The Earth Story

Bentonite This unit is a commonly used industrial mineral with a unique origin story. The distance shot shows the Bentonite Hills, a location in Utah from just outside Capitol Reef National Park, and the close-up image shows the texture found in units like that (that shot comes from the badlands of Dinosaur Provincial Park in Canada). Bentonite most commonly forms by the combination of volcanoes and lakes. 

Oops, we made a geyser!

Geysers are a pretty rare phenomenon—they require a unique set of conditions and only occur naturally in a few select places around the world. However, mankind has created some geysers of our own…and usually it’s on accident. Exhibit A is Crystal Geyser in Utah (shown erupting out of a pipe in its photo). An oil well was drilled here was in 1931. The well didn’t produce any oil, but it did create a new way for bubbly water to escape. The groundwater here has a high concentration of dissolved CO2, and since the well was never capped, a “geyser” was born. Crystal geyser is unique in another way—the water is cold and its eruption is only due to CO2, not hydrothermal activity.

At its peak, Crystal Geyser erupted plumes up to 100 feet high (30 m). In recent years, the activity has slowed. Impatient tourists often drop rocks down the pipe in attempt to trigger an eruption, which has clogged the plumbing. .

Another example is Fly Geyser in Nevada (shown erupting out of a cone). Fly Geyser has a similar origin to Crystal; a well was drilled for another purpose, and in this case that well accidentally tapped into VERY hot, pressurized water. Interestingly enough, this well WAS capped, but the water got out anyway.

Both geysers carry mineral-rich water, which precipitates into the quite beautiful travertine terraces and cones shown here.

-CM

Photo credit: Crystal Geyser: http://bit.ly/1a62J3y

Fly Geyser: Tanya Wheeler http://bit.ly/1CVqeXy

New survey of US methane leaks

This image, produced by NASA, shows methane concentrations over the United States between 2003 and 2009. Methane is pulled out of the ground and burned as natural gas, but if it leaks into the upper part of the atmosphere it is also a strong greenhouse gas that contributes to climate change.

In the years 2003-2009, new drilling techniques were developed in the United States that released methane from reservoirs that were previously inaccessible. The basic technique involves drilling holes into gas rich units and pumping sand and fluid into these units at high pressure; the pressure fractures the ground and the sand holds open the fractures, allowing gas to flow out.

If methane is used as an energy source instead of coal, there is a possible economic and environmental benefit as each molecule of methane has far more energy than the same mass of coal and burning it releases far fewer pollutants, including far less CO2. However, because of how methane atoms interact with infrared light, methane is also a far more potent greenhouse gas than CO2, so small methane leaks can totally swamp the environmental benefits of natural gas over coal. Therefore, monitoring the amount of methane that leaks out of the drilling and transportation operations is hugely important.

The research shown in this image from a few years ago showed a couple of methane leak hotspots, including a large one associated with drilling in Colorado. Although they did not prepare as pretty of an image as this one, a new study was just published updating these results and characterizing leaks from other gas fields.

In 2015, a P-3 aircraft operated by the National Oceanographic and Atmospheric Adminstration (NOAA) sampled the gas plumes above these drilling sites. They measured the atmospheric chemistry, the isotopic composition of gases, and other gases like ethane that can leak out associated with the methane. They matched gases measured in the atmosphere to the composition actually measured in wells in the units, to make sure they were measuring the methane actually leaking out of the ground.

In some cases, like the bullseye on this plot, their measurements suggest substantial progress. The methane measured leaking from Colorado has declined dramatically since this image was published; nearly 40% lower than what was observed in this time period. This reduction could be due to better procedures, or it could be due to there simply being less drilling now due to the drop in gas prices.

However, other areas showed higher leak rates. This area in Colorado, the Hayensville Shale in Arkansas, and the Eagle Ford shale in Texas all showed leaks that were comparable to 2-3% of the total methane gas produced. These leak rates are high enough that any benefit to using methane instead of coal is almost certainly lost.

However, that wasn’t nearly the worst. In North Dakota, the Bakken formation is also being used as a gas source. The amount of natural gas measured in the air above this formation implied that 5.4% of the produced natural gas from this formation was leaking to the atmosphere during the measurement period.

