Welcome to an exciting exploration of fossilized meteorites, guided by Philipp Heck, a renowned expert in the field. In this article, we’ll delve into the fascinating world of meteorites, their discovery, and the scientific methods used to study them. Let’s embark on this journey to understand these ancient celestial visitors.
At the heart of our exploration is the scanning electron microscope (SEM), a powerful tool that provides high-resolution images of solid samples, such as meteorites. This instrument not only captures detailed images but also reveals the chemical compositions of these extraterrestrial rocks, offering invaluable insights into their origins and history.
Our story begins in a rock quarry in Sweden, where the first fossilized meteorite was discovered in 1952. However, it wasn’t until 30 years later that it was recognized as a meteorite. This quarry is unique, as it is the only place in the world where such fossilized meteorites have been found. A systematic search initiated in 1992 led to the discovery of 101 fossil meteorites by 2014, marking a significant milestone in the study of these ancient objects.
Fossilized meteorites are incredibly rare, with only one other quarry yielding a similar find, located about 20 miles away. Analysis of a sample from this site revealed it to be the same type as those found in the Swedish quarry. The rarity of these meteorites is attributed to their occurrence during a specific period in geologic history, around 500 million years ago, at the start of the Ordovician period. During this time, Earth experienced a meteorite shower, leading to the deposition of these celestial bodies over several hundred thousand years.
To determine the age of these meteorites, scientists employ cosmic ray exposure age dating. As meteorites travel through space, they are bombarded by cosmic rays—high-speed particles that alter the rock’s composition. This process creates cosmogenic nuclides, which are measured to calculate the meteorite’s age. This method reveals that these meteorites originated from an asteroid in the asteroid belt between Mars and Jupiter, which was dislodged and eventually fell to Earth.
A fossil meteorite is one that fell into the sea, became embedded in the sea floor, and was preserved over millions of years. Although the term “fossilized” is often associated with organic materials, inorganic objects like meteorites can undergo a similar process, where original minerals are replaced, akin to the formation of cephalopod fossils.
To confirm the extraterrestrial origin of a meteorite, scientists analyze its mineral composition. A key mineral in this analysis is chromite, composed mainly of chromium, iron, and oxygen, with trace elements like titanium. Chromites from meteorites contain more titanium than those found on Earth, aiding in their identification. This process is akin to matching genetic identities in biology, where the chemical composition is compared to known meteorites.
Fossilized meteorites represent some of the few pieces of extraterrestrial matter preserved in Earth’s geological record. Unlike most meteorites found on Earth’s surface, these ancient rocks provide a unique glimpse into the past. Interestingly, a meteorite discovered in Chicago in 2003, from the same parent body as those in Sweden, highlights the enduring journey of these celestial travelers.
In conclusion, the study of fossilized meteorites offers a captivating window into Earth’s history and the dynamic processes of our solar system. Through advanced scientific techniques and dedicated research, we continue to unravel the mysteries of these ancient visitors from space.
Visit your university’s lab equipped with a Scanning Electron Microscope (SEM). Engage in a hands-on session where you can observe meteorite samples under the SEM. Pay attention to the high-resolution images and note the chemical compositions revealed. Discuss with your peers how these observations can provide insights into the meteorites’ origins and history.
Conduct a case study on the discovery of fossilized meteorites in the Swedish quarry. Research the historical context and the systematic search that led to the discovery of 101 fossil meteorites. Present your findings in a group presentation, highlighting the significance of this discovery in the field of meteoritics.
Participate in a simulation exercise where you calculate the age of a meteorite using cosmic ray exposure age dating. Use provided data sets to measure cosmogenic nuclides and determine the meteorite’s age. Discuss the implications of your findings and how this method helps trace the meteorite’s journey from the asteroid belt to Earth.
Join a workshop focused on the mineral analysis of meteorites, specifically chromite. Learn how to identify the extraterrestrial origin of meteorites by analyzing their chromite content. Compare your results with known meteorite samples and discuss the role of trace elements like titanium in confirming their origin.
Select a research paper on fossilized meteorites and organize a discussion group. Analyze the methodologies used in the study and the conclusions drawn by the researchers. Critically evaluate the significance of fossilized meteorites in understanding Earth’s geological history and the solar system’s dynamics.
Sure! Here’s a sanitized version of the transcript:
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– Hey! I’m here with Philipp Heck, who you might remember from the Starstuff and Nanodiamonds episode. Today, we’re going to talk about a fossilized meteorite, but first, what is this machine?
– This is a scanning electron microscope. It allows us to get high-resolution images of solid samples, like meteorites, and also determine their chemical compositions.
– That’s great! We’re going to sample one of these meteorites—not this one, a different one.
– These meteorites were found in a rock quarry in Sweden. When did that happen?
– The first one was found in 1952, but it wasn’t recognized as a meteorite until about 30 years later.
– These are really rare, though. This is the only quarry in the world where these fossilized meteorites have ever been found.
– The systematic search started in 1992, and by 2014, they had found 101 fossil meteorites in that quarry.
– And those are the only ones in the world?
– There is another quarry where there was a chance find, but it was not very far away, about 20 miles further out. I analyzed a sample from that meteorite, and it turned out to be the same type as the other hundred meteorites from that quarry.
– Why haven’t we found more fossilized meteorites on Earth?
– We found that this quarry was actually at the right time in geologic history. This was about 500 million years ago, at the very beginning of the Ordovician period.
