Adriana Alves out in the field, in Parana, Brazil
For two weeks in February, our department welcomed Dr. Adriana Alves from Brazil. Adriana flew directly to Houston on a nine hour flight from São Paulo. That’s Brazil’s largest city — which sits right beside a giant lava field. It’s this lava field that brought Adriana to Rice University.
The lava field is so giant that it’s actually larger than many countries. But since Brazil itself is huge, the lava field only extends over a single province — the province of Paraná.
Paraná is completely covered in rock-hardened lava. This lava is very special. It originates from a tremendous event in Earth’s history — the moment when Africa and South America (which once upon a time were a single colossal landmass) ripped apart. The separation of colossal landmasses is not accomplished in quiet serenity. Instead, the burning underbelly of the Earth is chucked up, heaving a layer of lava up to 1 kilometer thick all over Paraná.
Fast forward 134 million years later, Adriana and her students at the University of São Paulo are driving and hiking all over Paraná. They’ve visited railroad tracks, waterfalls, new roadworks: all in the quest to collect more than 700 freshly exposed rocks — rocks that hold clues for what exactly happened when Paraná was drowned in lava.
“This particular mass eruption of lava is interesting and notable,” Adriana says, “because it’s different from other similar events that have occurred in Earth’s stormy history. Quite often when such things happen, a mass extinction follows. We can see it in the fossil record — whole species of creatures and organisms will be wiped away.”
Map of Paraná. Credit: Mejs Hasan. Made with Natural Earth
Yet no such mass extinction is evident in the fossil record around Paraná, and Adriana wants to know why. She has a theory, too: perhaps the eruption around Paraná came with less toxic gases, such as sulfur, that otherwise would have killed many organisms.
So they’ve been hoping the lava-hardened rocks in Paraná hold a clue about the toxic gases like sulfur. It might sound crazy that a hard, unfeeling, uncommunicative rock could possibly tell you anything at all about the gases in the air 134 million years ago, but as it turns out, rocks surprise us.
After the bluster and trauma of an eruption is over, most of the lava cools and hardens into crystals that form a rock. Every once in a while, though, a little droplet of lava gets trapped within a crystal. Called a “melt inclusion”, this tiny once molten ball of liquid fire records the exact conditions as the eruption happened. When scientists find them millions of years later, it’s like a letter from long-ago. They can analyze that droplet of lava and get an idea of the gases that accompanied it.
Adriana and her students wanted to find these little lava droplets in Paraná — but among their 700 samples, they didn’t find a single one! It was odd.
So Adriana embarked on a different kind of hunt — a hunt from her computer. She was searching for ways to study the toxic eruptive gases without the melt inclusions. She found a paper published in 2012 by our very own Dr. Cin-Ty Lee. It gave her a different way to determine the amount of sulfur gas present 134 million years ago, when South America and Africa ripped apart, drowning Paraná in lava. Adriana didn’t need melt inclusions to apply Cin-Ty’s method. She needed more rocks from the lava.
Now it was more important than ever to gather the right rock samples. Adriana and her students had many adventures, sometimes traipsing out on dangerous railroad bridges as they moved from one rock cliff to another. “It’s a good thing we had good hearing,” Adriana recalls. They were caught by a train loaded with iron ore charging over the bridge they were walking across. “We heard a beep-beep, very loud, and we had to run as fast as we could.” Luckily, the whole team made it to a little side platform on the bridge as the train roared by.
Rock faces in Parana, similar to where Adriana and her students collected samples. Photo credit: Marcio Tadeu Duarte Silva.
Usually, rock-collecting occurs in the summer (which in Brazil means January and February.) It is humid, with temperatures soaring to 95 degrees Fahrenheit. Adriana (who happened to be pregnant with her second daughter for part of the campaign) and her students can’t stand to be in the sun for more than 40 minutes at any one stop. They establish a routine; drive to the sampling site, collect rocks, drink water, go get ice cream – wash, rinse and repeat. Rocks and ice cream all day long — not a bad way to spend your summer break.
In the lab, the rocks are smashed to pieces, ground into rock powder, doused in acids and finally analyzed. They are looking for the copper content. Copper and sulfur, in the element world, behave like “best friends”. Where one goes, the other follows. The idea is that even after the sulfur disappears, the amount of copper left indicates how much sulfur once was there.
Adriana collected data from over 150 rocks. She contacted Cin-Ty by email, thinking he might be interested in her work. He was — so interested that he didn’t want to discuss it through email. Instead he offered Adriana a visit to Rice for two weeks. “It’s always better to discuss science face-to-face,” Cin-Ty explains. During her two weeks here, Adriana and Cin-Ty strategized the best way to present her results. She also attended a special dinner sponsored by the Brazil@Rice program, which aims to build connections between our University and Adriana’s home country. In fact, Brazil@Rice funded Adriana’s trip. It’s Adriana’s second trip to the US, the previous of which was to Pasadena, California. This time, she got to explore a whole different part of the country, with the added bonus of attending a Rockets game – a dream for this NBA fan.
Waterfalls like these are also excellent locations to find fresh rock samples. Photo credit: Randolfo Santos.
What of the scientific results for the lava field covering Paraná? Contrary to expectations, the analyses indicate there was a lot of sulfur in the air at the time of the Africa-South America split. This means they can’t conclude, as Adriana had originally theorized, that the lack of sulfur gas is what saved organisms from extinction when the Paraná lava field formed. That’s science: you make your best guess and test it out. Sometimes, you’re proven right. Other times, you go back to the drawing board.
When Adriana returns to Brazil, she will continue her research on the Paraná lava field, trying to tell a different story through its rocks.
She will also continue to be a trailblazing, inspirational figure at the University of São Paulo.
Adriana began at the University in 1999 as an undergraduate. She was the third Black student ever to enroll. According to Adriana, Brazil has a 55% total Black population. Universities, though, are completely different. A prestigious university like São Paulo (which numbers 200,000 students, making it a mini-city) has populations that are almost entirely white and affluent. Adriana can remember feeling out of place — like on her first day of class, when a paper was passed around asking for students’ phone numbers. Adriana’s family didn’t have a phone. She pretended to “forget” her non-existent phone number to cover the moment, and passed the paper along.
Then there was the time she was readying for her first undergraduate geology fieldwork experience. The students teased her because she wasn’t prepared with proper boots or hiking gear. It didn’t occur to them that perhaps she couldn’t afford those supplies. Adriana completed her first field experience in regular shoes. She wasn’t able to purchase the preferred gear until her third year.
Through sheer tenacity and grace, Adriana has risen through the ranks of the professors at São Paulo to have her own research group, one of only a few Black professors there. These days, she tries to open up avenues for other disadvantaged students. She chairs the Human Rights Office, to which students can submit complaints of sexual harassment or racism. She has also started a fund which supports geology students that cannot afford boots and gear for fieldwork. We are very proud to have hosted such an amazing woman in our department for two weeks, and wish her and her group the best of luck! We hope she and her students will return to Rice in the future.
— Story by Mejs Hasan
