environment and the metabolisms they use. We find a surprisingly high degree of niche partitioning over small spatial scales and discuss implications for life detection strategies. Based on recent bioinformatic advancements in metagenomics, we also assemble dozens of high‐quality metagenome assembled genomes from the microbes living in the lava tubes, including several novel species.

Here, we present the draft genome for a new putative species, Gaiellasilicea maunaloa , most closely related to Gaiella occulta , within the phylum Actinobacteria. This group contains Gram-negative, aerobic mesophilic species. This metagenome-assembled genome (MAG) contributes to knowledge of life in volcanic environments and may inform investigations of life beyond Earth.

Volcanic flood basalt eruptions have been linked to or are contemporaneous with major climate disruptions, ocean anoxic events, and mass extinctions throughout at least the last 400 M years of Earth's history. Previous studies and recent history have shown that volcanically‐driven climate cooling can occur through reflection of sunlight by H₂SO₄ aerosols, while longer‐term climate warming can occur via CO₂ emissions. We use the Goddard Earth Observing System Chemistry‐Climate Model to simulate a 4‐year duration volcanic SO₂ emission of the scale of the Wapshilla Ridge member of the Columbia River Basalt eruption. Brief cooling from H₂SO₄ aerosols is outweighed by dynamically and radiatively driven warming of the climate through a three orders of magnitude increase in stratospheric H₂O vapor.

Volcanic flood basalt eruptions have been linked to or are contemporaneous with major climate disruptions, ocean anoxic events, and mass extinctions throughout at least the last 400M years of Earth’s history. Previous studies and recent history have shown that volcanically-driven climate cooling can occur through reflection of sunlight by H ₂ SO ₄ aerosols, while longer-term climate warming can occur via CO ₂ emissions. We use the Goddard Earth Observing System Chemistry-Climate Model to simulate a four-year duration volcanic SO ₂ emission of the scale of the Wapshilla Ridge member of the Columbia River Basalt eruption. Brief cooling from H ₂ SO ₄ aerosols is outweighed by dynamically and radiatively driven warming of the climate through a three orders of magnitude increase in stratospheric H ₂ O vapor.

Several large paterae in Arabia Terra are suggested to be calderas that produced colossal explosive eruptions (i.e., supereruptions). If these features are indeed explosive calderas, dispersion modeling suggests extensive ash deposits should be common throughout the region. However, such deposits have not previously been linked with the suggested calderas. Here, we describe layered deposits containing minerals both consistent with and diagnostic of altered volcanic ash throughout Arabia Terra. These deposits include Al‐dominant minerals such as montmorillonite, imogolite, and allophane among others. Altered ash deposits are found to thin (from 1‐km to 100‐m thickness) away from the suggested calderas. We estimate that the volcanic ash observed in Arabia Terra is the result of between 1,000 and 2,000 individual explosive eruptions over 500‐million years. Our observations support the hypothesis that Arabia Terra hosted supereruptions in the late Noachian‐early Hesperian that repeatedly blanketed the region with layers of ash.

Distributed‐style volcanism is an end member of terrestrial volcanism that produces clusters of small volcanoes when isolated magma bodies ascend from broad magma source regions. Volcano clusters can develop over millions of years, one volcano at a time, and can be used to infer unobserved geologic phenomena, including subsurface stresses and cracks during eruption periods. The Tharsis Volcanic Province covers approximately one‐quarter of the martian surface and hosts a large concentration of small volcanoes that formed from distributed volcanism. We present a catalog of 1,106 small volcanic vents identified within Tharsis Volcanic Province. This catalog includes morphologic measurements for each cataloged vent. Vent lengths range from 71 m to 51 km, widths range from 40 m to 3.1 km, and 90% of vents have lengths at least 1.5 times their widths. Additionally, 90% of edifices associated with vents have topographic prominences 1 Ga are found at the Tharsis periphery in the Tempe‐Mareotis region and Syria Planum. Vents in the Tharsis interior have reported ages <500 Ma. Regional trends in vent orientation and intervent alignment are dependent on nearby central volcanoes and fossae. We use these findings to hypothesize that within the most recent 500 Ma, magma was present under and to the east of the Tharsis Montes and that some of this magma erupted and built hundreds of small volcanoes in this region.