Featured Image: Scientist Ceth Parker moving through a passageway within an iron formation cave. Photo courtesy of the University of Akron.
Paper: Enhanced terrestrial Fe(II) mobilization identified through a novel mechanism of microbially driven cave formation in Fe(III)-rich rocks
Authors: Ceth W. Parker, John M. Senko, Augusto S. Auler, Ira D. Sasowsky, Frederik Schulz, Tanja Woyke, Hazel A. Barton
Consider this: microscopic creatures literally moving tons of rock before your very eyes. It seems too fantastical, but maybe not if you’re in the Brazilian tropics. In new work, scientists have detailed these stealthy and microscopic processes, naming a new cave generation pathway called exothenic biospeleogenesis, or “behind-wall life-created” caves.
Continue reading “Microscopic Miners: How invisible forces create tropical caves”
Featuring image: Plants slowly eroding limestone. Picture from Jon Sullivan, public domain (C0).
Paper: Composition of continental crust altered by the emergence of land plants
Authors: C. J. Spencer, N. S. Davies, T. M. Gernon, X. Wang, W. J. McMahon, T. R. I. Morrell, T. Hincks, P. K. Pufahl, A. Brasier, M. Seraine and G.-M. Lu
In the winter of 1990, the first Voyager spacecraft looked over its shoulder and snapped an iconic photo of Earth as a ‘pale blue dot’ in the vast cosmos. But when you look at it from Space, there is another very important colour: green. Plants cover a major portion of the landmasses. Besides bringing their bright chlorophyll colour to the continents, new research by Spencer and co-authors finds that plants have also slowly changed the composition of the Earth’s crust over hundreds of millions of years.
In a recent study, Spencer and co-workers were able to connect the development of land plants to changes in the geochemical composition of crustal rocks through the effects that plants had on landscapes, weathering, and sediments. Land plants arose during the early Ordovician period, about 440 million years ago, and today they cover approximately 84% of Earth’s landmasses. After they spread all over the continents, plants started to heavily influence the sedimentary cycles between continents and oceans.
Continue reading “How plants left a mark on history”
Featured image: A silver Roman Denarius, featuring the likeness of emperor Marcus Aurelius. CC BY-SA 3.0 via Wikimedia Commons
Paper: Silver isotope and volatile trace element systematics in galena samples from the Iberian Peninsula and the quest for silver sources of Roman coinage
Authors: Jean Milot; Janne Blichert-Toft; Mariano Ayarzagüena Sanz; Chloé Malod-Dognin; Philippe Télouk; Francis Albarède
The Roman Empire was a superpower thousands of years ago, and with great power comes great (fiscal) responsibilities, including minting the money. To mint silver coins, the Romans needed vast amounts of silver, which historians and archeologists believe originated in the Iberian Peninsula, or present-day Spain and Portugal. However, the geologic origin of that silver is unknown as the depleted mines were abandoned long ago.
Continue reading “Silver Doesn’t Grow on Trees: The Quest for the Ores that Formed Roman Coinage”
Feature Image: Outcrop of volcanic rock associated with the Central Atlantic Magmatic Province. This Large Igneous Province has a strong correlation to the onset of a mass extinction ~200 million years ago, however, an exact mechanism for the extinction has been difficult to determine. CC BY-SA 4.0, via Wikimedia Commons
Paper: Two-pronged kill mechanism at the end-Triassic mass extinction
Authors: Calum P. Fox; Jessica H. Whiteside; Paul E. Olsen; Xingquian Cui; Roger E. Summons; Kliti Grice
A recent study by Calum Fox and colleagues sheds light on what caused one of the “big five” mass extinctions on Earth since complex life emerged ~540 million years ago. They found that repeated pulses of volcanic activity were responsible for the extinction in two main ways: ocean poisoning caused by gaseous hydrogen sulfide (H2S) rising through the water column (known as euxinia) and ocean acidification.
Continue reading “What caused the end-Triassic Mass Extinction in the Oceans?”
Featured Image: Murky pond in Alaska with “rusty” iron-filled sediments. Image courtesy Jessica Buser. Used with permission.
Paper: Sulfate- and iron-dependent anaerobic methane oxidation occurring side-by-side in freshwater lake sediment
Authors: Alina Mostovaya, Michael Wind-Hansen, Paul Rousteau, Laura A. Bristow, Bo Thamdrup
The table has been set and the food is all prepared. But this is no ordinary dinner party, it’s a microbe party! The guests sit down and proceed to dig into the main course; sulfur, rusty iron, and methane. Curiously, the guests are feeding each other, not themselves! This image seems pretty weird to us humans, but it’s a delight to these microbes. This collaborative method of eating occurs in pond and lake mud all around the world. In a new study, Mostovaya and colleagues describe one such feast in Danish Lake Ørn, that is not only collaborative but may mitigate climate change.
