The Jurassic rocks of North America are in some ways world famous. Parts of the continent record the opening of the North Atlantic, create the major oil and gas deposits of the Gulf of Mexico, and host some of our most magnificent dinosaur fossils. This video takes you on a tour of the Jurassic rocks of North America.

A European Space Agency Earth-observing satellite caught the plume of diesel fuel released into the Ambarnaya river in Siberia after a fuel tank collapsed at the Norilsk Nickel Plant.

Are Dinos fuelling your car?

Judging by the internet many people believe that when they fill up at the pumps they are filling their cars with long dead and decayed dinosaurs. Even the most boring family hatchback sounds exciting when you think it’s being powered by liquefied T-rex. However, I have some very sad and disappointing news; it simply isn’t true. Oil does not form from dinosaurs, it forms from organisms far more boring and widespread.

So what are you filling your car with? Well predominantly a concoction of algae, plant remains and some woody material. This may sound boring, but the composition of the kerogen (defined as insoluble organic matter) can tell us a lot about the type of hydrocarbons the rock is producing. Kerogen is split into five groups; woody, herbaceous, amorphous (mainly algae), vitrinite and inertinite. Plant material is indicative of being either terrestrial or lacustrine in origin whereas algal matter tells us we’re dealing with a marine deposit.

Some of these groups contain more hydrogen in their structure than others and are known as ‘oil prone’ due to their predisposition to produce oil upon heating. More hydrogen is required to convert kerogen to oil than to gas and therefore rocks containing amorphous and herbaceous kerogen are known as oil prone. Woody and vitrinite kerogens contain far less hydrogen and therefore are gas prone. Inertinite, as the name suggests, produces neither oil nor gas and is usually disregarded.

Source rocks usually contain a mix of kerogen types meaning they will produce both oil and gas. However, kerogen isn’t the only control on the type of hydrocarbon produced, temperature also plays an important role.

This is because a rock has to be heated to a certain cut off before it starts breaking down the kerogen. Much like cooking you can either heat the rock at a very high temperature for a short period of time or at a lower temperature for much longer.

For example, there are source rocks producing hydrocarbons that are Ordovician (485 – 444 million years ago) in age where a low geothermal gradient (18oC/Km) (the increase in temperature with depth, averages at 27oC/Km) exists. In other areas, where the crust in thinner and therefore the geothermal gradient can be much higher (up to 90oC/km), Miocene (23 – 5.3 million years ago) source rocks are producing.

The temperature the rocks reach can help dictate the hydrocarbons produced. At 70 – 100 degrees Celsius (158 – 212 F) the rocks reach the oil window and the kerogen begins to transform into oil. At 100 – 120 (212 – 248 F) degrees both liquids and gas are produced in a stage known as ‘wet gas’. Beyond 120 (248 F) degrees only gas is produced and the rock has reach the dry gas window.

So by knowing the kerogen type and the temperature the rock reached, geochemists can tell the likely proportions of oil to gas that may be held in a reservoir. So even if algae are nowhere near as exciting to study as dinosaurs, they can still tell us a great deal about the rocks around us and help us to unravel the past.

References: http://bit.ly/1I7mkzE http://bit.ly/1JJyEXa

Further Reading: http://bit.ly/1dExr6p http://bit.ly/1KDZQEE http://on.doi.gov/1E6fMtT

Image Source: http://bit.ly/1IBw1Fp

You have spiders living inside your face right now

It sounds grosser than it really is. Researchers initially weren't sure if all humans hosted mites on their faces, or just some. But new reports have found that all healthy human adults do in fact have colonies of these little guys.

So what are they? Mites! Mites are great. Mites are in the class Arachnida (that's right, arachnid... it's technically a type of spider), sub class Acari. It's been estimated that over 48,000 species of mites exist on Earth, but most are too small to see, and are also quite evasive. Because they're so hard to study, very little is known about them.

Only two species are known to inhabit your face: Demodex brevis and Demodex folliculorum. The former inhabits your sweat glands, and the latter inhabits your hair follicles. They feed on your excreted oils, copulate on your face, and lay eggs in your pores. It's quite fascinating!