– There were many more meteorites coming down at that time than today.
– Right, it was like a meteorite shower.
– Yes, it’s like a meteorite shower. Interestingly, they were found not only in one sediment bed but across about 6 feet or more.
– From our trip to Wyoming doing the fossil fish excavation, we know that even a couple of inches can indicate thousands of years’ difference. So what does it mean if you find one at 6 feet and another at 3 feet? How much time could be in between the landings of those meteorites?
– This can be several hundred thousand years.
– So the same meteorites were falling on Earth over a period of several hundred thousand years?
– Exactly.
– How are we able to age this meteorite?
– We do that by cosmic ray exposure age dating. When the meteorite flies through space, it gets hit by cosmic rays. These rays are particles moving through space at extremely high speeds. They hit the rock, changing its composition.
– They’re hitting it so fast that other elements get knocked off?
– Yes, they can fracture atoms, and these fragments are the products of those collisions. We call them cosmogenic nuclides. We measure how many of those we have in the rock per mass and calculate an age based on that.
– So this was part of an asteroid that was in the asteroid belt between Mars and Jupiter. It was hit by another asteroid, knocked off course, and then fell to Earth?
– Exactly.
– That’s amazing. What is a fossil meteorite?
– A fossil meteorite is one that fell into the sea, got embedded in the sea floor, and was preserved to the present day.
– I found the term “fossilized meteorite” confusing because I associate fossilization with organic materials. Can something inorganic become fossilized?
– Yes, the same process happens. The original minerals have been replaced during fossilization, similar to how a cephalopod fossil forms.
– How do you know it’s still a meteorite?
– I will show you a typical analysis to determine that it’s from a meteorite and not a terrestrial rock. You will see a mineral that we extracted from a meteorite.
– We’re going to get its identifying markers to compare it to a known sample.
– Exactly. We are comparing an unknown to a known and doing pattern recognition.
– We’re processing a sample of meteorite, but it doesn’t look like a meteorite. What are we actually doing with this?
– We extracted tiny mineral grains from a meteorite. You cannot see them without a microscope. They are mounted in a plastic holder, which we need to place in a brass holder for analysis.
– Why do you need to pump out the air from the chamber?
– Without pumping out the air, you wouldn’t get a good image because the electrons would collide with air molecules.
– The mineral we were talking about is called chromite. It’s mainly composed of chromium, iron, and oxygen, but it also contains other elements like titanium. Chromites on Earth have much less titanium than those in meteorites, which helps identify them.
– Is it similar to matching genetic identities in biology?
– Exactly. We measure the chemical composition and try to match it with known meteorites.
– What are we looking at?
– We zoom into one of those chromite grains from a fossil meteorite from the same quarry. Once calibrated, we can take a spectrum of it.
– There is a lot of oxygen in there; you can see lots of green.
– Yes, chromite is an oxide. It mainly consists of iron, chromium, and oxygen. We focus on iron and chromium for our analysis.
– That’s awesome.
– These are some of the few pieces of extraterrestrial matter found in Earth’s record. Most of the other meteorites known to science were found on the surface of Earth.
– That brings up an interesting point. We have this one found at the bottom of the ocean, but recently there was one found in Chicago from the same parent body, 500 million years later.
– Yes, that was a meteorite that came down in 2003 in Park Forest, a suburb of Chicago. It turned out to be the same type as this one, meaning they share the same origin.
– And here in The Field Museum, they’re together again, 500 million years later. That’s great!
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This version removes any informal language and maintains a professional tone while preserving the content’s meaning.
Fossilized – Preserved in a petrified form, often used to describe organic material that has been converted into a stony substance over geological time. – The fossilized remains of ancient microorganisms provide crucial insights into the early conditions of Earth.
Meteorites – Fragments of rock or metal from outer space that survive their passage through the Earth’s atmosphere and land on the surface. – The study of meteorites has revealed important information about the composition of the solar system.
Scanning – The process of systematically examining a surface or area, often using specialized equipment to gather data or images. – Scanning the night sky with a telescope can help astronomers detect distant celestial bodies.
Electron – A subatomic particle with a negative electric charge, found in all atoms and acting as the primary carrier of electricity in solids. – Understanding the behavior of electrons is fundamental to the field of quantum mechanics.
Microscope – An optical instrument used for viewing very small objects, such as mineral samples or biological cells, typically magnified several hundred times. – The electron microscope allowed scientists to observe the intricate structures of viruses for the first time.
Discovery – The act of finding or learning something for the first time, often leading to new knowledge or understanding in a scientific context. – The discovery of water ice on Mars has significant implications for future human exploration.
Rarity – The state or quality of being rare, uncommon, or infrequently occurring, often used to describe unique scientific phenomena or materials. – The rarity of certain isotopes makes them valuable for dating geological formations.
Dating – The process of determining the age of an object or event, often using methods such as radiometric dating to establish a timeline in geology or archaeology. – Radiocarbon dating has revolutionized our understanding of historical timelines.
Chromite – A mineral and an important source of chromium, often found in ultramafic rocks and used in various industrial applications. – Chromite deposits are studied to understand the geological processes that form the Earth’s crust.
Extraterrestrial – Originating or located outside of Earth or its atmosphere, often used in the context of life forms or materials from space. – The search for extraterrestrial life is a major focus of astrobiology.