Overall there has been improvement in gas leaks in many areas. In fact, there should be improvement in gas leaks – gas that leaks to the atmosphere can’t be sold, if it’s leaking it’s literally money leaking into the sky. The previous administration made a point of working with gas producers to help them cut their gas release rates, but so far it still is not enough. The leak rates in some fields are approaching the levels we need (<1%), but as the Bakken formation shows, there needs to be a continued effort from industry to cut down on leaks and that effort has a long way to go.

-JBB

Image credit: https://www.jpl.nasa.gov/news/news.php?release=2014-348

Original paper: https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1029/2018JD028622

Magma power

In 2009, engineers in Iceland were drilling an exploratory well near the Krafla volcano on the island’s northern coast when something entirely unexpected happened. The temperature in the borehole suddenly spiked to over 1000°C – hot enough to melt rock.

In fact, that’s exactly what they struck; a magma chamber. This was the first time that a drill hole in Iceland had ever run into an active, liquid magma chamber.

The hole was part of a project to explore for new geothermal energy resources, and obviously the engineers had hit something hot, so they decided to try something new. They lined the bottom of the borehole with steel and concrete to keep the magma from intruding into it and began pumping water down.

Earlier this year, it was reported they had successfully pulled it off. By pumping water into that borehole, they produced steam at a temperature of 450°C which could be contained and used as a geothermal energy source.

Much of Iceland’s power is supplied from geothermal sources, but this one is unique as it is the first ever recorded use of actual magma for geothermal recovery. In addition, most geothermal systems take energy from rocks that aren’t as hot as magma, but the hotter the steam, the more energy it can generate, so energy directly from magma is going to be much more efficient. The 450°C steam broke a record for the hottest steam ever used in electricity generation.

Engineers in Iceland have effectively produced the world’s first magma-driven geothermal system. It might not be a technique that can be replicated everywhere since most places don’t have active magma chambers beneath them, but it is a remarkable new engineering result.

-JBB

Image credit: http://en.wikipedia.org/wiki/File:Fimmvorduhals_second_fissure_2010_04_02.JPG

Press release: http://ucrtoday.ucr.edu/20005

The language in here is a bit NSFW. Here you can watch a very dangerous oil well blowout. Original caption:

The history of the Yellowstone hotspot

This photo comes from an area of the United States known as the Snake River Plain. The rocks you see behind the river are part of a large series of igneous rocks that scrape across the western United States from Oregon through Idaho, finally ending at Yellowstone National Park. This area really is a plain – the land is fairly flat, filled with rolling hills and gentler river slopes, but it stands out because it’s surrounded by large, steep mountain ranges on all sides.

The Snake River Plain is believed to have been sculpted by the same forces that today produce Yellowstone; giant volcanoes. For the last 15 million years or more, a hotspot has been sitting beneath the western U.S., supplying heat that has driven large volcanic eruptions.

These eruptions form calderas – large craters like Yellowstone produced when huge amounts of magma are erupted to the surface, leaving a large gap in the earth at the top of the magma chamber and causing the rocks above to collapse downward. In a sense, the Snake River Plain was formed by the Earth devouring the mountain ranges that used to be there.

Some parts of the history of this hotspot are known, some parts are less well known. It’s believed there are many calderas along the Snake River Plain, but how many eruptions have taken place is not well known because many of the older calderas have been buried by rocks from the younger eruptions. We know pretty well when the Yellowstone caldera eruptions have taken place (the most recent eruption was 640,000 years ago), but the older calderas aren’t that well constrained. Understanding the behavior of previous eruptions will give us insights into how the Yellowstone volcano might work in the future.

New research from the lab of Dr. Bindeman at the University of Oregon tells the story of one of these calderas, the Picabo caldera, located in eastern Idaho not far from where this photo was taken (close to the city of Blackfoot, for reference). The caldera itself is buried under up to 2 kilometers of younger rocks, so the remnants of most of the eruptions were hidden. However, there are a series of recent drill cores through the SRP that sample these rocks, and using those cores they tell the story of this caldera’s activity.

Based on the drilled rocks, they identify 8 distinct eruptive units that could represent eruptions from this caldera. All took place between 6 and 9 million years ago. The sizes are difficult to estimate but several were likely on the scale of the Yellowstone eruptions.