So, whenever you feel lonely, just remember that thousands of microscopic spiders are banging on your face right now.

~Love, Rosie

Image sources and references: http://bit.ly/1DLXCSL

http://bit.ly/1GUk1y7[_

_](https://www.facebook.com/TheEarthStory/photos/a.352867368107647/858318010895911/?type=1&theater#)

1930′s vintage video of seismic exploration of the ground for oil reservoirs - using dynamite as the source of the seismic waves.

I’m glad I didn’t have to process that data by hand.

There’s a good chance that the last time you filled up a gas tank, some of the fuel was drilled from the West Texan Permian Basin, now the most productive oil and gas field in the world. There are many industrial stories involved in producing this field; here’s one in video form. Original caption:

From Phytoplankton to Jet Fuel

As you may know, petroleum forms from dead plants and animals which were buried millions of years ago under water (note: generally this material does not consist of dinosaurs). What most of us don’t know is exactly how and why this process works.

Petroleum formation is actually a lot like cooking. You start with the ingredients, turn up the heat and set the timer. The basic required elements are: organic matter (ingredients), a source rock (oven) and time.

Firstly an oil- or gas-prone source rock must be formed; this is our oven. Under normal marine conditions, where the organisms which die are scavenged, very little organic matter remains to be buried on the sea floor and therefore little to turn into petroleum. So where do the ingredients come from? There are two main ways to disrupt this cycle: (1) periods of high biological activity at the surface such as an algal bloom, and (2) the development of anoxic (oxygen poor) conditions at depth which greatly reduce the number of scavengers. Once the organic matter is actually buried, we’ve got our ingredients.

As the organic matter is buried under more and more layers of sediment, the temperature and pressure increase. The pressure increase is due to the weight of the overlying sediment whilst the temperature naturally increases with depth below the surface of the Earth; this is known as the geothermal gradient. After the first kilometer or so, the organic matter changes into kerogen.

Kerogen is the most abundant organic component on Earth and can be used to describe the collection of complex organic compounds depended on the original source organism.

These increases in temperature and pressure continue, ‘cooking’ the kerogen. At a depth of around 3-4km/100°C, the chemical bonds in the kerogen begin to break in a process known as catagenesis. Here the kerogen is within the ‘oil window’; the conditions where kerogen is converted to oil. With further depth the temperature will increase moving the kerogen into the ‘gas window’, where it is instead converted to methane a.k.a. natural gas. Whether the kerogen will produce oil or gas is dependent on several factors principally kerogen type and depth of burial.

It’s just like cooking; you get out what you put in, it’s all about how you cook it, and all good things come to those who wait.

-LO

Photo courtesy of Ian West, University of Southampton

How does oil form?

The image below shows the Kimmeridge Clay in Dorset, one of the major source rocks for the North Sea. But how do you produce oil?

It all starts with microscopic plankton and algae that live within the water column in oceans. When they die they rain down to the seafloor and accumulate. More often than not they are either scavenged by other organisms or broken down by bacteria,destroying the organic material. If the material is preserved within the sediment this usually occurs under anoxic conditions (less than 0.5 milligrams of oxygen per litre of water). They then become buried by overlying sediment and become lithified, forming the source rock (the rock from which hydrocarbons are produced). These are often shales such as the Kimmeridge Clay and have a high (over ten volume percent) total organic content (TOC). These rocks then need to be heated to 60-100ºC to produce oil and 120ºC - 200ºC to produced gas. With an average geothermal gradient of 25ºC/km, this means the rocks need to be buried to at least 3-4km beneath the surface to start producing hydrocarbons. Any hydrocarbons produced are lighter than the surrounding fluids or rocks and therefore migrate upwards towards the surface. This is only stopped when the hydrocarbons hit a seal (an impermeable rock, usually either mudstone or salt) causing the hydrocarbons to pool.

Contrary to popular belief the reservoir rock (the rock that holds the oil and gas) isn’t just a large cavern filled with hydrocarbons. The oil is actually held within the pores spaces (the gaps between grains) and this why so much of it can become trapped and hard to extract when drilling into the reservoir.