Continue reading “Metal-Eating Microbes Who Breathe Methane”
Featured image: Crystals of the mineral barite from the deep ocean (Adapted from Kastner (1999)). These crystals precipitated in ocean sediments and are about 9 million years old, similar in age to some of the barite samples from the study discussed here.
Paper: A 35-million-year record of seawater stable Sr isotopes reveals a fluctuating global carbon cycle
Authors: Adina Paytan, Elizabeth M. Griffith, Anton Eisenhauer, Mathis P. Hain, Klaus Wallmann, Andrew Ridgwell
What do ancient ocean sediments and the walls around x-ray machines have in common? One possible answer? Sometimes the mineral barite is an important part of both! Barite (or barium sulfate) is able to block gamma and x-ray emissions, and therefore is sometimes used in high-density concrete in hospitals and laboratories. In the deep ocean, tiny crystals of barite naturally accumulate on the seafloor over time, particularly in regions ideal for this mineral formation where many decaying remains of organisms sink to the seafloor. The chemistry of this barite can give scientists clues into Earth’s past, which is what Adina Paytan and her colleagues did in this study.
Continue reading “Buried treasure in the oceans: chemistry of small deep-sea crystals hints at past carbon cycling”
Article: Amagmatic hydrothermal systems on Mars from radiogenic heat
Authors: L. Ojha, S. Karunatillake, S. Karimi, and J. Buffo
Many people are familiar with Yellowstone National Park’s famous geyser, Old Faithful – but did you know that the heat fueling Old Faithful’s eruptions are from magma chambers that warm up underground fluids until they shoot out of the ground? Hydrothermal systems like this are found in other places, too, and can be fueled by different kinds of heat sources. In fact, scientists at Rutgers University have recently identified one such heat source – the heat generated by radioactive decay from certain chemical elements – that could help answer questions about whether liquid water, a critical component for life as we know it, could exist on Mars.
Continue reading “Life on Mars: a non-traditional source for warmer waters”
Featured Image: Zircon grain under the Scanning Electron Microscope (SEM). Image used with permission from Wikipedia (Emmanuel Roquette).
Article: The internal structure and geodynamics of Mars inferred from a 4.2-Gyr zircon record.
Authors: Maria M. Costa, Ninna K. Jensen, Laura C. Bouvier, James N. Connelly, Takashi Mikouchi, Matthew S. A. Horstwood, Jussi-Petteri Suuronen, Frédéric Moynier, Zhengbin Deng, Arnaud Agranier, Laure A. J. Martin, Tim E. Johnson, Alexander A. Nemchin, and Martin Bizzarro
While sitting in Geology 101 studying the geological time scale, most of us have gone through this experience where we imagined ourselves going back in time; visualizing mammoths passing by, dinosaurs hunting and fighting. But all these pictures start to become hazy and unclear when we reach close to 4 billion years. It is the time for which we have no rock records, and this is where zircons or what I would like to call “tiny survivors” comes in.
Continue reading “Tiny Crystals, Big Story: Time capsules from the Early Mars”
Featured image: Example of the rock type Pegmatite. Here, crystals of the mineral tourmaline (light-dark green color), and crystals of the mineral lepidolite (pink-purple color) can be seen, sourced from Wikipedia. This file is licensed under the Creative Commons Attribution-Share Alike 3.0 Unported license.
Paper: Episodes of fast crystal growth in pegmatites
Authors: Patrick R. Phelps, Cin-Ty A. Lee, Douglas M. Morton
Anyone who has ever wandered along a pebble-ridden beach or a mountainous trail has likely picked up a rock or two, and maybe these rocks contained an array of different crystals (see image above). Perhaps these rocks then skipped along the surface of a still lake, or made their way into the pockets of a snack-ridden backpack, either to never be seen again or to be added to an ever-growing rock collection. Yet, these little pieces of Earth’s history have the potential to do so much more. With the right tools, the crystals within these rocks can be used to inform us of the geological processes that have shaped our planet Earth.
Continue reading “Cooking up crystals in record time”
Paper: Unraveling biogeochemical phosphorus dynamics in hyperarid Mars‐analogue soils using stable oxygen isotopes in phosphate
Authors: Jianxun Shen, Andrew C. Smith, Mark W. Claire, Aubrey L. Zerkle
Many geologists believe that ancient Mars, with its warmer temperatures and water-rich environment, may have been home to life. To test this hypothesis, astrobiologists must find signifiers of life that can survive the billions of years of hyperaridity experienced on the Martian surface. One such method could be identifying biotic alteration of the geochemical cycling of phosphorus, as was highly publicized during the recent discovery of phosphine in the atmosphere of Venus. Researchers have taken the first step in this search by characterizing biological phosphorus cycling in the analog environment of the Atacama Desert – an endeavor that has applied novel techniques in chemistry to provide insights about the movement of phosphorus in arid environments.
Continue reading “To P, not to P? That is (an oversimplification of) the biogeochemical question—”