The authors also piece together how the magma chambers that gave rise to the eruptions formed. The mineral zircon is formed in magma chambers and generally does a good job of recording the chemistry of the magma that formed it.

By measuring zircon chemistries, the authors find that the first eruptions at a caldera are produced by the assembly of a series of smaller magma chambers, each with its own chemistry. These distinct magma chambers lead to the formation of distinct zircon compositions which survive until they are erupted, allowing them to be measured today.

After the first eruption(s), there is a transition. The first magmas have a variety of zircon compositions, but these are followed by eruptions with nearly-homogeneous zircon compositions.

This work therefore suggests that the mechanism for forming a caldera like Yellowstone involves a series of smaller magma chambers and eruptions that eventually join together to form the giant volcanoes. Those large calderas are then capable of multiple eruptions until they finally quiet as the magma supply moves away.

Several final details are also worth noting. First, the eruptions at this site took place roughly 500,000 years apart, similar to the age differences between eruptions recorded at Yellowstone (8 eruptions over about 4 million years). That result suggests the timing between eruptions at Yellowstone, of just over 500,000 years, is consistent through a large part of the Snake River Plain.

Finally, the timing of this caldera’s eruptions overlaps with the eruptions of two neighboring calderas. This result we’re less familiar with; only Yellowstone has erupted within the last 2 million years, but at this time, there were up to three Calderas erupting during the same time interval. This state could be one that the Yellowstone hotspot returns to in the future as it continues to migrate across the western U.S.

-JBB

Image credit: (creative commons license) http://www.flickr.com/photos/93452909@N00/5070061433/

Original paper (subscription): http://www.sciencedirect.com/science/article/pii/S0012821X13004275

Press report: http://phys.org/news/2013-10-crystals-picabo-recycled-super-volcanic-magma.html

Both this research project and the drilling operations funded in part by the National Science Foundation._ _

Pulling out samples during core drilling

Russian oil drilling rig starts up while pumping drilling mud through it - this is what it looks like drilling holes in the ground for oil and gas.

Geophysical Logging

Borehole geophysics is the science responsible for obtaining and analyzing measurements of the physical properties of rocks on a well or test hole. As an aspiring geologist, knowing how “logging” works is a vital step to understand better the rock formations beneath us. The basic process of logging involves lowering a probe into a well and measuring continuously or point data the desired physical property, and then translating that into a graph with the depth of the borehole and how the properties change with it. Some of the physical properties that can be obtain by logging are well/hole diameter, porosity, permeability, mineral contents, fractures/wash out zones and rock density, but there are much more. Geologists need this information to provide a better understanding of subsurface conditions when drilling and planning the construction of a well.

Some of the most common logs are the following:

-XY Caliper: This log records the diameter of the borehole in 2 directions (hence XY). This log is useful to determine the physical conditions of the borehole after drilling. Usually, harder materials and sediments will show a smaller diameter hole, while looser or weaker sediments will show a larger diameter hole (due to caving in) or even a large wash out zone. If you know the total diameter of the borehole, and you also know the outside diameter of the casing to be installed in that hole, with a little tweaking, the XY caliper log can also measure the amount of cement you will need to pour in the annular space of the hole to seal the well (between the rock formation and the outside of the casing).

-Natural Gamma Ray: This log records the natural gamma radiation emitted by rocks in the borehole. Rocks that emit higher gamma rays are those that contain more potassium, uranium and thorium. Clays normally show spikes in the amount of radiation, because they contain more quantities of these elements, hence this log is useful to determine the amount of clays in the formation rock.

-Resistivity (there are many types): This log records the changes in resistivity between two given points (either inside the borehole or on the surface) and records in ohms. The changes in resistivity can be attributed to the porosity/permeability of the rocks. Rocks with higher porosity and permeability have more water in them, and are more conductive. Rocks with less pores or not as permeable can’t conduct electricity as well and are more resistant. Resistivity logs are usually more complex than this, since they are affected by the drilling fluid (mud or water), the salinity of the water, and the bed thickness and borehole diameter.

This is just the tip on the iceberg of what geophysical logging is, but if you are interested, there’s more information on the links below.