Also contrary to some rumors you may have seen, oil does not come directly from dinosaurs. Many of the current oil and gas source rocks did form during the cretaceous when dinosaurs existed, but those rocks are marine sediments mostly filled with plankton and algae. 

The amount of oil actually extracted is only a small fraction of the oil ever produced, and I will describe this in another post.

Image Credit: Ian West Further Reading http://www.southampton.ac.uk/~imw/Kimmeridge-Bay.htm

How much oil can we actually extract?

When you hear about a company discovering 500mmbo (million barrels of oil) you assume they must be getting pretty much every last drop of oil out of the ground. However, this is very far from the truth as the example below shows.

If you start with 1 billion barrels of oil, only 600-700mmbo(60-70%) will ever be able to leave the source rock (the rock producing the hydrocarbons) as 30-40% will be trapped within the pore space. This remainder is why source rocks are also being targeted as reservoirs (rocks that hold oil and gas) and why fracking shales for oil has become such a big business in the past few years. While a lot of oil has remained trapped, you're still not doing too badly as you have two thirds of the oil left to extract right? Unfortunately not, only 10-20% of the oil ever reaches the reservoir due to processes that occur during migration, such as loss of oil to the surface as seeps or destruction by bacteria. Altogether, from the original billion barrels you now only have 120-140mmbo remaining.

This is about the size of a small oil field and depending on the field's location may still be economical to extract. However, most companies only achieve a 40% recovery rate, leaving you with just 48-56mmbol, a fairly small reserve by most people’s standards. This means in a supergiant (>500 billion barrels of oil) field, such as Ghawar in Saudi Arabia which has between 100 -200 billion barrels of recoverable resources, the amount of hydrocarbons initially produced by the source rock must have been immense. For Ghawar alone that figure is between 40,000-80,000 billion barrels of oil, while current global reserves together only account for 1687.9 billion barrels.

Recoverable reserves are only 4% of the total oil that was ever produced from the source rock(s). This is why many companies are researching into technologies that will allow them to recover a much greater proportion of hydrocarbons from their reservoirs. For example, BP has developed a product called LoSal, a type of EOR (enhanced oil recovery) technology designed to free oil bound to a rocks surface. The oil is bound to clay minerals by divalent cations such as calcium and when highly saline water is pumped into the reservoir these bonds are compressed forcing the oil closer to the clay surface. By reducing the salinity of the water, the molecules can expand exposing the bond between the oil and clay, allowing divalent cations to be replaced my monovalent ions (e.g. Sodium) and freeing the oil.

As fewer large oil fields are being discovered, it is improvements to current technology allowing greater recovery rates that will determine how much oil the world has left to extract.

Image Credit: http://www.telegraph.co.uk/ Further Reading: http://www.bp.com/en/global/corporate/press/press-releases/bp-technology-boosts-oil-recovery-adding-to-potential-energy-supplies.html https://www.rigzone.com/training/insight.asp?insight_id=313&c_id=4

Continental Crumple Zone: Zagros

The Arabian tectonic plate and the Eurasian plate meet in continental collision at the Zagros mountain range in southwest Iran. The Zagros are among the world’s most seismically active mountains, formed as a “fold-and-thrust” belt around 1500km long and 300 km wide. Part of the Alpine-Himalayan belt, Earth’s crust is shortening at up to 9 mm per year at the Zagros Mountains, accommodated as both thrust faults in the basement rocks and folds in the overlying sediments.

This Landsat image shows a small part of the Zagros Mountains, bordered to the southwest by the Persian Gulf. The crests of anticlines rise up, formed as closed folds. They are expressed as mountain ridges running NW-SE, like a crumple zone as the crust shortens SW-NE. Recent sediments that run off the anticline ridges hide the synclines between them. They fill the valleys, seen here with their meandering rivers.

The Zagros anticlines are famous as petroleum sources. Impermeable layers of shale and marl in the folded sediments trap hydrocarbons in reservoir limestones and sandstones beneath. The oil and gas rises and is trapped at the crests of the anticlines. The accumulated petroleum reservoirs represent a significant fraction of the world’s oil and gas reserves.

~SATR

Image: Landsat 7 image of the Mand River and town of Konari within the Zagros Mountains of western Iran (credit: USGS/NASA)

Links:

Talebian & Jackson, (2004) doi:10.1111/j.1365-246X.2004.02092.x

McQuarrie (2004) doi:10.1016/j.jsg.2003.08.009

Petroleum in quartz Unusual inclusions these, and they have the added bonus of making the usually inert quartz glow in UV light since crude oil fluoresces (for an explanation of this phenomenon see http://tinyurl.com/kebod3b). They form when hot hydrothermal fluids rich in silica flow in oil containing rocks and precipitate there in pores and gaps, forming crystals such as this Herkimer diamond type pair with petroleum trapped in the cavities within the crystal. This specimen comes from Pakistan, and measures 3.6 cm across. Loz Image credit: http://betweenarockandaheartyplace.blogspot.com/2012/02/quartz-with-petroleum-inclusions.html

The science of the smell of rain!

After >20 long days of little to no rain, Ireland has welcomed back its familiar friend and with it, the amazing ‘it’s finally raining’ smell.

This smell, which is typically associated with rainfall after a dry period, is termed Petrichor; from the Greek words 'petra' meaning stone and 'ichor' which refers to the golden fluid that was said to flow through the veins of the gods and the immortals in Greek Mythology.

The term petrichor was coined in 1964 in the Journal Nature, by two Australian scientists who were studying the smells of wet weather. In their study, they took rocks that had been exposed to dry, warm conditions and steam distilled them to reveal a coloured (yellowish) oil that had become trapped, or embedded in rocks and soil, and this substance created a smell.

They deduced that the source of the oil was a combination of oils secreted by plants during dry weather (which signals to halt root growth and seed germination) and chemicals released by soil-dwelling bacteria called actinomycetes.

When raindrops land on clay or quite dusty (from dry conditions) soils, they trap tiny air bubbles on the surface which then shoot upwards, bursting out of the raindrop and diffusing that lovely scent into the air as they go.

This can be seen here in the attached gif- the footage, captured using high-speed cameras by researchers at the Massachusetts Institute of Technology, shows raindrops landing and the emergence of petrichor aerosols as tiny white flecks of smelly goodness.

-Jean

Original Nature article: https://www.nature.com/articles/201993a0

MIT animation details: http://news.mit.edu/2015/rainfall-can-release-aerosols-0114

Major impacts on dolphins from Deepwater Horizon oil spill

It’s been several years since the Deepwater Horizon oil rig exploded in the Gulf of Mexico, leading to one of the largest oil spills in recorded history. That means we’re now getting good scientific studies of how the ecosystems in the gulf reacted to and recovered from the disaster.

A study has just been published in the journal Environmental Science and Technology looking at the health of dolphins in the Gulf after the spill and their results are disconcerting.

A team led by NOAA scientist Lori Schwacke visited Batavia Bay off the coast of Louisiana in 2011, over a year after the start of the oil spill, and investigated the health of local dolphins. Their results weren’t positive, to say the least.

Of that group, 48% were unhealthy. In the group exposed to the oil, they found a variety of issues, including hypoadrenocorticism (consistent with adrenal exposure to toxic chemicals), lung issues at 5 times the rate of the normal population, and large numbers that were underweight. Many of the dolphins with breathing issues also had growths on or within their lungs.

Of this group, they estimated that just under 20% would be unlikely to survive, and 30% were marginal cases.

By comparing this population to dolphins in Florida, unaffected by the spill, the scientists make a strong case that the problems in the Batavia Bay dolphins are directly related to the spill. Populations in the area not exposed to the oil don’t have similar problems, and the issues are the exact problems that would be expected from exposure to oil.

Most of the oil released by the Deepwater Horizon was consumed rapidly by microbes in the Gulf. However, it’s clear from this study that the spill caused damage to the ecosystem that was still visible in the dolphins over a year later.

-JBB

Image credit: NOAA http://blogs.nature.com/news/2011/03/counting_corpses_underestimate.html

Press report: http://www.nola.com/environment/index.ssf/2013/12/half_of_bottlenose_dolphins_of.html Original paper: http://pubs.acs.org/doi/full/10.1021/es403610f