BLEB

Photos: http://on.doi.gov/29OElVV http://on.doi.gov/29OEloS http://bit.ly/29rjvwy Sources: http://on.doi.gov/29yv99m http://bit.ly/29yvOHI

Shocked

This researcher is using a petrographic microscope to examine a mineral grain recovered from the just-completed effort to core and sample the rim of the crater generated during the Chicxulub Impact on the shores of what is today the Yucatan Peninsula (https://tmblr.co/Zyv2Js237-vel). The monitor shows the grain being seen under the microscope and also adds a scalebar.

The projected image is a grain of very fine sand only a hundred or so micrometers across. You’re actually looking at a bit of a sand grain that was shocked during the impact that killed the dinosaurs and was recovered from that drill core.

When an asteroid impacts a planet, part of the energy of that impact is converted into a shock wave. That wave propagates outwards through everything, distorting the atomic structures of every mineral grain it travels through. As the wave passes, first atoms are squeezed together, then they move back apart after the wave releases.

Shock waves can do lots of damage as they pass through a mineral. Some minerals can take the stress, but others fracture and some even completely melt. The mineral quartz responds to shock by producing “planar deformation features” – basically specific planes in the mineral have been kinked or broken, creating features that can be seen under a microscope.

The pattern of lines defined by the dark dots running from the upper left to the lower right of this grain establishes that it is a bit of shocked quartz (https://t.co/1N6HchliLV), a relic of the Chicxulub impact. The initial coring of this site is now complete and 1300 meters of core through the ring of the crater have been collected. They will now be taken back to facilities in the US and Germany where they will be opened and characterized.

-JBB

Image credit: Max Alexander/B612/Asteroid Day/BBC http://www.bbc.com/news/science-environment-36377679

Reference: http://bit.ly/1Z0rliw

There are still many scientists that believe an asteroid or comet (bit.ly/1XdMXqq), estimated at about 6 miles (10 kilometers) across, was to blame for the wipe out of the dinosaurs. Buried underneath the Yucatan Peninsula in Mexico, the Chicxulub (pronounced CHEEK-she-loob) crater is estimated to have created an initial hole 60 miles (100km) wide and more than 18 miles (30km) deep before collapsing to form a final crater more than 110 miles (180 km) wide and 12 miles (20 km) in depth.

Recently this theory has been challenged by more evidence researchers have been uncovering. A group of scientists led by Prof Gerta Keller of Princeton and Prof Wolfgang Stinnesbeck of the University of Karlsruhe found a series of geological clues in the rock formations where the iridium layer (bit.ly/1w9erCF) was separated from the spherule layer (bit.ly/1M9ymq0) by many meters of sandstone. They also found evidence of ancient worm borrows. In conclusion, the team theorize there must be a gap of some 300,000 years between the deposition of the spherules (from the crater) and the iridium (from the impact). The Chicxulub impact was too old therefore there had to have been two different impacts. That other crater has yet to be discovered.

In April, a $10 million drilling project will be constructed, sponsored by the International Ocean Discovery Program (IODP) and the International Continental Scientific Drilling Program, offshores in the Gulf of Mexico. Scientists and researchers will try to sink a diamond-tipped bit into the very center of this crater and retrieve rock cores that they hope will contain clues to novel microbial life and how ecosystems come back after such a tragedy. They also plan to drill into a circular ridge around the center of the crater's rim, called a "peak ring," to gain more information on how they form.

There are only two craters confirmed larger than Chicxulub that should also have peak rings: the 2-billion-year-old Vredefort crater in South Africa, and the 1.8-billion-year-old Sudbury crater in Canada. However, as University of Texas, Austin Sean Gulick, geophysicist and co-chief of this project says “Chicxulub is the only preserved structure with an intact peak ring that we can get to, all the other ones are either on another planet or they’ve been eroded.”

Although this is the first attempt at an offshore drilling, in the 1950s geologists for Pemex (Mexico’s national oil company) drilled several exploratory wells then lost interest when they found volcanic rocks instead of oil-bearing sediments. Then in 1991, Alan Hildebrand, a geologist at the University of Calgary in Canada, found quartz crystals shocked by an impact in the Pemex well core samples that had been sitting around for more than a decade. In 2005, a remote-sensing campaign, led by co–chief scientist Joanna Morgan of Imperial College London and Gulick, used small seismic explosions to illuminate the subterranean structures and pinpoint the best spot to reach the peak ring.

The researchers now are interested not only in the structure of the peak ring rocks but also what life they might host. Remote sensing has already suggested that the peak ring is less dense than expected for a granite - a sign that the rocks are porous and fractured in places. It is possible that these fractures, in the wake of the impact, were filled with hot fluids. They will count and culture any microbes found living in the fractures, and sequence their DNA. They could find genes showing that descendants of those that lived after the impact derive their energy not from carbon and oxygen, like most microbes, but from iron or sulfur deposited by the hot fluids percolating through the fractured rock.

--Mi

Image Credit: bit.ly/1pzHiAo Sources: bit.ly/1U4hGIv bit.ly/1TW92KO

Drilling the Chicxulub

Drilling platforms are not an unusual sight in the Gulf of Mexico (which is rich in oil and natural gas deposits), but the rig to be put in place at the end of this month will be drilling for information.

Halfway on top of the Yucatan Peninsula and halfway under the Gulf lays the Chicxulub impact crater (pronounced cheek’ she lube). Measuring 177 km (110 mi) in diameter, the crater is thought to have resulted from the impact of an object approximately 10 km (6 mi) in diameter striking the planet more than 66 million years ago. Linked with global occurrences of tektites (spheres of glassy material), shocked quartz, and a layer of the rare element iridium, the Chicxulub impact event is thought by many to have been the cause of the K-T (Cretaceous-Tertiary) mass extinction.

The most notable physical features of the crater are a ring of cenotes (water-filled sink holes which were once used in Mayan ceremonies) around its land-based rim and gravitational anomalies appearing on magnetic survey maps of the Gulf. The $10 million project is sponsored by the International Ocean Discovery Program (IODP) and the International Continental Scientific Drilling Program. The team will attempt to sink a diamond-tipped bit into the intact peak ring of the impact crater.

Thirty km (19 mi) offshore of the Mexican port of Progreso, the specially equipped vessel will sink three pylons in water 17 m (56 ft) deep and raise itself above the surface of the Gulf. Drilling is planned to begin in early April and continue for 2 months, passing through 500 m (1640 ft) of limestone to extract core samples, and allowing scientists to look for changes in rock types, catalog microfossils, and collect DNA samples. CW

Image

http://bit.ly/1TW92KO

Sources

http://bit.ly/1TW92KO

http://bit.ly/1LHxkXC

http://www.ucmp.berkeley.edu/education/events/cowen1b.html

http://neo.jpl.nasa.gov/images/yucatan.html

http://www.lpi.usra.edu/science/kring/epo_web/news/chicxulub1.html

http://minerals.cr.usgs.gov/gips/na/space.html

http://www.atlasobscura.com/places/chicxulub-crater

Fly Geyser

On a small, private ranch in Washoe County, Nevada, you will find this alien, rainbow, mound-like geyser spouting from a geothermal water pocket. What’s interesting is that this geyser is man-made. Accidentally.

It is one of two geysers found on the property. The first, also man-made, was created in an attempt to make barren desert usable for farming. Drilling into the ground, a geothermal pocket of 200-degree water was hit, and then left alone because the water was unsuitably hot. The ignored well grew into a calcium carbonate cone.

The second (that would later become Fly Geyser) was formed similarly - a geothermal energy company drilled at the same site, hit the same 200-degree water pocket, and decided it wasn’t hot enough for their use, and left it alone. This new geyser stole the first of its water pressure, which now sits dry a few hundred feet south of it.

The leaking geothermal water mixed with dissolved ground minerals has now created a stunning multicoloured statue amidst a dais of mud and ponds of warm water. The array of colours is caused by the presence of thermophilic algae, which flourish in the hot moist environment provided by the geyser.

The ranch is private property and generally off-limits to visitors due to vandalism concerns, but it is possible to get in touch with the property owners and organise a tour.

Ash

Source credit: http://bit.ly/1klI7JO Source credit: http://bit.ly/1mkvGPK Source credit: http://bit.ly/1OfwxME Image credit: http://bit.ly/1YJV1Py